Developmental Threshold Research Articles

The growth and development characteristics of Spodoptera frugipetda under different temperature conditions

In order to study the main biological characteristics of Spodoptera frugipetda,the developmental duration,fecundity,developmental threshold temperature and effective accumulated temperature of different stages were measured on maize seedlings were used as feed under five temperature conditions:20℃,25℃,28℃,32℃and 35℃,in laboratory.The results showed that the development duration of S.frugipetda(egg,larvae,pupae and adult)was gradually decreased with the increase of temperature within the range from 20℃to 35℃,and the generation development duration was 23.0~48.3 d.The developmental threshold temperatures of egg,larvae,pupa,adult and whole generation were 12.70℃,11.11℃,11.01℃,5.65℃and 9.21℃,respectively.And the effective accumulate temperatures were 39.4 d·℃、201.25 d·℃、134.12 d·℃、171.06 d·℃and 636.53 d·℃.The optimum temperature for eggs,larvae,pupa developing and adults oviposition was 20~32℃.However,the temperature of 15℃and 35℃were not conducive to S.frugiperda growth and development.Base on the tested developmental threshold temperature and effective accumulative temperature,the paper speculated that the generation numbers of S.frugipetda in the middle regions,west,south,southeast,southwest,northeast and northwest were 2.18~8.59,2.28~10.15,3.43~12.13,3.15~8.46,2.75~9.39,1.38~6.87 and 1.11~6.72 respectively in Yunnan Province.

Thermal resilience of Prostephanus truncatus (Horn): Can we derive optimum temperature-time combinations for commodity treatment?

Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), is a wood-boring, destructive quarantine insect pest of stored cereal grains and tuber crops. Current disinfestation methods against this pest mainly include fumigants, whose usage in some countries has been contested and discontinued owing to increasing pesticide resistance, public health risks and environmental hazards. Grain temperature treatments thus, offer a sustainable non-chemical and near universally acceptable form of disinfestation for international commodity movement. Currently, blanket temperature treatments are applied regardless of as-yet-unknown P. truncatus developmental stage thermal mortality thresholds that simultaneously optimise grain quality. Here, we used established static and dynamic protocols to determine the low and high thermal profile of P. truncatus larvae and adults measured as critical thermal minima (CTmin), lower lethal temperatures (LLT0), chill coma recovery time (CCRT), supercooling points (SCPs), critical thermal maxima (CTmax), upper lethal temperatures (ULT0) and heat knock-down time (HKDT). We tested the adult ULT-time matrices on maize and sorghum grain quality (germination %) to determine the most effective temperature-time combination(s) retaining optimum grain germination quality. Our results showed adults had higher basal heat (CTmax and HKDT), cold (CTmin, CCRT and SCP) and potential thermal plasticity than larvae (P < 0.05). The LLTs and ULTs ranged −1 to −15 °C and 41–49 °C respectively. Using LLT0 and ULT0, our results showed that for heat treatment, moderate temperature × long duration matrix; i.e. either 45.5 °C × 4 h or 47 °C × 2 h were more efficacious while retaining commodity quality. Similarly, for cold treatment; −9 °C × 4 h, −11 °C × 2 h, −13 °C × 1 h and −15 °C × 0.5 h were effective for complete mortality. These temperature-time combinations may be a sustainable alternative to fumigants in phytosanitary grain disinfestation against P. truncatus or related pests. Such pest- and commodity -specific thermal profiling is critical for development of effective standardised grain disinfestation protocols.

Warmer temperature and provision of natural substrate enable earlier metamorphosis in the critically endangered Baw Baw frog.

Temperature and food availability are known to independently trigger phenotypic change in ectotherms, but the interactive effects between these factors have rarely been considered. This study investigates the independent and interactive effects of water temperature and food availability on larval growth and development of the critically endangered Baw Baw frog, Philoria frosti. Larvae were reared at low (12°C) or high (17°C) water temperature in the absence or presence of substrate that controlled food availability, and body size and time to metamorphosis were quantified. Growth and development of larvae was influenced by the individual effects of temperature and food availability; time to metamorphosis was shorter in warm water treatment groups and in the presence of substrate and increased food. Unexpectedly, however, water temperature and food availability did not have an interactive effect on either time to metamorphose or body size at metamorphosis. Under all treatment groups, metamorphic onset occurred once a developmental size threshold was reached, indicating that growth rate and body size are key factors controlling the metamorphic process in Baw Baw frogs (consistent with the Wilbur-Collins model for ectotherm development). From an applied perspective, our findings have implications for amphibian conservation because they indicate that simple manipulations of temperature and food availability can be used to increase the rate of frog production in conservation breeding programs.

Ecological divergence among morphologically and genetically related Asphondylia species (Diptera: Cecidomyiidae), with new life history data for three congeners including the Alpinia fruit gall midge

AbstractEcological data is crucial for determining the degree of reproductive isolation among closely related species, and in identifying the factors that have produced this divergence. We studied life history traits for three Asphondylia (Diptera: Cecidomyiidae) species that induce fruit galls either on Alpinia, Ligustrum or Aucuba, and we compared the traits with those published for three other closely related Japanese Asphondylia species. We found that the six species were significantly differentiated in important life history traits, such as host range, voltinism, lower developmental threshold temperature, thermal constant and diapausing season. The data indicate that divergence in the assessed life history traits evolves before morphological divergence, and such ecological divergence could strengthen isolating barriers among the taxa. We present scenarios on how host range expansion, host plant shift and host organ shift for galling initiate the early stages of speciation. We also highlight the importance of ecological data in identifying cryptic species. Specifically, we confirm that Alpinia intermedia (Zingiberaceae) is not an autumn–spring host of the soybean pod gall midge Asphondylia yushimai based on many differences in the life history traits between the Alpinia fruit gall midge Asphondylia sp. and A. yushimai.

Life history traits of Nesidiocoris tenuis on Bemisia tabaci and Thrips palmi

To develop an augmentative biological control programme for Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and Thrips palmi Karny (Thysanoptera: Thripidae) using Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), we studied the life history traits of a Japanese strain of N. tenuis reared on B. tabaci and T. palmi in controlled environments. The lower developmental threshold during the nymphal period was far higher than those estimated for Spanish, Moroccan, and Iranian strains, indicating that the Japanese strain is better adapted to higher temperatures than the other three strains tested. The intrinsic rate of increase rm was highest at 30 °C and lowest at 20 °C. The rm value for individuals reared on T. palmi at 25 °C was lower than that for individuals reared on B. tabaci at the same temperature. Implications of these results for the biological control of B. tabaci and T. palmi in greenhouses are discussed.

Estimation and validation of developmental thresholds and thermal requirements for cotton pink bollworm Pectinophora gossypiella

The developmental thresholds and thermal requirements of pink bollworm were estimated using laboratory data on its development at six constant temperatures from 15 °C to 38 °C. The results were validated using field data on male moth catches in sex pheromone traps baited with gossyplure recorded at Nagpur (Maharashtra) during 2018 for predicting the initiation of moth emergence and completion of generation events. The theoretical lower and upper threshold temperatures estimated using non–linear Sharpe and DeMichele model applied to mean development rates were: 14.17/35.43, 15.18/35.48, 11.00/35.48 and 13.40/35.50 °C, and the thermal requirements estimated as inverse of slope of linear regression were: 72.99, 285.71, 144.92 and 503.62° days for development of eggs, larvae, pupae and egg – adult emergence, respectively. Simulation of life table parameters provided reasonably closer estimates across the tested locations. The estimated lower and upper threshold temperatures accumulated the heat units (489.90–497.90) closer to the laboratory estimates (503.62 DD) and sensibly predicted the developmental events in pink bollworm with ±1.0 day error of margin under field conditions. The estimated thresholds and thermal requirements may help in comprehending seasonal dynamics of pink bollworm in relation to timings of developmental events like beginning and peaks of moth emergence, oviposition and egg hatching. This could facilitate in undertaking timely pest management actions such as insecticidal applications.

The Establishment Risk of Lycorma delicatula (Hemiptera: Fulgoridae) in the United States and Globally.

Native to Asia, the spotted lanternfly, Lycorma delicatula (White), is an emerging pest of many commercially important plants in Korea, Japan, and the United States. Determining its potential distribution is important for proactive measures to protect commercially important commodities. The objective of this study was to assess the establishment risk of L. delicatula globally and in the United States using the ecological niche model MAXENT, with a focus on Washington State (WA), where large fruit industries exist. The MAXENT model predicted highly suitable areas for L. delicatula in Asia, Oceania, South America, North America, Africa, and Europe, but also predicted that tropical habitats are not suitable for its establishment, contrary to published information. Within the United States, the MAXENT model predicted that L. delicatula can establish in most of New England and the mid-Atlantic states, the central United States and the Pacific Coast states, including WA. If introduced, L. delicatula is likely to establish in fruit-growing regions of the Pacific Northwest. The most important environmental variables for predicting the potential distribution of L. delicatula were mean temperature of driest quarter, elevation, degree-days with a lower developmental threshold value of 11°C, isothermality, and precipitation of coldest quarter. Results of this study can be used by regulatory agencies to guide L. delicatula surveys and prioritize management interventions for this pest.

Integrating temperature-dependent life table data into Insect Life Cycle Model for predicting the potential distribution ofScapsipedus icipe Hugel & Tanga.

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

Temperature-dependent development of the blow fly Chrysomya pinguis and its significance in estimating postmortem interval.

Chrysomya pinguis (Walker) (Diptera: Calliphoridae) is an endemic Asiatic blow fly species of forensic importance. Chrysomya pinguis is one of the first species to colonize a corpse, especially in high altitude areas during spring and autumn when the ambient temperature is lower. Despite its potential for forensic investigations to estimate the minimum postmortem interval (PMImin), little is known about the development of C. pinguis. In this study, C. pinguis was collected from the Yangtze River Delta region of China and reared at seven constant temperatures between 16°C and 34°C to investigate the effect of temperature on development duration, accumulated degree hours and larval body length of C. pinguis. Isomorphen and isomegalen diagrams for C. pinguis were generated using the results, and equations describing the variation in larval body length during development and the temperature-induced variation in development time were also obtained. Chrysomya pinguis can complete its life cycle at 16–34°C. The mean (±s.d.) developmental durations of C. pinguis from egg to adult at 16°C, 19°C, 22°C, 25°C, 28°C, 31°C and 34°C were 811.0 ± 3.8, 544.8 ± 2.0, 379.8 ± 1.8, 306.7 ± 2.4, 250.0 ± 2.8, 203.2 ± 2.1 and 185.3 ± 1.6 h, respectively. The mean (±s.e.) developmental threshold temperature D0 and the thermal summation constant K of the whole developmental process of C. pinguis were estimated as 10.88 ± 0.21°C and 4256.50 ± 104.50 degree hours, respectively. This study provides fundamental development data for the use of C. pinguis to estimate PMImin.

Complete metamorphosis of insects.

The majority of described hexapod species are holometabolous insects, undergoing an extreme form of metamorphosis with an intercalated pupal stage between the larva and adult, in which organs and tissues are extensively remodelled and in some cases completely rebuilt. Here, we review how and why this developmental strategy has evolved. While there are many theories explaining the evolution of metamorphosis, many of which fit under the hypothesis of decoupling of life stages, there are few clear adaptive hypotheses on why complete metamorphosis evolved. We propose that the main adaptive benefit of complete metamorphosis is decoupling between growth and differentiation. This facilitates the exploitation of ephemeral resources and enhances the probability of the metamorphic transition escaping developmental size thresholds. The evolution of complete metamorphosis comes at the cost of exposure to predators, parasites and pathogens during pupal life and requires specific adaptations of the immune system at this time. Moreover, metamorphosis poses a challenge for the maintenance of symbionts and the gut microbiota, although it may also offer the benefit of allowing an extensive change in microbiota between the larval and adult stages. The regulation of metamorphosis by two main players, ecdysone and juvenile hormone, and the related signalling cascades are now relatively well understood. The mechanics of metamorphosis have recently been studied in detail because of the advent of micro-CT and research into the role of cell death in remodelling tissues and organs. We support the argument that the adult stage must necessarily have preceded the larval form of the insect. We do not resolve the still contentious question of whether the larva of insects in general originated through the modification of existing preadult forms or through heterochrony as a modified embryonic stage (pronymph), nor whether the holometabolous pupa arose as a modified hemimetabolous final stage larva. This article is part of the theme issue 'The evolution of complete metamorphosis'.

Occurrence model of first instars of Ricania shantungensis (Hemiptera: Ricaniidae)

Abstract An invasive planthopper, Ricania shantungensis, is an important pest in agriculture and forestry in Korea. Best target stage for insecticide application is known to be newly hatched first instar. Thus, the objective of the present study was to predict the occurrence of first instars of R. shantungensis. Effects of temperature on development and survival of R. shantungensis eggs were examined at seven constant temperatures (12.4, 16.4, 20.4, 24.8, 28.3, 32.4, and 36.9 °C). Development and survival of R. shantungensis eggs were quantitatively described by applying empirical models as a function of temperature over a wide thermal range. Lower developmental threshold, thermal constant, optimal developmental temperature, and upper developmental threshold were estimated to be 12.1 °C, 202 DD, 31 °C, and 36.9 °C, respectively. Survivorship was the highest at 23.3 °C. The models well predicted timing of field occurrences at three sites (Buyeo, Gwangyang, and Habcheon) in Korea. Therefore, results of this study would increase the prediction accuracy of R. shantungensis occurrence and management efficiency of R. shantungensis.

Laboratory evaluation of development and survival of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) under constant temperatures

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is a serious pest of stored products. The effect of temperature on the development and survival of this species was determined at five constant temperatures (20, 25, 30, 32.5 and 35 °C) in the laboratory. Results showed a temperature-dependent development of T. castaneum. Data were fitted to the nonlinear Briere model, which for the total immature period estimated the lower threshold at 20.2 °C, the upper developmental threshold at 35.3 °C, and the temperature for maximum developmental rate at 31.2 °C. The Ikemoto and Takai linear model indicated that 659.7 degree-days above a threshold of 16.9 °C were needed to complete immature development from egg to adult emergence. Survival of immature stages varied significantly across temperatures and was well described by an extreme-value function. The model indicated that the highest survival (73.0%) was estimated to occur at 27.4 °C. The curve shows a skewed bell shape, indicating that survival decreases at both ends of the temperature range. These results are useful tools for the prediction of T. castaneum phenology, as well as for its management.

Determinants and consequences of plant-insect phenological synchrony for a non-native herbivore on a deciduous conifer: implications for invasion success.

Phenological synchrony between herbivorous insects and host plants is an important determinant of insect distribution and abundance. Non-native insects often experience novel climates, photoperiods, and host plants. How critical time periods of insect life cycles coincide with-or diverge from-phenological windows of host plant suitability could affect invasion success and the dynamics of outbreaks. Larch casebearer is an invasive defoliator that has recently undergone anomalous outbreaks on eastern larch in North America. We conducted growth chamber, greenhouse, and field studies to quantify the spring phenological window for larch casebearer on eastern larch and importance of phenological synchrony for casebearer development and survival. We constructed degree-day models of spring activity for both species and investigated responses of casebearers to early and delayed activation relative to bud break. Both species had lower developmental thresholds of ~ 5°C, but mean activation of casebearers occurred 245 degree-days after bud break by eastern larch. In addition to forcing temperatures, phenologies of eastern larch and casebearer larvae were significantly influenced by chilling and photoperiod, respectively. Larvae were robust to both starvation and delayed activation; days betweenlarval activation and bud break (range: 0-58days) had no influence on larval development and survival to adulthood. Disparateplant-insect responses to environmental cues and robustness of casebearers to changes in phenology result in a wide phenological window that likely has contributed to the insect's broad distribution in easternNorth America. Changes in phenological synchrony, however, do not appear to have facilitated recent outbreaks of larch casebearer on eastern larch.

Life-History Traits of a Subtropical Cerambycid Beetle, Ropica honesta (Coleoptera: Cerambycidae).

Ropica honesta Pascoe is a small-sized cerambycid that has been recorded in tropical to subtropical Asia. In this study, life-history traits were examined for a local population collected from Iriomote Island (24.3°N, 123.8°E), Okinawa, Japan, by rearing insects on artificial diet as larval food. The egg period was 5.9 ± 0.3 d at 25°C. There was no significant difference in the duration of the larval, pupal, and adult preoviposition periods between long-day (14:10 [L:D]) and short-day (12:12 [L:D]) photoperiods at both 20 and 25°C. These periods at 25°C (14:10 [L:D]) were 28.5 ± 1.4, 8.4 ± 0.5, and 9.6 ± 1.9 d (mean ± SD), respectively. The relationship between the developmental rate and temperature followed the law of total effective temperature; thus, the developmental threshold temperature and thermal constant were estimated based on these data. Together with the finding that R. honesta may not have diapause in the egg stage, it is suggested that this beetle does not have diapause in the life cycle. Furthermore, when larvae were reared on natural food (dead twigs of hardwoods) adults emerged from the twigs 47.6 ± 2.9 d after oviposition, and this value was close to the total duration of the egg to pupal periods. Together with the data for annual temperature of the habitat and the fact that food resources for the species (dead twigs and leaves of hardwoods) are available throughout the year, we conclude that R. honesta develops and reproduces all year round, with five generations at maximum.

Effect of Temperature and Tissue Type on the Development of the Forensic Fly Chrysomya megacephala (Diptera: Calliphoridae).

Chrysomya megacephala Fabricius is one of the most common myiasis-causing and carrion-feeding fly species in the tropics. This species has a worldwide distribution due to globalization and therefore is of critical importance to the public health sector and forensic investigations. Development studies carried worldwide show that Ch. megacephala reared at similar temperatures may require different amounts of time to complete their cycle of growth. The present study determined for the first time the life-history information of this species in Sri Lanka. Chrysomya megacephala colonies were reared on three different food sources (bovine muscle, swine muscle, and swine liver) considering the most common forensic entomology rearing mediums and the capability of Ch. megacephala to cause myiasis in cattle. Furthermore, colonies were reared at four temperature regimes representing several specific development conditions of this blowfly: 1) 20°C representing the estimation of the lower developmental threshold for this species in Sri Lanka; 2) 25 and 27°C representing typical room/environmental temperatures in Sri Lanka; and 3) 38°C as this is the typical living animal temperature, representing myiasis conditions. Results show that temperature significantly affected larval length and width over time; however, tissue type was not a significant factor. The fastest development was recorded at 38°C for immature feeding on bovine muscle (162.15 h), followed by those fed swine liver (184.15 h) and swine muscle (208.00 h). The calculated minimum temperature threshold for Ch. megacephala was 13°C. Data generated will be crucial for future forensic investigations involving living or deceased individuals colonized by this species.

Temperature‐dependent development of the double‐spined spruce bark beetle Ips duplicatus (Sahlberg, 1836) (Coleoptera; Curculionidae)

AbstractDevelopment of the double‐spined spruce bark beetle Ips duplicatus (Sahlberg, 1836) was investigated using the sandwich method under long‐day conditions (LD 18 : 6 h) at 10 constant temperatures: 7, 10, 12, 15, 20, 25, 30, 33, 35 and 39 °C. The method proved unsuitable at lower temperatures (7–12 °C), where high mortality occurred. At higher temperatures, development from egg to eclosion of adults shortened from 39.0 days at 15 °C to 10.3 days at 30 °C. Temperatures over 33 °C were lethal to all eggs, larvae and pupae. The developmental rate increased linearly at temperatures between 15 and 25 °C. Stage‐specific parameters, such as upper and lower developmental thresholds and optimum temperature for development, were determined by linear and nonlinear (Logan‐Lactin) models. Lower developmental thresholds obtained from nonlinear regression were calculated to be 9 °C (eggs), 6.1 °C (larvae), 6.9 °C (pupae) and 6.3 °C (development from eggs to pupae). Upper developmental thresholds for all stages oscillated around 39 °C and optimal temperatures oscillated around 30 °C. The rapid development of I. duplicatus at 15 and 30 °C [10 and 4 days faster than Ips typographus (L.), respectively] may explain its recent outbreak dynamics and low effectivity of preventive control measures

Biological traits of Epitrix papa (Coleoptera: Chrysomelidae: Alticinae), a new potato pest in Europe, and implications for pest management

AbstractThe biological traits of Epitrix papa were studied at different temperatures. Development time decreased significantly with increasing temperature, from 102.3 days at 15 °C to 29.7 days at 30 °C. The preoviposition period ranged from 7.2 to 19.9 days, the oviposition period from 44 to 115 days, and the fecundity from 63.7 to 190.2 eggs per female, respectively, at 15 and 25 °C. Eggs hatched in 7–9 days and 50.1% developed to adults. Female longevity ranged from 150 and 160 days at 15 °C to 60 days at 22 and 25 °C. At 20 °C, both sexes had a similar life span of approximately 90 days but, at 15 °C, males had a significantly longer life span (189 days) than females (150 days). The development rate (y) was related to temperature (x) by the function y = 0.0016× −0. 013 (r2 = 0.921), the lower developmental threshold was 8.1 °C and 625 degree‐days were required for completing development. Based on this model, three or four generations per year were predicted in Central Portugal, although only the first‐ and second‐generation larvae develop during the main cropping season. By predicting the emergence of first‐generation adults, the model provides a tool for improving the pest management strategy.

Seasonal Development of Plant Bugs (Heteroptera, Miridae): Subfamily Bryocorinae

Data on seasonal development of plant bugs from subfamily Bryocorinae (Miridae) are reviewed and analyzed. All of the species of bryocorines whose seasonal development has been studied so far belong to the tribe Dicyphini, owing to the latter’s economic importance as agents of biological control in greenhouses. Macrolophus melanotoma, M. pygmaeus, and Nesidiocoris tenuis have homodynamic seasonal development and the lower developmental threshold of about 8–9°C. If food is available, they can remain active all year round and produce annually a varying number of generations, depending on the local climatic conditions. To survive adverse low-temperature winter conditions these species use various natural protected microhabitats and can overwinter at different developmental stages. The other two bryocorines studied (Dicyphus errans and D. hesperus) exhibit heterodynamic seasonal development and overwinter in the state of adult diapause. Induction of this diapause is controlled by a long day-type photoperiodic response. Also, the nymphal growth rate of D. errans is affected by day length and this quantitative photoperiodic response ensures that nymphs of this species reach the diapausing stage (adult) in appropriate time, which is crucial for successful overwintering. The threshold photoperiod for induction of winter adult diapause varies with latitude in D. hesperus, only nymphs being sensitive to day length in this species. Pilot experimental studies should precede any planned introduction of a biocontrol agent, as these may reduce the risk of invasions. During the early stages of settling in a new area, it is seasonal adaptations controlling development of bug populations in their natural environments that are particularly important. In greenhouses, higher efficiency of biocontrol measures can be achieved with southern multivoltine populations of homodynamic species, especially if these grow rapidly as immatures, have high reproduction rates at the adult stage, and easily switch to novel prey. Under field conditions, polyphagous heterodynamic univoltine species and populations with deep obligate diapause are more likely to naturalize successfully.

The Influence of Temperature Variation on Life History Parameters and Thermal Performance Curves of Tamarixia radiata (Hymenoptera: Eulophidae), a Parasitoid of the Asian Citrus Psyllid (Hemiptera: Liviidae).

This study examined the effects of seven constant and fluctuating temperature profiles with corresponding averages of 12 to 38°C on the life history of the Punjab, Pakistan-sourced Tamarixia radiata (Waterston) released in California for biological control of Diaphorina citri Kuwayama. One linear and seven nonlinear regression functions were fit to egg-to-adult development rate data to characterize thermal performance curves. Temperature fluctuations significantly affected both development and longevity of T. radiata. Estimates of degree-days predicted by the linear model were 30% higher for the fluctuating regime than the constant regime. Nonlinear model estimations of theoretical minimum and maximum developmental thresholds were lower for the fluctuating regime when compared to the constant regime. These predictions align with experimental observations. Parasitoids reared under fluctuating profiles at low average temperatures developed faster (15°C) and survived longer (15-20°C) when compared to those reared under constant regimes with corresponding means. In contrast, high average fluctuating temperatures produced parasitoids with an extended developmental period (35°C) and reduced longevity (30-35°C). A meta-analysis of published T. radiata development datasets, together with the results of this study, indicated convergence in degree-days and theoretical minimum developmental thresholds among geographically distinct parasitoid populations. These findings demonstrate the significant effects of temperature on T. radiata life history and have important implications for optimization of mass-rearing and release efforts, improvement of predictions from climate modeling, and comparison of T. radiata population performance across climatic gradients and geographic regions.

Development of Chrysomya rufifacies (Diptera: Calliphoridae) at Constant Temperatures Within its Colony Range in Yangtze River Delta Region of China.

The age of insects found on corpses is often used to estimate the minimum postmortem interval by forensic entomologists. Insect development is affected by biotic and abiotic factors, and temperature is the most important environmental factor that determines the length of insect development. Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) is a globally distributed fly that is commonly found on corpses, and this study investigated the development of C. rufifacies from China at various constant temperatures. At 16, 19, 22, 25, 28, 31, and 34°C, the developmental time from egg to adult was 870.17 ± 11.50, 566.20 ± 8.79, 406.38 ± 10.98, 291.14 ± 4.71, 232.59 ± 5.96, 192.47 ± 3.45, and 160.48 ± 7.15 h, respectively. We established three developmental models for C. rufifacies to estimate the age of the developing insect: the isomorphen diagram model, the isomegalen diagram model and the thermal summation model. Regression analysis was conducted to obtain the relationship between body length and development time of the larvae from hatching to wandering. The developmental threshold temperatures of the egg, 1st instar, 2nd instar, 3rd instar, and wandering larvae, and intra-puparial stages were 12.28 ± 0.30, 11.74 ± 0.95, 12.70 ± 0.55, 11.68 ± 0.96, 10.53 ± 1.53, and 12.51 ± 0.41°C, respectively. The developmental threshold temperature, and the thermal summation constant during the entire developmental period were 3759.95 ± 170.80 degree hours and 11.96 ± 0.38°C, respectively. This study provides an improved dataset to estimate the postmortem interval of corpses using C. rufifacies.