جستجوی مقالات مرتبط با کلیدواژه « Egg Parasitoid » در نشریات گروه « گیاهپزشکی »

Trissolcuss grandis Thomson, is an important egg parasitoid of Eurygaster integriceps Puton that can control its population in wheat and barley fields. Despite valuable results from previous studies, the thermal development of T. grandis over a wide range of temperatures had not been elucidated completely. This study was conducted to evaluate the thermal effect on the development of T. grandis using Sunn pest eggs as hosts in a wide range of temperatures (12.5 to 40 ±0.5℃, 65 ± 5% RH., and a photoperiod of 16L:8D h) in the laboratory condition. The development times of the immature stage (Egg-Adult) of T. grandis decreased with increasing temperatures up to 35 ºC for both sexes. Patterns of temperature-dependent development times of the immature stage of females and males (i.e. emergence of females and males of T. grandis adults) were modeled and simulated with linear and nonlinear regression analyses. The estimated low-threshold temperatures (Tb) were 10.61 and 10.62 ºC for females and males, respectively. Thermal constants (k) of the immature stage of females and males were 179.85 and 161.03 degree-days (DD), respectively. Stage transition models for females and males adults of T. grandis were constructed using two basic components of nonlinear development rate (modified Sharpe & DeMichele model function) and distribution models (two-parameter Weibull function) to simulate the proportion of individuals shifted from egg to adult. These models will be useful in building a T. grandis population model that will describe its seasonal occurrence pattern and population dynamics under various wheat and barley fields and optimize environmental conditions in mass rearing.

Trichogrammatid wasps are the most common natural enemies around the world used for biocontrol many important lepidoptran pests. Therefore, the availability of suitable storage methods for these parasitoids is valuable in biological control. In this study, the performance of Trichogramma brassicae reared on two different hosts and in two different cold storage periods was investigated. Wasp pupae formed on Ephestia kuehniella and Ectomyelois ceratoniae eggs, were kept in 10 ᵒC for 30 days and then in 4 ᵒC for 4 and 8 weeks. The effect of the treatment combinations on wasp's emergence rate, sex ratio and the number of female and male parasitoids in parental wasps (F0) and their progeny (F1) were estimated. In addition, adult wasp's shape (wingless and abnormality) and parasitism rate were investigated in parental wasps (F0) and their progeny (F1). The results of this study showed that emergence rate of T. brassicae in F0 was significantly influenced by the interaction between host and cold storage period. The highest and lowest emergence rate were respectively found on E. creatoniae in control and E. kuehniella in 8 weeks cold storage period. Sex ratio and the number of female parasitoids in F0 and F1 were significantly influenced either by host or cold storage period, whereas interactive effect of these factors did not affect significantly sex ratio and the number of females in both generations. Also, wingless and abnormality of wasps in F0 was not significantly influenced by any treatment combination. Parasitism rate of wasps reared on both hosts in F1, significantly decreased by increasing in cold storage duration. Finally, the results indicated that the most of qualitative characteristics of wasps grown on E. ceratoniae, were clearly better than those of wasps grown on E. kuehniella both in F0 and F1

Two chalcidoid parasitic wasps (Hym.: Chalcidoidea) of two lepidopterous pests on willow trees, Salix spp., were collected in Tehran and Alborz provinces, Iran. Ooencyrtus populicola Myartseva, 1995 (Hym.: Encyrtidae) and Colpoclypeus florus (Walker, 1938) (Hym.: Eulophidae) were reared on Ceruravinula (L., 1758) (Lep.: Notodontidae) and Nycteola asiatica (Krulikovsky, 1904) (Lep.: Nolidae), respectively. Ooencyrtus populicola is a parasitoid of egg and C. florus is an ectoparasitoid of larval stage. Ooencyrtus populicola is a new record for Iran, but C. florus was previously reported as a parasitoid of an unknown leaf-roller larva.

Abstract. Trissolcus grandis Thompson (Hymenoptera: Scelionidae), a native Sunn pest egg parasitoid in Iran, has the potential as a biological control agent for sunn pest, Eurygaster integriceps Puton (Het.: Scutelleridae). However, its ecological characteristics have remained unclear. Thus, this study aimed to develop a parasitism model of T. grandis with sunn pest egg as host. In order to obtain the data for the model, the longevity, survivorship and parasitism capacity of the adult female T. grandis were examined at nine constant temperatures (15, 17.5, 20, 25, 27.5, 30, 32.5, 35, and 37.5±0.5 °C), relative humidity 65 ± 5 % RH, and a photoperiod of 16:8 (L:D) h. Longevity (mean±SE) decreased as temperature increased and was the longest at 15°C (73.18±3.86 days) and the shortest at 35°C (18.98±0.48 days). A modified model of Sharp-DeMichele well described adult developmental rate (1/mean longevity) in the range of studied temperatures (r2 = 0.994) and was used to calculate the physiological age. The mean total host eggs parasitized/female (mean±SE) was greatest at 17.5°C (275.84 ± 3.21 host eggs) and lowest at 15°C (25.06 ± 3.221 host eggs). The temperature-dependent total parasitism, the age-specific cumulative parasitism rate, and the age-specific survival rate were best described by an extreme value function (r2 = 0.934), the two-parameter Weibull function (r2 = 0.967), and a sigmoid function (r2 = 0.979), respectively. I anticipate that the fitted models and parameters may be useful in developing a population model for T. grandis and lead to a better understanding of its parasitism strategy.

Trichogramma is an important genus of egg parasitoids that is frequently used as biological control agents against lepidopteran pests. The most widespread species of Trichogramma in Iran is Trichogramma brassicae Bezdenko that is widely used against rice stem borrer, Chilo suppressalis (Walker). In this study, the sublethal effects of LC30 concentration of diazinon and fipronil were studied on the functional response of T. brassicae to different densities (2, 4, 8, 16, 32 and 64) of Sitotroga cerealella (Olivier) eggs. The experiment was carried out in an insectarium at 25 ± 1 ºC, 70 ± 10% RH, and a photoperiod of 16: 8 (L: D) h. Young adult females of the parasitoid were exposed to LC30 of either insecticides for an appropriate time of exposure. Then, fresh host egges were offered to survived female wasps for parasitim for 24 h. The type of functional response was determined using logistic regression and the parameters including searching efficiency (a) and handling time (Th) were estimated by non-linear regression. The results revealed a type II functional response in the control and fipronil, and type III for diazinon. In this study, application of insecticides caused a decrease in the attack rate and an increase in the handling time of exposed wasps compared with the control. The longest handling time (3.76 ± 0.4 h) and the lowest attack rate (0.001 ± 0.0004) were observed in diazinon. The results suggested that the adverse effect of this insecticide on searching ability of T. brassicae should be considered in integrated pest management programs (IPM).

​Trichogramma evanescens Westwood is an important biological control agent of lepidopteran pests and is widely distributed throughout Iran and neighboring countries. Laboratory studies were conducted to determine the influence of Ephestia kuehniella Zeller eggs age on the number of parasitized eggs, development time, sex ratio, progeny longevity and fecundity. Understanding this influence is important for developing biological control programs. Mated female parasitoids (24 h age) were provided with 1, 2, 3, and 4-days-old E. kuehniella eggs in no-choice experiments, individually. T. evanescens developed on E. kuehniella eggs of all ages tested, while showing a better adaptation to younger host eggs with significantly faster developmental time, higher survival and more female progeny on 1-day-old eggs. Progeny emerged from 1-day-old eggs had also higher longevity and fecundity than those emerging from other host ages tested. The intrinsic rate of increase (r) values of T. evanescens reared on 1, 2, 3 and 4-days-old E. kuehniella eggs were 0.345, 0.322, 0.281 and 0.233 day-1 and the mean generation time (T) was 12.19, 12.13, 12.01 and 11.82 days, respectively. The current study provides useful information to use suitable host age of E. kuehniella for mass production of T. evanescens.