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The swallow-wort biological control agent, Hypena opulenta, undergoes facultative diapause mediated by photoperiod. However, some individuals enter diapause even at long daylengths, resulting in univoltine populations in the field and reducing the efficiency of rearing programmes. Through laboratory experiments, we identified a strong positive correlation between pupal weight and early diapause. Additionally, we compared two metrics of reproductive preparedness (female egg-load and male lipid stores) between first (diapausing) and second (continuously developing) summer generations. Females had higher egg-loads in the second generation than the first. Generational polyphenisms, combined with early diapause, may exacerbate slow population growth by Hypena opulenta. [ABSTRACT FROM AUTHOR]

We explored how the ratio of blood‐feeding behaviour—nonfeeding, bird feeding (ornithophily) and mammal feeding (mammalophily)—and voltinism (univoltine and multivoltine) vary over a latitudinal gradient from Alaska to Florida. These two fixed species traits were divided into five mutually exclusive combinations of trait states—nonfeeding/univoltine, ornithophilic/univoltine, mammalophilic/univoltine, ornithophilic/multivoltine and mammalophilic/multivoltine—within each of three datasets (north, east and west). We found a significant association between location (north, east and west) and trait state, which was driven by the large percentage of nonfeeding females in the north. When this trait state was removed, no significant differences were found for the remaining trait states and locations. Although the distribution of trait states did not differ between east and west datasets, the distribution with relation to 1° changes in latitude within each of these datasets showed distinct differences. In the east, both ornithophilic/univoltine and mammalophilic/univoltine species significantly increased with latitude, in proportion to the total species present. In contrast, the proportion of mammalophilic/multivoltine species decreased as latitude increased. Ornithophilic/multivoltine species in the east and the trait states in the west did not show any significant relationship to latitude. [ABSTRACT FROM AUTHOR]

Summary Societal impact statement The European spruce bark‐beetle, Ips typographus, is a major pest of Norway spruce across mainland Europe; however, until 2018, it was considered absent from the United Kingdom (UK). The finding of a breeding population of I. typographus in Kent, England, in 2018 and subsequent findings in pheromone traps across the southeast of England, has led to an urgent need to improve understanding of environmental suitability across the UK. Two distinct published phenological models for I. typographus, developed in Sweden and Austria, were adapted for use in the UK and validated against pheromone trap data collected at the original site of infestation and in the surrounding area from 2019 to 2022. Both models captured some, but not all, of the within‐season variation in trap catches. One, the PHENIPS model, more accurately captured early season flight patterns. The climate in the southeast of England is mild enough to facilitate two generations of the beetle, while further north the pest is expected to be univoltine. At high altitude in Scotland, there is insufficient thermal warming within a season for the completion of one annual generation. Phenological modelling does not explain why the pest failed to establish in England prior to 2018 including when a large amount of infested material was imported to sawmills in the 1940s. Under 2 and 3°C global warming scenarios, we might expect to see an increase in potential voltinism across the UK in the next few decades, increasing the risk of large outbreaks of I. typographus were it allowed to establish. In 2018, a breeding population of the European spruce bark‐beetle, Ips typographus, was discovered in woodland in southeast England. Ips typographus is a major forest pest in continental Europe; however, despite previous findings at ports and sawmills, this was the first recorded infestation in the UK. The number of generations per year (voltinism) varies with latitude and altitude. Applying a phenological model, we find that the current climate in southern UK could support two generations, while temperature accumulation in parts of Scotland may be insufficient to support one generation. Global warming will increase voltinism and hence the risk of establishment. [ABSTRACT FROM AUTHOR]

The impact of climate change on forests is difficult to predict, as it depends on multiple factors and the final effect may vary in different parts of our planet. However, these effects can be sorted in "direct", when they act directly on plants, and "indirect", when they act through other agents. Among the indirect ones, there are those mediated by biotic factors, particularly insect pests. The impact of climate change on insect pests varies depending on the insect species and the type of forest. Some plant-feeding insects may be disfavoured by climate change, with a consequent reduction in population density and thus in damage to forests. However, many outbreaks of forest insects have been recently recorded as related to climate change. In fact, some insect pests, in certain regions of the world, may benefit from higher temperatures, as it has been demonstrated for some devastating defoliators. In addition, more frequent drought and extreme events may favour other pests, particularly bark beetles and wood-boring insects. Bark beetles are the most dangerous ones because their aggressiveness changes with population density. They can attack only stressed trees at low population densities, while, once the populations have reached high density, they are even able to attack healthy trees in widespread areas. [ABSTRACT FROM AUTHOR]

During the last two decades there has been growing recognition of the importance of Allee effects in population dynamics and applied ecology. The Allee effect, that is decreased fitness at lower population densities, has been recognized as potentially playing an important role in the conservation of endangered species, in the practice of biological control, and the eradication of invasive species. Although a number of theoretical studies have been devoted to the role of Allee effects in the population dynamics of insects and other terrestrial arthropods, experimental evidence documenting Allee effects is still scarce. Here, we reviewed the literature reporting on density-dependent relationships in low-density populations and conducted a meta-analysis of 191 case studies to identify the occurrence of Allee effects and associated species traits. Allee effects are not rare in terrestrial arthropods, as they were reported in 47% of the cases we reviewed, comprising 46 out of 68 species. Ample examples exist for both demographic Allee effects (28 out of 74 cases cases), and component Allee effects (61 out of 117 cases). Insufficient mating success, cooperative feeding, and enemy escape were the three main mechanisms associated with Allee effects in terrestrial arthropods. Insufficient reproductive success was the mechanism with the highest proportion of related Allee effects (71%). Voltinism and host specialization were common species traits behind demographic Allee effects. Host specialists with univoltine life cycles tended to have stronger Allee effects. The high frequency of Allee effects in terrestrial arthropods reported here and the identified mechanisms behind them have important implications for the selection of management strategies. [ABSTRACT FROM AUTHOR]

Thermal regimes of aquatic ecosystems are predicted to change as climate warming progresses over the next century, with high‐latitude and high‐elevation regions predicted to be particularly impacted. Here, we have modelled alpine stream water temperatures from air temperature data and used future predicted air temperature trajectories (representative concentration pathway [rcp] 4.5 and 8.5) to predict future water temperatures. Modelled stream water temperatures have been used to calculate cumulative degree days (CDDs) under current and future climate conditions. These calculations show that degree days will accumulate more rapidly under the future climate scenarios, and with a stronger effect for higher CDD values (e.g., rcp 4.5: 18–28 days earlier [CDD = 500]; 42–55 days earlier [CDD = 2000]). Changes to the time to achieve specific CDDs may have profound and unexpected consequences for alpine ecosystems. Our calculations show that while the effect of increased CDDs may be relatively small for organisms that emerge in spring–summer, the effects for organisms emerging in late summer–autumn may be substantial. For these organisms, the air temperatures experienced upon emergence could reach 9°C (rcp 4.5) or 12°C (rcp 8.5) higher than under current climate conditions, likely impacting on the metabolism of adults, the availability of resources, including food and suitable oviposition habitat, and reproductive success. Given that the movement of aquatic fauna to the terrestrial environment represents an important flux of energy and nutrients, differential changes in the time periods to achieve CDDs for aquatic and terrestrial fauna may de‐couple existing predator–prey interactions. [ABSTRACT FROM AUTHOR]

Recently, an outbreak of Ips sexdentatus (Börner, 1776) has caused considerable damage in the pine forests of the Czech Republic. As historical data on the biology of this pest are scarce due to its rare occurrence in recent decades, our work focused on monitoring flight activity and voltinism and investigating methods for monitoring its activity during the growing season. Observations were conducted from March to September 2021 and 2022 at three sites using 12 Theysohn traps with four types of pheromone lures (ACUMIPROTECT, ACUWIT, SEXOWIT and Pheagr IAC) together with data loggers to record weather conditions. The first beetles occurred in early May (daily mean temperatures above 13 °C). After the first egg laying stage, females re-emerged to establish a sister brood. The maximum flight activity appeared between late June and mid-July (daily mean temperatures about 20 °C), and the offspring occurred at the turn of June/July and in the first half of August. Since then, flight activity had a downward trend and quietened in September. According to the data, monitoring of I. sexdentatus should be conducted between May and September using the ACUMIPROTECT pheromone bait exhibiting the highest capturing efficacy. In future, however, the behavior of I. sexdentatus might alter due to climate change. [ABSTRACT FROM AUTHOR]

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We test the hypothesis of Marshall et al. (2013) that in the United States there is a converse Bergmann's cline in body size of Agrilus planipennis (emerald ash borer, EAB), with the largest females (x¯ = 12.6 mm length) collected at the most southern latitudes tested (37° N).In 2020, we employed three techniques to collect EAB at a North Carolina (NC) site located at 35.64° N (purple prism traps [PPTs], log emergence, Cerceris fumipennis biosurveillance). The study was repeated in 2021, but with green funnel traps replacing log emergence. EAB collected by C. fumipennis in three altitudinally disparate regions of NC were also measured.Overall, EAB collected in 2020 averaged 12.02 mm, with those emerged from logs significantly smaller than those from PPTs. Length of females collected from C. fumipennis at three elevations was not significantly different and averaged 12.01 mm. In 2021, females collected from funnel traps, PPTs and C. fumipennis were not significantly different and larger (x¯ = 12.41 mm) than in 2020; eliminating the smaller log‐emerged EAB from the 2020 data set did not change the outcome.Mean EAB size in NC never reached the reported 12.6 mm at 37° N, regardless of the technique or altitude tested. Our expansion of the latitudinal range in which EAB body size has been studied may shift the proposed converse Bergmann's cline to that of a sawtooth or other non‐linear model, likely associated with a transition in EAB voltinism at or near NC latitudes. [ABSTRACT FROM AUTHOR]

The Karner blue butterfly (Lycaeides melissa samuelis) (hereafter Karner blue) is a federally listed endangered species occurring in disjunct locations within the Midwest and Eastern United States. As a hostplant specialist and an ectotherm, the Karner blue is likely to be susceptible to effects of climate change. We undertook warming experiments to explore the temperature sensitivity of various Karner blue life history stages and traits. Over a two-year period, we exposed all Karner blue life stages to temperature increases of + 2, + 4, and + 6 °C above 1952–1999 mean temperatures. We analyzed the effect of these treatments on life history parameters likely related to fitness and population size, including development time, voltinism, degree-day accumulation, body weight, and morphology. Warming treatments resulted in earlier emergence and accelerated development, leading to additional generations. Warming also increased the number of degree-days accumulated during pre-adult development (i.e., egg hatch to eclosion). Results suggest that Karner blues developed in fewer days, in part, by putting on less mass as temperatures increased. As treatment temperature increased, adult body mass, length, and area decreased and voltinism increased. Females with lower adult mass and smaller body size produced fewer eggs. These results suggest a trade-off between accelerated development and decreased body size with decrease in adult mass and abdominal area being associated with reduced fecundity. Implications for insect conservation: Changes in development timing and in voltinism can negatively affect phenological matching between the Karner blue and its obligate host plant, Wild lupine (Lupinus perennis), resulting in population decrease. Poorer phenological matching between insect and hostplant can occur across multiple generations, for example, negatively affecting overwintering population size. With increasing temperatures, smaller females will produce fewer eggs, which can also lead to poorer population outcomes across generations. [ABSTRACT FROM AUTHOR]

Adults of the migratory locust Locusta migratoria (Linnaeus, 1758) were collected in the Japanese Archipelago, which extends from the Ryukyu subtropical region to the Hokkaido cool-temperate region, covering more than 2,500 km. A saw-toothed pattern was observed in body size along the latitudinal or annual mean temperature gradient, which is similar to Masaki's clines initially described for crickets. The latitudinal cline of locusts was also observed in the laboratory, suggesting that this cline was primarily due to genetic variation. In the northern univoltine zone, locust body size increased toward the south. The latitudinal size trend was reversed in the transitional zones where the voltinism shifted from univoltine to bivoltine and from bivoltine to trivoltine life cycles. These patterns may be explained by changes in the length of the growing season for development and reproduction. Body size varied with growth efficiency but not with the variable lengths of nymphal development. Larger females had more ovarioles and produced fatter egg pods containing more eggs per pod. The morphometric ratio, F/C (hind femur length/head width), tended to decrease with latitude, but this characteristic could be primarily due to phylogenetic differences between the northern and southern clades. It was confirmed that F/C ratio decreased when the locusts were reared in a group. The sexual size dimorphism, or SSD, tended to increase as the mean body sizes of populations increased, converse to Rensch's rule. The relative body size of females and males correlated with latitude and was greatly reduced when the insects were reared in a group. The smaller rate of increase at higher latitudes may be related to male-female associations and predation pressure. [ABSTRACT FROM AUTHOR]

The Brown marmorated stink bug (BMSB) [Halyomorpha halys (Hemiptera: Pentatomidae)] is a polyphagous pest causing significant damage to approximately 300 crops, such as nuts, vegetables, and ornamentals. In 2017, the BMSB was discovered for the first time in Türkiye. There is currently no published data available on the biology of the pest in Türkiye. This preliminary study was carried out in Sakarya province, where the BMSB has observed a low population since 2021. In this study, some biological parameters such as voltinism, mortality rates, egg hatching rates, and egg-adult developmental times of the 1st and 2nd generations of the insect populations were determined. The study was carried out under semi-field conditions and laboratory. Considering the BMSB's minimum temperature threshold, which has yet to be determined in Turkey, the accumulation of degree days was calculated using the references to four possible thresholds (DD12, 12.5, 13, 13.5) and was determined to be between 536.91 - 608.69 DD. The average egg-adult developmental time was 47.85 days for the 1st generation at naturally fluctuating temperatures and 47.13 days for the 2nd generation under laboratory conditions at 25 ֯C. The hatching rate of egg masses was determined to 90.63% in the 1st generation and 57.75% in the 2nd generation. Total mortality in the first generation was 22.97% and 90.24% in the second generation. It was revealed that the insect could produce two generations in Türkiye, but the number of egg-producing adults and eggs laid in the second generation was significantly lower than that in the first. This preliminary study was carried out with a limited number of samples due to the initial infesting in the region and, therefore more comprehensive research is needed to reveal the the biology of BMSB in the country.

Recent hot droughts in California resulted in ponderosa pine (Pinus ponderosa) mortality attributed to drought and western pine beetle (WPB, Dendroctonus brevicomis). While drought alone can cause tree death, direct warming effects on WPB are a contributing factor. Research on WPB generation timing (voltinism), however, is lacking.We monitored WPB tree attacks and adult emergence timing at two California sites and developed a degree‐day model from field‐observed data. Historical, contemporary, and future temperatures for several California sites were used with the model to examine trends in WPB voltinism.Field data showed a single summer and an overwinter generation at a northern California site. As summer temperatures increased beyond 1900–1980 averages, the predicted number of full and partial WPB generations by 2021 had increased from ~2 annual (one summer and one overwinter) generations historically to ~2.3 at two northern California sites and from ~2.3 to ~3.2 at two warmer California sites.Historical and contemporary data suggest winter warming was not sufficient for an additional generation overwinter. Instead, increases in generations were driven by summer and fall temperatures.Unconstrained increases in the number of future annual generations will be limited by complex, but not well understood, WPB thermal adaptations. Increased knowledge of temperature‐driven WPB population growth will improve forest vegetation models aimed at predicting ponderosa pine mortality in a changing climate. [ABSTRACT FROM AUTHOR]

As global climate continues to change, so too will phenology of a wide range of insects. Changes in flight season usually are characterised as shifts to earlier dates or means, with attention less often paid to flight season breadth or whether seasons are now skewed. We amassed flight season data for the insect order Odonata, the dragonflies and damselflies, for Norway over the past century‐and‐a‐half to examine the form of flight season change. By means of Bayesian analyses that incorporated uncertainty relative to annual variability in survey effort, we estimated shifts in flight season mean, breadth, and skew. We focussed on flight season breadth, positing that it will track documented growing season expansion. A specific mechanism explored was shifts in voltinism, the number of generations per year, which tends to increase with warming. We found strong evidence for an increase in flight season breadth but much less for a shift in mean, with any shift of the latter tending toward a later mean. Skew has become rightward for suborder Zygoptera, the damselflies, but not for Anisoptera, the dragonflies, or for the Odonata as a whole. We found weak support for voltinism as a predictor of broader flight season; instead, voltinism acted interactively with use of human‐modified habitats, including decrease in shading (e.g. from timber extraction). Other potential mechanisms that link warming with broadening of flight season include protracted emergence and cohort splitting, both of which have been documented in the Odonata. It is likely that warming‐induced broadening of flight seasons of these widespread insect predators will have wide‐ranging consequences for freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Rising temperature can affect forests negatively through its impact on insect pests. The present study focused on two invasive alien insect species (Dryocosmus kuriphilus and Leptoglossus occidentalis) to understand how rising temperature might affect their damage in Turkish forests. For D. kuriphilus, the timing of chestnut budburst, gall induction and emergence of its introduced parasitoid, Torymus sinensis, were monitored between 2015 and 2019, and each phenological event was compared annually with fluctuations in temperature to observe the parasitoid-host synchrony. For L. occidentalis, cumulative degree days (CDD) were calculated, and the possible number of generations produced in 2020 in different regions of Turkey were predicted. The CDD calculations were repeated under increasing temperature and different photoperiod-diapause induction scenarios. Evaluation of the monitoring data on the D. kuriphilus system showed that gall induction occurred at the same time as budburst, whereas T. sinensis emergence was independent from the budburst, and that the parasitoid-host synchrony was disrupted after the abnormally warm winter in 2018. The CDD calculations estimated that L. occidentalis produced one to five generations from north to south in 2020. They also suggested a significant increase in the number of generations in the southern Turkey under temperature increase scenarios. Including photoperiod as a time-limiting factor reduced the highest possible number of generations from five to two. In conclusion, rising temperature has a potential to threaten the biocontrol against D. kuriphilus, and it can increase voltinism in L. occidentalis.

Simple Summary: An evolutionary shift in insect diapause strategy has been revealed in a historically univoltine population of Ostrinia furnacalis, a commonly facultative diapause species. Warmer climates are likely to stimulate facultative individuals in the population to shift from univoltinism to bivoltinism due to the compensatory effect of elevated temperature. Climate warming has driven the population to evolve toward dominantly bivoltine or even trivoltine, further leading to more severe damage. To accurately predict phenology and population dynamics in O. furnacalis, it is imperative to account for both the proportions of different diapause individuals with the population and temperature. Herbivorous insects having variable numbers of generations annually depending on climate and day length conditions are increasingly breeding additional generations driven by elevated temperature under the scenario of global warming, which will increase insect abundance and result in more frequent damage events. Theoretically, this relies on two premises, i.e., either an evolutionary shift to facultative diapause for an insect behaving an obligatory diapause or developmental plasticity to alter voltinism productively for an insect with facultative diapause before shortening photoperiods inducing diapause. Inter-population evidence supporting the premise (theory) comes primarily from a model system with voltinism linked to thermal gradients across latitude. We examined the intra-population evidence in the field (47°24′ N, 123°68′ E) with Ostrinia furnacalis, one of the most destructive pests, on corn in Asia and Pacific islands. The species was univoltine in high latitudinal areas (≤46° N). Divergence of the diapause feature (obligatory and facultative) was observed within the field populations from 2016 to 2021. Warmer climates would provoke more facultative diapause individuals to initiate a second generation, which will significantly drive the population to evolve toward facultative diapause (multi-voltinism). Both divergent diapause and temperature must be considered for accurate prediction of phenology and population dynamics in ACB. [ABSTRACT FROM AUTHOR]

We used European geometrid moths (>630 species) as a model group to investigate how life history traits linked to larval host plant use (i.e., diet breadth and host‐plant growth form) and seasonal life cycle (i.e., voltinism, overwintering stage and caterpillar phenology) are related to adult body size in holometabolous insect herbivores. To do so, we applied phylogenetic comparative methods to account for shared evolutionary history among herbivore species. We further categorized larval diet breadth based on the phylogenetic structure of utilized host plant genera. Our results indicate that species associated with woody plants are, on average, larger than herb feeders and increase in size with increasing diet breadth. Obligatorily univoltine species are larger than multivoltine species, and attain larger sizes when their larvae occur exclusively in the early season. Furthermore, the adult body size is significantly smaller in species that overwinter in the pupal stage compared to those that overwinter as eggs or caterpillars. In summary, our results indicate that the ecological niche of holometabolous insect herbivores is strongly interrelated with body size at maturity. [ABSTRACT FROM AUTHOR]

Secondary production in aquatic insects is a theme of great relevance and insufficiently studied. This topic allows an understanding of the rate variability of biomass by consumers in lotic systems. Plecoptera are one of the most abundant and widely used groups of aquatic insects used in this field. Therefore, the objective of this work was to determine the secondary production of the two dominant species of stoneflies (Anacroneuria marta and A. caraca) in the middle section of the Gaira River (Sierra Nevada de Santa Marta, Colombia). Sampling was carried out every 20 days during a year (14 samplings in total), in the gravel microhabitats in slow current and fast current. The identification of the nymphs was made based on morphological characters and descriptions available in the bibliography. Secondary production was estimated using the length frequency method for unrecognized cohorts. The annual biomass of A. marta was similar to A. caraca (B= 457.41 and B= 432.28 mg/m², respectively). The annual production of A. caraca (4.198 g/m²/a) was greater than A marta (2.582 g/m²/a). However, the annual production per biomass ratio P/B was 9.71 a-1 for A. marta and 5.65 for a-1 A. caraca. The production of both species was high compared to other studies done in the neotropical region. These results demonstrated that the species are multivoltine and that there is no seasonal growth pattern moderated by rainfall. [ABSTRACT FROM AUTHOR]

Simple Summary: The Asian corn borer (ACB), Ostrinia furnacalis, is a devastating corn pest widely distributed in China. Depending on the climate, ACB may have one or up to seven generations each year, from north to south, respectively. Previous investigations suggested co-existence of the uni- and multivoltine patterns in northeast regions (45°38′ N). Efforts have been conducted to isolate uni-voltinism (with obligate diapause), multi-voltinism (with facultative diapause), and a non-diapausing strain using recurrent selections under various simulated temperature and photoperiod environments. The univoltine (Lu) strain has evolved a stable univoltinism under a diapause suppressing condition (16 h daylength at 28 °C). The multivoltine strain (Lm) was shown to have a typical facultative diapause induced by a range of short-day lengths (11–13.5 h). The majority (94.4%) of the developed Ln strain still maintained the non-diapausing nature under a diapause enhancing condition, i.e., a short (13 h) daylength at a low temperature (22 °C). The study suggests that ACB has evolutionary intra-population variation in voltinism. Under the climate change scenario warmer spring and summer will affect the proportion of sympatric voltine biotype populations that evolve toward being multivoltine. The Asian corn borer (ACB) Ostrinia furnacalis (Guenée) can occur in one to seven generations annually from cool (48°00′ N) to warm (18°10′ N) region of corn cultivation in China. Although ACB is commonly known as a facultative larval diapause insect, the co-existence of various voltinism suggests that intra-population variation may have evolved for the nature of diapause, i.e., voltinism plasticity. Here, we conducted recurrent selection efforts to establish three strains of, respectively, univoltine (with obligate diapause), multivoltine (with facultative diapause), and non-diapausing ACB under various temperature and photoperiod environments. The univoltine (Lu) strain has evolved a stable univoltinism under a diapause suppressing condition (16 h daylength at 28 °C), with the diapause incidence constantly over 80% after three generations of selection. The multivoltine strain (Lm) under the high temperature (28 °C) was shown to have a typical facultative diapause induced by a range of short-day lengths (11–13.5 h). Diapause incidence was constantly <2.6% under the long day length (16 h) when the temperature was from 18 to 28 °C, i.e., low temperature could not enhance the diapause response in the Lm strain. However, the development was prolonged from 14.2 ± 0.3 d to 46.0 ± 0.8 d when the temperature was reduced from 28 °C to 18 °C. The majority (94.4%) of the developed Ln strain still maintained the non-diapausing nature under a diapause enhancing condition, i.e., a short (13 h) daylength at a low temperature (22 °C). Lm and Ln were able to complete their second generation in Heihe (50°14′ N) if the first-generation moth oviposits before 18 June. The study suggests that ACB has evolutionary intra-population variation in voltinism. Under the climate change scenario warmer spring and summer might affect the proportion of sympatric voltine biotype populations that evolve toward being multivoltine. [ABSTRACT FROM AUTHOR]

Identifying which species are being negatively impacted by climate change and the mechanisms driving their decline is essential to effectively protect biodiversity.Coenonympha pamphilus is a common and generalist butterfly, widely distributed throughout the Western Palearctic, being multivoltine in southern Europe. Previous studies indicate that it will not be substantially affected by climate change; however, it has seemingly disappeared from the southeast of the Iberian Peninsula in the last decades.Here, we aim to determine if it has effectively disappeared from this area, as well as identify the environmental conditions limiting its distribution and the potential causes behind this a priori local extinction.We downloaded all the occurrence records of C. pamphilus and analysed their spatial and temporal trends. To identify the climatic variables driving the distribution of this butterfly in the Iberian Peninsula, we performed an ensemble species distribution model (SDM), combining 600 individual models produced with 6 algorithms.We confirmed that C. pamphilus has not been observed in the southeast of the Iberian Peninsula since 2008. Aridity was the main factor limiting the distribution of C. pamphilus in our ensemble SDM, with areas with high aridity being unsuitable for this species.We hypothesise that multivoltinism is the mechanism driving this local extirpation, as high aridity is causing host plants (Poaceae) to wither prematurely, precluding the development of the second and/or third generations of the butterfly. Even though generalist species are theoretically more resilient to climate change, other traits such as multivoltinism may increase their vulnerability and need to be further investigated. [ABSTRACT FROM AUTHOR]

Brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive pest of Asian origin first detected in North Carolina in 2009. By 2015, it became an important pest in the mountain and Piedmont regions, but its population densities have remained low in the eastern plains regions. Starting with a cohort of diapausing adults in January of 2018 and 2019, semi-field cage studies were used to document the phenology and reproductive capacity of H. halys through October of each year at Mills River (mountains) and Goldsboro (Southeastern Plains) sites, which have the same photoperiod, but different temperature profiles. Halyomorpha halys was univoltine in the cooler mountain site, but bivoltine in the warmer plains site, leading to earlier emergence from overwintering diapause, greater heat unit accumulations, and a F1 adult generation that emerged before on-set of diapause-inducing conditions, which allowed for an F2 generation. However, only 17.2% of ovipositing F1 females laid egg masses that hatched, compared to > 90% of overwintered females. Poor establishment of H. halys in the plains versus mountains was attributed to heat stress that contributed to a higher percentage of overwintered adults that emerged early and did not oviposit, a truncated oviposition pattern by overwintered adults, and poor F2 egg hatch. Quadratic equations fit relationships between cumulative degree-days from biofix and proportional oviposition and adult eclosion of respective generations. Utility of the phenology model on a wider scale will depend on how well H. halys populations in other areas conform to North Carolina population's response to photoperiod and temperature. [ABSTRACT FROM AUTHOR]

Abstract This work aims to estimate the voltinism differences in the studied lines and the influence of biological and environmental variables on this trait. Three Bombyx mori. lines were used. One polyvoltine (Indian, C. Nichi) and two bivoltine (Chinese6-C6 and Japanese7-J7). Silkworms were reared under controlled conditions of temperature (24±1, 26±1, 28±1°C) and photoperiod (8-16, 12-12, 16-8 light/darkness) during the life cycle. The measured biological characters were duration of larval period (DLP), larval weight on fifth day of V instar (LW(V-5)), rate of weight (RWV), duration of life cycle (DLC), fecunditiy (NE), fertility (F) and voltinism (V). Voltinism was estimated using a linear regression model; the variables that influence voltinism were found using a multiple regression analysis; and the effect of environmental conditions on change of voltinism employing an ANOVA. The results show that the variables that affect voltinism are different for each line, which demonstrates the effect of the line factor. Nichi voltinism was affected by the six measured variables, while in C6 and J7 where voltinisms depends on the duration of diapause, some variables were excluded from the model. In Indian tropical polyvoltine, the temperature was the influencing factor, while in Chinese and Japanese bivoltines lines was the photoperiod.

The European grapevine moth (Lobesia botrana) is one of the major pests of the grapevine (Vitis vinifera) in Europe. The phenology of both the insect pest and the plant has already changed over the last decades in response to rising temperatures, with a tendency towards an earlier development. The impact of a warming climate, among other factors, could alter matches in phenology between two trophic levels, being either beneficial or detrimental to V. vinifera. As a consequence, when considering a European latitudinal transect, the changes toward synchrony or a mismatch are not fully understood. In this study, we applied the results of sequential models to simulate the phenological development of V. vinifera from dormancy to physiological maturity of Chardonnay or a similar grape variety. Likewise, we simulated the phenology of L. botrana with a process-based voltinism model. Both models were calibrated and validated in previous studies. The present study aims at simulating the future evolution of both trophic levels under changing climatic conditions at four representative European locations by using quasi-transient climate scenarios up to the year 2100 that consider the RCP4.5 and RCP8.5 greenhouse-gas forcing pathways. Although some physiological adaptations could alter these results, simulations of synchrony under climate change are crucial for the adaptation of grape cultivation and varieties. This modelling work seeks to improve our understanding of the probable shifts in the timing and spatial distribution of the plant-insect interactions in a warmer climate and how this may impact their synchrony. A risk index of damage has been implemented for the different sites and greenhouse gas forcing trajectories. Results suggest an increasing damage risk for V. vinifera close to the timing of harvests in northern Europe. They also point to increasing mortality rates of the fourth generation of L. botrana in southern Europe, where temperatures will increasingly reach the upper thermal limit for insect development.

Empirical studies have shown a positive relationship between migration and fecundity, suggesting a 'migration syndrome' that also includes delayed reproduction and an extended reproductive lifespan. At the same time, life history theory predicts that the cost of migration should result in lower fecundity because both traits draw from a common resource.We test whether migration is associated with higher fecundity and delayed reproduction in five closely related butterfly species in the Nymphalini tribe. Two of these are migratory, Vanessa cardui and Vanessa atalanta, and three are non‐migratory, Aglais urticae, Aglais io, and Polygonia c‐album, which appears in a diapausing and a non‐diapausing generation.Laboratory experiment of this study demonstrated a higher lifetime fecundity in the non‐migratory species A. urticae and A. io, compared with the migratory species. When reproductive output was measured in terms of egg mass over adult female mass, also the non‐migratory species P. c‐album had a higher reproductive investment than the two migratory species, and the non‐diapausing generation had a higher reproductive output than the diapausing generation. All species but P. c‐album delayed reproduction until 5–7 days after eclosion/emergence.These results indicate that a migratory lifestyle carries a reproductive cost and suggests that the migratory habit has not resulted in selection for higher fecundity. However, the migratory species are highly fecund in a wider phylogenetic perspective, which leads to the conclusion that rather than selection having selected for high fecundity and delayed reproduction, these traits may be prerequisites for evolving a migratory lifestyle. [ABSTRACT FROM AUTHOR]

The species Coenonympha pamphilus (Linnaeus, 1758) (Lepidoptera, Nymphalidae) is a diurnal butterfly considered a common and generalist species. More than 80,000 records for the Western Palaearctic and more than 3,000 for the Iberian Peninsula have been analysed, showing that there has been an exponential increase in the records of this species in the last decade. However, the number of records has decreased in the southeast of the Iberian Peninsula. Therefore, species distribution models have been carried out to explain this change in its current distribution. The models and analyses carried out indicate that aridity has an effect on the distribution of C. pamphilus, causing it to retreat towards the centre and west of the peninsula, probably because, being a polyvoltine species, with more generations at lower altitudes, C. pamphilus would not find its available resource (different species of Poaceae) in drier areas, as the vegetation becomes parched in the summer months, making the development of second and successive generations impossible. [ABSTRACT FROM AUTHOR]

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has killed millions of ash (Fraxinus spp.) trees across North America. Classical biological control using introductions of parasitoid wasps may provide a sustainable approach to managing this invasive insect. However, the establishment of parasitoids in the southern United States has been difficult. The phenology of emerald ash borer was studied in central North Carolina to inform biological control efforts that better align with the seasonal availability of susceptible emerald ash borer life stages in the warm climate of this region. Biweekly emerald ash borer life stage assessments were conducted in stands of infested green ash (Fraxinus pennsylvanica Marshall, Lamiales: Oleaceae) over 26 consecutive months (June 2019 through August 2021). Adult trapping was also conducted in these stands in the spring and summer of 2019, 2020, and 2021. Based on these collections, emerald ash borer exhibits a univoltine (1-yr) life cycle. Parasitoid-susceptible larvae (third and fourth instars in galleries) are present from late June through October (∼1,100–3,000 degree days base 10°C) and are mostly absent during the remainder of the year. Parasitoid release timings and the life history of selected parasitoid species should be aligned with this window of host availability to be effective. This characterization of emerald ash borer phenology and voltinism will help improve the timing and effectiveness of management efforts as this forest pest continues to spread in southern North America. [ABSTRACT FROM AUTHOR]

Climate change has been shown to advance spring phenology, increase the number of insect generations per year (multivoltinism) and increase pathogen infection levels.However, we lack insights into the effects of plant spring phenology and the biotic environment on the preference and performance of multivoltine herbivores and whether such effects extend into the later part of the growing season.To this aim, we used a multifactorial growth chamber experiment to examine the influence of spring phenology on plant pathogen infection, and how the independent and interactive effects of spring phenology and plant pathogen infection affect the preference and performance of multigenerational attackers (the leaf miner Tischeria ekebladella and the aphid Tuberculatus annulatus) on the pedunculate oak in the early, mid and late parts of the plant growing season.Pathogen infection was highest on late phenology plants, irrespective of whether inoculations were conducted in the early, mid or late season. The leaf miner consistently preferred to oviposit on middle and late phenology plants, as well as healthy plants, during all parts of the growing season, whereas we detected an interactive effect between spring phenology and pathogen infection on the performance of the leaf miner. Aphids preferred healthy, late phenology plants during the early season, healthy plants during the mid season, and middle phenology plants during the late season, whereas aphid performance was consistently higher on healthy plants during all parts of the growing season.Our findings highlight that the impact of spring phenology on pathogen infection and the preference and performance of insect herbivores is not restricted to the early season, but that its imprint is still present – and sometimes equally strong – during the peak and end of the growing season. Plant pathogens generally negatively affected herbivore preference and performance, and modulated the effects of spring phenology. We conclude that spring phenology and pathogen infection are two important factors shaping the preference and performance of multigenerational plant attackers, which is particularly relevant given the current advance in spring phenology, pathogen outbreaks and increase in voltinism with climate change. [ABSTRACT FROM AUTHOR]

Simple Summary: The invasive brown marmorated stink bug Halyomorpha halys, native to East Asia, has become one of the most damaging agricultural pests worldwide. After being first detected in Europe (in Switzerland), it is now widely spread throughout the European continent and many countries in Eurasia. Since its first appearance in Slovenia in 2017, it has caused extensive damage to fruit and vegetable production. Investigating the biology and behavior in local environmental conditions is the first step towards effective pest control. Information on the number of generations per year is crucial for anticipating critical phases of pest development and for adapting control measures that target the pest's vulnerable life stages. A 3-year study (2019–2021) on the biological parameters of H. halys was performed outdoors in Nova Gorica (western Slovenia), confirming that in the sub-Mediterranean climate this pest has two overlapping generations per year. The net reproductive rates observed over the period studied indicate growing populations. The highest population growth was recorded in 2019, when the net reproductive rate of increase (R0) reached 14.84 for the summer generation and 5.64 for the overwintering generation. These findings reflect the current situation in Slovenia, where the growing populations of H. halys has been causing considerable damage to agricultural crops since 2019. In the last decade, the invasive brown marmorated stink bug Halyomorpha halys, native to East Asia, has become one of the most serious pests for agricultural crops worldwide. First detected in Europe (in Switzerland), the insect is now widely found across the European continent and many Eurasian countries. Since its first appearance in Slovenia in 2017 it has caused considerable damage to fruit and vegetable production. Understanding the biology and behavior in the local environmental conditions is of key importance for an effective pest management. Knowledge of the voltinism of the species is crucial to anticipate critical phases of pest development and for adapting control measures that target the vulnerable life stages of the pest. A 3-year study (2019–2021) of H. halys biological parameters was performed outdoors in Nova Gorica (western Slovenia), confirming that in the sub-Mediterranean climate this pest has two overlapping generations per year. The net reproductive rates observed in the studied period indicate growing populations. The highest population growth was recorded in 2019, when the net reproductive rate of increase (R0) reached 14.84 for the summer generation and 5.64 for the overwintering generation. These findings match the current situation in Slovenia, where increasing populations of H. halys and severe crop damage have been observed since 2019. [ABSTRACT FROM AUTHOR]

Climate change has been repeatedly linked to phenological shifts in many taxa, but the factors that drive variation in phenological sensitivity remain unclear. For example, relatively little is known about phenological responses in areas that have not exhibited a consistent warming trend, making it difficult to project phenological responses in response to future climate scenarios for these regions. We used an extensive community science dataset to examine changes in the adult flight onset dates of 38 butterfly species with interannual variation in spring temperatures in the Piedmont region of North Carolina, a region that did not experience a significant overall warming trend in the second half of the 20th century. We also explored whether voltinism, overwintering stage, and mean adult flight onset dates explain interspecific variation in phenological sensitivity to spring temperature. We found that 12 out of 38 species exhibited a significant advance in adult flight onset dates with higher spring temperatures. In comparison, none of the 38 species exhibited a significant advance with year. There was a significant interaction between mean onset flight date and voltinism, such that late-emerging, multivoltine species tended to be the most sensitive to spring temperature changes. We did not observe a significant correlation between phenological sensitivity and the overwintering stage. These results suggest that butterfly arrival dates may shift as temperatures are projected to rise in the southeastern United States, with late-emerging, multivoltine species potentially exhibiting the greatest shifts in adult flight onset dates., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

The body size of an adult insect is strongly determined by the environmental factors to which it is exposed during growth and development. Insect species confronted with a high environmental variability across their geographical range (i.e. wide ecological niche breadth) may therefore reveal broader variation in body size than those species which are more specialised (i.e. narrow ecological niche). In this study, we aim to investigate whether characteristics related to the ecological niche breadth of a holometabolous insect species (i.e. its ecological specialisation) affect its intraspecific variation in adult body size. By using European geometrid moths as a model group, we specifically tested whether latitudinal range size, larval resource use and voltinism affect intraspecific body size variation. We hypothesised that body size variation will increase along with latitudinal range and larval diet breadth. We further expected that univoltine species reveal a lower body size variation compared to those with multiple generations per year. To test these hypotheses, we compiled a comprehensive trait database for 631 species of European geometrid moths from literature, including information on adult body size, life history and distribution. We further reconstructed a molecular phylogeny including all analysed geometrid species and applied phylogenetic comparative methods in order to test our predictions. In support of our hypotheses, we found that intraspecific size variation is positively related to latitudinal range size and larval diet breadth, and that multivoltine species reveal a higher heterogeneity in body size than taxa with a strictly univoltine life style. Based on our results, we demonstrated that intraspecific body size variation in geometrid moths is negatively related to ecological specialisation. We further suggest that increased variation in body size with increasing niche breadth is a general pattern, which likely applies to many other insect groups as well. This assumption, however, demands further empirical scrutiny. [ABSTRACT FROM AUTHOR]

Insect phenology consists of the timing of life events, as well as the number of generations (voltinism). While several studies have focused on the impact of climate on the timing of seasonal events, or the voltinism of single species, we have few insights into the factors that shape patterns of voltinism within ecological communities. Importantly, voltinism can have a major impact on population growth, species interactions, and rate of evolution.We investigated the relative importance of spatial variation in temperature and species traits in shaping patterns of voltinism within an herbivore community feeding on deciduous oaks across a temperature gradient in Europe.Voltinism increased with temperature, where the probability for a species to be univoltine decreased with temperature, whereas the probability for a species to be strictly multivoltine increased with temperature. The relative abundance of the first and subsequent generations of multivoltine species did not significantly change along the temperature gradient. Resource specialisation affected voltinism, where oligophagous and polyphagous species were more likely to be strictly multivoltine than narrow oligophagous species. Overwintering stage and body size did not affect voltinism, and there was no evidence that species traits influenced the relationship between temperature and voltinism.Our findings highlight that temperature and species traits shape variation in voltinism within an herbivore community associated with oak trees. These temperature‐induced shifts in voltinism within the oak‐associated herbivore community may have profound effects on the synchrony within and between trophic levels, and consequently for food web structure and outbreak dynamics. [ABSTRACT FROM AUTHOR]

The spruce bark beetle Ips typographus is the most important pest on Norway spruce in Europe. To improve predictions of bark beetle phenology in a warmer climate, correct thermal sums representing the development time of the new generation are needed.A standardized method for classifying adults into five different colours was used for describing the seasonal change in colour of beetles in breeding substrate and in weekly trap catches from regions located in southern, central and northern Sweden in 2015–2020.Repeated sampling of I. typographus from breeding substrate demonstrated that the adults get gradually darker, from light brown when newly moulted to dark brown or black in the following summer.In spring, four to five colours co‐occurred among trapped beetles. Over time, the proportions of darker individuals increased until the two lightest colours were absent except for 2 cases out of 21 trapping locations/years. Thereafter, the individuals of the two lightest colours started to occur again, indicating that they belonged to the new generation.The average thermal sum from start of flight of parental generation in spring until onset of new‐generation flight in summer was higher for southern Sweden [lower developmental threshold (LDT) 5°C = 744 degree‐days (dd); LDT 8.3°C = 467 dd] than for northern Sweden (LDT 5°C = 668 dd; LDT 8.3°C = 418 dd).New‐generation flight occurred in every year and region, but generally constituted only a small proportion of total seasonal flight activity. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate warming affects phenological events of cold-blooded organisms. In this analysis we studied, in laboratory conditions, the impact of warming and hatching dates on key life history and physiological traits in a cannibalistic damselfly, Ischnura elegans. Larvae were reared in groups from hatching to emergence through one or two growth seasons, depending on the voltinism. Larvae were equally divided by hatching dates (early and late) and temperature treatment (current and warming). Early and late hatched groups were not mixed. Despite no difference in cannibalism rate between different hatching dates and temperatures, early hatched larvae reared under warming had elevated immune function measured as phenoloxidase (PO) activity. This increased PO activity was not traded off with life history traits. Instead, age and mass at emergence, and growth rate were mainly affected by temperature and voltinism. Our results confirm the importance of phenological shifts in a warming world for shaping physiology and life history in a freshwater insect. Under climate warming, temperate ectotherms are expected to hatch earlier and grow faster, increase the number of generations per season, i.e., voltinism. Here, we studied, under laboratory conditions, the impact of artificial warming and manipulated hatching dates on life history (voltinism, age and mass at emergence and growth rate) and physiological traits (phenoloxidase (PO) activity at emergence, as an indicator of investment in immune function) and larval survival rate in high-latitude populations of the damselfly Ischnura elegans. Larvae were divided into four groups based on crossing two treatments: early versus late hatching dates and warmer versus control rearing temperature. Damselflies were reared in groups over the course of one (univoltine) or two (semivoltine) growth seasons, depending on the voltinism. Warming temperature did not affect survival rate. However, warming increased the number of univoltine larvae compared to semivoltine larvae. There was no effect of hatching phenology on voltinism. Early hatched larvae reared under warming had elevated PO activity, regardless of their voltinism, indicating increased investment in immune function against pathogens. Increased PO activity was not associated with effects on age or mass at emergence or growth rate. Instead, life history traits were mainly affected by temperature and voltinism. Warming decreased development time and increased growth rate in univoltine females, yet decreased growth rate in univoltine males. This indicates a stronger direct impact of warming and voltinism compared to impacts of hatching phenology on life history traits. The results strengthen the evidence that phenological shifts in a warming world may affect physiology and life history in freshwater insects. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown marmorated stink bug originates in East Asia and recently invaded Europe and North America. It is considered a serious pest because it damages 300+ species of wild and cultivated crops. Studies on the seasonal development of local populations of invasive insects are important for monitoring damage and predicting their dispersion. We investigated the seasonal development of this pest in Sochi (Krasnodar Territory, Russia) from 2018 to 2021 by regular field sampling. The results suggest that the brown marmorated stink bug normally produces two generations per year in the studied region: the main period when overwintered females lay eggs occurs from June to July; the second period of egg-laying (by females of the new generation) occurs in August. Reproductively active adult bugs were recorded from the end of May to the beginning of September. Such seasonal activity correlates with day length: when days became shorter than the experimentally determined critical value (15.0–15.5 h), the proportion of females with fully developed reproductive organs sharply dropped to zero. The timing of the beginning of the winter dormancy observed under the natural conditions agrees with the predictions based on the results of the earlier conducted laboratory experiments. Studies on the phenology of local populations of invasive insects are necessary for monitoring and predicting their dispersion. We investigated the phenology of the brown marmorated stink bug, Halyomorpha halys, in the Sochi region (Krasnodar Territory, Russia) from 2018 to 2021 by regular field sampling and dissecting. The results of the sampling suggest that H. halys is at least partially bivoltine in the studied region: the main period of mass oviposition (by the overwintered females) occurs from June to July; the second, much shorter period of egg-laying (by females of the new, i.e., the first generation) occurs in August. Reproductively active individuals (i.e., females with developed ovaries and filled spermatheca and males with filled ectodermal sac) were recorded from the end of May to the beginning of September. Such a seasonal pattern correlated with day length: when the natural photoperiod decreased below the experimentally determined critical day length (15.0–15.5 h), the proportions of females with fully developed ovaries sharply dropped to zero. Both the rate of H. halys pre-adult development and the timing of the induction of winter adult diapause observed under natural conditions fully agreed with the earlier predictions that had been based on the results of laboratory experiments. [ABSTRACT FROM AUTHOR]

As insect development depends on temperature, so the change in biology, behavior habits, frequency, and severity of outbreaks of foliage-browsing insects considered pests can follow the climate change. The reactions of species to the same climate changes can be specific, therefore, an unpredictable change in their ratio in the community will affect the consequences of climate change. The details of such changes must be studied to quantitatively assess future trends and the threats to deciduous forests. The aim of this research was to evaluate the representation in deciduous forests the foliage-browsing lepidopterous insects if different groups of size, lifestyle, voltinism, trophic relations, and ability to mass propagation in different periods of assessment for recent 70 years. In the analysis, we used a list of 118 lepidopterous species of foliage-browsing insects of deciduous forests, compiled on the basis of archival data from 1940–1975, and in the course of our own field research from 1975 to the present in the forests of Ukraine. Following trends were expected to be confirmed for these time intervals: to increase the number of species of small size, the number of species with hidden lifestyle, multivoltine species, polyphagous species, and so-called indifferent species. For each species, all these parameters were identified and proportions of species of each category for certain time intervals (1940–1950, 1960–1970, 1980–1990, and 2010–2020). Their distribution for size, voltinism, lifestyle, trophic features, and outbreak potential at these time intervals was compared using χ2-test. Among lepidopterous foliage-browsing insects of deciduous forests of Ukraine, the increase for recent 70 years was proved for the proportion of indifferent species (do not able to mass propagation), small species (with wingspan below 20 mm), as well as species with hidden (leaf-miners) and semi-hidden lifestyle (leaf-rollers). All trends are expressed the most obviously in 1940–1950 and further periods. The hypothesis about decrease the proportion of the univoltine and monophagous species for this period is not supported statistically.

Herbivorous insects having variable numbers of generations annually depending on climate and day length conditions are increasingly breeding additional generations driven by elevated temperature under the scenario of global warming, which will increase insect abundance and result in more frequent damage events. Theoretically, this relies on two premises, i.e., either an evolutionary shift to facultative diapause for an insect behaving an obligatory diapause or developmental plasticity to alter voltinism productively for an insect with facultative diapause before shortening photoperiods inducing diapause. Inter-population evidence supporting the premise (theory) comes primarily from a model system with voltinism linked to thermal gradients across latitude. We examined the intra-population evidence in the field (47°24′ N, 123°68′ E) with Ostrinia furnacalis, one of the most destructive pests, on corn in Asia and Pacific islands. The species was univoltine in high latitudinal areas (≤46° N). Divergence of the diapause feature (obligatory and facultative) was observed within the field populations from 2016 to 2021. Warmer climates would provoke more facultative diapause individuals to initiate a second generation, which will significantly drive the population to evolve toward facultative diapause (multi-voltinism). Both divergent diapause and temperature must be considered for accurate prediction of phenology and population dynamics in ACB.

A wide variety of organisms use the regular seasonal changes in photoperiod as a cue to align their life cycles with favorable conditions. Yet the phenological consequences of photoperiodism for organisms exposed to new climates are often overlooked. We present a conceptual approach and phenology model that maps voltinism (generations per year) and the degree of phenological mismatch that can arise when organisms with a short‐day diapause response are introduced to new regions or are otherwise exposed to new climates. Our degree‐day‐based model combines continent‐wide spatialized daily climate data, calculated date‐specific and latitude‐specific day lengths, and experimentally determined developmental responses to both photoperiod and temperature. Using the case of the knotweed psyllid Aphalara itadori, a new biological control agent being introduced from Japan to North America and Europe to control an invasive weed, we show how incorporating a short‐day diapause response will result in geographic patterns of attempted voltinism that are strikingly different from the potential number of generations based on degree‐days alone. The difference between the attempted and potential generations represents a quantitative measure of phenological mismatch between diapause timing and the end of the growing season. We conclude that insects moved from lower to higher latitudes (or to cooler climates) will tend to diapause too late, potentially resulting in high mortality from inclement weather, and those moved from higher to lower latitude (to warmer climates) may be prone to diapausing too early, therefore not fully exploiting the growing season and/or suffering from insufficient reserves for the longer duration in diapause. Mapped output reveals a central region with good phenology match that shifts north or south depending on the geographic source of the insect and its corresponding critical photoperiod for diapause. These results have direct relevance for efforts to establish populations of classical biocontrol agents. More generally, our approach and model could be applied to a wide variety of photoperiod‐ and temperature‐sensitive organisms that are exposed to changes in climate, including resident and invasive agricultural pests and species of conservation concern. [ABSTRACT FROM AUTHOR]

Many insects exhibit geographical variation in voltinism, the number of generations produced per year. This includes high‐latitude species in previously glaciated areas, meaning that divergent selection on life cycle traits has taken place during or shortly after recent colonization. Here, we use a population genomics approach to compare a set of nine Scandinavian populations of the butterfly Pararge aegeria that differ in life cycle traits (diapause thresholds and voltinism) along both north–south and east–west clines. Using a de novo‐assembled genome, we reconstruct colonization histories and demographic relationships. Based on the inferred population structure, we then scan the genome for candidate loci showing signs of divergent selection potentially associated with population differences in life cycle traits. The identified candidate genes include a number of components of the insect circadian clock (timeless, timeless2, period, cryptochrome and clockwork orange). Most notably, the gene timeless, which has previously been experimentally linked to life cycle regulation in P. aegeria, is here found to contain a novel 97‐amino acid deletion unique to, and fixed in, a single population. These results add to a growing body of research framing circadian gene variation as a potential mechanism for generating local adaptation of life cycles. [ABSTRACT FROM AUTHOR]

The bark beetle Ips typographus is the most destructive insect pest in Norway spruce-dominated forests. Its potential to establish multiple generations per year (multivoltinism) is one major trait that makes this beetle a severe pest. Ips typographus enters diapause to adjust its life cycle to seasonally changing environments. Diapause is characterized by developmental and reproductive arrest; it prolongs generation time and thus affects voltinism. In I. typographus a facultative, photoperiod-regulated diapause in the adult stage has been described. In addition, the presence of an obligate, photoperiod-independent, diapause has been hypothesized. The diapause phenotype has important implications for I. typographus voltinism, as populations with obligate diapausing individuals would be univoltine. To test for the presence of different I. typographus diapause phenotypes, we exposed Central and Northern European individuals to a set of photoperiodic treatments. We used two ovarian traits (egg number and vitellarium size) that are associated with gonad development, to infer reproductive arrest and thus diapause. We found a distinct effect of photoperiod on ovarian development, with variable responses in Central and Northern European beetles. We observed obligate diapausing (independent of photoperiod) individuals in Northern Europe, and both facultative (photoperiod-regulated) as well as obligate diapausing individuals in Central Europe. Our results show within-species variation for diapause induction, an adaptation to match life cycles with seasonally fluctuating environmental conditions. As the diapause phenotype affects the potential number of generations per season, our data are the basis for assessing the risk of outbreaks of this destructive bark beetle. [ABSTRACT FROM AUTHOR]

The review analyzes the available literature data on the seasonal development of plant bugs of the subfamily Phylinae distributed in the Holarctic Region. The data set concerns 39 species from 3 tribes: Pilophorini, Hallodapini, and Phylini. The tribe Pilophorini is represented by 5 species, 3 of which complete one generation per year and hibernate at the egg stage. However, there is no reason to believe that their annual cycles are obligatory univoltine, since they have been studied only in regions with a relatively cold climate. Two other species of this tribe, Pilophorus confusus and P. typicus, are multivoltine in regions with a warmer climate (Spain and Japan, respectively), where they also overwinter at the egg stage. The data on 3 species of the tribe Hallodapini indicate that they have similar seasonal cycles with a single generation per year and overwintering at the egg stage. The greatest diversity of seasonal patterns is known in the tribe Phylini. Two out of 5 Chlamydatus species included in this review overwinter as adults, although overwintering at the egg stage is generally characteristic of the family Miridae. Three species of this genus have a multivoltine seasonal cycle, and no data are available on the voltinism and overwintering stage of two other species, Ch. allii and Ch. wilkinsoni. Of the remaining 26 species of the tribe Phylini, 6 species have a multivoltine seasonal cycle and complete from 2 to 4 generations per year in different climatic zones. The bivoltine Campylomma verbasci from the same tribe has a seasonal adaptation unusual for true bugs, namely the shift of host plants during the year realized by different generations: after overwintering, the bugs move from woody plants to herbaceous ones. In general, the subfamily Phylinae is very species-rich and has highly diverse ecological characteristics, such as trophic specialization, voltinism, overwintering stage, seasonal shift of host plants, wing polymorphism, etc. [ABSTRACT FROM AUTHOR]

An account is given of finding the larvae of Anania coronata (Hufnagel, 1767) and Anania hortulata (linnaeus, 1758) in Devon, England, in 2021 feeding on Hedge Bindweed Calystegia sepium (l.) R. Br., an overlooked foodplant of the former and an apparently rarely recorded one of the latter in the British Isles. Descriptions and photographs of the larva of A. coronata in various instars are provided and the final instar of A. hortulata is compared and an image provided. Voltinism of A. coronata is considered. [ABSTRACT FROM AUTHOR]

Changing abiotic conditions can affect the phenology of animals and plants with implications for their reproductive output, especially in rapidly changing regions like the Arctic. For instance in arthropods, it was recently shown that females of the spider species Pardosa glacialis (Thorell 1872) (Lycosidae) are able to produce two clutches within one growing season in years when snowmelt occurs particularly early. This phenomenon could be widespread in northern latitudes, and here we investigated the voltinism of two other very abundant species of wolf spiders in the Low-Arctic, Pardosa hyperborea (Thorell 1872) and Pardosa furcifera (Thorell 1875), over the period 2015–2017. Whilst a bimodal pattern in the clutch size frequency distribution was only revealed for P. hyperborea, we were able to show that both species can produce a second clutch over the active season by using information on the embryonic stages. We also observed significantly larger first than second clutches. We argue that information about the embryonic stage can be critical for evaluating evidence of wolf spider populations producing more than one clutch in a season. Our study provides evidence that bivoltinism could be a more widespread pattern than expected in Arctic wolf spiders. It remains to be investigated what the trophic consequences of such patterns are in a global warming context. We thus highlight the need for a coordinated framework for such further studies, integrating and relating various functional traits. [ABSTRACT FROM AUTHOR]

The current climate warming is associated with the development of a second generation in populations of species such as Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae), which, in Central Europe, were univoltine in the 1980s. Females of the first generation that develop in spring either enter diapause immediately following the adult moult or after a period of oviposition that gives rise to a second generation. In 2005-2010, in overwintering populations, 3 ± 0.6% of females were fertilized. We explored the possibility that the females that overwintered in a fertilized state were those that had oviposited in the previous season. To test this hypothesis, we reared females of the first generation that moulted to the adult stage in June-August under natural conditions. For these females, we recorded oviposition, mortality and overwintering in the fertilized state. In 2004-2007, the majority (78%) of the first-generation females that oviposited in summer also died before winter and the rest entered dormancy and overwintered. Most of the overwintering females that had laid eggs before overwintering were fertilized. However, the majority (63%) of females that overwintered in the fertilized state had not laid eggs in the previous season; they only copulated and stored the sperm until the next spring. The presence of fertilized females in a hibernating population thus indicates pre-winter sexual activity but not the percentage of first-generation females that oviposit before overwintering.

The Asian corn borer (ACB) Ostrinia furnacalis (Guenée) can occur in one to seven generations annually from cool (48°00′ N) to warm (18°10′ N) region of corn cultivation in China. Although ACB is commonly known as a facultative larval diapause insect, the co-existence of various voltinism suggests that intra-population variation may have evolved for the nature of diapause, i.e., voltinism plasticity. Here, we conducted recurrent selection efforts to establish three strains of, respectively, univoltine (with obligate diapause), multivoltine (with facultative diapause), and non-diapausing ACB under various temperature and photoperiod environments. The univoltine (Lu) strain has evolved a stable univoltinism under a diapause suppressing condition (16 h daylength at 28 °C), with the diapause incidence constantly over 80% after three generations of selection. The multivoltine strain (Lm) under the high temperature (28 °C) was shown to have a typical facultative diapause induced by a range of short-day lengths (11–13.5 h). Diapause incidence was constantly

Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates and overall activity duration. We used community‐science and museum specimen data to investigate the effects of climate and urbanisation on timing of adult insect activity for 101 species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Species extended their period of adult activity similarly in warmer conditions regardless of voltinism classification. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments are likely underreported. This effort provides a framework to address the drivers of adult insect phenology at continental scales and a basis for predicting species response to environmental change. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pareumenes quadrispinosus is a common species using trap nests in North Vietnam. • The nests are built from mid-April to last October. • The number of provisioned cells in a nest is one to four. • Brood cells were provisioned with caterpillars. • It is multivoltine, with two alternative life histories and overlapping generations. Nests of Pareumenes quadrispinosus (de Saussure, 1855) were obtained at Me Linh Station for Biodiversity (323 nests) and Tam Dao Town (283 nests), Vinh Phuc Province, as well as at Phu Luong, Thai Nguyen Province (9 nests) and Kim Boi, Hoa Binh Province (62 nests). The wasps nested in segments of bamboo canes and reed stems, 5 to 18 mm in internal diameter. Each nest consisted of a linear series of one to four cells, separated by mud partitions. Brood cells were provisioned with caterpillars and eggs were attached to the ceiling of the cells by thin threads. The life history and sex ratio of this species nesting in trap nests in North Vietnam were recorded from mid-April to last October. The species is multivoltine, with likely up to four generations per year. It has two alternative life histories (diapause and direct development) and overlapping generations. The sex ratio is strongly female-biased. Only 46% of the provisioned cells were successful; the others were damaged by nine parasitoid species or died during development for unknown reasons. [ABSTRACT FROM AUTHOR]

Butterflies and moths (Lepidoptera) are one of the most studied, diverse, and widespread animal groups, making them an ideal model for climate change research. They are a particularly informative model for studying the effects of climate change on species ecology because they are ectotherms that thermoregulate with a suite of physiological, behavioural, and phenotypic traits. While some species have been negatively impacted by climatic disturbances, others have prospered, largely in accordance with their diversity in life‐history traits. Here we take advantage of a large repertoire of studies on butterflies and moths to provide a review of the many ways in which climate change is impacting insects, animals, and ecosystems. By studying these climate‐based impacts on ecological processes of Lepidoptera, we propose appropriate strategies for species conservation and habitat management broadly across animals. [ABSTRACT FROM AUTHOR]