Total Immature Development Research Articles

제주 재배 감귤 품종에서 귤응애(Panonychus citri)의 생명표 통계량

The citrus red mite, Panonychus citri (Acari: Tetranychidae), is a serious pest in citrus orchards in Jeju, Korea. In this studies, life table parameters of P. citri were estimated by using the age-specific survival and age-specific fecundity data on six cultivars of citrus. The egg incubation times were shorter on Shiranui, Kiyomi and Lemon as 7.7, 7.8, 7.5 days(d), respectively, than other species of citrus. The development time of deutonymph was shortest on Kiyomi as 1.7 d. Total immature development time was shortest on Kiyomi as 13.3 d, while it was longest on Miyagawa as 15.4 d. In the experiments for the fecundity on different species of citrus, a higher fecundity was observed on Shiranui and Lemonon as 39.6 and 29.7 eggs, respectively, while a lower fecundity was obtained on Kiyomi and Setoka as 21.6 and 21.1 eggs, respectively. The obtained development and fecundity data were subjected to estimate the life table parameters of P. citri on different species of citrus leaves: net reproductive rate, generation time, intrinsic rate of natural increase, finite rate of increase and doubling time. The estimated values for intrinsic rate of natural increase which affect directly population increase in the field were high on Shiranui and Lemon as 0.1519 and 0.1395, respectively; while the values were low on Setoka and Kabusu as 0.1056 and 0.1177, respectively. To analyse the effects of inorganic nutrient contents in citrus leaves on the development time and fecundity of P. citri , Pearson correlation coefficients were estimated between the paired variables. The results showed no statistical significantly between differences contents and development or fecundity, although there were a higher positive correlation in P, K, and Na contents.

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.

Facultative deuterotokous parthenogenesis in Callosobruchus maculatus

The seed beetle, Callosobruchus maculatus (Coleoptera: Chrysomelidae), is a severe cosmopolitan pest of various stored legumes. Since no parthenogenesis has been reported in the genus Callosobruchus, here we report the evidence of a rare event of deuterotokous parthenogenesis in this species. Interestingly, 11.11% of females out of 600 tested virgin females were capable of reproducing by parthenogenesis. Unfertilized-eggs developed into viable adults with a sex ratio of 1:1. Parthenogenetically-produced males and females could successfully copulate and generate the next generation. They achieved statistically the same total immature development, adult longevity, egg number, and hatchability as sexually produced progeny. However, none of the 60 female offspring produced via parthenogenesis were capable of reproducing by parthenogenesis. Mating disruption and sterile insect technique for pest control could not be efficient in insects with parthenogenetic reproduction because parthenogenesis will compensate for males’ absence by producing viable male and female offspring, saving species from possible extinction in the future. Therefore, these findings are important not only for considering in the Integrated Pest Management programs but also from an evolutionary perspective. Biodiversity and genetic differentiation among the current worldwide distribution of C. maculatus could be the origin of this facultative deuterotokous parthenogenesis evolution.

Intrapuparial Age Estimation of Forensically Important Dohrniphora cornuta (Diptera: Phoridae).

Dohrniphora cornuta (Bigot) is a forensically important phorid fly indoors and in burial environments. The determination of a minimum postmortem interval (PMImin) often relies on the determination of the age of the immatures. Although the larval development data of D. cornuta under different temperatures has been established, the intrapuparial stage which lasts for about half of the total immature development is scarce. In this study, we investigated the key morphological changes during intrapuparial development at constant temperatures (15, 18, 21, 24, 27, 30, 33, and 36°C), with an aim to estimate the intrapuparial age of D. cornuta. Puparia were sampled at 12-h (24, 27, 30, and 33°C), 24-h (18 and 21°C), and 48-h (15°C) intervals. The morphological developments within the puparium were analyzed using a stereomicroscope after the puparium was removed. The average minimum duration of intrapuparial stage was inversely related to temperature, ranging from 184.79 ± 3.00 h at 30°C to 1102.86 ± 25.55 h at 15°C for female, and 197.40 ± 4.12 h at 30°C to 1175.33 ± 18.55 h at 15°C for male. It did not develop at 36°C. Some morphological traits that changed during development within the puparium could be used as age markers. According to these changes, the intrapuparial stage of D. cornuta was divided into nine stages which could be used for both sexes. This study provides relatively systematic development data of D. cornuta intrapuparial for the estimation of PMImin in forensic entomology.

Effect of the temperature on development of Tetranychus urticae (Acari: Tetranychidae) feeding on cucumber leaves

ABSTRACT The effect of seven constant temperatures (15, 20, 25, 27.5, 30, 32.5, and 35 ± 1°C) on developmental time of Tetranychus urticae Koch on cucumber leaf discs was determined under laboratory conditions of 60 ± 5% RH and a photoperiod of 16 L:8D. The egg-to-adult developmental time decreased significantly with increasing temperature, except at 35°C. To describe the developmental rate of T. urticae as a function of temperature, one linear, and nine nonlinear models (Logan-6 & 10, Lactin-1& 2, Briere-1& 2, Analytis-3, Polynomial, and Equation-16) were fitted to data. By means of the linear model, the lower temperature threshold (T 0) and thermal constant (K) were estimated for the entire immature development of female mites as 7.11°C and 227.27 ± 9.72 DD, respectively. Based on Akaike Information Criterion (AIC) and R 2 adj, Logan-10, Lactin-1, Analytis-3, Logan-10, Analytis-3 were found to be the best models to describe the temperature-dependent development rate of eggs, larvae, protonymphs, and deutonymphs, as well as of total immature development from egg to adult. The results may serve as input for the development of a simulation model that can be used to predict the population dynamics of T. urticae inhabiting cucumber crops.

Developmental Plasticity of the Flesh Fly Blaesoxipha plinthopyga (Diptera: Sarcophagidae) on Different Substrates.

Forensic entomologists rely on laboratory growth data to estimate the time of colonization on human remains thus extrapolating a minimum postmortem interval (PMI) if assumptions are satisfied. The flesh fly Blaesoxipha plinthopyga (Wiedemann) is one species that occurs in casework in Idaho, Texas, and central California. Because of the few laboratory studies on the development of this fly, the following study was conducted to determine if different substrates impact immature development of the species. In this study, flies were reared on different substrates that are likely to be encountered at indoor and outdoor scenes (Wet Sand, Dry Sand, Clothes [Polyester fibers], and Carpet [Polypropylene fibers]) to determine the influence of substrate on larval, intrapuparial, and total immature development times at 25°C, 50% RH, and 14:10 (L:D) h cycle. The results revealed that substrate significantly affected minimum immature development times without affecting the sexes differently; though a female bias in sex ratio was observed consistently. Average minimum larval developmental times were 160-179 h with a significantly faster development in Carpet than in Clothes. Similarly, average minimum intrapuparial developmental times were 331-352 h; fastest on Carpet and the slowest in Dry Sand. For this species, it may be important to consider the substrates encountered at a death scene as they may affect the development of B. plinthopyga (Wiedemann) in casework by up to 29 h at 25°C and 50% humidity. These effects will also be important to consider when planning future development studies with the species.

Estimation of physiological age at emergence based on traits of the forensically useful adult carrion beetle Necrodes littoralis L. (Silphidae)

The main entomological method for post-mortem interval involves estimation of age for immature insects found on a cadaver. Forensic entomologists frequently use the thermal summation value for the total immature development (K), which is a measure of physiological time needed to complete development of a species (age at emergence). K is highly variable within the species. Its true value for an adult insect may be estimated based on insect traits such as size and sex at maturity. Here, we have tested, if size and sex of adult beetles of Necrodes littoralis may be useful for the estimation of the true K. Necrodes littoralis is a Palearctic carrion beetle that frequently colonizes human cadavers in forest and agricultural environments.General and sex-specific thermal summation models for the emergence and models for the relationship between size of adult beetles and their age at emergence were developed for N. littoralis. The models were subsequently tested in the validation study. The general K for N. littoralis was about 469 (+/-25 SE) accumulated degree-days above the developmental threshold of about 8.5 (+/-0.45 SE) °C. Thermal summation parameters of the sex-specific models revealed minor differences compared to the general model. A true K was negatively related to the beetle size. Methods for the estimation of K represented its true value with different accuracy. The highest accuracy was obtained when K was estimated using beetle weight as a predictor variable and the sex-specific models for the relationship between K and size, although sex contributed slightly to this improvement. Using this method the estimated K represented the true K with the error of 6.3%, while the error for K from the general thermal summation model was about 9.7%.In conclusion, the findings demonstrate that physiological age at emergence of N. littoralis may be accurately predicted based on the adult beetle size. Necrodes littoralis is a second beetle species in which the age at maturity was more accurately represented by size-based estimates of K than K from the general thermal summation model. Therefore, we encourage testing the relationship between K and size in all insect species that are used in forensic entomology; particularly blow flies and flesh flies.

Effect of Temperature on the Survival and Developmental Rate of Immature Ooencyrtus mirus (Hymenoptera: Encyrtidae).

Bagrada hilaris (Burmeister) is an invasive pest of cole crops in the southwestern United States. To find potential biocontrol agents of B. hilaris, three egg parasitoids were imported from Pakistan, including Ooencyrtus mirus, a recently described uniparental species. We investigated the effect of temperature on survival and developmental rate in O. mirus from egg to adult. At 14 and 16°C, no adults emerged unless the immatures were transferred later to a warmer temperature. At constant 18°C, a low percentage emerged, but again more emerged if the immatures were transferred to a warmer temperature. Survival ranged from 80 to 96% at 20-37°C and did not differ significantly among these temperatures. No adults emerged at 38°C. Regardless of the amount of time the parasitized eggs were held at 14 and 16°C, the developmental times after returning the eggs to 26°C were similar, suggesting a quiescence process rather than simply slow development. At higher temperatures, the developmental rate increased linearly from 18 to 36°C and then declined at 37°C. The Wang model provided the best fit of the data and estimated a lower developmental threshold at 13.0°C, an optimal temperature at 35.6°C, and an upper developmental threshold of 38.3°C. The thermal constant for total immature development is 168.4 degree-days. The results show 36°C to be the best temperature for rearing O. mirus, and that O. mirus-parasitized eggs can be stored at 14°C for months without losing viability. These are crucial data to consider when mass rearing this biological control agent.

Temperature-dependent development, survival and reproduction ofApanteles hemara(Nixon) (Hymenoptera: Braconidae) onSpoladea recurvalis(F.) (Lepidoptera: Crambidae)

The temperature-dependent development of Apanteles hemara (Nixon), a larval endoparasitoid of the devastating amaranth pest Spoladea recurvalis (F.) was studied in the laboratory at six constant temperatures (10, 15, 20, 25, 30 and 35 °C), a photoperiod of 12L:12D and a relative humidity of 60-70%. Developmental time decreased significantly with increasing temperature within the range of 15-30 °C. The parasitoid's pupal mortality, successful parasitism rate, adult emergence rate and longevity, sex ratio and fecundity were affected by temperature. The population of A. hemara failed to develop at 10 and 35 °C. The development threshold (Tmin) and the thermal constant (K) were calculated by the linear model while the lethal temperature (Tmax) was determined by the Lactin-1 model. The estimated values of Tmin, Tmax and K by the two models were 10.3 °C, 35.0 °C and 185.18 DD respectively for the total immature development. The estimated value of the optimum temperature using the Taylor model was 30.8 °C. This is the first study to report on the effect of temperature on the developmental parameters of A. hemara giving an insight into its biology. The implications of these findings for the use of A. hemara in biological control are discussed.

Effect of temperature and diet on Plodia interpunctella (Lepidoptera: Pyralidae) development with special reference to Isomegalen diagram and accumulated degree days

Immature development times of the Indian meal moth, Plodia interpunctella were studied in the laboratory at four different constant temperatures (20, 23, 25, 27°C) reared on a standard diet (D1) and chocolate (D2). The minimal duration of development from oviposition to adult emergence was inversely related to temperature, ranging from 2.3±0.36 days to 50.5±0.5 days for D1 and from 36.7±0.53 days to 106.73±1.10 days for D2 for 27°C and 20°C, respectively. The minimum development threshold (tL), obtained from linear regression model of the development rates at the four studied constant temperature regimes, for total immature development is 15.3°C and 17.1°C for D1 and D2, respectively and the accumulated degree days (ADD) for P. interpunctella is 249.51°C for D1 and 358.4°C for D2 above the threshold.

Effects of Two Cultivated Brassica spp. on the Development and Performance of Diadegma semiclausum (Hymenoptera: Ichneumonidae) and Cotesia vestalis (Hymenoptera: Braconidae) Parasitizing Plutella xylostella (Lepidoptera: Plutellidae) in Kenya.

The diamondback moth (DBM), Plutella xylostella L., is the most destructive pest affecting vegetable production in Kenya and around the world. Parasitoids have shown promising results in lowering the pest populations and damage caused by DBM. However, variations in host plant quality have been reported to have bottom-up effects up to the third and fourth trophic levels. We assessed the effects of two cultivated Brassica varieties (cabbage, Brassica oleracea var. capitata L. cultivar 'Gloria F1' and kale, B. oleracea var. acephala L. cultivar 'Thousand headed') on the development and performance of the specialist pest P. xylostella and two exotic parasitoids Diadegma semiclausum (Hellen) and Cotesia vestalis (Haliday). The exposed larval period of DBM took about 1.5 d longer on kale than cabbage and the total immature development time of both females and males was significantly longer on kale than cabbage. Higher pupal weight and higher fecundity were recorded on DBM fed on kale. Development time of D. semiclausum and C. vestalis was not affected by the host crop as was the parasitism rate of D. semiclausum. Heavier male pupae and larger adults of D. semiclausum, as well as more fecund adults of C. vestalis, were obtained from hosts fed on cabbage. Larger adults of C. vestalis were obtained from herbivores fed on kale. These results show potentially positive effects of host plant allelochemicals that are detrimental to herbivores while promoting parasitoid development and performance, which can be harnessed for the control of DBM.

Occurrence and predictive utility of isochronal, equiproportional, and other types of development among arthropods

In isochronal (ICD) and equiproportional development (EPD), the proportion of total immature (egg, larval, and/or juvenile) development spent in each stage (developmental proportion) does not vary among stages or temperatures, respectively. ICD and EPD have mainly been reported in copepods, and whether they occur in other arthropods is not known. If they did, then rearing studies could be simplified because the durations of later developmental stages could be predicted based on those of earlier ones. The goal of this study was to test whether different taxa have ICD, EPD, or an alternative development type in which stage-specific proportions depend on temperature, termed ‘variable proportional’ development (VPD), and also how well each development type allowed later-stage durations to be predicted from earlier ones. Data for 71 arthropods (arachnids, copepod and decapod crustaceans, and insects) were tested, and most (85.9%) species were concluded to have VPD, meaning that ICD and EPD do not occur generally. However, EPD predicted later-stage durations comparably well to VPD (within 19–23%), and thus may still be useful. Interestingly, some species showed a ‘mixed’ form of development, where some stages' developmental proportions varied with temperature while those of others did not, which should be further investigated.

Non-target toxicity of synthetic insecticides on the biological performance and population growth of Bracon hebetor Say.

Bracon hebetor Say (Hymenoptera: Braconidae) is an important biological control agent of various species of order Lepidoptera and extensively used in biological control program worldwide. Present study evaluated the lethal and sublethal effects of insecticides on B. hebetor using demographic and population growth parameters. Doses of all the tested insecticides were within a maximum range of their recommended field dosages and adults were treated using residual glass vials method. For control experiments adults were treated with distilled water. Among the tested insecticides, the survivorship of various stages of B. hebetor was considerably prolonged on cyantraniliprole followed by chlorantraniliprole and shortest on chlorpyrifos and profenofos treated group. Total immature development time was prolonged in chlorpyrifos and profenofos treated group. Population growth parameters like intrinsic rate of natural increase (rm), net reproductive rate (R0), finite rate of increase (λ) and mean generation time (Tc) were considerably reduced in B. hebetor groups treated with chlorpyrifos and profenofos. However, B. hebetor groups treated with chlorantraniliprole and cyantraniliprole showed a little or no much difference in population growth parameters when compared with untreated group. It was also observed that chlorpyrifos and profenofos modified the sex ratio, thereby female emergence get reduced. On the basis of present findings it can be concluded that all tested insecticides caused considerable ecotoxic effects on B. hebetor compared to control. However, comparisons among the tested insecticides on the basis of IOBC criteria showed that chlorantraniliprol and cyntraniliprol was less toxic as compared to other insecticides tested on this biological control agent.

Potential of Macrocheles species (Acari: Mesostigmata: Macrochelidae) as control agents of harmful flies (Diptera) and biology of Macrocheles embersoni Azevedo, Castilho and Berto on Stomoxys calcitrans (L.) and Musca domestica L. (Diptera: Muscidae)

The stable fly (Stomoxys calcitrans) and horn fly (Haematobia irritans) are mainly parasites of cattle that spend the early phase of their life cycle in decaying vegetation, manure and soil, as members of a wide range of other harmful and beneficial arthropods. Predators of the family Macrochelidae are considered beneficial mites that have been considered promising biological control agents of fly eggs and larvae and of other harmful organisms. The objectives of this study were: a) to compare the predation and oviposition rates of three Macrocheles species, M. embersoni, M. muscaedomesticae and M. robustulus, on six prey species: S. calcitrans, Musca domestica , H. irritans, Bradysia matogrossensis, Rhizoglyphus echinopus and the free living nematode Rhabditella axei; b) to evaluate the life cycle of the best performing predator (M. embersoni) on the most suitable prey species at 30 ± 2 °C, 95 ± 5% RH and in the dark. The three macrochelid species consumed all evaluated prey species, but M. embersoni had higher predation and daily oviposition rates on larvae of S. calcitrans (23.8 larvae consumed and laid about 4.0 eggs, respectively) than other species. Total immature development of M. embersoni was completed in at most about 1.3 days on eggs of S. calcitrans and M. domestica and 1.5 days on R. axei. Macrocheles embersoni produced most eggs (0.28–0.34 female/female/day; rm: 0.28–0.34) on those same prey. The results of this study suggest that M. embersoni is a promising biological control agent of S. calcitrans and M. domestica.

Estimation of postmortem interval (PMI) based on empty puparia of Phormia regina (Meigen) (Diptera: Calliphoridae) and third larval stage of Necrodes littoralis (L.) (Coleoptera: Silphidae) – Advantages of using different PMI indicators

On 16 July 2015, a body of a 64-year-old man in advanced decomposition was found in an open area of the suburb of Śrem (western Poland). Postmortem interval (PMI) was estimated by forensic pathologist for 3–6 weeks. Insects were sampled from the cadaver and the soil from below the cadaver. Empty puparia of Phormia regina were the most developmentally advanced specimens of blowflies. Moreover, third instar larva of Necrodes littoralis was collected directly from the cadaver. For the estimation of minimum PMI from puparia of P. regina, thermal summation method was used to estimate the total immature development interval of this species. In the case of larval N. littoralis, the pre-appearance interval (PAI) was estimated using temperature method and the development interval (DI) using thermal summation method. Average daily temperatures from the nearby weather station were used, as well as the weather station temperatures corrected by 1 °C and 2 °C. The estimates were as follows: 36–38 days using empty puparia of P. regina and 37–40 days using larva of N. littoralis (for the uncorrected temperatures), 31–34 days using both P. regina and N. littoralis (temperatures corrected by +1 °C), 24–27 days using P. regina and 28–29 days using N. littoralis (temperatures corrected by +2 °C). It was concluded that death occurred 24–40 days before the body was found and most probably 24–34 days before the body was found. This is the first report when PMI was approximated by the age estimates combined with the PAI estimates. Moreover, the case demonstrates the advantages of using different entomological indicators and an urgent need for the more robust developmental model for N. littoralis, as it proved to be highly useful for the estimation of PMI.

Intrapuparial Development of Sarconesia Chlorogaster (Diptera: Calliphoridae) for Postmortem Interval Estimation (PMI).

Sarconesia chlorogaster (Wiedemann) (Diptera: Calliphoridae) is an endemic blow fly species of forensic importance in South America, and whose duration of pupal development is about 70% of the total immature development time. Therefore, morphological changes during this stage, if refined, may provide greater accuracy and reliability in the calculation of minimum postmortem interval. Considering the importance of this species, the main objective of this work was to identify and describe temporal intrapuparial morphological changes of S. chlorogaster. The development of S. chlorogaster reared on an artificial diet and at two constant temperatures (20 and 25ºC) was monitored. Every 8 h until the end of the pupal stage, 10 pupae were killed, fixed, and had their external morphology described and photographed. Of the 29 morphological characteristics described, 13 are potentially informative for estimating the age of S. chlorogaster. In general, body shape (presence or absence of tagmatization), general coloration, visible presence of the mouth hook (portion of the mandible), thoracic appendages, change in eye color, and bristle formation are the most useful characteristics for determining specific age. The results presented here make it possible to estimate the postmortem interval of a corpse using intrapuparial morphological characters, expanding one's ability to estimate postmortem interval.

Sex-specific developmental models for Creophilus maxillosus (L.) (Coleoptera: Staphylinidae): searching for larger accuracy of insect age estimates

Differences in size between males and females, called the sexual size dimorphism, are common in insects. These differences may be followed by differences in the duration of development. Accordingly, it is believed that insect sex may be used to increase the accuracy of insect age estimates in forensic entomology. Here, the sex-specific differences in the development of Creophilus maxillosus were studied at seven constant temperatures. We have also created separate developmental models for males and females of C. maxillosus and tested them in a validation study to answer a question whether sex-specific developmental models improve the accuracy of insect age estimates. Results demonstrate that males of C. maxillosus developed significantly longer than females. The sex-specific and general models for the total immature development had the same optimal temperature range and similar developmental threshold but different thermal constant K, which was the largest in the case of the male-specific model and the smallest in the case of the female-specific model. Despite these differences, validation study revealed just minimal and statistically insignificant differences in the accuracy of age estimates using sex-specific and general thermal summation models. This finding indicates that in spite of statistically significant differences in the duration of immature development between females and males of C. maxillosus, there is no increase in the accuracy of insect age estimates while using the sex-specific thermal summation models compared to the general model. Accordingly, this study does not support the use of sex-specific developmental data for the estimation of insect age in forensic entomology.

Effect of temperature on rate of development, survival and adult longevity of Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is a major pest of potato, Solanum tuberosum L. (Solanales: Solanaceae), both in the field and storehouses. The rate of development and survival of P. operculella, reared on potato tubers cv. Spunta at eight constant temperatures (17.5, 20, 22.5, 25, 27.5, 30, 32.5 and 35°C), were studied in the laboratory. The duration of development of the immature stages was recorded. Adult longevity was also recorded under the same conditions. Developmental time decreased significantly with increase in temperature within the range 17.5-32.5°C. No development occurred at 35°C. Survival (%) from egg to adult was higher at temperatures within the range 17.5-27.5°C than at either 30 or 32.5°C. Linear and a non-linear (Logan I) models were fitted to our data in order to describe the developmental rate of the immature stages of P. operculella as a function of temperature and estimate the thermal constant (K) and critical temperatures (i.e., lower developmental threshold, optimum temperature for development, upper developmental threshold). Lower developmental threshold and optimum temperature for development ranged between 12.5-16.2 and 31.7-33.8°C, respectively. The estimated upper developmental threshold for total immature development was 35.0°C. Thermal constant for total development was 294.0 degree-days. Adult longevity was significantly shorter at high (30 and 32.5°C) than at low temperatures (17.5-27.5°C). Our results not only provide a broader insight into the thermal biology of P. operculella, but also can be used as an important tool in planning an effective pest control program both in the field and storehouses.

Influences of Temperature and Ootheca Age on the Life History of the Cockroach Ootheca Parasitoid Aprostocetus hagenowii (Hymenoptera: Eulophidae).

The influences of ootheca age and temperature on the life history of Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae), a gregarious ootheca parasitoid of the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae), were evaluated. Oothecae were incubated at 20, 25, and 30 °C to produce oothecae aged 1-60, 1-40, and 1-30 d old, respectively. Fitness traits (development time, percentage emergence, number of progeny, percentage female progeny, and female body size) of A. hagenowii developing in these different-aged oothecae were determined. For oothecae incubated at 20, 25, and 30 °C, parasitoids successfully developed in oothecae aged up to 50, 30, and 20 d old, which represent 72.9%, 65.9%, and 61.9% of the total embryonic development time of P. americana, respectively, without any changes in their fitness traits. When A. hagenowii from oothecae kept at constant temperatures (20, 25, 30, 32, and 35 °C) were compared, the immature development time (71.0-34.0 d) and adult life span decreased with increasing temperature. No parasitoid emerged at 35 °C. The lower, upper, and optimal temperature-dependent developmental thresholds were 9.5, 34.2, and 31.1 °C, respectively. Thermal constant for total immature development was 666.7 degree-days. Temperature did not affect lifetime realized fecundity and number of oothecae parasitized by females but did influence parasitism activities over time. Sugar-fed females sustained longer periods of high parasitism rates (≥70%) at 20-30 °C (15-30 d) than at 32-35 °C (1-5 d). These results are useful for determining the ootheca age and temperature range optimal for parasitoid rearing and for estimating the effectiveness of biological control by the wasps.

Temperature effects on the development, body size, and sex ratio of the walnut leaf beetle Gastrolina depressa (Coleoptera: Chrysomelidae)

Insect development times can only be compared over a relatively wide range of permissible temperatures. Both basic and applied branches of entomology widely adopt linear regression that describes the temperature-dependence of developmental rate, which is a reciprocal of time. There is a wealth of literature reporting these parameters for hundreds of economically important species, including leaf beetles. This study begins with a suspicion that the previously published parameters for the temperature-dependent development in the walnut leaf beetle Gastrolina depressa may be imprecise because they disagree with the general variation pattern typical of the family Chrysomelidae. Thus, the immature development in G. depressa is re-studied in order to verify the values of the lower temperature threshold and the slope of developmental rate on temperature. It is found that G. depressa requires 220.2 degree-days accumulated above the threshold of 8.2°C for total immature development. For example, at 28°C, the developmental period from oviposition to adult eclosion is as short as 11.4days. Although development in G. depressa is indeed unusually fast, it does not depart from the general tendencies observed at the family level. Therefore, with extensive published evidence at hand, it has now become possible to approximately predict developmental rates in unstudied species and reveal questionable results in previous studies. In addition, rearing temperature is found to affect adult body mass and sex ratio in this species with males being less abundant at higher temperatures. The latter phenomenon is discussed in light of possible activity of a male-killing microorganism.