Prepupal Diapause Research Articles

Convergent evolution associated with the loss of developmental diapause may promote extended lifespan in bees.

Diapause has long been proposed to play a significant role in the evolution of eusociality in Hymenoptera. Recent studies have shown that shifts in the diapause stage precede social evolution in wasps and bees, however, the genomic basis remains unknown. Given the overlap in molecular pathways that regulate diapause and lifespan, we hypothesized that the evolutionary loss of developmental diapause may lead to extended lifespan among adults, which is a prerequisite for the evolution of eusociality. To test whether the loss of prepupal diapause is followed by genomic changes associated with lifespan extension, we compared 27 bee genomes with or without prepupal diapause. Our results point to several potential mechanisms for lifespan extension in species lacking prepupal diapause, including the loss of the growth hormone PTTH and its receptor TORSO, along with convergent selection in genes known to regulates lifespan in animals. Specifically, we observed purifying selection of pro-longevity genes and relaxed selection of anti-longevity genes within the IIS/TOR pathway in species that have lost prepupal diapause. Changes in selection pressures on this pathway may lead to the evolution of new phenotypes, such as lifespan extension and altered responses to nutritional signals, that are crucial for social evolution.

Telomere length is longer following diapause in two solitary bee species

The mechanisms that underlie senescence are not well understood in insects. Telomeres are conserved repetitive sequences at chromosome ends that protect DNA during replication. In many vertebrates, telomeres shorten during cell division and in response to stress and are often used as a cellular marker of senescence. However, little is known about telomere dynamics across the lifespan in invertebrates. We measured telomere length in larvae, prepupae, pupae, and adults of two species of solitary bees, Osmia lignaria and Megachile rotundata. Contrary to our predictions, telomere length was longer in later developmental stages in both O. lignaria and M. rotundata. Longer telomeres occurred after emergence from diapause, which is a physiological state with increased tolerance to stress. In O. lignaria, telomeres were longer in adults when they emerged following diapause. In M. rotundata, telomeres were longer in the pupal stage and subsequent adult stage, which occurs after prepupal diapause. In both species, telomere length did not change during the 8 months of diapause. Telomere length did not differ by mass similarly across species or sex. We also did not see a difference in telomere length after adult O. lignaria were exposed to a nutritional stress, nor did length change during their adult lifespan. Taken together, these results suggest that telomere dynamics in solitary bees differ from what is commonly reported in vertebrates and suggest that insect diapause may influence telomere dynamics.

A transcriptomic approach reveals the molecular basis of pre-pupal diapause of Red Banded Mango Caterpillar, Deanolis sublimbalis

A transcriptomic approach reveals the molecular basis of pre-pupal diapause of Red Banded Mango Caterpillar, Deanolis sublimbalis

Staying in touch: how highly specialised moth pollinators track host plant phenology in unpredictable climates

BackgroundFor specialised pollinators, the synchrony of plant and pollinator life history is critical to the persistence of pollinator populations. This is even more critical in nursery pollination, where pollinators are obligately dependant on female host plant flowers for oviposition sites. Epicephala moths (Gracillariidae) form highly specialised nursery pollination mutualisms with Phyllanthaceae plants. Several hundred Phyllanthaceae are estimated to be exclusively pollinated by highly specific Epicephala moths, making these mutualisms an outstanding example of plant–insect coevolution. However, there have been no studies of how Epicephala moths synchronise their activity with host plant flowering or persist through periods when flowers are absent. Such knowledge is critical to understanding the ecology and evolutionary stability of these mutualisms. We surveyed multiple populations of both Breynia oblongifolia (Phyllanthaceae) and it’s Epicephala pollinators for over two years to determine their phenology and modelled the environmental factors that underpin their interactions.ResultsThe abundance of flowers and fruits was highly variable and strongly linked to local rainfall and photoperiod. Unlike male flowers and fruits, female flowers were present throughout the entire year, including winter. Fruit abundance was a significant predictor of adult Epicephala activity, suggesting that eggs or early instar larvae diapause within dormant female flowers and emerge as fruits mature. Searches of overwintering female flowers confirmed that many contained pollen and diapausing pollinators. We also observed diapause in Epicephala prior to pupation, finding that 12% (9/78) of larvae emerging from fruits in the autumn entered an extended diapause for 38–48 weeks. The remaining autumn emerging larvae pupated directly without diapause, suggesting a possible bet-hedging strategy.ConclusionsEpicephala appear to use diapause at multiple stages in their lifecycle to survive variable host plant phenology. Furthermore, moth abundance was predicted by the same environmental variables as male flowers, suggesting that moths track flowering through temperature. These adaptations may thereby mitigate against unpredictability in the timing of fruiting and flowering because of variable rainfall. It remains to be seen how widespread egg diapause and pre-pupal diapause may be within Epicephala moths, and, furthermore, to what degree these traits may have facilitated the evolution of these highly diverse mutualisms.

Environmental impacts on diapause and survival of the alfalfa leafcutting bee, Megachile rotundata

Megachile rotundata exhibits a facultative prepupal diapause but the cues regulating diapause initiation are not well understood. Possible cues include daylength and temperature. Megachile rotundata females experience changing daylengths over the nesting season that may influence diapause incidence in their offspring through a maternal effect. Juvenile M. rotundata spend their developmental period confined in a nesting cavity, potentially subjected to stressful temperatures that may affect diapause incidence and survival. To estimate the impact of daylength and nest cavity temperature on offspring diapause, we designed a 3D printed box with iButtons that measured nest cavity temperature. We observed nest building throughout the season, monitored nest cavity temperature, and followed offspring through development to measure diapause incidence and mortality. We found that daylength was a cue for diapause, and nest cavity temperature did not influence diapause incidence. Eggs laid during long days had a lower probability of diapause. Siblings tended to have the same diapause status, explaining a lot of the remaining variance in diapause incidence. Some females established nests that contained both diapausing and nondiapausing individuals, which were distributed throughout the nest. Nest cavities reached stressful temperatures, which decreased survival. Mortality was significantly higher in nondiapausing bees and the individuals that were laid first in the nest. In conclusion, we demonstrate a maternal effect for diapause that is mediated by daylength and is independent of nest box temperature.

The remarkable biology of a new species of Gelis Thunberg, 1827 (Ichneumonidae, Phygadeuontinae), a solitary endoparasitoid of fresh eggs of Timarcha (Coleoptera, Chrysomelidae)

A new species, Gelis timarchae Schwarz, Shaw & Kan, is figured and described from specimens reared as a solitary endoparasitoid of fresh eggs of Timarcha nicaeensis in the south of France. Oviposition behaviour of the adult parasitoid, directly into the host cytoplasm, is described and links to videos are given. This appears to be the first record of any ichneumonid developing as an endoparasitoid of an insect egg, and it is a major departure from hitherto known ectoparasitoid (or spiders’ egg-predation) behaviour in the genus Gelis. Fluid from the host egg issuing from the base of the parasitoid’s ovipositor early in the oviposition process is interpreted as a necessary reduction of hydrostatic pressure before the parasitoid egg can be forced down the ovipositor. The egg and first instar larva are figured; the latter is caudate, with the caudal appendage very unusual in being bifurcate. The complex phenology and diapause of the parasitoid were investigated partly experimentally; it is broadly bivoltine with a prepupal diapause in summer, but extra generations and prolonged diapause were both also seen.

Influence of Temperature on Breaking Diapause, Development and Emergence of Megachile minutissima (Hymenoptera, Megachilidae)

Abstract The leafcutting bee, Megachile minutissima Radoszkowski, 1876, is a valuable pollinator of alfalfa grown for seed production in Egypt. In order to control adult emergence of M. minutissima to be synchronized with the expected changes in flowering times of alfalfa crop, breaking the prepupal diapause to initiate the subsequent developmental stages of this insect pollinator is necessary. Laboratory experiments were conducted to estimate the influence of incubation temperature at 30 ± 0.4 °C after different intervals of cold storage at 10 ± 0. 4 °C on loose bee cells containing diapaused prepupae, which were obtained during the previous season from the successful nesting straws of the artificial nests. Results indicated that the shortest incubation time required for breaking prepupal diapause was about 12 and 19 days to reach the pupal and adult stages, respectively. The percentage of emerged adults was about 60 % at 152 days cold store, and gradually decreased with the increase of cold storage periods in 2009. Meanwhile, the percentage of emerged adults ranged between 40–60 % at all cold storage periods in 2010. Moreover, the results indicated that the optimal period of cold storage at 10 ± 0.4 °C for diapaused prepupae in their loose cells should be between 146 to 153 days, where the maximum rate of adult emergence was occurred. The maximum rate of newly emerged males and females of M. minutissima was recorded at 10 % and 26 % in April 26, 2009 and 30 % and 20 % in May 4, 2010, respectively. However, the minimum rate of adult emergence was occurred in August, September and October months.

Exploiting diapause and cold tolerance to enhance the use of the green lacewing Chrysopa formosa for biological control

Knowledge of environmental regulation of diapause in the green lacewing Chrysopa formosa, an important polyphagous predator against various pests, is essential for understanding seasonal adaptations of insects and for increasing the shelf-life and shipment of chrysopids used in biological control programs. In the present study, we identified environmental factors responsible for induction and termination of diapause and cold tolerance in this chrysopid. C. formosa exhibits a facultative, prepupal diapause within its cocoon. The free-living third instar larva is the stage most sensitive to photoperiodic stimuli. Photoperiod is the major factor governing the induction of prepupal diapause, and temperature exerts a modulating effect. Photoperiodic response curves for C. formosa showed a typical long day response over a wide range of temperatures. Critical daylength for diapause induction was estimated to be 14.3 h at 20 °C, with a shift towards short daylengths at higher temperatures. The diapause response was maximal with a short daylength of 8L: 16D at 18 °C or 20 °C, and no diapause was induced under 16L: 8D at any temperature examined. Chilling temperature had a pronounced effect on the completion of diapause termination and post-diapause development. A chilling period of 60 days or more at 5 °C was sufficient to terminate diapause in most prepupae. An increase of chilling exposure duration synchronized post-diapause development and adult emergence. What was particularly attractive is that diapausing chrysopids could be stored at 5 °C as long as 300 days with high survival and short adult emergence time. The developmental period prior to diapause was extended significantly for diapause-destined chrysopids. Prepupal diapause in C. formosa distinctly enhanced the cold tolerance. These results suggest mechanisms that could be exploited to improve shelf-life and long distance shipment of chrysopids for release in biological control program.

The lifecycle of Agrilus biguttatus: the role of temperature in its development and distribution, and implications for Acute Oak Decline

Abstract The two spotted oak buprestid, Agrilus biguttatus Fabricus, is implicated in oak decline events across Europe, and is strongly linked to Acute Oak Decline in the U.K., although its role in the syndrome remains under investigation. In the U.K., the beetle is restricted to south and central England. The present study aimed to improve our understanding of the beetle's life history and thermal requirements, intending to explain its U.K. distribution, and to collect data for lifecycle modelling. Novel methods were developed to collect and culture the beetle in the laboratory, which enabled experiments to be carried out, providing data on the beetle's sex ratio, longevity and fecundity, and the development rates of eggs, larvae and pupae at constant temperatures. On average, females lived for 63 days and laid 82 eggs. Larvae developed through four instars. Sex ratio varied by site, with no overall trend apparent. The development rates of eggs, larvae and pupae (to adult emergence) had linear relationships with temperature, with lower developmental thresholds of 12.1, 11.9 and 15.1 °C, respectively. For each life stage, degree‐day values were calculated. Beetles appeared to have an obligatory prepupal diapause at all temperatures studied, up to and including 25 °C. The implications of the developmental findings for the beetle's current distribution, as well as the possible effects of climate change, are discussed. The beetle appears to be thermally limited in the U.K. and, if so, its distribution, and perhaps that of Acute Oak Decline, may alter under climate change.

Diapause and overwintering of two spruce bark beetle species.

Diapause, a strategy to endure unfavourable conditions (e.g. cold winters) is commonly found in ectothermic organisms and is characterized by an arrest of development and reproduction, a reduction of metabolic rate, and an increased resistance to adversity. Diapause, in addition to adaptations for surviving low winter temperatures, significantly influences phenology, voltinism and ultimately population growth. We review the literature on diapause and overwintering behaviour of two bark beetle species that affect spruce‐dominated forests in the northern hemisphere, and describe and compare how these strategies can influence population dynamics. The European spruce bark beetle Ips typographus (L.) (Coleoptera, Curculionidae) is the most important forest pest of Norway spruce in Europe. It enters an adult reproductive diapause that might be either facultative or obligate. Obligate diapausing beetles are considered strictly univoltine, entering this dormancy type regardless of environmental cues. Facultative diapausing individuals enter diapause induced by photoperiod, modified by temperature, thus being potentially multivoltine. The spruce beetle Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae) infests all spruce species in its natural range in North America. A facultative prepupal diapause is averted by relatively warm temperatures, resulting in a univoltine life cycle, whereas cool temperatures induce prepupal diapause leading to a semivoltine cycle. An adult obligate diapause in D. rufipennis could limit bi‐ or multivoltinism. We discuss and compare the influence of diapause and overwinter survival on voltinism and population dynamics of these two species in a changing climate and provide an outlook on future research.

Natural History ofTetrapedia diversipes(Hymenoptera: Apidae) in an Atlantic Semideciduous Forest Remnant Surrounded by Coffee Crops,Coffea arabica(Rubiaceae)

Exotic plants can alter habitat composition and reduce the diversity of pollinators by competing with native species for resources. In a forest fragment surrounded by coffee crops, Coffea arabica L. (Rubiaceae), in southeastern Brazil, the life history of the oil-collecting bee Tetrapedia diversipes Klug (Apidae) was studied. Besides providing data on the phenology, nesting biology, and natural enemies of this bee species, we aimed to investigate if the intense mass flowering of coffee trees would attract T . diversipes specimens rather than native plants in bloom. As T. diversipes females nest in preexisting cavities, we displayed in the study site two types of trap-nests: bamboo canes and 5.8- by 0.6-cm black cardboard tubes. The trap-nests were inspected once a month from June 2011 to May 2013 and 494 nests were collected. Tetrapedia diversipes is a multivoltine species. Prepupal diapause occurred in nests collected at the end of the hot and wet season and during the cold and dry season. Nests were attacked by 14 species of natural enemies, and the most abundant species were the cuckoo bee Coelioxoides waltheriae Ducke (Apidae); the bee fly Anthrax oedipus F. (Bombyliidae); and the beetle Nemognatha cf. plaumanni Borchmann (Meloidae). Despite the mass flowering of coffee trees, pollen grains of C . arabica were not found in the pollen analysis. Our study reveals that even in the presence of an abundant source of floral resources of exotic origin, the studied population of T . diversipes preferred to use the native plant species to obtain the necessary resources for their survival.

Photoperiodic induction of prepupal diapause and its role in synchronization with host phenology in the hibiscus caterpillar, Xanthodes transversa

AbstractThe hibiscus caterpillar, Xanthodes transversa (Lepidoptera: Noctuidae), is a multivoltine insect that is an important pest of Malvaceae plants such as the okra, Abelmoschus esculentus, and the common rose mallow, Hibiscus mutabilis, in Japan. In the present study, the effects of photoperiod and temperature on the induction of prepupal diapause and the adaptive significance of this diapause were examined in a local population of X. transversa in Miyazaki, Kyushu, southwestern Japan. Larvae showed a long‐day photoperiodic response for controlling the induction of prepupal diapause with a critical day length between 13 and 14 h at 20 to 25°C. Under long‐day conditions larvae rapidly pupated from the sixth instar, but under short‐day conditions they entered diapause in the prepupal stage. Diapause occurrence in the field increased in late September, which was consistent with the laboratory results in terms of the photoperiodic response. Non‐diapause development after this time is maladaptive because most larvae of the next generation could not reach the critical stage (prepupae) before winter and died during early winter in outdoor experiments. Larvae suffered from a high rate of mortality when fed leaves collected late in autumn. The photoperiodic response for controlling the induction of diapause in this insect may play an important role in synchronizing the life cycle with the seasonal changes in food and temperature conditions.

The peculiarities of diapause induction by photoperiod and temperature in Trichogramma evanescens Westw. and T. chilonis Ishii (Hymenoptera, Trichogrammatidae) from the south of the Russian Far East

The induction of diapause in the populations of Trichogramma evanescens Westw. and T. chilonis Ishii from the south of Primorskii Territory in the Russian Far East was studied at the constant temperatures of 7, 8, 10, 15, 20, and 25°C. The parental generations developed at either 25° or 20°C and a day length of 16 or 10 hours. The maximum fraction of diapausing prepupae of T. evanescens (nearly 100 %) was observed at the temperatures of 8–10°C, that of T. chilonis only at 10°C, regardless of parental photoperiodic or thermal conditions. The influence of parental temperature and photoperiod on diapause of the progeny was found only in T. evanescens. In this species, after the parental generation had been kept under short-day conditions and a temperature of 25°C, the progeny showed higher incidence of prepupal diapause in the short-day line than in the long-day line at the temperatures of 7 and 15°C.

Nesting biology ofMegachile(Chrysosarus)guaraniticaand high mortality caused by its cleptoparasiteCoelioxys bertonii(Hymenoptera: Megachilidae) in Brazil

Twenty-six nests of Megachile guaranitica Schrottky were obtained during a study of trap-nesting bees and wasps in a forest remnant surrounded by crop areas in the central-western region of Sao Paulo State, Brazil. Fieldwork was performed monthly from June 2011 to May 2013. Females of M. guaranitica nested during the hotter/wetter season, from December to March. Brood cells consisted of three layers: an outer one made with oblong pieces of leaves, a thick middle wall of mud and an inner layer of oblong pieces of leaves. Pollen analysis of the contents of 10 nests revealed the dominance (97.6%) of pollen from the subfamily Mimosoidae (Fabaceae). The immature stages underwent prepupal diapause and took approximately 277 days to emerge. Seventeen of the 26 nests (65%) were attacked by the cleptoparasite Coelioxys bertonii Schrottky, and more individuals of this species (69%) emerged than females and males of the host species (31%). Coelioxys bertonii also underwent prepupal diapause, with development lasting approximately 240 days. The parasitoid wasp Melittobia australica Girault (Eulophidae) is recorded as a parasitoid of M. guaranitica.

Extended family: a caddisfly new to Saskatchewan, Canada with notes on the life history ofNeophylax splendens(Trichoptera: Thremmatidae)

AbstractStreams draining the Cypress Hills support unique and understudied macroinvertebrate communities in Saskatchewan, Canada. Here, we report the discovery of a species of caddisfly new to the Cypress Hills and Saskatchewan,Neophylax splendensDenning (Trichoptera: Thremmatidae). Larvae were collected early in May 2012, and are found to enter pre-pupal diapause in mid-June until mid-September. Larvae were identified asN. splendensby morphological characters and verified with genetic analysis. Its occurrence strengthens the biogeographical link between the montane regions in British Columbia, Canada and Utah, United States of America with the southwest corner of Saskatchewan. This study highlights the importance of seasonal sampling, resolute species level identifications in biological surveys and the use of genetic analyses to obtain this level of identification.

Biological aspects of Tiracola grandirena (Herrich-Schäffer, 1868) (Lepidoptera: Noctuidae): a polyphagous armyworm.

We studied the biology of Tiracola grandirena (Herrich-Schäffer, 1868) (Lepidoptera: Noctuidae: Hadeninae) at 25 ± 1 °C, 70 ± 10% RH and 14 hours of photo phase. Three experiments, using 150 larvae each, were conducted for the larval stage. In the first, used to assess the duration and survival of all stages, insects were reared individually and fed an artificial diet (Grenee). In the second, individuals were also reared separately, but were fed leaves of 10 plants from different families. In the third, the larvae were not individualised, the food plants were rotated such as to provide three plant species every 48 hours. In the first experiment, the viability of the eggs, larvae, pupae and prepupae was 91.9, 94.7, 32.49 and 43.5%, respectively. The average duration of the egg, larvae, prepupae, pupae and adult were 6.0, 25.3, 25.7, 21.4 and 12.7 days, respectively. The prolonged prepupal period indicates that T. grandirena can develop larval (prepupal) diapause. The results of the experiments with different host plants showed that T. grandirena is polyphagous at species, population and individual level.

Diapause and cold tolerance inAsian species of the parasitoidLeptopilina(Hymenoptera:Figitidae)

AbstractDiapause and cold tolerance are essential for temperate insects to pass the winter, with the mechanisms controlling these two traits varying considerably among insects. In the present study, diapause and cold tolerance are compared among threeLeptopilinaspecies:Leptopilina japonicaNovković & Kimura,Leptopilina victoriaeNordlander andLeptopilina ryukyuensisNovković & Kimura, all larval parasitoids of frugivorous drosophilid flies, with the aim of understanding their climatic adaptations. The first species is divided into the temperate (Leptopilina japonica japonica) and subtropical subspecies (Leptopilina japonica formosana), and the latter two species are distributed in the tropical and subtropical regions. The temperate subspecies ofL. japonicaenters prepupal diapause at low temperatures (15 or 18 °C), irrespective of photoperiod, and some individuals enter diapause when exposed to 0 °C for 1 or 2 day(s) or when placed at low humidity.Leptopilina victoriaealso shows signs of diapause initiation at 15 °C, althoughL.ryukyuensisandL. j. formosanafrom the subtropical regions do not. Preimaginal viability at low temperature (13, 14 or 15 °C) is usually lower inL. victoriaefrom the tropical regions compared withL. japonicaorL. ryukyuensisfrom the temperate or subtropical regions. Diapausing prepupae of the temperate subspecies appear to be cold tolerant. However, the cold tolerance of nondiapausing prepupae, pupae and adult females varies little among the tropical, subtropical and temperate species or subspecies, and adult males of the temperate subspecies ofL. japonicaare less cold tolerant than those of the tropical or subtropical species or subspecies. Cold tolerance may be unnecessary, except for diapausing individuals of the temperate species, because nondiapausing individuals appear in warmer seasons.

Photo-thermal regulation of diapause in Trichogramma piceum Djur. (Hymenoptera, Trichogrammatidae)

Interaction of the photoperiodic conditions of development of maternal females (day lengths of 2 to 22 h at 20°C) with the thermal regime of development of their progeny (temperature of 12 to 15°C at day length of 12 h) in determination of prepupal diapause in Trichogramma piceum was studied under laboratory conditions. At 15°C the diapause was practically absent. At lower temperatures, the proportion of diapausing prepupae was maximal (25% of larvae at 14°C, 70% of larvae at 13°, and 80% of larvae at 12°C) if the maternal females developed under short day conditions (10–12 h). When maternal females developed at day lengths of 18–20 h, diapause was rarely recorded at all temperatures, while ultra-short (less than 8–10 h) days also caused a decrease in the proportion of diapausing progeny. The right (ecologically important) threshold of this maternal long-day photoperiodic response was about 14–15 h independently of the temperature during the progeny development. These results make it possible to clarify the mechanism of the “maternal photoperiodic correction of the progeny thermal response.” Although the impact of the maternal photoperiodic response can be revealed only within a very narrow thermal range, the relative strength of the diapause-inducing effect of different day lengths is independent of the temperature regimen of the progeny development.

Nesting biology and life cycle of Nomia (Acunomia) chalybeata Smith on Iriomote Island, southernmost Archipelago of Japan, with notes on the simultaneous occurrence of diapausing and non-diapausing prepupae within the same nests (Hymenoptera: Halictidae)

Nesting biology of the nomiine bee, Nomia (Acunomia) chalybeata Smith, was studied in Iriomote Island, Japan (N24°15–25′) in 2003 and 2004. Its nesting period extended for 6months from around the end of April to October. The nest aggregation was found in clay soil under shady conditions. Twenty nests/m2 were present at the highest density spot. Brood numbers in solitary nests were 5–20 (mean±SD: 11.8±4.7, n=14), and in communal nests 12–101 (43.0±41.0, n=3). Each brood cluster in communal nests contained 0–32 brood cells (10.1±8.0, n=13), suggesting that each cohabitant provisioned independently own brood cells. At least 2 and partially 3 generations were estimated to occur in the year; however each nest produced simultaneously non-diapausing and diapausing prepupae. The percent rate of diapausing prepupae differed seasonally, and was 20.0–37.5% (30.3±7.5%, n=3) in overwintered generation and 0–100% (50.0±39.8%, n=9) in first generation, suggesting that the rate of production of dormant prepupae increased toward the later activity season. Production of the diapausing prepupae may function potentially to inhabit widely throughout different climatic zones. Female ratio (females/females+males) in overwintered generation was 0.347 (50/144). Nest architecture, occurrence of communal nests and breaking of prepupal diapause are also mentioned.

The effect of temperature on the development and life cycle regulation of the pine weevil Hylobius abietis and the potential impacts of climate change

The pine weevil Hylobius abietis is widely distributed in the Palaearctic region where it is a major pest. Although predominantly semi‐voltine, with a 2‐year life cycle, the generation time across its range can vary from 1 to 4 years. The duration of the life cycle and the seasonal timing of weevil activity affect the economic impact and management of this pest, all of which are likely to change in a warming climate. To determine the effect of temperature and tree species on weevil growth and development, laboratory experiments were performed with eggs, larvae, prepupae, pupae and adults, using, as appropriate, the host species Scots pine Pinus sylvestris L. and Sitka spruce Picea sitchensis (Bong.) Carr. under constant or alternating temperatures. The development rate was linearly related to temperature, with developmental thresholds for eggs, larvae and pupae of 8, 4.5 and 7.3 °C, respectively. Day‐degrees were estimated for each life stage. Larval development was affected by tree species, being slower on Sitka spruce than on Scots pine, and was faster under alternating than constant temperatures. The development time for prepupae was highly variable, with an apparent facultative prepupal diapause initiated by temperature. The temperature range 20–17.5 °C marked the transition between median prepupal development times of approximately 25 and 90 days. The prepupal stage may serve to minimize the risk of overwintering mortality in the pupal stage and help to synchronize the life cycle. Larval and adult mass was positively related to developmental temperature, demonstrating an inverse temperature size rule, and weevils were heavier when developing on Scots pine than Sitka spruce. Development in alternating temperatures reduced weevil mass on Scots pine. The influence of temperature on weevil mass is likely to have a positive effect on fecundity and overwintering survival. The effects of climate change on development, voltinism and weevil mass are discussed.