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Since the discovery that entomopathogenic fungi can live inside plants as endophytes, researchers have been trying to understand how this affects mainly plants and herbivores. We studied how inoculation of Vicia faba L. (Fabales: Fabaceae) plants with Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Ascomycota: Hypocreales) (strain GHA) either via the seeds or leaves influenced the nymph production of two successive generations of Aphis fabae Scopoli (Hemiptera: Aphididae). While we did not find any difference in nymph production for the first generation of aphids, second-generation aphids on both seed- and spray inoculated plants produced significantly higher numbers of nymphs than aphids on uninoculated plants. This emphasizes the importance of two (or multi-) generational experimentation. Beauveria bassiana was recovered from 26.0, 68.8 and 6.3% of respectively seed-, spray inoculated and control plants, thus, demonstrating its ability to live as an endophyte in V. faba. The confirmation that plants inoculated with entomopathogenic fungi can have a positive effect on pest insects makes careful consideration of these multi-trophic interactions imperative. [ABSTRACT FROM AUTHOR]

In the absence of constraints, preference for larger mates is expected to evolve, as larger individuals are typical of higher potential fitness. Large females are often more fecund and carry larger eggs (which result in higher number and better quality of offspring), whereas large males usually have more conspicuous ornaments and are better at defending resources. However, intrasexual competition can constrain the access to larger partners, especially when opportunities for mate takeover abound. Here we investigate the relationship between individual’s size and mate choice in relation to one’s own size and their respective mate’s size using the sailfin tetra, a sexually dimorphic Amazonian fish species. We show that ornaments of larger males are exponentially more conspicuous, and larger females are more fecund and carry larger eggs. Contrary to expectation, neither males nor females associated for longer with the larger of two offered potential mates. Instead, individuals of both genders chose opposite-sex individuals of similar sizes to themselves. Additionally, similar-sized pairs were more likely to spawn than couples with higher size asymmetries. Grounded on field observations, we propose that prudent choice should be particularly important in this system, since courtship is long (often taking several days), which offers opportunities for mate takeover. Intrasexual competition, however, cannot readily explain female choice for similar-sized males. We thus suggest that such preference might be best explained by avoidance of filial cannibalism. [ABSTRACT FROM AUTHOR]

Scapsipedus icipe Hugel and Tanga (Orthoptera: Gryllidae) is a newly described edible cricket species. Although, there is substantial interest in mass production of S. icipe for human food and animal feed, no information exists on the impact of temperature on their bionomics. Temperature-dependent development, survival, reproductive and life table parameters of S. icipe was generated and integrated into advanced Insect Life Cycle Modeling software to describe relative S. icipe population increase and spatial spread based on nine constant temperature conditions. We examined model predictions and implications for S. icipe potential distribution in Africa under current and future climate. These regions where entomophagy is widely practiced have distinctly different climates. Our results showed that S. icipe eggs were unable to hatch at 10 and 40°C, while emerged nymphs failed to complete development at 15°C. The developmental time of S. icipe was observed to decrease with increased in temperature. The lowest developmental threshold temperatures estimated using linear regressions was 14.3, 12.67 and 19.12°C and the thermal constants for development were 185.2, 1111.1- and 40.7-degree days (DD) for egg, nymph and pre-adult stages, respectively. The highest total fecundity (3416 individuals/female/generation), intrinsic rate of natural increase (0.075 days), net reproductive rate (1330.8 female/female/generation) and shortest doubling time (9.2 days) was recorded at 30°C. The regions predicted to be suitable by the model suggest that S. icipe is tolerant to a wider range of climatic conditions. Our findings provide for the first-time important information on the impact of temperature on the biology, establishment and spread of S. icipe across the Africa continent. The prospect of edible S. icipe production to become a new sector in food and feed industry is discussed. [ABSTRACT FROM AUTHOR]

Sexual selection promotes the evolution of conspicuous animal ornaments. To evolve as signals, these traits must reliably express the “quality” of the bearer, an indicator of individual fitness. Direct estimates of individual fitness may include the contribution of longevity and fecundity. However, evidence of a correlation between the level of signal expression and these two fitness components are scarce, at least among vertebrates. Relative fitness is difficult to assess in the wild as age at death and extra-pair paternity rates are often unknown. Here, in captive male red-legged partridges, we show that carotenoid-based ornament expression, i.e., redness of the bill and eye rings, at the beginning of reproductive life predicts both longevity (1–7 years) and lifetime breeding output (offspring number and hatching success). The recently proposed link between the individual capacity to produce red (keto) carotenoid pigments and the efficiency of cell respiration could, ultimately, explain the correlation with lifespan and, indirectly, fecundity. Nonetheless, in males of avian species, carotenoid-based coloration in bare parts is also partially controlled by testosterone. We also manipulated androgen levels throughout life by treating males with testosterone or antiandrogen compounds. Treatments caused correlations between signal levels and both fitness components to disappear, thus making the signals unreliable. This suggests that the evolution of carotenoid-based sexual signals requires a tightly-controlled steroid metabolism. [ABSTRACT FROM AUTHOR]

Among calyptraeid gastropods, males become females as they get older, and egg capsules containing developing embryos are maintained beneath the mother’s shell until the encapsulated embryos hatch. Crepipatella dilatata is an interesting biological model considering that is an estuarine species and thus periodically exposed to elevated environment-physiological pressures. Presently, there is not much information about the reproductive biology and brooding parameters of this gastropod. This paper describes field and laboratory observations monitoring sex changes, brooding frequencies, sizes of brooding females, egg mass characteristics, and embryonic hatching conditions. Our findings indicate that C. dilatata is a direct-developing protandric hermaphrodite, changing from male to female when individuals were between 18 and 20 mm in shell length. At our study site in Quempillén estuary, females were found to be brooding almost continuously throughout the year, having an average maximum of 85% of simultaneous brooding, with a short rest from April through June. No relationship was found between the number of capsules per egg mass and the size of the brooding female. However, capsule size and the number of embryos and nurse eggs were strongly related to female size. The offspring hatched with an average shell length > 1 mm. About 25% of the hatched capsules were found to contain both metamorphosed (juveniles) and non-metamorphosed (veliger) individuals. The sizes of the latter were < 1000 μm. The length of hatching juveniles was inversely related to the number of individuals per capsule, which seems related to differences in the availability of nurse eggs per embryo. Although fecundity per reproductive event of this species is relatively low (maximum approx. 800 offspring per egg mass) compared with those of calyptraeid species showing mixed development, the overall reproductive potential of C. dilatata seems to be high considering that females can reproduce up to 5 times per year, protecting their encapsulated embryos from physical stresses until well-developed juveniles are released into the population, avoiding a dangerous pelagic period prior to metamorphosis. [ABSTRACT FROM AUTHOR]

In insects, the gustatory system has a critical function not only in selecting food and feeding behaviours but also in growth and metabolism. Gustatory receptors play an irreplaceable role in insect gustatory signalling. Trichogramma chilonis is an effective biocontrol agent against agricultural insect pests. However, the molecular mechanism of gustation in T. chilonis remains elusive. In this study, we found that T. chilonis adults had a preference for D-fructose and that D-fructose contributed to prolong longevity and improve fecundity. Then, We also isolated the full-length cDNA encoding candidate gustatory receptor (TchiGR43a) based on the transcriptome data of T. chilonis, and observed that the candidate gustatory receptor gene was expressed from the larval to adult stages. The expression levels of TchiGR43a were similar between female and male. A Xenopus oocyte expression system and two-electrode voltage-clamp recording further verified the function analysis of TchiGR43a. Electrophysiological results showed that TchiGR43a was exclusively tuned to D-fructose. By the studies of behaviour, molecular biology and electrophysiology in T. chilonis, our results lay a basic fundation of further study on the molecular mechanisms of gustatory reception and provide theoretical basis for the nutritional requirement of T. chilonis in biocontrol. [ABSTRACT FROM AUTHOR]

Exposure to plant compounds and analogues of juvenile hormone (JH) increase male mating success in several species of tephritid fruit flies. Most of these species exhibit a lek mating system, characterized by active female choice. Although the pattern of enhanced male mating success is evident, few studies have investigated what benefits, if any, females gain via choice of exposed males in the lek mating system. In the South American fruit fly, Anastrepha fraterculus, females mate preferentially with males that were exposed to volatiles released by guava fruit or treated with methoprene (a JH analogue). Here, we tested the hypothesis that female choice confers direct fitness benefits in terms of fecundity and fertility. We first carried out mate choice experiments presenting females with males treated and non-treated with guava volatiles or, alternatively, treated and non-treated with methoprene. After we confirmed female preference for treated males, we compared the fecundity and fertility between females mated with treated males and non-treated ones. We found that A. fraterculus females that mated with males exposed to guava volatiles showed higher fecundity than females mated to non-exposed males. On the other hand, females that mated methoprene-treated males showed no evidence of direct benefits. Our findings represent the first evidence of a direct benefit associated to female preference for males that were exposed to host fruit odors in tephritid fruit flies. Differences between the two treatments are discussed in evolutionary and pest management terms. [ABSTRACT FROM AUTHOR]

The fungus gnat Bradysia difformis Frey not only attacks edible and medicinal fungi, it also causes the damages to leek, green onion, garlic and other vegetable crops. To confirm the effects of temperature and sex ratio on adult fecundity, longevity and egg hatchability of B. difformis, we assayed the adults survival longevity and numbers of oviposition, as well as egg hatching rate under female-male ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 at 10, 15, 20, 25 and 30°C. Female fecundity and egg hatchability were increased with temperature and peaked at 25°C, which, however, were adverse to adult longevity. Furthermore, female-male ratio of 1:1, 1:2 and 1:3 seemed suitable for female fecundity, of which the sex ratio of 1:1 was the most suitable ratio for its oviposition behavior. These results provide an insight for predicting the population density of B. difformis and offer a literature reference in the effective treatment of harmful insects by controlling and changing the sex ratio artificially. [ABSTRACT FROM AUTHOR]

Both Grapholita molesta (Busck) and Grapholita dimorpha Komai (Lepidoptera: Tortricidae) are important pests of pome and stone fruits. Mature fruits of peach and plum have been tested as food sources for G. molesta, but no studies have examined the suitability of immature fruits, which are the fruit stage more likely to be available for the spring populations of both G. molesta and G. dimorpha. Thus, we evaluated immature fruits of peach, plum, and apple as food sources by assessing their effects on biological and behavioral attributes of these moths in the laboratory. Immature fruits were collected in May and June of 2016 and again in 2017. The first-instar larvae of G. molesta preferred either peach or plum, which showed exit rates of mature larvae of 81.0 and 100.0% for the two fruits, respectively. On peach, development time was shorter, and fecundity was lower than plum. However, G. dimorpha preferred plum and apple, showing the lowest fruit-boring rate and lowest mature larval exit rate on peach, from which only one female moth emerged but produced no eggs. In conclusion, it seems that at the immature fruit stage, plum and apple are better food sources for both G. molesta and G. dimorpha than is peach. [ABSTRACT FROM AUTHOR]

Selection pressures leading to extreme, female-biased sexual size dimorphism (SSD) in spiders continue to be debated. It has been proposed that males of sexually size dimorphic spiders could be small because gravity constrains adult agility (locomotor abilities). Accordingly, small males should achieve higher vertical climbing speeds and should be more prone to bridge. The curvilinear model of the gravity hypothesis predicts a negative relationship between vertical climbing speed and male body size only over a threshold of 7.6 mm, 42.5 mg. Because males of most species with extreme SSD fall well below this threshold, the relationship between male size and agility at this scale remains vague. Here, we tested three hypotheses on how male size, mass and age (after maturation) relate to vertical climbing and bridging ability in Nephilingis cruentata, a highly sexually dimorphic orb-weaver with males well below the size threshold. We placed males of different sizes and adult ages in a vertical platform and recorded their climbing speeds. Contrary to the original study testing male bridging ability as binary variable, we measured the duration of the crossing of the bridging thread, as well as its sagging distance. Male body size and mass positively related to the vertical climbing speed and to the distance of the sagging thread during bridging, but had no influence on the bridging duration. The detected positive correlation between male size/mass and vertical climbing speed goes against our first prediction, that small males would have vertical climbing advantage in Nephilingis cruentata, but agrees with the curvilinear model. Against our second prediction, small males were not faster during bridging. Finally, in agreement with our third prediction, threads sagged more in heavier males. These results suggest that small male size confers no agility advantages in Nephilingis cruentata. [ABSTRACT FROM AUTHOR]

The development and fecundity of the predator Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) were assessed by feeding Aphis gossypii Glover (Hemiptera: Aphididae) that had been reared on transgenic Bacillus thuringiensis (Bt) cotton SGK321 and a non-Bt cotton control (SY321) for two successive generations. We found no significant differences in the developmental stage duration, stage survival, or egg hatch rate between C. carnea fed A. gossypii reared on the Bt and non-Bt cotton. The fecundity per female over a 25-day observation period was very similar between treatments; for C. carnea fed A. gossypii reared on SGK321 vs. SY321, the amount of eggs laid was not significantly different in both generations. Furthermore, a population dynamics of A. gossypii and lacewing (mainly C. carnea) were highly similar in the SGK321 and SY321 treatments during 2016–2017. These results suggest that Bt cotton does not have a significantly negative or positive effect on C. carnea in terms of development, survival, fecundity, or population dynamics. [ABSTRACT FROM AUTHOR]

Capital breeders develop gametes by using energy that was stored before the spawning season. Energy is allocated to growth and reproduction, and limited food availability affects the balance of energy allocation, especially in fish that mature within a year, such as western sand lance (Ammodytes japonicus). This species aestivates without feeding until winter spawning and utilize energy stores that were accumulated prior to aestivation for maturation and spawning. This study aimed to evaluate the growth, energy storage, maturation rate, and reproduction of A. japonicus in response to food availability before aestivation. We conducted laboratory experiments in which young-of-the-year A. japonicus were fed at rates of 4% and 1% of their body weight per day; assigned as high and low ration groups, respectively. In June, body length was found to be significantly larger in the high ration group than in the low ration group, but the somatic condition did not differ significantly between the groups. Maturation rates and average fecundities were 1.0 and 6297 in the high ration group and 0.8 and 2251 in the low ration group, respectively. These results indicate that food availability before aestivation strongly governs the reproductive potential of A. japonicus, and suggest the involvement of mechanisms in the inter-annual recruitment variation in sand lance species. [ABSTRACT FROM AUTHOR]

The western corn rootworm, Diabrotica virgifera virgifera (LeConte) (Coleoptera: Chrysomelidae), is an economically important pest of corn in the northern United States. Some populations have developed resistance to management strategies including transgenic corn that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Knowledge of insect dispersal is of critical importance for models of resistance evolution. Larval density affects survival in the field, and stress from crowding often affects facultative long-distance dispersal of adult insects. In this study, we used laboratory flight mills to characterize western corn rootworm flight performance as a function of larval rearing density. Larvae were reared under three densities and the resulting adult females were either allowed to fly voluntarily for 22 h or forced to fly specified durations. For both experiments we also measured lifetime fecundity following flight. The three rearing densities placed differential levels of stress on individuals, as evidenced by decreased survival to adulthood and decreased size of adults at greater rearing density. When larvae were reared under crowded conditions the resulting females were more likely to engage in flight activity, including long uninterrupted flights lasting >10 min, than those reared under low density conditions. Flight and egg production are both energy intensive processes. However, we found no evidence in either voluntary or forced flight experiments of a tradeoff between flight activity and female fecundity. The results suggest that females emerging from high density populations in cornfields are more likely to disperse and disperse farther than those emerging from low density populations. These results are important because they imply that variation in population density in the landscape will affect dispersal, which may in turn require computer models of resistance evolution to incorporate multiple dispersal rates arising from varying larval densities among fields. [ABSTRACT FROM AUTHOR]

The role of microplastic (MP) as a carrier of persistent organic pollutants (POPs) to aquatic organisms has been a topic of debate. However, the reverse POP transport can occur if relative contaminant concentrations are higher in the organism than in the microplastic. We evaluated the effect of microplastic on the PCB removal in planktonic animals by exposing the cladoceran Daphnia magna with a high body burden of polychlorinated biphenyls (PCB 18, 40, 128 and 209) to a mixture of microplastic and algae; daphnids exposed to only algae served as the control. As the endpoints, we used PCB body burden, growth, fecundity and elemental composition (%C and %N) of the daphnids. In the daphnids fed with microplastic, PCB 209 was removed more efficiently, while there was no difference for any other congeners and ΣPCBs between the microplastic-exposed and control animals. Also, higher size-specific egg production in the animals carrying PCB and receiving food mixed with microplastics was observed. However, the effects of the microplastic exposure on fecundity were of low biological significance, because the PCB body burden and the microplastic exposure concentrations were greatly exceeding environmentally relevant concentrations. [ABSTRACT FROM AUTHOR]

The invasive dermestid khapra beetle, Trogoderma granarium, is an important pest of stored products that is subject to strict phytosanitary measures. In this study, we conducted a demographic analysis of this species at 30, 35 and 40°C, combining deterministic and stochastic approaches. The net reproductive rate, the intrinsic rate of increase, the finite rate of increase and the doubling time did not differ significantly between 30 and 35°C, while at 40°C we detected negative values of the intrinsic rate of increase and the doubling time. The Briere model fit the data well with respect to the intrinsic rate of increase. Females of roughly 63, 42 and 21 days old reached their maximum reproductive potential at 30, 35 and 40°C, respectively. The stochastic models of this study allowed for checking model fit and the characterization of the most suitable distribution for each component of the process. We expect these results to have bearing on the management of T. granarium since they could be combined with models related to international trade and climatic change, alerting specialists towards early detection strategies against this species. [ABSTRACT FROM AUTHOR]

Both inhibitory and stimulatory (known as hormesis) effects of the sublethal flupyradifurone, a butenolide insecticide, on Myzus persicae Sulzer (Hemiptera: Aphididae) were investigated for incorporating it into integrated pest management (IPM). A leaf-dip bioassay showed that flupyradifurone was very toxic against adult M. persicae with a 48 h LC50 of 8.491 mg/L. Using the age-stage two-sex life table approach, we assessed the effects of LC25 of flupyradifurone on adult M. persicae and its progeny (F1 and F2). On the one hand, aphids exposed to flupyradifurone had significantly negative effects on the life history traits acrossing the generations, such as reduced the adult longevity and fecundity of F0, shortened the duration of third instar and fourth instar nymphs, preadult period and the pre-reproductive period of F1, and decreased the reproductive days and adult longevity of F2. On the other hand, stimulatory effects on the duration of pre-adult, adult reproductive days, and reproduction of F1 were observed in the flupyradifurone-treated aphids. Consistently with the stimulation on individual traits, a higher net reproductive rate (R0) of F1 and a shorter mean generation time (T) of F2 were observed in the flupyradifurone-treated aphids, although the other population parameters including the intrinsic rate of increase (r), finite rate of increase (λ) and T of F1 and R0, r and λ of F2 were not significantly affected. These results revealed that adult M. persicae exposed to sublethal concentration of flupyradifurone can induce hormetic effects on F1, and also cause negative effects on F2. Our results would be useful for assessing the overall effects of flupyradifurone on M. persicae and the hormetic effects should take into consideration when use flupyradifurone for control M. persicae. [ABSTRACT FROM AUTHOR]

Salinity is increasing in aquatic ecosystems in the Mediterranean region due to global change, and this is likely to have an important impact on host-parasite interactions. Here we studied the relationships between infection by ectoparasitic water mites and salinity variation, on survival and fecundity of water boatmen Corixidae in the laboratory. Larvae of Sigara lateralis parasitised by larval mites (Hydrachna skorikowi) had lower survivorship, and failed to moult to the adult stage. In adult corixids (S. lateralis and Corixa affinis) fitness was reduced at high salinities and in individuals infected by H. skorikowi, both in terms of survival and fecundity. We also found evidence for parasitism-salinity interactions. Our results suggest that ongoing increases in salinity in Mediterranean ponds due to climate change and water abstraction for agriculture or urban use have a strong impact on water bugs, and that their interactions with ectoparasites may modify salinity effects. [ABSTRACT FROM AUTHOR]

Mate choice is an important process in sexual selection and usually prevents inbreeding depression in populations. In the terrestrial isopod Armadillidium vulgare, the close physical proximity between individuals may increase the risk of reproducing with siblings. Moreover, individuals of this species can be infected with the feminizing bacteria of Wolbachia, which influence male mate choice. However, little is known about the kinship or familiarity assessment of the selected partner that occurs when a male can choose between females with or without Wolbachia. To investigate the potential mechanisms leading to mate choice and the potential impact of the parasite, we performed behavioral choice tests on males where they could choose between sibling vs. nonsibling females, familiar vs. unfamiliar females, and sibling familiar vs. unfamiliar nonsibling females. To investigate the costs of inbreeding, we compared the reproductive success of both sibling and nonsibling mates. Our results revealed that male copulation attempts were higher for familiar females and for nonsibling females when both females were Wolbachia-infected, but the duration was longer when both females were Wolbachia-free. When males mated with a sibling female, their fecundity was severely decreased, consistent with inbreeding depression. Overall, we observed copulations with all types of females and demonstrated discrimination capacities and potential preferences. We highlight the complexity of the tradeoff between kinship, familiarity and parasite transmission assessment for mate choice. [ABSTRACT FROM AUTHOR]

Objective: Over 12% of women in the United States have reduced fertility and/or fecundity. Environmental factors, such as temperature, and socioeconomic factors have been implicated in reducing female fecundity. The purpose of this study is to investigate the effect of environmental factors coupled with socioeconomic factors on birth rate at the country-level. We use birth rate as a proxy for female fecundity. This will enable us to identify the most important factors affecting female fecundity. Methods: Using country-specific data from 182 countries, we constructed a regression model of the effects of environmental and socioeconomic factors on birth rate at the country-level. Our model assesses the role of temperature, Gross Domestic Product (GDP) per capita, fine air particulate matter (PM 2.5), and prevalence of male and female Body Mass Index (BMI) > = 25 (age-standardized) on birth rate per country. Because many of these factors are inter-dependent, we include all possible two-way interaction terms to assess the role of individual factors and interactions between multiple factors in the model. Results: In the full regression model, we found that GDP per capita along with 5 interaction terms were significant after adjusting for multiple testing. Female BMI was only nominally significant. GDP per capita was independently associated with birth rate (adjusted p-value <0.001). Prevalence of BMI > = 25 age-standardized in males and females were also significant when interacting with air pollution or GDP on female fecundity (birth rate). Temperature did not affect birth rate either independently or as an interaction unless BMI was removed from the model. Conclusion: A country’s economic wealth was the most significant factor in predicting birth rate in a statistical model that includes environmental and socioeconomic variables. This is important for future studies investigating environmental factors involved in increasing or decreasing female fecundity. [ABSTRACT FROM AUTHOR]

Knowledge of the impact of pesticides on predators is crucial for developing integrated pest management (IPM) programs. Amblyseius swirskii (Acari: Phytoseiidae) is a predatory mite used to control several species of pest including Tetranychus urticae (Acari: Tetranychidae) and arthropods. T. urticae is a major pest of multiple greenhouse-grown and field crops including apples in Iran. Lethal and sublethal effects of fenpyroximate and thiacloprid were investigated on A. swirskii, using these chemicals separately at recommended rates or in combination at reduced rates. Recommended tested rates of both pesticides negatively influenced the biological parameters of A. swirskii such as the net reproductive rate (R0) and the intrinsic rate of increase (r). However, the combined treatment of the two pesticides at their reduced rates was less hazardous to A. swirskii. Our findings indicate that the combined use of these chemicals may be compatible with IPM programs utilizing A. swirskii as biological control tool against phytophagous mites and other pests. However, semifield and field studies to investigate the effects of reduced rate treatments of fenpyroximate and thiacloprid alone and in combination on T. urticae and A. swirskii are required for developing IPM programs. [ABSTRACT FROM AUTHOR]

Objective: Tetranychus cinnabarinus (Boisduval) is an agricultural mite pest threatens crops throughout the world, causing serious economic loses. Exploring the effects of acaricides on predatory mites is crucial for the combination of biological and chemical control of T. cinnabarinus. Neoseiulus californicus (McGregor) is one of the principal natural enemies of T. cinnabarinus, which can be applied in protected agriculture. In this study, the effects of sublethal concentrations of a new acaricide, SYP-9625 on two mite species, and the effects of the application concentration on predatory mite, N. californicus were assessed. The aim of the present study was to evaluate the effect of SYP-9625 on life parameters and predation capacity of N. californicus based on the concentration-response bioassay of T. cinnabarinus to explor the application of the new acaricide with natural enemy N. californicus. Method: All of the experiments were conducted under laboratory conditions [25 ± 1°C, 16: 8 h (L: D) and 75 ± 5% RH]. The sublethal concentrations LC10 (0.375μg/mL) and the LC30 (0.841μg/mL) against T. cinnabarinus and the application concentration (100μg/mL) against N. californicus were used to evaluate the effects of SYP-9625 on population parameters of N. californicus based on an age-stage, two-sex life table and its predation capacity by functional response. Result: cinnabarinus females treated with LC30 exhibited significantly reduced net reproductive rates (R0 = 11.02) in their offspring compared with females treated with LC10 (R0 = 14.96) and untreated females (R0 = 32.74). However, the intrinsic rate of increase (rm) and the finite rate of increase (λ) of N. californicus indicated that the application concentration of SYP-9625 had no significant negative effect on N. californicus eggs (rm = 0.277, λ = 1.319) compared to the control (rm = 0.292, λ = 1.338). Additionally, most population parameters of N. californicus showed a dose-dependent manner with the increase of the concentration of SYP-9625 against T. cinnabarinus. SYP-9625 also stimulated the control efficiency of N. californicus against immobile stages including eggs and larvae. Conclusion: This study demonstrated that sublethal concentrations of SYP-9625 can inhibit the population growth of T. cinnabarinus. In addition, the sublethal concentrations and the application concentration showed no effect on the population growth of N. californicus. These two advantages described above showed great commercial potential of this new acaricide based on population parameters of the two mite species and predation capacity of the predatory mite under laboratory conditions. [ABSTRACT FROM AUTHOR]

Efforts to recycle organic wastes using black soldier fly (BSF) Hermetia illucens into high-nutrient biomass that constitutes a sustainable fat (biodiesel) and high-quality protein ingredient in animal feeds have recently gained momentum worldwide. However, there is little information on the most suitable rearing conditions for growth, development and survivorship of these flies, which is a prerequisite for mass production technologies. We evaluated the physiological requirements for growth and reproduction of H. illucens on two diets [spent grains supplemented with brewers’ yeast (D1) and un-supplemented (D2)]. Development rates at nine constant temperatures (10–42°C) were fitted to temperature-dependent linear and non-linear day-degree models. Thereafter, life history table parameters were determined within a range of favourable temperatures. The thermal maximum (TM) estimates for larval, pre-pupal and pupal development using non-linear model ranged between 37.2 ± 0.3 and 44.0 ± 2.3°C. The non-linear and linear day-degree model estimations of lower developmental temperature threshold for larvae were 11.7 ± 0.9 and 12.3 ± 1.4°C for D1, and 10.4 ± 1.7 and 11.7 ± 3.0°C for D2, respectively. The estimated thermal constant of immature life stages development of BSF was higher for the larval stage (250±25 DD for D1 and 333±51 for D2) than the other stages evaluated. Final larval wet weight was higher on D1 compared to D2. The population growth rate was most favourable at 30-degree celsius (°C) with higher intrinsic rate of natural increase (rm = 0.127 for D1 and 0.122 for D2) and shorter doubling time (5.5 days for D1 and 5.7 days for D2) compared to the other temperatures. These results are valuable for the optimization of commercial mass rearing procedures of BSF under various environmental conditions and prediction of population dynamics patterns using computer simulation models. [ABSTRACT FROM AUTHOR]

Objectives: Projections of fertility of HIV positive women as ART scales up are needed to plan prevention of mother-to-child transmission (PMTCT) services. We describe differences in exposure to pregnancy between HIV positive and HIV negative women by age, region and national ART coverage to evaluate the extent to which behavioural differences explain lower fertility among HIV positive women and assess whether exposure to pregnancy has changed with antiretroviral treatment (ART) scale-up. Methods: We analysed 46 nationally representative household surveys in sub-Saharan Africa conducted between 2003 and 2015 to estimate risk of exposure to recent sex and pregnancy of HIV positive and HIV negative women by age using a log binomial model. We tested for regional and urban/rural differences and associations with national ART coverage. We estimated an adjusted fertility rate ratio of HIV positive to HIV negative women adjusting for differences in exposure to pregnancy. Results: Exposure to pregnancy differs significantly between HIV positive and negative women by age, modified by region. Younger HIV positive women have a higher exposure to pregnancy than HIV negative women and the opposite is true at older ages. The switch occurs at 25–29 for rural women and 30–34 for urban women. There was no evidence that exposure to pregnancy of HIV positive women have changed as national ART coverage increased. The inferred rate of fecundity of HIV positive women when adjusted for differences in exposure to pregnancy were lower than unadjusted fertility rate ratios in women aged 20–29 and 20–24 in urban and rural areas respectively varying between 0.6 and 0.9 over regions. Discussion: The direct effects of HIV on fertility are broadly similar across ages, while the dramatic age gradient that has frequently been observed is largely attributable to variation in relative sexual exposure by age. [ABSTRACT FROM AUTHOR]

Secondary cavity-nesting birds depend on tree cavities for nesting and roosting, but many studies of these birds are conducted using nest boxes. Implementation of effective conservation strategies for cavity-nesting species such as nest-site supplementation requires careful comparisons of fecundity and other vital rates for birds using both natural and artificial nest site types. We compared breeding phenology, clutch and brood sizes, and fledging success of Tree Swallows (Tachycineta bicolor) nesting in tree cavities and nest boxes during 2001–2003 in British Columbia, Canada. Swallows using nest boxes initiated egg-laying and hatched young at approximately the same time as those in tree cavities (2 June, 23 June, respectively). Female Tree Swallows in boxes laid larger clutches (5.9 ± 0.9 eggs, N = 76) than those in tree cavities (4.2 ± 1.6 eggs, N = 67). The mean number of nestlings hatched was greater in nest boxes (5.2 ± 1.1 nestlings, N = 67) than in tree cavities (2.6 ± 2.0 nestlings, N = 58). Pairs in boxes were over twice as successful in producing fledglings (93.4%; 57 of 61 pairs fledged > 1 young) than those in tree cavities (35.8%; 19 of 53 pairs). Of those successful nests, pairs nesting in boxes fledged 5.1 ± 1.1 young (N = 57), whereas those in tree cavities fledged 3.5 ± 1.2 young (N = 18). Because cavities in nest boxes averaged 60% larger in volume and 1.8 cm wider internally than tree cavities, we suggest that increased reproductive output was correlated with boxes enabling a larger clutch size. In previous research, we found that Tree Swallows were a poor competitor with other cavity-nesting passerines for tree cavities. The addition of nest boxes may serve as an effective way to supplement local reproduction for secondary cavity-nesting bird populations by reducing competition for limited nest sites. This is especially true in regions where the availability of natural nesting sites is highly variable, and where species compete with many other cavity-nesting passerines using a similar ecological niche and nesting cavities. [ABSTRACT FROM AUTHOR]

The bird cherry-oat aphid, Rhopalosiphum padi (L.), is a major insect pest of cereal crops in many countries. Imidacloprid has been widely used for controlling piercing-sucking insect pests worldwide, but its sublethal effects on R. padi have not been well addressed. In this study, we investigated the sublethal effects of imidacloprid on biological parameters and five enzyme activities of R. padi. The LC10, LC20, and LC25 of imidacloprid to adult aphids were 0.0053, 0.0329 and 0.0659 mg L-1, respectively. These concentrations significantly decreased pre-adult survival rate, but prolonged the development duration of 1st instar nymphs, pre-oviposition period, and adult longevity. Adult oviposition period was also extended by LC20. The intrinsic rate of increase (r), net reproductive rate (R0), and finite rate (λ) decreased at all three concentrations, whereas mean generation time (T) increased. Moreover, LC20 and LC25 significantly inhibited superoxide dismutase (SOD) activity, but increased catalase (CAT) activity. Acetylcholinesterase (AChE) activity also increased at LC20. However, cytochrome P450 enzyme and peroxidase (POD) activity did not differ between imidacloprid treatments and the control. In conclusion, the imidacloprid concentrations tested here have negative impacts on the performance of R. padi by reducing its nymphal survival, extending the development duration of some stages, decreasing the rate of population growth, and altering enzyme activities. [ABSTRACT FROM AUTHOR]

Helicoverpa armigera is an universal pest around the world, which has recovered again in recent years because of the adjustment of cropping structure and resistance to Bacillus thuringiensis (Bt) in China. As a new insecticide spinetoram is extensively used to control many pest insects, including H. armigera. However the lethal and sublethal effects of spinetoram on cotton bollworm have not been assessed. In the present study, the toxicity of spinetoram against cotton bollworm was tested under laboratory conditions. Results demonstrated spinetoram showed an excellent activity against H. armigera, especially, against Bt (Cry1Ac) resistant H. armigera. Treatment with spinetoram at the doses of 0.19 mg/kg and 0.36 mg/kg (LC8 and LC20 after 24h oral exposure) significantly arrested the development of surviving larvae and caused significant decrease in larvae wet weight. Besides, the survivors after spinetoram treatments showed significant reduction of pupation ratio, pupal weight, emergence ratio, longevity and fecundity of adults. At same time, spinetoram treatments resulted in significant increase in the prepupal and pupal periods of survivors. In summary, these results showed that spinetoram could be used as an effective pesticide to control H. armigera, especially Cry1Ac-ressitacne, consequently to take both lethal and sublethal effects to cotton bollworm into consideration in cotton bollworm control strategy. [ABSTRACT FROM AUTHOR]

The cost of reproduction is a key concept in life-history trade-offs. However, our understanding of the reproductive costs is biased towards measures of reproductive effort obtained before offspring independence. During the post-fledging dependence period (PFDP), it is well known that parents feed and protect their offspring. However, the effort devoted to this reproductive activity has never been considered in the context of of the costs of reproduction. Moreover, the potential fitness benefits and costs for offspring and parents, respectively, of the duration of the PFDP are largely unknown. We estimated the duration of the PFDP over 5 years using wild common kestrels (Falco tinnunculus) and studied its association with survival probability and future parental reproductive performance. Our results show that longer PFDPs increase the survival probability of fledglings, probably due to the benefits obtained from parental care. In addition, we found that providing longer PFDPs was associated with reduced clutch sizes but not the number of fledglings in the subsequent breeding season in males. We suggest that increased parental expenditures on offspring during the PFDP may represent a potential cost of reproduction in breeding males. [ABSTRACT FROM AUTHOR]

Human activities are exposing organisms not only to direct threats (e.g. habitat loss) but also to indirect environmental pressures such as climate change, which involves not just directional global warming but also increasing climatic variability. Such changes will impact whole communities of organisms and the possible effects on population dynamics have raised concerns about increased extinction rates. Conservation-minded approaches to extinction risk vary from range shifts predicted by climate envelope models with no population dynamics to population viability analyses that ignore environmental variability altogether. Our modelling study shows that these extremes are modelling responses to a spectrum of environmental sensitivity that organisms may exhibit. We show how the survival curve plays a major role in how environmental variability leads to population fluctuations. While it is often supposed that low-fecundity organisms (those with high parental investment) will be the most vulnerable to climate change, it is those with high fecundity (low parental investment) that are likely to be more sensitive to such changes. We also find that abundance variations in high fecundity populations is driven primarily by fluctuations in the survival of early life stages, the more so if those environmental changes are autocorrelated in time. We show which types of conservation actions are most appropriate for a number of real populations. While the most effective conservation actions for organisms of low fecundity is to avoid killing them, for populations with high fecundity (and low parental investment), our study suggests conservation should focus more on protecting early life stages from hostile environments. [ABSTRACT FROM AUTHOR]

Demographic analyses and ecological niche modeling (ENM) are two popular tools that address species persistence in relation to environmental conditions. Classic demography provides detailed information about the mechanisms that allow a population to grow or remain stable at a local scale, while ENM infers distributions from conditions suitable for species persistence at geographic scales by relating species’ occurrences with environmental variables. By integrating these two tools, we may better understand population processes that determine species persistence at a geographic scale. To test this idea, we developed a model that relates climate to demography of the cactus Opuntia rastrera using 15 years of data from one locality. Using this model we determined the geographic area where populations would have positive growth rates given its climatic conditions. The climate-dependent demographic model showed poor performance as a distribution model, but it was helpful in defining some mechanisms that determine species’ distributions. For instance, high rainfall had a negative impact on the population growth rate by increasing mortality. Rainy areas to the west of the distribution of O. rastrera were identified as unsuitable both by our climate-dependent demographic model and by a popular ENM algorithm (MaxEnt), suggesting that distribution is constrained by excessive rains due to high mortality. Areas projected to be climatically suitable by MaxEnt were not related with higher population growth rates. Instead, we found a strong correlation between environmental distance to the niche centroid (center of the niche hypervolume, where optimal conditions may occur) and population growth rate, meaning that the niche centroid approach is helpful in finding high-fitness areas. [ABSTRACT FROM AUTHOR]

The emergence of functional specialization is a core problem in biology. In this work we focus on the emergence of reproductive (germ) and vegetative viability-enhancing (soma) cell functions (or germ-soma specialization). We consider a group of cells and assume that they contribute to two different evolutionary tasks, fecundity and viability. The potential of cells to contribute to fitness components is traded off. As embodied in current models, the curvature of the trade-off between fecundity and viability is concave in small-sized organisms and convex in large-sized multicellular organisms. We present a general mathematical model that explores how the division of labor in a cell colony depends on the trade-off curvatures, a resource constraint and different fecundity and viability rates. Moreover, we consider the case of different trade-off functions for different cells. We describe the set of all possible solutions of the formulated mathematical programming problem and show some interesting examples of optimal specialization strategies found for our objective fitness function. Our results suggest that the transition to specialized organisms can be achieved in several ways. The evolution of Volvocalean green algae is considered to illustrate the application of our model. The proposed model can be generalized to address a number of important biological issues, including the evolution of specialized enzymes and the emergence of complex organs. [ABSTRACT FROM AUTHOR]

Population growth models are integral to ecological studies by providing estimates of population performance across space and time. Several models have been developed that estimate population growth through correlates of demographic traits, as measuring each parameter of the model can be prohibitive in experimental studies. Since differences in female size can accurately reflect changes in fecundity for many taxa, Livdahl and Sugihara developed a population growth index that incorporates size-fecundity relationships as a proxy for fecundity. To investigate the extent to which this model is robust to variation of this proxy, we tested if genetic (source population), temperature and resource treatments affect the size-fecundity relationship in Aedes albopictus (Skuse), the Asian tiger mosquito. We then determined if variation in the size-fecundity relationship alters the population growth estimates, lambda (λ’), when applied to Livdahl and Sugihara’s model. We performed 2 laboratory experiments in which we reared cohorts of four different geographic populations of A. albopictus across 5 temperature treatments (18, 21, 25, 18, 31°C) and three resource treatments (low, medium, high larval resources). We determined if the slope of the size-fecundity relationship varied by source population, temperature, or resource; and if variation in this relationship affects lambda (λ’) estimates in a competition study between A. albopictus and Culex pipiens (Linnaeus), the northern house mosquito. Temperature treatments significantly affected the size-fecundity relationship, resource level marginally affected the relationship, while source population had no effect. We found positive relationships between size and fecundity when mosquito larvae were reared at high temperatures and low resource levels but the relationship disappeared when mosquitoes were reared at a low temperature or with high levels of resources. The variation in the size-fecundity relationship produced from different temperatures resulted in statistically different lambda (λ’) estimates. However, these changes in lambda (λ’) did not alter the trends in the population performance across treatments or conclusions of the competition study. This study provides evidence that the population growth model is sensitive to variation in size-fecundity relationships and we recommend biologists apply the most compatible size-fecundity relationship to the models to obtain the most accurate estimates of population performance. [ABSTRACT FROM AUTHOR]

The impact of senescence and pathogen infection on Aedes aegypti life-history traits remains poorly understood. This laboratory study focused on the impact of Zika virus (ZIKV) infection and the age of first blood intake on blood meal and clutch sizes, and more importantly on the egg production ratio per μL of blood. Three groups of ZIKV-infected and uninfected Ae. aegypti females that received their first blood meal at 7 (young feeders), 14 (mature feeders) and 21 days old (old feeders) were monitored daily for survival and received a blood meal free of ZIKV once a week. The number of eggs laid per female were registered 3–4 days after blood feeding. Infection by ZIKV and age of feeding produced a strong negative impact on survival and oviposition success (e.g. likelihood of laying at least one egg per gonotrophic cycle). Interestingly, clutch size presented a dramatic reduction on uninfected mosquitoes, but raised from 36.5 in clutch1 to 55.1 eggs in clutch 3. Blood meal size remained stable in uninfected females, while a slight increase was observed for the infected counterparts. In uninfected Ae. aegypti, egg production was strongly affected by the age of feeding with younger females laying three times more eggs than when older. On the other hand, ZIKV-infected mosquitoes had a constant but low egg production. Overall, mosquito senescence and ZIKV infection had an impact on mosquito egg production by causing a sharp decrease in the number of eggs along the clutches for uninfected mosquitoes and a slight increase for infected mosquitoes. Despite some study limitations, our results contribute to a better understanding of the effects of mosquito aging and pathogen infection on the vectorial capacity of Ae. aegypti. [ABSTRACT FROM AUTHOR]

The reproductive biology of three yellow catfish congeners was studied in the Three Gorges Reservoir of the Yangtze River, China. We compared reproductive traits among the lentic, transitional, and lotic zones. A total of 4502 individuals of the three species was collected, and the sex ratio, size at 50% maturity, spawning season, fecundity, and egg size were determined. Results showed that populations inhabiting the lotic zone spawned earlier than those inhabiting the lentic zone. For the three species, fecundities were significantly higher for populations in the lotic zone than for those in the lentic and transitional zones (P < 0.05). Pelteobagrus vachelli (Richardson) and P. fulvidraco (Richardson) displayed an obvious trade-off between egg size and fecundity, whereas P. nitidus (Sauvage et Dabry) produced the largest eggs in the lotic zone. Sex ratios were significantly different among zones (P < 0.05, for each species), but the bias patterns were different. Sizes at 50% maturity of female P. nitidus and P. vachelli were the largest in the lotic zone and the smallest in the transitional zone, but was similar among zones for P. fulvidraco. Overall results suggest that the three yellow catfish species developed different reproductive traits among the three habitats in the TGR, whereas the variations reflected further interspecific differences. Our study indicates the importance of riverine habitats for the conservation of species of fish, even for species such as these eurytopic catfish inhabiting the upper reach of the Yangtze River. This study further suggests that species-specific responses should be considered when evaluating the influences of new hydropower projects, even for such closely related species of fish. [ABSTRACT FROM AUTHOR]

Qualitative risk assessment frameworks, such as the Productivity Susceptibility Analysis (PSA), have been developed to rapidly evaluate the risks of fishing to marine populations and prioritize management and research among species. Despite being applied to over 1,000 fish populations, and an ongoing debate about the most appropriate method to convert biological and fishery characteristics into an overall measure of risk, the assumptions and predictive capacity of these approaches have not been evaluated. Several interpretations of the PSA were mapped to a conventional age-structured fisheries dynamics model to evaluate the performance of the approach under a range of assumptions regarding exploitation rates and measures of biological risk. The results demonstrate that the underlying assumptions of these qualitative risk-based approaches are inappropriate, and the expected performance is poor for a wide range of conditions. The information required to score a fishery using a PSA-type approach is comparable to that required to populate an operating model and evaluating the population dynamics within a simulation framework. In addition to providing a more credible characterization of complex system dynamics, the operating model approach is transparent, reproducible and can evaluate alternative management strategies over a range of plausible hypotheses for the system. [ABSTRACT FROM AUTHOR]

The preference-performance hypothesis states that ovipositing phytophagous insects will select host plants that are well-suited for their offspring and avoid host plants that do not support offspring performance (survival, development and fitness). The mountain pine beetle (Dendroctonus ponderosae), a native insect herbivore in western North America, can successfully attack and reproduce in most species of Pinus throughout its native range. However, mountain pine beetles avoid attacking Great Basin bristlecone pine (Pinus longaeva), despite recent climate-driven increases in mountain pine beetle populations at the high elevations where Great Basin bristlecone pine grows. Low preference for a potential host plant species may not persist if the plant supports favorable insect offspring performance, and Great Basin bristlecone pine suitability for mountain pine beetle offspring performance is unclear. We infested cut bolts of Great Basin bristlecone pine and two susceptible host tree species, limber (P. flexilis) and lodgepole (P. contorta) pines with adult mountain pine beetles and compared offspring performance. To investigate the potential for variation in offspring performance among mountain pine beetles from different areas, we tested beetles from geographically-separated populations within and outside the current range of Great Basin bristlecone pine. Although mountain pine beetles constructed galleries and laid viable eggs in all three tree species, extremely few offspring emerged from Great Basin bristlecone pine, regardless of the beetle population. Our observed low offspring performance in Great Basin bristlecone pine corresponds with previously documented low mountain pine beetle attack preference. A low preference-low performance relationship suggests that Great Basin bristlecone pine resistance to mountain pine beetle is likely to be retained through climate-driven high-elevation mountain pine beetle outbreaks. [ABSTRACT FROM AUTHOR]

In contrast to theoretical predictions of even adult sex ratios, males are dominating in many bird populations. Such bias among adults may be critical to population growth and viability. Nevertheless, demographic mechanisms for biased adult sex ratios are still poorly understood. Here, we examined potential demographic mechanisms for the recent dramatic shift from a slight female bias among adult eider ducks (Somateria mollissima) to a male bias (about 65% males) in the Baltic Sea, where the species is currently declining. We analysed a nine-year dataset on offspring sex ratio at hatching based on molecularly sexed ducklings of individually known mothers. Moreover, using demographic data from long-term individual-based capture-recapture records, we investigated how sex-specific survival at different ages after fledgling can modify the adult sex ratio. More specifically, we constructed a stochastic two-sex matrix population model and simulated scenarios of different survival probabilities for males and females. We found that sex ratio at hatching was slightly female-biased (52.8%) and therefore unlikely to explain the observed male bias among adult birds. Our stochastic simulations with higher survival for males than for females revealed that despite a slight female bias at hatching, study populations shifted to a male-biased adult sex ratio (> 60% males) in a few decades. This shift was driven by prime reproductive-age individuals (≥5-year-old), with sex-specific survival of younger age classes playing a minor role. Hence, different age classes contributed disproportionally to population dynamics. We argue that an alternative explanation for the observed male dominance among adults–sex-biased dispersal–can be considered redundant and is unlikely, given the ecology of the species. The present study highlights the importance of considering population structure and age-specific vital rates when assessing population dynamics and management targets. [ABSTRACT FROM AUTHOR]

We developed a model for estimating demographic rates and population abundance based on multiple data sets revealing information about population age- and sex structure. Such models have previously been described in the literature as change-in-ratio models, but we extend the applicability of the models by i) using time series data allowing the full temporal dynamics to be modelled, by ii) casting the model in an explicit hierarchical modelling framework, and by iii) estimating parameters based on Bayesian inference. Based on sensitivity analyses we conclude that the approach developed here is able to obtain estimates of demographic rate with high precision whenever unbiased data of population structure are available. Our simulations revealed that this was true also when data on population abundance are not available or not included in the modelling framework. Nevertheless, when data on population structure are biased due to different observability of different age- and sex categories this will affect estimates of all demographic rates. Estimates of population size is particularly sensitive to such biases, whereas demographic rates can be relatively precisely estimated even with biased observation data as long as the bias is not severe. We then use the models to estimate demographic rates and population abundance for two Norwegian reindeer (Rangifer tarandus) populations where age-sex data were available for all harvested animals, and where population structure surveys were carried out in early summer (after calving) and late fall (after hunting season), and population size is counted in winter. We found that demographic rates were similar regardless whether we include population count data in the modelling, but that the estimated population size is affected by this decision. This suggest that monitoring programs that focus on population age- and sex structure will benefit from collecting additional data that allow estimation of observability for different age- and sex classes. In addition, our sensitivity analysis suggests that focusing monitoring towards changes in demographic rates might be more feasible than monitoring abundance in many situations where data on population age- and sex structure can be collected. [ABSTRACT FROM AUTHOR]

Higher trophic-level species are an integral component of any marine ecosystem. Despite their importance, methods for representing these species in end-to-end ecosystem models often have limited representation of life histories, energetics and behaviour. We built an individual-based model coupled with a dynamic energy budget for female southern elephant seals Mirounga leonina to demonstrate a method for detailed representation of marine mammals. We aimed to develop a model which could i) simulate energy use and life histories, as well as breeding traits of southern elephant seals in an emergent manner, ii) project a stable population over time, and iii) have realistic population dynamics and structure based on emergent life history features (such as age at first breeding, lifespan, fecundity and (yearling) survival). We evaluated the model’s ability to represent a stable population over long time periods (>10 generations), including the sensitivity of the emergent properties to variations in key parameters. Analyses indicated that the model is sensitive to changes in resource availability and energy requirements for the transition from pup to juvenile, and juvenile to adult stage. This was particularly the case for breeding success and yearling survival. This model is suitable for use as a standalone tool for investigating the impacts of changes to behaviour and population responses of southern elephant seals. [ABSTRACT FROM AUTHOR]

Aphids are serious pests in crop plants. In an effort to identify plant genes controlling resistance against aphids, we have here studied a protease inhibitor, CI2c in barley (Hordeum vulgare L.). The CI2c gene was earlier shown to be upregulated by herbivory of the bird cherry-oat aphid (Rhopalosiphum padi L.) in barley genotypes with moderate resistance against this aphid, but not in susceptible lines. We hypothesized that CI2c contributes to the resistance. To test this idea, cDNA encoding CI2c was overexpressed in barley and bioassays were carried out with R. padi. For comparison, tests were carried out with the green peach aphid (Myzus persicae Sulzer), for which barley is a poor host. The performance of R. padi was not different on the CI2c-overexpressing lines in comparison to controls in test monitoring behavior and fecundity. M. persicae preference was affected as shown in the choice test, this species moved away from control plants, but remained on the CI2c-overexpressing lines. R. padi-induced responses related to defense were repressed in the overexpressing lines as compared to in control plants or the moderately resistant genotypes. A putative susceptibility gene, coding for a β-1,3-glucanase was more strongly induced by aphids in one of the CI2c-overexpressing lines. The results indicate that the CI2c inhibitor in overexpressing lines affects aphid-induced responses by suppressing defense. This is of little consequence to the specialist R.padi, but causes lower non-host resistance towards the generalist M. persicae in barley. [ABSTRACT FROM AUTHOR]

Eusociality, one of the most complex forms of social organization, is thought to have evolved in several animal clades in response to competition for resources and reproductive opportunities. Several species of snapping shrimp in the genus Synalpheus, the only marine organisms known to exhibit eusociality, form colonies characterized by high reproductive skew, and aggressive territoriality coupled with cooperative defense. In eusocial Synalpheus colonies, individual reproduction is limited to female ‘queens’, whose fecundity dictates colony growth. Given that individual reproduction and defense are both energetically costly, individual and colony fitness likely depend on the optimal allocation of resources by these reproducing individuals towards these potentially competing demands. Synalpheus species, however, display varying degrees of eusociality, suggesting that reproducing females have adopted different strategies for allocation among reproduction and defense. Here, we use structural equation modeling to characterize the relationships between the allometry of queen reproductive capacity and defensive weaponry, and colony size in six eusocial Synalpheus species, estimating trade-offs between reproduction and defense. We document strong trade-offs between mass of the fighting claw (defense) and egg number (reproduction) in queens from weakly eusocial species, while the trade-off is reduced or absent in those from strongly eusocial species. These results suggest that in less cooperative species, intra-colony conflict selects for queen retention of weapons that have significant costs to fecundity, while reproducing females from highly eusocial species, i.e., those with a single queen, have been able to reduce the cost of weapons as a result of protection by other colony members. [ABSTRACT FROM AUTHOR]

The aryl hydrocarbon receptor (AHR) is a conserved ligand-activated transcription factor required for proper vertebrate development and homeostasis. The inappropriate activation of AHR by ubiquitous pollutants can lead to adverse effects on wildlife and human health. The zebrafish is a powerful model system that provides a vertebrate data stream that anchors hypothesis at the genetic and cellular levels to observations at the morphological and behavioral level, in a high-throughput format. In order to investigate the endogenous functions of AHR, we generated an AHR2 (homolog of human AHR)-null zebrafish line (ahr2osu1) using the clustered, regulatory interspaced, short palindromic repeats (CRISPR)-Cas9 precision genome editing method. In zebrafish, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) mediated toxicity requires AHR2. The AHR2-null line was resistant to TCDD-induced toxicity, indicating the line can be used to investigate the biological and toxicological functions of AHR2. The AHR2-null zebrafish exhibited decreased survival and fecundity compared to the wild type line. At 36 weeks, histological evaluations of the AHR2-null ovaries revealed a reduction of mature follicles when compared to wild type ovaries, suggesting AHR2 regulates follicle growth in zebrafish. AHR2-null adults had malformed cranial skeletal bones and severely damaged fins. Our data suggests AHR2 regulates some aspect(s) of neuromuscular and/or sensory system development, with impaired behavioral responses observed in larval and adult AHR2-null zebrafish. This study increases our understanding of the endogenous functions of AHR, which may help foster a better understanding of the target organs and molecular mechanisms involved in AHR-mediated toxicities. [ABSTRACT FROM AUTHOR]

Parent-offspring communication remains an unresolved challenge for biologist. The difficulty of the challenge comes from the fact that it is a multifaceted problem with connections to life-history evolution, parent-offspring conflict, kin selection and signalling. Previous efforts mainly focused on modelling resource allocation at the expense of the dynamic interaction during a reproductive season. Here we present a two-stage model of begging where the first stage models the interaction between nestlings and parents within a nest and the second stage models the life-history trade-offs. We show in an asexual population that honest begging results in decreased variance of collected food between siblings, which leads to mean number of surviving offspring. Thus, honest begging can be seen as a special bet-hedging against informational uncertainty, which not just decreases the variance of fitness but also increases the arithmetic mean. [ABSTRACT FROM AUTHOR]

Concerns over cat homelessness, over-taxed animal shelters, public health risks, and environmental impacts has raised attention on urban-cat populations. To truly understand cat population dynamics, the collective population of owned cats, unowned cats, and cats in the shelter system must be considered simultaneously because each subpopulation contributes differently to the overall population of cats in a community (e.g., differences in neuter rates, differences in impacts on wildlife) and cats move among categories through human interventions (e.g., adoption, abandonment). To assess this complex socio-ecological system, we developed a multistate matrix model of cats in urban areas that include owned cats, unowned cats (free-roaming and feral), and cats that move through the shelter system. Our model requires three inputs—location, number of human dwellings, and urban area—to provide testable predictions of cat abundance for any city in North America. Model-predicted population size of unowned cats in seven Canadian cities were not significantly different than published estimates (p = 0.23). Model-predicted proportions of sterile feral cats did not match observed sterile cat proportions for six USA cities (p = 0.001). Using a case study from Guelph, Ontario, Canada, we compared model-predicted to empirical estimates of cat abundance in each subpopulation and used perturbation analysis to calculate relative sensitivity of vital rates to cat abundance to demonstrate how management or mismanagement in one portion of the population could have repercussions across all portions of the network. Our study provides a general framework to consider cat population abundance in urban areas and, with refinement that includes city-specific parameter estimates and modeling, could provide a better understanding of population dynamics of cats in our communities. [ABSTRACT FROM AUTHOR]

African forest elephants face severe threats from illegal killing for ivory and bushmeat and habitat conversion. Due to their cryptic nature and inaccessible range, little information on the biology of this species has been collected despite its iconic status. Compiling individual based monitoring data collected over 20 years from the Dzanga Bai population in Central African Republic, we summarize sex and age specific survivorship and female age specific fecundity for a cohort of 1625 individually identified elephants. Annual mortality (average = 3.5%) and natality (average = 5.3%) were lower and markedly less variable relative to rates reported for savanna elephant populations. New individuals consistently entered the study system, leading to a 2.5% average annual increase in the registered population. Calf sex ratios among known birth did not differ from parity. A weak seasonal signal in births was detected suggesting increased conceptions during the wet season. Inter-calf intervals and age of primiparity were longer relative to savanna elephant populations. Within the population, females between the ages of 25–39 demonstrated the shortest inter-calf intervals and highest fecundity, and previous calf sex had no influence on the interval. Calf survivorship was high (97%) the first two years after birth and did not differ by sex. Male and female survival began to differ by the age of 13 years, and males demonstrated significantly lower survival relative to females by the age of 20. It is suspected these differences are driven by human selection for ivory. Forest elephants were found to have one of the longest generation times recorded for any species at 31 years. These data provide fundamental understanding of forest elephant demography, providing baseline data for projecting population status and trends. [ABSTRACT FROM AUTHOR]

The transmission of Plasmodium within a vertebrate host population is strongly associated with the life history traits of its vector. Therefore the effect of malaria infection on mosquito fecundity and longevity has traditionally received a lot of attention. Several species of malaria parasites reduce mosquito fecundity, nevertheless almost all of the studies have focused only on the first gonotrophic cycle. Yet, during their lifetime, female mosquitoes go through several gonotrophic cycles, which raises the question of whether they are able to compensate the fecundity costs induced by the parasite. The impact of Plasmodium infection on female longevity is not so clear and has produced conflicting results. Here we measured the impact of Plasmodium relictum on its vector’s longevity and fecundity during three consecutive gonotrophic cycles. In accordance with previous studies, we observed a negative impact of Plasmodium infection on mosquito (Culex pipiens) fecundity in the first gonotrophic cycle. Interestingly, despite having taken two subsequent uninfected blood meals, the negative impact of malaria parasite persisted. Nevertheless no impact of infection on mosquito longevity was observed. Our results are not in line with the hypothesis that the reduction of fecundity observed in infected mosquitoes is an adaptive strategy of Plasmodium to increase the longevity of its vector. We discuss the different underlying mechanisms that may explain our results. [ABSTRACT FROM AUTHOR]

House flies (Musca domestica) are worldwide agricultural pests with estimated control costs at $375 million annually in the U.S. Non-target effects and widespread resistance challenge the efficacy of traditional chemical control. Double stranded RNA (dsRNA) has been suggested as a biopesticide for M. domestica but a phenotypic response due to the induction of the RNAi pathway has not been demonstrated in adults. In this study female house flies were injected with dsRNA targeting actin-5C or ribosomal protein (RP) transcripts RPL26 and RPS6. Ovaries showed highly reduced provisioning and clutch reductions of 94–99% in RP dsRNA treated flies but not in actin-5C or GFP treated flies. Gene expression levels were significantly and specifically reduced in dsRNA injected groups but remained unchanged in the control dsGFP treated group. Furthermore, injections with an Aedes aegypti conspecific dsRNA designed against RPS6 did not impact fecundity, demonstrating species specificity of the RNAi response. Analysis of M. domestica tissues following RPS6 dsRNA injection showed significant reduction of transcript levels in the head, thorax, and abdomen but increased expression in ovarian tissues. This study demonstrates that exogenous dsRNA is specifically effective and has potential efficacy as a highly specific biocontrol intervention in adult house flies. Further work is required to develop effective methods for delivery of dsRNA to adult flies. [ABSTRACT FROM AUTHOR]

Autophagy is a highly conserved mechanism for cellular repair that becomes progressively down-regulated during normal ageing. Hence, manipulations that activate autophagy could increase lifespan. Previous reports show that manipulations to the autophagy pathway can result in longevity extension in yeast, flies, worms and mammals. Under standard nutrition, autophagy is inhibited by the nutrient sensing kinase Target of Rapamycin (TOR). Therefore, manipulations of TOR that increase autophagy may offer a mechanism for extending lifespan. Ideally, such manipulations should be specific and minimise off-target effects, and it is important to discover additional methods for ‘clean’ lifespan manipulation. Here we report an initial study into the effect of up-regulating autophagy on lifespan and fertility in Drosophila melanogaster by dietary addition of Torin1. Activation of autophagy using this selective TOR inhibitor was associated with significantly increased lifespan in both sexes. Torin1 induced a dose-dependent increase in lifespan in once-mated females. There was no evidence of a trade-off between longevity and fecundity or fertility. Torin1-fed females exhibited significantly elevated fecundity, but also elevated egg infertility, resulting in no net change in overall fertility. This supports the idea that lifespan can be extended without trade-offs in fertility and suggest that Torin1 may be a useful tool with which to pursue anti-ageing research. [ABSTRACT FROM AUTHOR]

Integrative taxonomy has resolved the species status of the potentially invasive Ceratitis rosa Karsch into two separate species with distinct ecological requirements: C. rosa “lowland type” and the newly described species Ceratitis quilicii De Meyer, Mwatawala & Virgilio sp. nov. “highland type”. Both species are tephritid pests threatening the production of horticultural crops in Africa and beyond. Studies were carried out by constructing thermal reaction norms for each life stage of both species at constant and fluctuating temperatures. Non-linear functions were fitted to continuously model species development, mortality, longevity and oviposition to establish phenology models that were stochastically simulated to estimate the life table parameters of each species. For spatial analysis of pest risk, three generic risk indices were visualized using the advanced Insect Life Cycle Modeling software. The study revealed that the highest fecundity, intrinsic rate of natural increase and net reproductive rate for C. rosa and C. quilicii was at 25 and 30°C, respectively. The resulting model successfully fits the known distribution of C. rosa and C. quilicii in Africa and the two Indian Ocean islands of La Réunion and Mauritius. Globally, the model highlights the substantial invasion risk posed by C. rosa and C. quilicii to cropping regions in the Americas, Australia, India, China, Southeast Asia, Europe, and West and Central Africa. However, the proportion of the regions predicted to be climatically suitable for both pests is narrower for C. rosa in comparison with C. quilicii, suggesting that C. quilicii will be more tolerant to a wider range of climatic conditions than C. rosa. This implies that these pests are of significant concern to biosecurity agencies in the uninvaded regions. Therefore, these findings provide important information to enhance monitoring/surveillance and designing pest management strategies to limit the spread and reduce their impact in the invaded range. [ABSTRACT FROM AUTHOR]

Ocean warming and acidification (OA) may alter the fitness of species in marine pelagic ecosystems through community effects or direct physiological impacts. We used the zooplanktonic appendicularian, Oikopleura dioica, to assess temperature and pH effects at mesocosm and microcosm scales. In mesocosms, both OA and warming positively impacted O. dioica abundance over successive generations. In microcosms, the positive impact of OA, was observed to result from increased fecundity. In contrast, increased pH, observed for example during phytoplankton blooms, reduced fecundity. Oocyte fertility and juvenile development were equivalent under all pH conditions, indicating that the positive effect of lower pH on O. dioica abundance was principally due to increased egg number. This effect was influenced by food quantity and quality, supporting possible improved digestion and assimilation at lowered pH. Higher temperature resulted in more rapid growth, faster maturation and earlier reproduction. Thus, increased temperature and reduced pH had significant positive impacts on O. dioica fitness through increased fecundity and shortened generation time, suggesting that predicted future ocean conditions may favour this zooplankton species. [ABSTRACT FROM AUTHOR]

Here we determine the sex-specific influence of mtDNA type (mitotype) and diet on mitochondrial functions and physiology in two Drosophila melanogaster lines. In many species, males and females differ in aspects of their energy production. These sex-specific influences may be caused by differences in evolutionary history and physiological functions. We predicted the influence of mtDNA mutations should be stronger in males than females as a result of the organelle’s maternal mode of inheritance in the majority of metazoans. In contrast, we predicted the influence of diet would be greater in females due to higher metabolic flexibility. We included four diets that differed in their protein: carbohydrate (P:C) ratios as they are the two-major energy-yielding macronutrients in the fly diet. We assayed four mitochondrial function traits (Complex I oxidative phosphorylation, reactive oxygen species production, superoxide dismutase activity, and mtDNA copy number) and four physiological traits (fecundity, longevity, lipid content, and starvation resistance). Traits were assayed at 11 d and 25 d of age. Consistent with predictions we observe that the mitotype influenced males more than females supporting the hypothesis of a sex-specific selective sieve in the mitochondrial genome caused by the maternal inheritance of mitochondria. Also, consistent with predictions, we found that the diet influenced females more than males. [ABSTRACT FROM AUTHOR]