Thermal Threshold For Development Research Articles

Validation of degree-day models for predicting the emergence of two fruit flies (Diptera: Tephritidae) in northeast Egypt.

We estimated thermal developmental thresholds (T0 ) and degree-day (DD) constants for the immature stages of two tephritid pests, Bactrocera zonata (Saunders) and Ceratitis capitata (Weidenmann). Males of both species were trapped in an Egyptian guava orchard during the fruiting seasons of 2016 and 2017 and trap catches were compared with peak flights predicted by the DD model based on local weather data. Ceratitis capitata had faster development than B. zonata at 20 and 25 °C, but their overall developmental rate was similar at 30 and 35 °C. The thermal threshold of development (T0 ) of B. zonata was higher than that of C. capitata, indicating greater sensitivity to cold. Although 35 °C yielded the fastest development of both species, survival was higher at 30 °C, with B. zonata experiencing a slight advantage, suggesting better tropical adaptation. Immature development of B. zonata and C. capitata was estimated to require 338 and 373 d, respectively, and 616 and 424 DD for a complete generation. Trap catches over both seasons showed good correspondence to peaks of fly activity predicted by the DD models; deviations from expectation ranged from 0 to 7 d for both fly species. Both species had four overlapping generations per season, with B. zonata abundance peaking in the first generation in both years, but only in 2016 for C. capitata. The models predict about eight and 12 generations per year in northeast Egypt for B. zonata and C. capitata, respectively. These models should be useful for timing pest control measures to coincide with periods of peak fly activity in fruit orchards.

Establishment Probability of Anastrepha grandis and Zeugodacus cucurbitae (Diptera: Tephritidae) in Brazilian Semiarid Based on Thermal Requirements.

The quarantine pests, Anastrepha grandis (Macquart) and Zeugodacus cucurbitae (Coquillett), are economically important for the fruit fly-free area in Brazilian semiarid, an area in which they are not yet present. Therefore, the objective of this study was to assess the probability of establishment of A. grandis and Z. cucurbitae based on the estimate number of generations in different climatic regions of the Brazilian semiarid. For scenarios of future projections, it was estimated the number of generations with increase of 1°C (low radiative forcing scenario) and 4°C (high radiative forcing scenario) in the air temperature. Finally, we also estimate the quarantine period to eliminate the invading population of cucurbit fruit flies in Brazilian semiarid. For this, the average historical air temperature of 32 semiarid municipalities was used and the biology data of fruit flies (thermal threshold of development and thermal constant) were used. The fruit flies are able to present several generations per year in Brazilian semiarid. Anastrepha grandis can present from 7.99 (Sergipe) to 9.66 (Piauí) generations. The melon fly Z. cucurbitae may present from 31.25 (Sergipe) to 40.66 (Piauí) generations. The estimation of species multiplication is accentuated in any season, with greater amplitude in spring and summer. The municipalities of Piauí, Ceará, and Rio Grande do Norte presented the highest estimates of fruit fly generations. The increase of air temperature in a future scenario may favor the quarantine pests, A. grandis and Z. cucurbitae, in Brazilian semiarid. In conclusion, the species A. grandis and Z. cucurbitae can be established in Brazilian semiarid, with particular concern for the fruit fly-free area.

Temperature affects phenological synchrony in a tree-killing bark beetle.

Phenological synchrony can promote population growth in species with positive density dependence. Variation among life stages in the thermal thresholds for development can foster phenological synchrony under thermal regimes that include frequent occurrence of temperatures between developmental thresholds. The southern pine beetle is an insect with positive density dependence that has recently undergone important shifts in population abundance at the northern extremes of their distribution. We evaluated the hypothesis that cooler winter temperatures in their northern range cause a convergence of the population life stage structure that leads to synchrony in spring flight phenology. We used a combination of approaches. First, in situ laboratory experiments demonstrated a threshold temperature for pupation that was greater than was required for larval development; rearing larvae at lower temperatures increased the pooling of individuals at the end stage of larval development and synchrony in adult emergence. Second, a development rate model showed a similar convergence of the majority of the population at the end stage of larval development when brood experienced the cooler temperatures of the northern region, but not with temperatures from the southern region, or as a null model. Finally, field trapping of wild beetles showed greater synchrony in the pine forests of New Jersey than in the warmer, historically occupied forests of Georgia and Mississippi. Given these results, pine-dominated forests in the northern edge of the southern pine beetle's range may experience more frequent occurrence of outbreaks, due to the positive feedbacks associated with a synchronous spring emergence of this insect.

Interspecific and intraspecific variation of the duration and thermal requirements for egg development in carabid beetles (Coleoptera, Carabidae) in the North-West of Russia

The thermal norms of egg development were studied in the ground beetles Amara communis, A. nitida, Carabus granulatus, Platynus assimilis, Poecilus versicolor, Pterostichus oblongopunctatus (spring breeding species), P. melanarius, and P. niger (autumn breeding species). The adults were collected in soil traps near Arkhangelsk, St. Petersburg, Moscow, and Bryansk in May–June. Females and males were kept in pairs at 20°C and 22 h light per day. The eggs laid by females were kept at constant temperatures (12, 14, 16, 18, 20, and 22 ± 0.1°C). The development time for each egg was determined accurate to 0.5 day. From the values of the individual development rate (a reciprocal of development time) at all the temperatures, the thermal constants for development were calculated: the coefficient of linear regression (CLR) of the development rate on temperature, the sum of degree-days, and the thermal threshold for development (TTD). The egg development time was found to vary significantly between the species, except for A. communis, A. nitida, and C. granulatus. The values of CLR (i.e., the slopes of the regression lines) and TTD varied rather distinctly between the species and populations that revealed differences in the thermal requirements for egg development. In the spring breeding species the mean egg development time was significantly shorter, and the CLR and TTD values were on average higher than those of the autumn breeding species. Intraspecific latitudinal variation of the development time and the thermal requirements for egg development was revealed. The eggs laid by beetles from the Arkhangelsk population developed faster than those of the same species from the southern populations at all experimental temperatures. These differences were not great but statistically significant. At the same time, the differences between the CLR and TTD values for the northern and southern populations of the same species were non-significant in most cases. Thus, the main ecophysiological adaptation of carabid beetles during their northward expansion was the shortening of development time within the entire range of favorable temperatures, while the CLR and TTD values only insignificantly changed.

Thermal requirements and estimate number of generations of Palmistichus elaeisis (Hymenoptera: Eulophidae) in different Eucalyptus plantations regions

To use Palmistichus elaeisis Delvare and LaSalle, 1993 (Hymenoptera: Eulophidae) in a biological control programme of Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), it is necessary to study thermal requirements, because temperature can affect the metabolism and bioecological aspects. The objective was to determine the thermal requirements and estimate the number of generations of P. elaeisis in different Eucalyptus plantations regions. After 24 hours in contact with the parasitoid, the pupae was placed in 16, 19, 22, 25, 28 and 31 °C, 70 ± 10% of relative humidity and 14 hours of photophase. The duration of the life cycle of P. elaeisis was reduced with the increase in the temperature. At 31 °C the parasitoid could not finish the cycle in T. arnobia pupae. The emergence of P. elaeisis was not affected by the temperature, except at 31 °C. The number of individuals was between six and 1238 per pupae, being higher at 16 °C. The thermal threshold of development (Tb) and the thermal constant (K) of this parasitoid were 3.92 °C and 478.85 degree-days (GD), respectively, allowing for the completion of 14.98 generations per year in Linhares, Espírito Santo State, 13.87 in Pompéu and 11.75 in Viçosa, Minas Gerais State and 14.10 in Dourados, Mato Grosso do Sul State.

Desenvolvimento de Oligonychus ilicis em Coffea canephora sob diferentes temperaturas

Oligonychus ilicis (McGregor) (Acari) (Tetranychidae) é uma das principais pragas de Coffea canephora Pierre & Froehner. Neste trabalho, avaliou-se o efeito de diferentes temperaturas no desenvolvimento desse ácaro-vermelho em folhas de C. canephora, em laboratório. Confinaram-se 80 fêmeas em 40 arenas, constituídas de disco foliar de 4 cm, para oviposição nas temperaturas de 21, 24, 27, 30 e 33 ºC. Foram selecionados ao acaso pelo menos dois ovos para avaliar o desenvolvimento embrionário. Após a eclosão da larva, foram realizadas avaliações a cada 12 horas para obtenção da duração e sobrevivência larval. Para avaliar a longevidade foi transferido um ácaro macho da criação para as arenas com uma fêmea para acasalamento. O limite térmico de desenvolvimento inferior e a constante térmica foram determinados para a duração do desenvolvimento de ovo a adulto. O tempo de desenvolvimento das fases imaturas diminuiu com o aumento da temperatura. As fases de ovo, larva, protocrisálida, protoninfa, deutocrisálida, deutoninfa e teleiocrisálida variaram, respectivamente, de 10,4 a 4,3; 2,4 a 1,2; 2,0 a 1,0; 2,3 a 1,2; 1,9 a 1,0; 3,0 a 1,5 e 2,3 a 1,0 dias. O aumento da temperatura afetou o período de desenvolvimento, reduzindo a duração de ovo-adulto e a longevidade. O limite térmico inferior foi de 9,0 ºC para o período de ovo-adulto e constante térmica de 256,4 graus-dias. Em condições de laboratório, a faixa de temperatura que favorece o desenvolvimento do ácaro em C. canephora foi de 24 a 30 ºC. O limite térmico inferior não é limitante para ocorrência de O. ilicis em áreas cultivadas com C. canephora no estado do Espírito Santo.

Thermal requirements of Trissolcus grandis (Hymenoptera: Scelionidae), an egg parasitoid of sunn pest

Trissolcus grandis is an important egg parasitoid of sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), the most serious pest of wheat in Iran. The thermal requirements of two populations of T. grandis were studied at five constant temperatures ranging from 20-32°C. Thermal thresholds for development were calculated using linear regression and degree-day models were determined by fitting non-linear equations to the data. The lower threshold for development was estimated to be 12.5 and 12.1°C, respectively, for males and females of the Bonab population, compared to 14.4 and 14.5°C for those of the Qaramalek population. Complete development required 143.8 and 162.8 degree-days, respectively, for males and females of the Bonab population and 116.9 and 124.6 for those of the Qaramalek population. Thus, wasps from the warmer region (Qaramalek) developed faster than those from the cooler region (Bonab), but had a higher thermal threshold for initiating development. Bonab females attained their highest fecundity (117.7 ± 7.2) at the lowest temperature tested (20°C), whereas the fecundity of Qaramalek females was maximal (96.8 ± 11.5) at 26°C. Biological control programmes that seek to augment wasp populations in wheat fields early in the spring, when natural rates of sunn pest parasitism tend to be low, should consider wasp thermal requirements to ensure the selection and release of locally-adapted parasitoids.

Biology and Development of the Wild and Golden Sport ofGrapholita prunivora(Lepidoptera: Tortricidae)

The development of the lesser appleworm, Grapholita prunivora (Walsh), was studied using immature apples as the food source. Degree-hour developmental rates for all life stages were calculated. Developmental rates in degree-hours at 25°C for the eggs, four instars, pupae, and adults were 1,503 (4 d), first larval ecdysis 1,109 (3 d posthatch), second larval ecdysis 1,941 (5 d posthatch), third larval ecdysis 3,186 (8 d posthatch), pupation 5,196 (13 d posthatch), and adult 8,925 (22 d posthatch), respectively. It was determined that 8.5°C was the lower thermal threshold for development of lesser appleworm eggs. Comparisons of growth, survival, and reproduction were made between two different laboratory populations, the wild type and a golden color sport (strain).

Cold Storage of Coleomegilla maculata larvae

Short-term storage of second and third instars of the coccinellid Coleomegilla maculata lengi Timberlake can be achieved efficiently through utilization of temperatures below its thermal threshold of development. Survival, voracity and preimaginal development time were evaluated for larvae kept at 4 and 8°C for up to 5 weeks. Survival was close to 100% for the first two weeks of storage, but decreased drastically afterward and was 0% after 5 weeks. Storage at low temperatures did not diminish the voracity of larvae after storage. Development completely stopped during cold storage but resumed without significant effect after larvae were returned to 24°C. This study indicates for the first time that cold storage of C. maculata second and third instars is possible for a period of up to 2 weeks and provides a technique that could benefit biological control programs by increasing availability of beneficial insects.

Developmental time of Blattisocius tarsalis (Acari: Ascidae) at different temperatures.

The developmental time of the predatory mite Blattisocius tarsalis (Berlese) (Acari: Ascidae) was investigated at temperatures of 15, 21 and 25 degrees C and 75% r.h. Eggs 1-3 days old of Ephestia kuehniella Zeller (Lep.: Pyralidae), killed by freezing, were used as food. Mean developmental times were found to be 22.4, 8.5 and 7.0 days, respectively. Within the investigated thermal limits the developmental rate showed a linear relationship with temperature and the corresponding thermal threshold for development was calculated to 10.2 degrees C.

Environmental Effects on the Development and Survival of the Scale Insect Abgrallaspis cyanophylli (Signoret) (Homoptera: Diaspididae) with Reference to its Suitability for Use as a Host for Rearing Biological Control Agents

Developmental and survival rates of the locally important diaspidid pest, Abgrallaspis cyanophylli (Signoret) reared on Solanum tuberosum L . tubers were examined under light and dark conditions; humidities of 33, 53, 62 and 75% relative humidity (RH); varying population densities; constant temperatures in the range of 20 to 30oC and at cycling temperatures of 12 h at 14°C and 12 h at 30°C. Developmental rate was slightly lower under constant light conditions but mortality was higher in the dark, particularly amongst the males. At 26°C, there were no differences in developmental rate in relation to the various humidity levels. However, survival was significantly lower at 33% RH, with females suffering higher mortality than males. Population density was found to have no effect on developmental rate or size of the females. Overall mortality increased in line with population density although the result was poorly correlated. Within the range 20-28°C developmental rate increased with rising temperature but decreased at 30°C. Thermal summation and polynomial regression data show a theoretical lower thermal threshold for development of 12.47°C. The thermal constant was 541.7 degree days. Survival was lowest at 20°C and 30°C and highest at temperatures in the median range and under cycling conditions. Male survival was significantly higher than that of the females at 30°C and under the cycling regime of 14/30°C. The results suggest that the optimum conditions for rearing A. cyanophylli on potatoes would be at temperatures in the range 24-26°C and humidities of 55-65% RH.

Thermal Requirements for Development of <I>Diaprepes abbreviatus</I> (Coleoptera: Curculionidae)

The root weevil Diaprepes abbreviatus (L.) was reared on artificial diet under controlled conditions of temperature and humidity. The lower thermal threshold for development of neonate larvae was estimated to be 15°C. The growth rate of neonate larvae increased exponentially with increasing temperature up to 30°C. The growth rate of later instars, however, was suppressed at 30°C and mortality was higher than that of larvae reared at 26°C. Larvae reared as late instars only (>56 d old), or continuously at 30°C, had increased mortality and produced smaller adults than larvae reared at 22 and 26°C. Larvae reared as late instars only (>56 d) or continuously at 22°C had similar survival rates compared with those reared at 26°C, and they emerged as larger adults compared with larvae reared at 26 or 30°C. The time required for development from neonate to pupation was 125 ± 3 d (mean ± SEM, n = 38) at 26°C. Duration of the pupal stage was inversely proportional to temperature between 22 and 30°C. Pupal mortality was higher at 30°C than at 22 or 26°C. The total time required for a single generation from oviposition to adult emergence was estimated to be 154 d at 26°C and adequate humidity. Cumulative mean air and soil temperatures and rainfall for a location in central Florida were analyzed and presented for the period October 1991 through January 1999.

Northern Corn Rootworm (Coleoptera: Chrysomelidae) Temperature Requirements for Egg Development

Temperature-dependent development of laboratory-wintered eggs of northern corn rootworm, Diabrotica barberi Smith & Lawrence, was described using data from constant temperature laboratory experiments. Median development of postdiapause eggs at constant temperatures of 15, 18, 20, 23, 25, 27, and 30°C required 59, 30, 24, 17, 15.5, 14, and 14 d, respectively. Linear and nonlinear models were fitted to temperature versus developmental rate data. Variation in developmental rates across temperatures was modeled with a cumulative Weibull distribution. Mean developmental rate was linear between 15 and 27°C, optimal at 27°C, and decreased at 30°C. The thermal threshold for development (10.9°C) was determined by extrapolation with median egg hatch occurring after 238 DD (10.9).

Modeling the age-specific per capita growth and reproduction ofRhizobius lophanthae (Col: Coccinellidae)

A per capita model for the growth, development and reproduction of the coccinellid predatorRhizobius lophanthae (Blaisd) feeding on the oleander scale(Aspidiotus nerii Bouche (Homoptera: Diaspididae)) was developed. A thermal threshold for development of 9.4°C was found. Under conditions of unlimited food, the relationship of mass at time t + 1 to that at t (in days at 25°C) suggests an 8.7 percent growth rate per mg larvae per day at 25°C. An adult female beetle produces approximately 20 eggs per day while consuming an average of 8.5 scales/day. This is approximately 2.16 eggs per scale consumed above the maintenance level of 1.88 scales per day. More precisely, this compensation point is 0.12 mg of prey/mg of predator/day at 25°C and the egestion rate is 1 - β = 0.63

Why does only Athalia Japonica enter summer diapause among three sympatric Athalia sawflies feeding on crucifers?

SummaryThis report assesses the primary factor for the evolution of summer diapause of the three species of sawfly, Athalia japonica, A. rosae and A. infumata that feed on cruciferous plants and coexist in the same area. A. japonica has two discrete spring and autumn generations, but A. rosae and A. infumata 5–6 generations. Only A. japonica enters summer diapause in response to the long daylengths in spring. Although these three sawflies usually feed on the same cultivated crucifers, they differ markedly in the utilization of wild crucifers. They oviposit only on young leaves. A. japonica mainly uses Cardamine plants which sprout in spring and autumn. A. rosae and A. infumata primarily use hosts with new leaves all the year round, i.e. cultivated crucifers and Rorippa indica, respectively. The thermal threshold for development is lower in A. japonica than in the other two species. The low heat tolerance of A. japonica is adapted only to cool shady habitats where Cardamine grows. Presumably, summer diapause of A. japonica is adaptation to the deterioration of the primary host plants rather than unfavorable climatic conditions. This interpretation is supported by the movement patterns of the three Athalia sawflies, alternative means to escape from deteriorated habitat conditions.

Thermal Requirements for Development in Chrysopa Oculata: A Geographically Stable Trait

Chrysopa oculata from five widespread localities (southern Canada to montane Mexico), exhibited remarkable similarities in their thermal requirements for nondiapause development. Lower thermal thresholds (t) varied by only 1.2°C., and the degree—days required for total preimaginal development (K) differed among the populations by °85°d. Despite the similarities among populations, the results suggest that the thermal requirements for development are genetically variable. However, two factors may limit the geographical expression of this variation: (1) the multivoltine life cycle could result in seasonal oscillations in the magnitude and projection of directional selection on the nondiapause thermal responses, and/or (2) the thermal thresholds for development and the rates of development above the thresholds may be functionally correlated and constrained in their evolution. Males from all populations emerged slightly but consistently earlier than females. Temperature did not affect sex or survival, other than at 15.6.° where mortality was significantly increased. Among the five populations, only one large difference occurred in the thermal responses; under low temperatures, a relatively high proportion of the two northern populations entered diapause. The differences in diapause induction resulted from the differential effect of temperature on the critical photoperiod for diapause induction, rather than on the developmental rates.

AGE, FECUNDITY, WEIGHT, AND THE INTRINSIC RATE OF INCREASE OF THE LUPINE APHID MACROSIPHUM ALBIFRONS (HOMOPTERA: APHIDIDAE)

AbstractThe fecundity, survivorship, and rate of development of the lupine aphid Macrosiphum albifrons Essig were determined and summarized into life tables from which the intrinsic rate of increase was computed. The life tables, using a time scale in days, were converted to a variable life table model using a physiological time scale based on an estimated thermal threshold of development of 3.59° (± 0.587°). A method of determining age and fecundity of adult aphids was developed from weight and embryo content. The use of intrinsic rate of increase and of the method of aging in field population dynamics are discussed.

Seasonal responses and their geographic variation in Chrysopa downesi: ecophysiological and evolutionary considerations

A comparison of Chrysopa downesi strains from Montana and from New York indicates that they share several characteristics in their seasonal cycles: (1) a short-day – long-day requirement for diapause prevention, (2) dark green adult coloration all year round, (3) relatively high t values (lower thermal thresholds for development), and (4) sensitivity to photoperiod during the nondiapause preoviposition period.Responsiveness to prey differs between the two strains. Prey presence very slightly reduces diapause incidence and greatly shortens the nondiapause preoviposition period in the strain from Montana, whereas prey presence has little or no influence on the strain from the northeastern United States. The strains also differ in their ability to terminate diapause spontaneously; unlike the northeastern strain, a proportion of the northwestern strain ends diapause without an overt, external stimulus.The two populations of C. downesi thus share the two characteristics that are basic to the model of C. downesi's sympatric speciation from an ancestor like C. carnea. In contrast, the differences between the two populations in their responsiveness to prey presence parallels the geographic variation in C. carnea. We propose two alternate pathways (polyphyletic and monophyletic) for the evolution of the seasonal responses of the two geographic populations.