Temperature Development Research Articles

Developmental temperature affects thermal dependence of locomotor activity in Drosophila.

In their natural environments, animals have to cope with fluctuations in numerous abiotic and biotic factors, and phenotypic plasticity can facilitate survival under such variable conditions. However, organisms may differ substantially in the ability to adjust their phenotypes in response to external factors. Here, we investigated how developmental temperature affects the thermal performance curve for locomotor activity in adult fruit flies (Drosophila melanogaster). We examined the thermal dependence of spontaneous activity in individuals originating from two natural populations (from tropical (India) and temperate climate zone (Slovakia)) that developed at three different temperatures (19°C, 25°C, and 29°C). Firstly, we found that developmental temperature has a significant impact on overall activity - flies that developed at high temperature (29°C) were, on average, less active than individuals that developed at lower temperatures. Secondly, developmental acclimation had a population-specific effect on the thermal optimum for activity. Whereas the optimal temperature was not affected by thermal conditions experienced during development in flies from India, developmental temperature shifted thermal optimum in flies from Slovakia. Thirdly, high developmental temperature broadened performance breadth in flies from the Indian population but narrowed it in individuals from the Slovak population. Finally, we did not detect a consistent effect of acclimation temperature on circadian rhythms of spontaneous activity. Altogether, our results demonstrate that developmental temperature can alter different parameters (maximum performance, thermal optimum, performance breadth) of the thermal performance curve for spontaneous activity. Since adult fruit flies are highly vagile, this sensitivity of locomotion to developmental conditions may be an important factor affecting fitness in changing environments.

Effect of developmental temperatures on Aphidius colemani host-foraging behavior at high temperature

Temperatures experienced by insects during their adult life often differ from developmental temperatures. Yet, developmental thermal acclimation can play an important role in shaping physiological, morphological, and behavioral traits at the adult stage. We explored how three rearing temperatures (10, 20, and 28°C) affected host-foraging behaviors and associated traits under warm conditions in the parasitoid Aphidius colemani, a key model in behavioral ecology and an important natural enemy of aphids. Developmental time was longer at lower temperatures, resulting in bigger emerging parasitoids, with higher egg-loads. Parasitism rates, emergence rates, and parasitoid survival (once placed at high temperature) were the highest for parasitoids developed at 20°C. When exposed to 28°C, the expression of all behavioral items (time spent walking searching for hosts, number of antennal and ovipositor contacts with hosts) was higher for parasitoids reared at 20°C, followed by those reared at 10°C, then those reared at 28°C. Finally, we showed that parasitoid residence time on aphid patches was determined by both developmental temperatures and the number of host encounter without oviposition, representative of the resource quality. We revealed that developing at 28°C did not lead to increased adult performance at this temperature, probably because of complex interactions and trade-offs between developmental costs at high temperature and optimal foraging behaviors (e.g., parasitoid size and host-handling capacities). Our results strengthen the idea that thermal developmental plasticity may play an important role in insect behavioral responses to varying temperatures, and is important to consider in the context of climate change.

Influence of photoperiod on thermal responses in body size, growth and development in Lycaena phlaeas (Lepidoptera: Lycaenidae).

Many ectotherms species grow faster but attain a smaller body size when reared under warmer conditions, a phenomenon known as the Temperature-Size Rule (TSR). This rule appears to be stronger in aquatic ectotherms than in terrestrial ectotherms. The difference could be related to difficulties for oxygen uptake in water, whereas on land, adaptive responses in body size may relate to seasonal time constraints. To assess the role of seasonal time constraints in temperature size response of terrestrial ectotherms, we reared the small copper Lycaena phlaeas at three temperatures (18 ˚C, 23˚C and 28˚C) and two photoperiods (16L: 8D and 12L: 12D). We examined whether differences in body size across treatments was related to (1) differences in growth and development, (2) differences in breakpoints during growth trajectories, or (3) differences in ommatidia size (as a proxy for cell size). We found a weak inverse relationship between developmental temperature and the body size of adult butterflies; adult size decreased by approximately 1% for every degree warmer. Under warmer temperatures, caterpillars developed more quickly and had higher growth rates but reached a smaller body size. Under a short photoperiod, both growth and development were slower, especially at the two lower temperatures, but the body size resulting from slow growth over a longer developmental period did not vary with photoperiod. Breakpoints in growth trajectories occurred when larvae reached ∼40% of their maximum mass and these breakpoints were strongly correlated with the size of the resulting adults, suggesting that adult size is predetermined at an early stage. Temperature did not appear to cause reductions in body size through reductions in cell size. Butterflies were largely able to buffer their body size by modulating larval growth and development in tandem. They appear to use photoperiod as a cue to gauge the availability of time (with 12L: 12D indicating less time available) while temperature speeds up growth and development and as such governs the amount of time they need to complete a developmental cycle. Temperature and photoperiod thus induce changes in voltinism to fit a discrete number of generations into a growing season.

Proteomic analysis of temperature-dependent developmental plasticity within the ventricle of juvenile Atlantic salmon (Salmo salar).

In teleosts, cardiac plasticity plays a central role in mediating thermal acclimation. Previously, we demonstrated that exposure to elevated temperatures throughout development (+4°C) improved acute thermal tolerance of the heart in juvenile Atlantic salmon. Fish raised in a warmer thermal regime also displayed higher proportions of compact myocardium within their ventricles. In the present study, we investigated the molecular mechanisms supporting this temperature-specific phenotype by comparing relative protein abundance in ventricular tissue from the same experimental fish using mass spectrometry. We provide the first description of the ventricular proteome in juvenile Atlantic salmon and identify 79 proteins displaying differential abundance between developmental treatments. The subset of proteins showing higher abundance in fish raised under elevated temperatures was significantly enriched for processes related to ventricular tissue morphogenesis, and changes in protein abundance support a hypertrophic model of compact myocardium growth. Proteins associated with the vasculature and angiogenesis also showed higher abundance in the warm-developmental group, suggesting capillarization of the compact myocardium in the hearts of these fish. Proteins related to oxidative metabolism and protein homeostasis also displayed substantive shifts in abundance between developmental treatments, underscoring the importance of these processes in mediating thermal plasticity of cardiac function. While rapid growth under warm developmental temperatures has been linked to cardiomyopathies in farmed salmon, markers of cardiac pathology were not implicated in the present study. Thus, our findings offer a molecular footprint for adaptive temperature-dependent plasticity within the ventricle of a juvenile salmonid.

Pest categorisation of Maconellicoccus hirsutus.

The EFSA Panel on Plant Health performed a pest categorisation of Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), the pink hibiscus mealybug, for the EU. M. hirsutus is native to Southern Asia and has established in many countries in tropical and subtropical regions throughout the world. Within the EU, the pest has been reported from Cyprus and Greece (Rhodes). M. hirsutus is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. It is highly polyphagous, feeding on plants assigned to 229 genera in 78 plant families, and shows some preference for hosts in the families Malvaceae, Fabaceae and Moraceae. Economically important crops in the EU such as cotton (Gossypium spp.), citrus (Citrus spp.), ornamentals (Hibiscus spp.), grapes (Vitis vinifera), soybean (Glycinae max), avocado (Persea americana) and mulberry trees (Morus alba) may be significantly affected by M. hirsutus. The lower and upper developmental temperature threshold of M. hirsutus on Hibiscus rosa‐sinensis are 14.5 and 35.0°C, respectively, with optimal female development estimated to be at 29.0°C. There are about 10 generations a year in the subtropics but as many as 15 may occur under optimal conditions. Plants for planting, fruits, vegetables and cut flowers provide potential pathways for entry into the EU. Climatic conditions in EU member states around the Mediterranean Sea and host plant availability in those areas are conducive for establishment. The introduction of M. hirsutus is expected to have an economic impact in the EU through damage to various ornamental plants, as already observed in Cyprus and Greece, and reduction in yield and quality of many significant crops. Phytosanitary measures are available to reduce the likelihood of entry and further spread. Some uncertainties include the area of establishment, whether it could become a greenhouse pest, impact, and the influence of natural enemies. M. hirsutus meets the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest.

Higher developmental temperature increases queen production and decreases worker body size in the bumblebee Bombus terrestris

Climate change and increasing average temperatures are now affecting most ecosystems. Social insects such as bumblebees are especially impacted because these changes create spatial, temporal and morphological mismatches that could impede their ability to find food resources and mate. However, few studies have assessed how the colony and life cycle are affected when temperatures rise above optimal rearing temperature. It has become imperative to understand how heat stress affects the life history traits of insect pollinators as well as how changes in life history interact with other traits like morphology. For example, a decrease in the number of foraging workers could be balanced by producing larger workers, able to forage at longer distances and gather more resources. Here, we investigated the impact of temperature on colony production and body size in the bumblebee Bombus terrestris. Colonies were exposed to two temperatures: 25 °C, which is around the optimal temperature for larval development and 33 °C, which is slightly above the set-point that is considered stressful for bumblebees. Although the production of males and workers wasn’t significantly affected by these different temperatures, queen production and reproductive investment were much higher for colonies placed in 33 °C than in 25 °C. We also found that, in agreement with the temperature-size rule, workers were significantly smaller in the higher temperature. The decrease in worker body size could affect resource collection and pollination if their foraging distance and the quantity of food they are taking back to the colony decreases. While in our controlled conditions the bumblebees were fed ad libitum, the decrease of resource collection in field conditions could prevent colonies from producing as many queens as in our study. Together with the decrease of worker body size, our results suggest that elevated temperatures could ultimately have a negative impact on bumblebee colony fitness. Indeed, smaller workers are known to have weaker flight performance which could affect foraging performance and consequently colony development.

Temperature-dependent development of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) parasitizing Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

Inundated release of parasitoids is an environmentally friendly pest insect control method. Deep understanding influence of different temperatures on development of parasitoids is very helpful for improving biological control effectiveness. Thus, the life history parameters of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) reared on mature larvae (about 30 days old) of Lasioderma serricorne (F.) (Coleoptera: Anobiidae) were investigated at 15, 20, 25, 30, 35, and 40 °C. Anisopteromalus calandrae completed development with adult emergence at 25, 30, and 35 °C. The developmental rate of A. calandrae increased significantly with increasing temperature, and the favorable temperature for A. calandrae development was 25 °C. The mean generation survival rates were 49.67, 50.33, and 40.00% at 25, 30, and 35 °C, respectively. The developmental threshold temperatures of eggs, larvae, pupae, and preoviposition were 22.55, 18.86, 10.02, and 23.38 °C, respectively, and their effective accumulated temperatures were 5.33, 43.69, 152.48, and 2.90 °C·d, respectively. The present results are in favor of further understanding the biological characteristics of A. calandrae and designing effective biological control protocols.

Brain connectivity inversely scales with developmental temperature in Drosophila

Variability of synapse numbers and partners despite identical genes reveals the limits of genetic determinism. Here, we use developmental temperature as a non-genetic perturbation to study variability of brain wiring and behavior in Drosophila. Unexpectedly, slower development at lower temperatures increases axo-dendritic branching, synapse numbers, and non-canonical synaptic partnerships of various neurons, while maintaining robust ratios of canonical synapses. Using R7 photoreceptors as a model, we show that changing the relative availability of synaptic partners using a DIPγ mutant that ablates R7's preferred partner leads to temperature-dependent recruitment of non-canonical partners to reach normal synapse numbers. Hence, R7 synaptic specificity is not absolute but based on the relative availability of postsynaptic partners and presynaptic control of synapse numbers. Behaviorally, movement precision is temperature robust, while movement activity is optimized for the developmentally encountered temperature. These findings suggest genetically encoded relative and scalable synapse formation to develop functional, but not identical, brains and behaviors.

Identification of reference genes for normalization of gene expression in Liposcelis entomophila (Psocoptera: Liposcelididae)

• L. entomophila is a small nuisance insect and threatens food security. • To find suitable reference genes, expression stabilities of 12 genes were tested. • The combination of ACTB and EF1a was the best reference gene for L. entomophila. • It provided a basic foundation for studies of gene expression in L. entomophila. Liposcelis entomophila is a nuisance pest that seriously threatens the safety of stored grains owing in part of pesticide resistance. To facilitate better control of L. entomophila , future studies need to focus on gene function characterization. This requires the identification of suitable reference genes (RGs) for reverse-transcription quantitative PCR (RT-qPCR), which is crucial for the normalization of target gene expression. Here, we evaluated the expression stability of 12 candidate RGs in L. entomophila across six experimental conditions (developmental stage, population, body part, phosphine fumigation, hypoxia induction, and temperature treatment). Under developmental conditions, ACTB , HSP70 , and RPL23 were the most stable RGs. Among the different populations and body parts, RPL23 , EF1a , and ACTB were the most stable RGs. Comparison of gene expression among adults under different environmental conditions revealed that at least seven RGs were fit for normalizing gene expression data. Among them, RPL23, EF1a , and ACTB showed the best fit as RGs in RT-qPCR analysis. After validation, our results demonstrated that EF1a and ACTB , as well as their combination, were the ideal RGs for L. entomophila across various experimental conditions. This study provides a comprehensive RG selection suggestion for gene expression studies of L. entomophila and will facilitate future functional genomic research on the development and tolerance of environmental factors in psocids.

A new allele of engrailed, enNK14, causes supernumerary spermathecae in Drosophila melanogaster.

A spontaneous mutation, enNK14, was a new allele of engrailed (en) in Drosophila melanogaster. Females of enNK14 have three spermathecae, instead of two in wild type, under a wide range of developmental temperatures, while the males show no abnormal phenotype. Spermathecae of the mutant female can accept inseminated sperms, albeit with a delay of at least an hour until full acceptance compared with wild type. The time course of decrease in the number of stored sperms was thoroughly similar between the mutant and wild type. enNK14 females produced fewer progeny than wild type females despite storing a larger number of sperms. The delay of sperm entry and lower fecundity suggested some functional defects in secretory products of the spermathecae. In addition, some spermathecae in the mutant were accompanied by a mass of brown pigments in the adipose tissue surrounding the capsule. Six contiguous amino acids, Ser340-Ala345, were replaced by one Thr in enNK14. In another mutant, enspt, Ser325 was also shown to be substituted by a Cys. These amino acid changes were located within a serine-rich region, in which Ser325, Ser340 and Thr341 were suggested as targets of Protein Kinase C by an in silico analysis. The splicing pattern of en mRNA did not differ between enNK14 and wild type in embryo, larva, pupa or adult. Our results suggest that en plays an important role in determining the number of spermathecae as well as in sperm storage function in the Drosophila female.

Temperature‐based phenology model of African citrus triozid (Trioza erytreae Del Guercio): Vector of citrus greening disease

AbstractThe African citrus triozid (ACT), Trioza erytreae Del Guercio (Hemiptera: Triozidae), is the major vector of the ‘Candidatus Liberibacter africanus’, associated with the African citrus greening disease [huanglongbing (HLB)]. Although T. erytreae is a very destructive pest in citrus production with yield losses up to 100%, there is limited information on its thermal biology, which is a prerequisite for developing an environmentally friendly management strategy. This study investigated the effect of temperature on the development and survival of T. erytreae under eight constant temperatures (10, 15, 18, 20, 22, 24, 27 and 30°C), relative humidity of 65 ± 5% and a photoperiod of 12D:12L. Using Insect Life Cycle Modeling software, we fitted linear and non‐linear models to T. erytreae development and mortality data. The best‐fitted functions were compiled for each life stage to yield a phenology model. Our findings revealed that temperature had a significant effect on the development of all the immature stages. No complete development was observed at 10, 27 and 30°C. The developmental time of eggs ranged from 5.27 days at 24°C to 13.5 days at 15°C. The lowest developmental temperature threshold ranged between 3 and 15°C, with thermal constants ranging between 16.7 and 100 degree‐days. The 1st nymphal instars recorded the highest mortality at 15°C. The highest survival rates of the 3rd instar nymphs were recorded at 20°C. The model predicted that temperatures between 20 and 25°C were optimal for the survival of all the immature life stages, except for the 1st nymphal instars. Our results provide relevant information on the impact of temperature on the development and survival of T. erytreae, which is essential for the development of more efficient management strategies.

Evaluation of linear and nonlinear models for temperature driven development of Spodoptera litura (Fabricius) on soybean crop


 The tobacco caterpillar, Spodoptera litura, a major pest of soybean in India is under surveillance in all soybean growing areas in Maharashtra in order to issue alerts to farmers and prevent economic losses. In this context, two linear models were fitted to developmental data of S. litura life stages reared on soybean at five constant temperatures viz. 15, 20, 25, 30 and 35°C through laboratory experiments. Optimum temperature for development (Topt) and upper temperature threshold (Tmax) were estimated from three nonlinear models by additionally including developmental response at >35°C. Topt estimates for the total immature development were 34.5°C (Lactin-2), 33.7°C (Briere-1) and 33.2°C (Simplified Beta type function) while Tmax estimates were in the range of 38 to 40°C. Application of a thermodynamic non-linear model (Optim SSI) gave estimate ofintrinsic optimum temperature (Tφ) for development of egg (28.3°C), larva (27.5°C) and pupal stage (30.3°C). The phenology model of S. litura on soybean based on estimated developmental threshold temperatures and thermal constants was validated using available field surveillance data to facilitate informed pest management decisions.

Screening and validation of reference genes using in RT-qPCR for gene expression studies in Paederus fuscipes, a medically and agriculturally important insect

Paederus fuscipes is a medically and agriculturally important insect all over the world. P. fuscipes cause not only a skin condition but is also an aggressive predator in different agro-ecosystems. Prior to performing RT-qPCR under a variety of conditions to investigate the function of target genes in P. fuscipes, it is essential to screen reference genes. However, no P. fuscipes reference gene(s) has yet been discovered. Using the RefFinder software package, which includes ΔCt, geNorm, NormFinder, and BestKeeper, we evaluated the stability of seven housekeeping genes of P. fuscipes under five conditions (developmental stage, diet, temperature, tissue and sex). During the RT-qPCR analysis, geNorm software was used to evaluate pairwise variation in order to identify the most appropriate number of reference genes. The results revealed that for developmental stages RPL-13, EF1A and β-tubulin; for sex-related experiments β-tubulin and Actin, for tissue-related experiments PRS-18, 18S and RPL-13; for temperature-related experiments β-tubulin and PRL-13 and diet-related experiments, β-tubulin and PRS-18 are suitable reference genes. Furthermore, the associated HSP-70 (as the reporter gene) expression patterns differed significantly when the three most stable and three least stable reference genes were selected in different temperature treatments. This is the first time that a complete list of standardized reference genes has been given for P. fuscipes to use in an RT-qPCR study, which could be helpful for potential functional studies of target genes in P. fuscipes.

Ambient temperature as a factor contributing to the developmental divergence in sympatric salmonids.

Factors and mechanisms promoting resource-based radiation in animals still represent a main challenge to evolutionary biology. The modifications of phenotype tied with adaptive diversification may result from an environmentally related shift having occurred at the early stage of development. Here, we study the role of temperature dynamics on the reproductive sites in the early-life divergence and adaptive radiation of the salmonid fish Salvelinus malma dwelling in the Lake Kronotskoe basin (North-East Asia). Local sympatric charr ecomorphs demonstrate strict homing behaviour guiding the preordained distribution along tributaries and, hence, further development under different temperatures. We thoroughly assessed the annual temperature dynamics at the spawning grounds of each morph as compared to an ancestral anadromous morph. Then we carried out an experimental rearing of both under naturally diverging and uniformed temperatures. To compare the morphs’ development under the dynamically changing temperatures, we have designed a method based on calculating the accumulated heat by the Arrhenius equation. The proposed equation shows a strong predictive power and, at the same time, is not bias-susceptible when the developmental temperature approximates 0°C. The temperature was found to significantly affect the charrs’ early ontogeny, which underlies the divergence of developmental and growth rates between the morphs, as well as morph-specific ontogenetic adaptations to the spawning site’s temperatures. As opposed to the endemic morphs from Lake Kronotskoe, the anadromous S. malma, being unexposed to selection оn highly specific reproduction conditions, showed a wide temperature tolerance, Our findings demonstrate that the hatch, onset timing of external feeding, and size dissimilarities between the sympatric morphs reveal themselves during the development under contrast temperatures. As a result of the observed developmental disparities, the morphs occupy specific definitive foraging niches in the lake.

Heightened among-individual variation in life history but not morphology is related to developmental temperature in reptiles.

Increases in phenotypic variation under extreme (e.g. novel or stressful) environmental conditions are emerging as a crucial process through which evolutionary adaptation can occur. Lack of prior stabilizing selection, as well as potential instability of developmental processes in these environments, may lead to a release of phenotypic variation that can have important evolutionary consequences. Although such patterns have been shown in model study organisms, we know little about the generality of trait variance across environments for non-model organisms. Here, we test whether extreme developmental temperatures increase the phenotypic variation across diverse reptile taxa. We find that the among-individual variation in a key life-history trait (post-hatching growth) increases at extreme cold and hot temperatures. However, variations in two measures of hatchling morphology and in hatchling performance were not related to developmental temperature. Although extreme developmental temperatures may increase the variation in growth, our results suggest that plastic responses to stressful incubation conditions do not generally make more extreme phenotypes available to selection. We discuss the reasons for the general lack of increased variability at extreme incubation temperatures and the implications this has for local adaptation in hatchling morphology and physiology.

Responses to Developmental Temperature Fluctuation in Life History Traits of Five Drosophila Species (Diptera: Drosophilidae) from Different Thermal Niches.

Simple SummaryMost laboratory experiments on insects to date have been conducted using constant temperature settings. Even when the purpose of the study was to investigate effects of temperature, insects have mostly been kept at different but constant temperatures ignoring natural variation in temperature. Here we investigated effects of simple daily temperature fluctuation (22.5/27.5 °C and 20/30 °C) on some development characteristics in five species of fruit flies (Drosophila) originating from areas with different temperature profiles. We demonstrated how species of the same genus can show substantial differences when developing at fluctuating temperatures not always predictable by development at comparable constant temperature (25 °C).Temperature has profound effects on biochemical processes as suggested by the extensive variation in performance of organisms across temperatures. Nonetheless, the use of fluctuating temperature (FT) regimes in laboratory experiments compared to constant temperature (CT) regimes is still mainly applied in studies of model organisms. We investigated how two amplitudes of developmental temperature fluctuation (22.5/27.5 °C and 20/30 °C, 12/12 h) affected several fitness-related traits in five Drosophila species with markedly different thermal resistance. Egg-to-adult viability did not change much with temperature except in the cold-adapted D. immigrans. Developmental time increased with FT among all species compared to the same mean CT. The impact of FT on wing size was quite diverse among species. Whereas wing size decreased quasi-linearly with CT in all species, there were large qualitative differences with FT. Changes in wing aspect ratio due to FT were large compared to the other traits and presumably a consequence of thermal stress. These results demonstrate that species of the same genus but with different thermal resistance can show substantial differences in responses to fluctuating developmental temperatures not predictable by constant developmental temperatures. Testing multiple traits facilitated the interpretation of responses to FT in a broader context.

Temperature-based phenology model for predicting the present and future establishment and distribution of recently invasive Spodoptera frugiperda (J. E. Smith) in India.

Fall armyworm, Spodoptera frugiperda (J. E. Smith) is a polyphagous and highly destructive invasive insect pest of many crops. It was recently introduced into India and widely reported in almost all parts of India. Development of a temperature-based phenology model for predicting its rate of development and distribution will help in understanding the establishment and further spread of introduced invasive insect pests. Development, survival and reproduction parameters of S. frugiperda at six constant temperature conditions (15, 20, 25, 27, 30 and 35°C) were investigated and further validated with data generated under fluctuating temperature conditions. The estimated lower developmental threshold temperatures were 12.1°C for eggs, 11°C for larvae, 12.2°C for pupae, 15.13°C for males and 12.66°C for females. Degree-day (DD) requirements for the development of the different stages of S. frugiperda were 50, 250 and 200 DD for egg, larva and pupa, respectively. The best-fitted functions were compiled for each life stage to yield a phenology model, which was stochastically simulated to estimate the life table parameters. The developed phenology model predicted temperature ranges between 27 and 30°C as favourable for S. frugiperda development, survival and reproduction. The results revealed that maximum net reproductive rate (215.66 females/female/generation) and total fecundity (981.08 individuals/female/generation) were attained at 30°C constant temperature. The mean length of generations decreased from 74.29 days at 15°C to 38.74 days at 30°C. The maximum intrinsic rate of increase (0.138 females/female/day) and shortest doubling time (4.9 days) were also observed at 30°C. Results of simulated life table parameters showed high temperature-dependent development of S. frugiperda and complete development within all the tested constant temperature ranges (15-35°C). Simulated life table parameters for predicting risk indices of S. frugiperda in India indicated a significant increase in activity indices and establishment risk indices with a higher number of generations during future (2050 and 2070) climatic change scenarios compared to present conditions. Our results indicate that India will be highly suitable for the establishment and survival of S. frugiperda in future time periods.

Spatial and temporal variation in phenotypes and fitness in response to developmental thermal environments

AbstractPhenotypic variation within populations is influenced by the environment via plasticity and natural selection. How phenotypes respond to the environment can vary among traits, populations and life stages in ways that can influence fitness.Plastic responses during early development are particularly important because they can affect components of fitness throughout an individual's life. Consequently, how natural selection shapes developmental plasticity could be influenced by fitness consequences across different life stages. Moreover, spatial variation in selection pressures could generate differences in plastic responses among populations.To gain insight into sources of variation in phenotypes and survival, we used a laboratory egg incubation experiment using brown anole lizardsAnolis sagreifrom mainland (ancestral) and island (descendent) populations, combined with a mark–release–recapture experiment in the field. Our study was designed to (a) quantify the effects developmental temperature on embryo development and offspring morphology, (b) assess how developmental temperature influences offspring survival across different life stages and (c) quantify how thermal reaction norms vary among ancestral and descendant populations.Developmental temperature influenced offspring morphology, but thermal reaction norms of embryos showed little variation among populations. Developmental temperature influenced offspring survival, but the patterns differed between embryo and hatchling stages; the optimal temperature for embryos was about 5℃ lower than that for hatchlings. High temperatures were thermally stressful to embryos, but they reduced incubation duration and led to early hatching. In turn, earlier hatching increased the probability of survival to adulthood. Moreover, the effect of developmental temperature on hatchling survival was most pronounced for offspring that hatched late in the season.The difference in optimal developmental temperatures between life stages may be driven by physiological tolerance for embryos and by ecological factors for hatchlings. Moreover, the fitness consequences of the developmental environment depend on the phenology of hatching. Overall, these results highlight how the developmental environment can differentially affect fitness across life stages and show that temporal thermal heterogeneity can influence survival of embryos, but the consequences on post‐hatching stages may vary at different times of the season.A freePlain Language Summarycan be found within the Supporting Information of this article.

Selection and Evaluation of Reference Genes for qRT-PCR in Spodoptera frugiperda (Lepidoptera: Noctuidae).

Simple SummaryThe fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is an extremely important omnivorous agricultural pest, it poses a severe threat to food security and agricultural production. Quantitative real-time PCR (qRT-PCR) is an important molecular technology widely used for expression profile analyses of various target genes. It is essential to use reference genes as the benchmark to eliminate various errors and normalize the qRT-PCR analysis. In our study, 10 reference genes were evaluated under six experimental conditions, including developmental stages, tissues, mating status, hormones, diets, and temperatures. Finally, the expression profile of the target gene SfrOBP1 in various tissues of S. frugiperda was evaluated to verify the accuracy of the results. This study will provide a preliminary evaluation of reference genes of S. frugiperda, which can be beneficial to the further research of functional gene expression.As an accurate and convenient technique, the qRT-PCR is always used in the quantitative expression analysis of functional genes. Normalization of the data relies on stable reference genes. The fall armyworm Spodoptera frugiperda (J. E. Smith) is an important invasive and migratory pest that seriously threatens corn production around the world. In this paper, we selected 10 candidate reference genes (18S, AK, RPL10, RPS24, 28S, SOD, ATP, GAPDH, ACT, and a-TUB) and determined their expression levels under different conditions (different developmental stages, various tissues, mating status, hormones, diets, and temperatures). Subsequently, the stability of reference genes was evaluated by four algorithms (Delta Ct method, geNorm, NormFinder, BestKeeper). The optimal combination of reference genes for each treatment was obtained by geNorm. Finally, the comprehensive ranks were determined by the online tool RefFinder. Results showed that the most stable reference genes were SOD, RPL10, and RPS24 for developmental stages, α-TUB, RPL10, and ATP for different tissues, AK, RPL10, and 18S for mating status, 18S and AK under hormone treatment, 18S, RPL10, and SOD under diet treatment, RPL10, 18S, and RPS24 under temperature treatment. This study confirmed recent data on a few reference genes and provided an evaluation of a number of additional reference genes of S. frugiperda under various conditions.

Thermal development of the endoparasitoid Aphelinus maculatus Yasnosh (Hymenoptera: Aphelinidae) parasitizing Myzus persicae Sulzer (Homoptera: Aphididae).

The aphid parasitoid, Aphelinus maculatus Yasnosh, was first documented in China in 2016. It is important to make clear of the effects of temperatures on the development of this aphid parasitoid for the future using as a aphid biological control agent. So the thermal requirements, lower developmental threshold (t), thermal constant (K), upper developmental threshold (Tm) and optimum developmental temperature (To) for the egg-mummy, mummy-adult and egg-adult periods of A. maculatus were established under the laboratory conditions. The studies were conducted at five constant temperatures (13, 18, 23, 28, and 33°C) and with a 16L: 8D photoperiod. Lower developmental threshold (t) and thermal constant (K) were estimated by fitting linear model. Upper developmental threshold (Tm) and optimal developmental temperature (To) were estimated by fitting Logan I non-linear model. The results turned out that the lower (t) and the upper developmental thresholds (Tm) for egg-adult period were 5.59°C and 28.17°C, respectively. The thermal constants (K) for egg-mummy, mummy-adult, and egg-adult periods were estimated at 121.51, 127.88, and 243.90 degree-days, respectively. The optimal developmental temperature (To) for egg-adult period was 27.45°C calculated by the model, but the survival rate was only 40.68% at the temperature of 28°C. The highest survival rate was 74.32% at temperature of 23°C, implying that A. maculatus preferentially developed at the temperate regions of temperature.