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The initial phase in optimizing the efficacy of multiple predators in biocontrol programs involves elucidating their reactions in the presence of heterospecific competitors. Predators sharing the same trophic level may interfere with one another through competition for food resources and engage in internal predation dynamics. This study explored the compatibility of two predatory mite species, Phytoseiulus persimilis, and Neoseiulus californicus, as biocontrol agents targeting Tetranychus urticae. Plants with prey and those with prey plus heterospecifics were used to assess the preference of adult females of the predatory mite competitors. Our results indicated no significant preference by either predatory mite species for plants with spider mites alone or alongside heterospecifics. Additionally, the fecundity rates of both species remained unaffected by the presence of heterospecifics. Notably, N. californicus strongly preferred aggregating eggs on the side with spider mite webs, contrasting with the more random distribution of P. persimilis eggs, although the distribution of eggs on leaf discs was altered in the presence of higher densities of heterospecifics. The total number of eggs of each predator species remained unaffected by the presence of heterospecifics. While our findings suggest compatibility between P. persimilis and N. californicus, which could enhance their combined use in pest management, further field studies are necessary to validate this potential under diverse environmental conditions and pest densities. [ABSTRACT FROM AUTHOR]

Egg-laying decisions by female insects should balance aspects related to immature survival and foraging profitability of emerging larvae. Using field-captured individuals, we characterized the egg distribution of Istocheta aldrichi (Diptera: Tachinidae) on the body of its adult host, the Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae). We determined whether the pattern varies as a function of host sex and the number of eggs laid on a given host. Out of the 5667 eggs observed, 95.9% were located on the host pronotum. Furthermore, eggs on the pronotum were mostly positioned in the center of this sclerite and oriented perpendicular to the host body axis. The proportion of eggs placed on other parts of the host body increased with the number of eggs per host (superparasitism). Successful development of I. aldrichi into pupae was maximum for eggs laid on the host pronotum than for eggs laid on other parts of the host. Oviposition decisions in I. aldrichi are likely shaped by trade-offs between vulnerability to grooming by the host and foraging profitability of neonate larvae (i.e., their capacity to penetrate the host cuticle), but also by the mating and defensive behaviors of the Japanese beetle. [ABSTRACT FROM AUTHOR]

The Adzuki bean beetle (ABB), Callosobruchus chinensis infests and produces several successive generations in stored lentil (Lens culinaris); although all grains are not equally damaged by the insect. Thus, to answer the question why some of the grains are left undamaged, this study was conducted with the objective of determining if the observed difference either as damaged or undamaged in a stored grain is due to the difference in level of resistance to ABB. To achieve this objective a standard choice and no-choice tests were conducted using four lentil genotypes and 0 to 24 h old ABB. The two genotypes were derived from damaged lentil grains by ABB. Lentil genotypes and genotype by age interaction did not affect the number of eggs laid per female per day; the proportion of grains with eggs or holes; eggs per grain, holes per grain and mean developmental time. On the other hand, ABB age significantly affected all the parameters considered. The number of eggs laid per female per day increased from age two to age three and declined thereafter. All parameters but mean developmental time followed a similar patter as the number of eggs per female per day. On the contrary, mean developmental time increased continuously as the age of the ABB increased. This study confirmed that grains left undamaged in bulk stored grain are not resistant to Adzuki bean beetle. [ABSTRACT FROM AUTHOR]

Summary: Internet of underwater things (IoUT) has garnered significant attention for monitoring and exploration applications in underwater scenarios. The interconnected devices used in IoUT have power constraint as batteries are difficult to recharge or replace. Multihop cooperative communication can help reduce the power requirement of a single node by breaking the long distance links into two or more high quality segments. In this paper, we investigate the end‐to‐end average bit error rate (BER) of the multihop underwater relay network. The nodes are connected to each other using optical wireless communication link which provides high data rates with low latency. Closed form expressions for average BER are derived for two scenarios: (1) where every hop channel has the same statistical behavior and (2) each channel is characterized by different statistical behavior. Further, the impact of channel parameters on the system performance is analyzed and discussed. [ABSTRACT FROM AUTHOR]

This paper presents the Hybrid and Self-Adaptive Differential Evolution algorithms (HSADE) to solve an egg distribution problem in Thailand. We introduce and formalize a model for a multi-product, multi-depot vehicle routing problem with a time window, a heterogeneous fleet and inventory restrictions. The goal of the problem is to minimize the total cost. The multiple products comprise customers' demands with different egg sizes. This paper presents a Mixed Integer Linear Programming (MILP) model, an initial solution-based constructive heuristic, a new self-adaptive mutation strategy, and a neighborhood search structure with the probability to improve DE. The two measurements of criteria are the heuristic performance (HP) compared with the solution obtained by MILP and the relative improvement (RI) of the solution compared with Thailand's current egg distribution practice. The computational results show that the performance of HSADE is better than the current practice, and HSADE can provide on average a 14.13% improvement in total cost. Additionally, our proposed algorithm can be applied to similar agriculture logistics in Thailand and worldwide. [ABSTRACT FROM AUTHOR]

This paper presents the Hybrid and Self-Adaptive Differential Evolution algorithms (HSADE) to solve an egg distribution problem in Thailand. We introduce and formalize a model for a multi-product, multi-depot vehicle routing problem with a time window, a heterogeneous fleet and inventory restrictions. The goal of the problem is to minimize the total cost. The multiple products comprise customers’ demands with different egg sizes. This paper presents a Mixed Integer Linear Programming (MILP) model, an initial solution-based constructive heuristic, a new self-adaptive mutation strategy, and a neighborhood search structure with the probability to improve DE. The two measurements of criteria are the heuristic performance (HP) compared with the solution obtained by MILP and the relative improvement (RI) of the solution compared with Thailand’s current egg distribution practice. The computational results show that the performance of HSADE is better than the current practice, and HSADE can provide on average a 14.13% improvement in total cost. Additionally, our proposed algorithm can be applied to similar agriculture logistics in Thailand and worldwide.

Pagellus bogaraveo (Brünnich) and P. erythrinus (L.) (Perciformes, Sparidae) are highly appreciated by Mediterranean consumers and good candidates for the Mediterranean aquaculture diversification. Parasitological and histological analyses of both sparid species, collected off Santa Pola (Spanish Mediterranean), have been performed in order to detect blood flukes (Trematoda, Aporocotylidae) and the pathologies related to their presence in these valuable hosts. Eggs of two different species of Skoulekia Alama-Bermejo, Montero, Raga and Holzer, 2011 have been found in both fishes: S. erythrini Palacios-Abella, Georgieva, Mele, Raga, Isbert, Kostadinova and Montero, 2017 in P. erythrinus and S. bogaraveo n. sp. in P. bogaraveo . Both parasite species showed differences in egg distribution inside the host gill vessels apparently related to their different sizes. The adult blood flukes were also located in specific microhabitats in the host such as the kidney, heart, gills, in the case of S. erythrini , and the brain in the case of S. bogaraveo n. sp. The distribution of each species implies alterations at different host areas, probably leading to different pathologies. Morphological and molecular studies support the specific identity of S. bogaraveo n. sp. The new species differs in its slender body, more conspicuous and lobed testis and the shorter and less numerous tegumental spines. Highly transmission rates and pathogenic potential of this species suggest considering aporocotylidoses as possible emerging diseases for the culture of these sparid species. [ABSTRACT FROM AUTHOR]

1. Leafminer larvae are sedentary and make feeding tracks called mines. Their spatial distribution in trees affects their growth and survival through interaction with the heterogeneity of environments, such as leaf traits and microclimate. Lepidopteran leafminers that mine lower leaf surfaces have shown evolutionary radiation, suggesting that lower surfaces improve leafminer performance. 2. The lepidopteran multivoltine leafminer Phyllocnistis sp. Zeller ( Gracirallidae: Phyllocnistinae) uses the Japanese privet Ligustrum japonicum Thunb. ( Oleaceae). It mines only the lower-surface epidermal layer of primary shoot leaves early in the occurrence season, but once lammas shoots appear, which happens in seasons other than spring, it preferentially uses the lower surface, but also uses the upper surface of the leaves. This study examined whether selection of oviposition sites was associated with the structural traits and microclimate of the leaf surface. 3. The shift of oviposition site from primary to lammas shoot leaves followed increasing hardness and epidermal cell wall thickness of primary shoot leaves during leaf development, and mine initiation rates decreased below 20% after oviposition on mature primary shoot leaves. Preference for the lower surface was related to the thinner cuticle. However, the thinner cuticle of the upper surface on lammas shoot leaves allowed Phyllocnistis sp. to expand its mining sites to both surfaces with no decrease in mine initiation and emergence rates. 4. Microclimates (leaf surface and mine temperatures) did not differ between upper and lower surfaces, suggesting that microclimate did not affect oviposition site selection by Phyllocnistis sp. These results suggest that the adaptive radiation of lower-surface mining may have been influenced by the leaf surface characteristics. [ABSTRACT FROM AUTHOR]

Cisco Coregonus artedi , a historically abundant and commercially important fish in the Great Lakes, have declined drastically in the last century due to the impacts of invasive species, overfishing, and habitat degradation. Chaumont Bay, New York is believed to contain one of the last remaining spawning populations of cisco in Lake Ontario although direct evidence of spawning has remained elusive. We document cisco spawning in Chaumont Bay for the first time in decades through the use of an egg pumping device specifically developed to sample through lake ice. Forty-one eggs were identified as cisco using genetic barcoding of the mitochondrial cytochrome c oxidase I (COI) gene. Cisco eggs were associated with shallow, rocky shoals. Contemporary knowledge of spawning behavior is an important step toward the successful restoration of cisco in Lake Ontario and across the Great Lakes. [ABSTRACT FROM AUTHOR]

Aphelinus asychis Walker (Hymenoptera: Aphelinidae) is a solitary koinobiont endoparasitoid, which parasitizes the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). Host discrimination is the ability of a parasitoid to distinguish between unparasitized and parasitized hosts, so parasitoids can avoid wasting eggs and time. We determined the influence of host density (5, 10, 15, 20, and 25 aphids per experienced parasitoid during a 24-h period) on egg distribution, and tested the effects of different time intervals (0, 24, 48, and 72h) between successive ovipositions on host discrimination between unparasitized and self- or conspecific-parasitized aphids. The results demonstrated that superparasitism decreased with increasing host density. Egg distributions were nonrandomat all host densities, and the observed number of self-superparasitized hosts was lower than expected at all host densities. At 0-h interval, most parasitoids used only antennation to examine and reject parasitized aphids, which might be associated with an external marker. At longer time intervals (≥24 h), A. asychis most often used antennation followed by ovipositor insertion to examine and reject previously parasitized aphids, probably responding to an internal, from chemical substances injected during the first oviposition or changes in host quality associated with parasitism. The results showed that host discrimination in A. asychis was mediated by two consecutive cues, the first external and the second internal, with the relevancy of each depending on the time interval between two ovipositions. Consequently, A. asychis was able to discriminate between unparasitized and self- or conspecific-parasitizedM. persicae, but always engaged in some superparasitism. [ABSTRACT FROM AUTHOR]

• New model for parasitoid functional response. • Controls for non parasitised host depletion in parasitoids. • Unifies Holling's disk equation and Rogers' random predator and parasite model. • Allows for non-sequential host search. • Models superparasitism and egg distribution. A new model of host depletion in the functional response of parasitoids is presented. Most existing models describe the dynamics of prey consumption as a sequential-memoryless/Markovian process of searching for, handling, and consuming prey, but the feeding interaction between a parasitoid and its host is different. One of the most important characteristics is that the host is not consumed, and remains in the arena. On the other hand, functional response models of solitary parasitoids assume that each host can accommodate an infinite number of oviposition events without being killed or becoming unsuitable as a host without the parasitoid noticing it. As a consequence, host depletion is never considered in parasitoid functional response models. To solve that issue, we extended the traditional random predator and random parasitoid functional response models of Rogers into a compartmental model formulated with ordinary differential equations, to group hosts with a different number of attacks to simulate how the parasitoid spreads the attacks between already parasitized and non-parasitized hosts. This model was further modified to simulate non-sequential memoryless search, handling and oviposition. We studied the behaviour of these models to understand how a variation of their parameters led to different shapes of functional response curves and statistical distributions of the number of parasitoid eggs laid per host. The results showed that the expected curves differ from those predicted by the simpler Holling's disk equation (type II functional response), random parasitoid models (no depletion), and the random predator model (proportional depletion). Finally, the non-sequential-memoryless models predict straight curves resembling a type I functional response at low host densities. [ABSTRACT FROM AUTHOR]

Abstract: The functional value of spawning habitats makes them critically important for the completion of fish life cycles and spawning grounds are now considered to be “essential habitats”. Inter-annual fluctuations in spawning ground distributions of dab (Limanda Limanda), plaice (Pleuronectes platessa), cod (Gadus morhua) and whiting (Merlangius merlangus) were investigated in the southern North Sea and eastern English Channel, from 2006 to 2009. The preferential spawning habitats of these species were modelled using generalised linear models, with egg distribution being used as proxy of spawners' location. Egg spatial and temporal distributions were explored based on six environmental variables: sea surface temperature and salinity, chlorophyll a concentration, depth, bedstress and seabed sediment types. In most cases, egg density was found to be strongly related to these environmental variables. Egg densities were positively correlated with shallow to intermediate depths having low temperature and relatively high salinity. Habitat models were used to map annual, i.e. 2006 to 2009, winter spatial distributions of eggs, for each species separately. Then, annual maps were combined to explore the spatial variability of each species' spawning grounds, and define recurrent, occasional, rare and unfavourable spawning areas. The recurrent spawning grounds of all four species were located in the south-eastern part of the study area, mainly along the Dutch and German coasts. This study contributes knowledge necessary to the spatial management of fishery resources in the area, and may also be used to identify marine areas with particular habitat features that need to be preserved. [Copyright &y& Elsevier]

The oviposition behaviour of Plutella xylostella L. (Lepidoptera: Plutellidae) on Chinese cabbage ( Brassica rapa L. Pekinensis, cv. Wombok), canola ( Brassica napus L. cv. Thunder TT), and cabbage ( Brassica oleracea L. Capitata, cv. sugarloaf) (Brassicaceae) was studied in the laboratory. In no-choice experiments moths laid most eggs on the stems and lower three leaves of cabbage plants, the lower three leaves of canola plants, but on the upper three leaves of Chinese cabbage plants. The effects of conspecific herbivore damage to foliage could be replicated by mechanical damage. When foliage was damaged, injured cabbage and canola plants were preferred for oviposition over intact conspecifics, whereas injured Chinese cabbage plants were less preferred than intact conspecifics. However, when root tissue was damaged, intact cabbage and canola plants were preferred over injured conspecifics, whereas moths did not discriminate between root-damaged and intact Chinese cabbage plants. Injury to upper leaves significantly affected the intra-plant distribution of eggs. In cabbage and canola plants, injury to leaf 6 significantly increased the number of eggs laid on this leaf, resulting in a significant decrease in the number of eggs laid on the lower foliage/stem of plants, whereas in Chinese cabbage plants it significantly decreased the number of eggs laid on leaf 6. Following oviposition on intact plants, neonate larvae established the vast majority of feeding sites on leaves 5-8 in all three host plants, indicating that larvae moved a considerable distance from preferred oviposition sites in cabbage and canola plants. The growth rate of neonates fed on leaf-6 tissue was significantly greater than that of those fed on leaf-1 tissue; >90% of larvae completed development when fed exclusively on leaf-6 tissue but no larvae completed development when fed exclusively on leaf-1 tissue. The study demonstrates the complex and unpredictable interactions between P. xylostella and its host plants and provides a basis from which we can begin to understand observed distributions of the pest in Brassica crops. [ABSTRACT FROM AUTHOR]

The effects of competition on populations of the bean weevil Zabrotes subfasciatus were analyzed during 41 generations under different competition levels. Three competition environments were established by maintaining the number of couples (6) and varying the amount of available host seeds: HC, high (limited availability of host: 1.35 g); IC, intermediate (intermediate availability of host: 6 g); and LC, low competition (abundance of host: 36 g). It was found that the distribution of the eggs laid on grains was different among treatments: in LC, for example, although females showed high fecundity (35.4 ± 5.6 eggs/female) the number of eggs laid on each grain was small (1.2 ± 0.4 eggs on each seed), thus avoiding larval competition of their offspring; whereas in HC treatment, females showed low fecundity (27.04 ± 4.5 eggs/female) but laid many eggs on each grain (15.03 ± 4.3 eggs). There were no changes in the ability to respond to different amounts of host via oviposition behavior (egg distribution) during 41 generations. However, HC females had more offspring than LC females under HC conditions. This suggests that HC insects evolved toward higher fitness in crowded conditions. In addition, after inverting the competition level, insects behaved independently of the treatment conditions they experienced through generations, thus showing that oviposition behavior is flexible. Taken together, our results show that Z. subfasciatus presents a broad range of behavioral and physiological responses which allows for quick and reversible adjustments to sudden changes in the amount of resources. [ABSTRACT FROM AUTHOR]

Fish eggs collected in the West Mariana region of the western North Pacific (7°–18°N, 137°–144°E) were identified using mitochondrial 16S ribosomal RNA (16S rRNA) gene sequences, and their morphology and distribution were analyzed. Of the 5,321 eggs collected, 2,698 live eggs were morphologically divided into 108 types based on the character of shape, diameter, chorion, oil globule, pigmentation, yolk segmentation and perivitelline space. Excluding 20 types of formalin preserved eggs, partial sequences of 16S rRNA gene (1,019–1,190 base pairs) obtained for all remaining 88 types of ethanol preserved eggs were compared with sequences deposited in the DDBJ/EMBL/GenBank using Basic Local Alignment Search Tool. This resulted in 16 species being genetically identified and their morphological characters were observed including the first description of the eggs of three species, Ventrifossa garmani, Diodon hystrix, and Scopelogadus mizolepis. Distribution analysis showed that 52–100% eggs of eight species, Katsuwonus pelamis, D. hystrix, S. mizolepis, Thunnus spp., Xiphias gladius, Cepalopholis spp., Naso spp. and V. garmani were collected around seamounts of the West Mariana region, whereas the other eight species, Lampris guttatus, Oxyporhamphus micropterus, Ranzania laevis, Istiophorus platypterus, Exocoetidae spp., Lactoria diaphana, Tetrapturus angustirostris and Regalecus glesne showed no tendency to be concentrated around the seamounts and were widely distributed through the study area. These distributional patterns of eggs appeared to correspond well with the life histories of each species. The present study suggests that DNA species identification can provide a significant new tool for ecological studies on fish eggs. [ABSTRACT FROM AUTHOR]

The article presents a study that investigates the fitness of the egg-spreading strategy during partial clutch loss. The article states that optimal fitness is achieved when eggs are in large clutches due to the dilution of predator risk. It also discusses how fitness of egg-distribution strategies vary with the rate of predation, the frequency of partial clutch loss, and the damages of partial predation. According to the article, nest parasitism could increase with the egg-distribution strategy.

Stage-dependent spatial distributions of anchovy Engraulis encrasicolus, sardine Sardinops sagax and round herring Etrumeus whiteheadi eggs over the western Agulhas Bank South Africa were examined from samples collected at a fine-scale (1.8 km) resolution using a continuous underway fish egg sampler (CUFES). Spatial structure in egg distributions was assessed using variograms for three developmental stage groups (early-, middle- and late-stage eggs), and indices of aggregation were also computed for those stage groups. No early- or middle-stage anchovy eggs were collected, but indices of aggregation showed that early-stage sardine eggs were more aggregated than those of round herring, suggesting that adult sardine have a more contiguous distribution during spawning than have round herring. Middle-stage eggs were equally aggregated, whereas late-stage eggs were aggregated differently in all three species. Fitted empirical variograms showed that early-stage sardine eggs have low small-scale variability (nugget effect) (⩽10% of total variance) compared with round herring eggs (⩾50% of total variance). The autocorrelation range of both those species extends to 3.7 km. Middlestage sardine eggs have a low nugget effect (⩽10%) compared with round herring eggs (⩽50%), with autocorrelation ranges of 7.4 km and 5.6 km respectively. Late-stage anchovy eggs have a lower nugget effect (⩽20%) than that of sardine (⩽50%) and round herring (⩾100%) eggs, with autocorrelation ranges of 3.7 km for all three species. The spatial structures of the eggs of the three species were heterogeneous at the sampling scale used, indicating differences in spatial organisation of the adults during spawning. The spatial variability of the eggs of the three species is not well captured using the sampling strategy during current ichthyoplankton surveys in the southern Benguela, in which stations are spaced 18.5 km apart. [ABSTRACT FROM AUTHOR]

Abstract: Data on the occurrence of sardine (Sardina pilchardus) eggs from 42 national ichthyoplankton surveys along the European Atlantic coast were collated in order to describe the spawning habitat and spawning distribution of sardine in recent decades (1985–2005). A modification of existing spawning habitat characterisation techniques and a newly developed method to compare the probability of egg presence across surveys carried out with different sampling gears were used. Results showed that sardine spawning off the Atlantic European coast is mainly restricted to the shelf area, with the main geographical range being between the Strait of Gibraltar (the southern limit of data available for this analysis) and the middle part of the Armorican shelf (latitude around 47.5° North), and along a temperature range of 12–17°C. Spawning grounds within these limits show a nearly continuous geographical distribution, covering a large proportion of the shelf of the Iberian peninsula and adjacent waters, except for: (1) a persistent gap at the north west corner of the Iberian peninsula, (2) a small secondary break at the Spanish–French border in the inner part of the Bay of Biscay and (3) at the south west corner of the peninsula where there is a narrowing of the shelf width. These discontinuities were used to separate spawning into four nuclei and to describe the changes in spawning distribution in the time series. The relative importance of each nucleus and the degree of separation between adjacent nuclei varies between years, with the exception of the permanent gap at the northwest corner of the Iberian peninsula, which is persistent throughout the time series. Year to year changes in the proportion of the potential spawning habitat in which spawning actually occurred, changing from around 60% before the mid 1990s to around 40% thereafter, and did not show any relationship with spawning stock biomass. Evolution of potential habitat occupation over the Armorican shelf shows larger variability than that observed in the Iberian peninsula, with percentages of occupation ranging from around 30% up to nearly 80% of the shelf in recent years (within the limitations of the relatively sparse data for this region). [Copyright &y& Elsevier]

Ophelimus maskelli (Ashmead) (Hymenoptera: Eulophidae), an invasive species in the Mediterranean area that occurs naturally on Eucalyptus camaldulensis at Wagga Wagga in New South Wales, was studied in Israel on the same host plant. The most distinctive characteristic of O. maskelli as compared with other congeners is the presence of only a single seta on the submarginal vein. O. maskelli shows a clear tendency to oviposit in developed, immature leaves, and it prefers to oviposit on an area of the leaf blade near the petiole. The female lays an average of 109 eggs when maintained on water alone. The egglaying distribution tended towards aggregation, and the same tendency has also been observed within and among trees. The wasp prefers to attack the lower canopy. The gall diameter ranged from 1.2 to 0.9 mm, and gall density from 11.5 to 36.0 galls cm−2, respectively. The typical color of the gall appeared as soon as third instar larva developed. Galls on shaded leaves remained green or greenish-yellow, whereas those that were exposed to the sun were reddish. O. maskelli produces three generations per year in Israel. High flight occurs among the spring generations, starting in early March. The wasps were attracted to green sticky plates much more than to the other tested colors. Heavy galling by O. maskelli results in premature shedding of the leaves, soon after the emergence of the wasps. Among the 84 eucalyptus species tested, the following 14 species were found to be suitable hosts: E. botryoides, E. bridgesiana, E. camaldulensis, E. cinerea, E. globulus, E. gunii, E. nicholii, E. pulverulenta, E. robusta, E. rudis, E. saligna, E. tereticornis and E. viminalis. This study focused on morphological and development characters that can clearly distinguish O. maskelli from Ophelimus eucalypti Gahan, and on examining the effect of crossing between eucalyptus species on the development possibilities of the wasps. Also considered were the effect of the food on adult survival, the competition between the eulophid gall maker Leptocybe invasa Fisher & LaSalle and O. maskelli, the heavy damage inflicted on eucalyptus, and the health problems and nuisance to people caused by the wasp near heavily infested trees during the mass emergence of adults. [ABSTRACT FROM AUTHOR]

Indianmeal moth, Plodia interpunctella (Hübner), is one of the most important pests in retail stores and processed food facilities, but little is known about its ovipositional response to varying sizes and qualities of food sources. In this study, we monitored oviposition for 48 hours divided into 16 consecutive 3-h intervals, and found that, on average, P. interpunctella females laid eggs 6.4 times. We found a positive correlation between number of oviposition events and total oviposition. We conducted laboratory experiments to examine the distribution of eggs laid by P. interpunctella females in dishes that varied in size and number. Experiments were conducted with "improved" food (cracked or walnut oil-treated wheat kernels) and "control" food (plain untreated wheat kernels). In trials with dishes of two different sizes, P. interpunctella females seemed to distribute eggs according to the surface area of dishes regardless of the food. In trials with improved food, total oviposition was positively associated with the number of dishes, whereas the number of control dishes had no apparent effect on total oviposition. In trials with one improved food dish and one to eight control food dishes, P. interpunctella females consistently preferred oil-treated wheat kernels, whereas they showed no preference for cracked wheat kernels. Using an index of randomness (Dp), we demonstrated that the distribution of eggs was significantly different from a Poisson distribution, thus indicating that it was nonrandom, regardless of the number of dishes. Using an index of aggregation (Im2), we showed that for all the foods, the distribution of eggs became increasingly aggregated with higher numbers of dishes and that this trend was most pronounced in trials with improved foods. [ABSTRACT FROM AUTHOR]

Studies the egg distributions of Drosophila solitary larval parasitoids. Mean number of eggs in a host; Maximum likelihood of the observed egg distribution; Probability of superparasitism; Egg laying behavior of the parasitoids.

Approximately three decades ago the question was first answered “whether parasitoids are able to assess the number or origin of eggs in a host” for a solitary parasitoid, Leptopilina heterotoma, by fitting theoretically derived distributions to empirical ones. We extend the set of different theoretically postulated distributions of eggs among hosts by combining searching modes and abilities in assessing host quality. In the models, parasitoids search either randomly (Poisson) (1) or by vibrotaxis (Negative Binomial) (2). Parasitoids are: (a) assumed to treat all hosts equally, (b) able to distinguish them in unparasitised and parasitised hosts only, (c) able to distinguish them by the number of eggs they contained, or (d) able to recognise their own eggs. Mathematically tractable combinations of searching mode (1 and 2) and abilities (a,b,c,d) result in seven different models ( M1 a, M1 b, M1 c, M1 d, M2 a, M2 b and M2 c). These models have been simulated for a varying number of searching parasitoids and various mean numbers of eggs per host. Each resulting distribution is fitted to all theoretical models. The model with the minimum Akaike's information criterion ( AIC) is chosen as the best fitting for each simulated distribution. We thus investigate the power of the AIC and for each distribution with a specified mean number of eggs per host we derive a frequency distribution for classification. Firstly, we discuss the simulations of models including random search ( M1 a, M1 b, M1 c and M1 d). For M1 a, M1 c and M1 d the simulated distributions are correctly classified in at least 70% of all cases. However, in a few cases model M1 b is only properly classified for intermediate mean values of eggs per host. The models including vibrotaxis as searching behaviour ( M2 a, M2 b and M2 c) cannot be distinguished from those with random search if the mean number of eggs per host is low. Among the models incorporating vibrotaxis the three abilities are detected analogously as in models with random search. Experiments with two species of solitary parasitoids ( L. heterotoma and Asobara tabida) are conducted. All theoretically postulated distributions are separately fitted to the resulting experimental egg distributions. The AIC criterion is used to choose the best fitting theoretical distribution. For both parasitoid species the frequency distribution of best fitting models for experimental data is compared to the classification of distributions generated by simulations. This leads to the conclusion that both L. heterotoma and A. tabida are able to distinguish between parasitised and unparasitised hosts. For L. heterotoma the results point to an ability to assess the number of eggs in a host, whereas A. tabida does not seem to have this ability. This difference suggests that an egg is more valuable for L. heterotoma than for A. tabida. [ABSTRACT FROM AUTHOR]

The locations and timing of plaice Pleuronectes platessa spawning around the Isle of Man were studied from distributions of recently spawned eggs recorded in plankton samples. The area of intense spawning activity south-east of the Isle of Man was found to be further north than indicated in the literature. A previously disregarded spawning ground off the west coast of the Isle of Man was identified in 1991, 1992 and 1993, although egg densities were lower than off the east coast. Production of stage I eggs on the west coast spawning site was estimated at approximately 2% of the total plaice egg production in the Irish Sea. This would be sufficient to supply the local nursery grounds on the west coast of the Isle of Man with plaice larvae. Plaice spawned between early February and early April off the west coast of the Isle of Man, with March as the main period of egg production. Plaice therefore spawn well before the spring plankton bloom in the Irish Sea. [ABSTRACT FROM PUBLISHER]

Aphelinus asychis Walker (Hymenoptera: Aphelinidae) is a solitary koinobiont endoparasitoid, which parasitizes the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). Host discrimination is the ability of a parasitoid to distinguish between unparasitized and parasitized hosts, so parasitoids can avoid wasting eggs and time. We determined the influence of host density (5, 10, 15, 20, and 25 aphids per experienced parasitoid during a 24-h period) on egg distribution, and tested the effects of different time intervals (0, 24, 48, and 72 h) between successive ovipositions on host discrimination between unparasitized and self- or conspecific-parasitized aphids. The results demonstrated that superparasitism decreased with increasing host density. Egg distributions were nonrandom at all host densities, and the observed number of self-superparasitized hosts was lower than expected at all host densities. At 0-h interval, most parasitoids used only antennation to examine and reject parasitized aphids, which might be associated with an external marker. At longer time intervals (≥24 h), A. asychis most often used antennation followed by ovipositor insertion to examine and reject previously parasitized aphids, probably responding to an internal, from chemical substances injected during the first oviposition or changes in host quality associated with parasitism. The results showed that host discrimination in A. asychis was mediated by two consecutive cues, the first external and the second internal, with the relevancy of each depending on the time interval between two ovipositions. Consequently, A. asychis was able to discriminate between unparasitized and self- or conspecific-parasitized M. persicae, but always engaged in some superparasitism., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Aedes albopictus (Skuse) is a container-breeding species with considerable public health importance. To date, Ae. albopictus oviposition behavior has been assessed in outdoor conditions, but only with laboratory-reared specimens. In outdoor large-cage and field studies, we used an attractive self-marking ovipositional device to assess Ae. albopictus skip oviposition behavior. In field studies, 37 wild Ae. albopictus that visited an attractive self-marking ovisite were subsequently captured at a sticky ovitrap within a 4-d period. Because the average Ae. albopictus gonotrophic period is 4.5-6 d, the wild-caught Ae. albopictus visited at least two oviposition sites within a single gonotrophic period. This provided field-based indirect evidence of skip oviposition. The mean distance traveled (MDT) during the 20-d evaluations ranged from 58 to 78 m. The maximum observed distance traveled was 149 m, which was the outer edge of our trapping ability. As populations of Ae. albopictus increased, the MDT during the 4- and 20-d post-marking period increased significantly. Additional observations of wild-marked and captured Aedes triseriatus (Say) are discussed., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)