Influence of temperature on the functional response of Ooencyrtus egeria (Hymenoptera: Encyrtidae), an egg parasitoid of Acrosternum arabicum (Hemiptera: Pentatomidae)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
The egg parasitoid Ooencyrtua egeria Huang & Noyes (Hymenoptera: Encyrtidae) is a candidate for biological control of several green stink bugs that are important in pistachio orchards, like Acrosternum arabicum Wagner (Hemiptera: Pentatomidae). Functional response curves were constructed on six egg densities (8, 12, 15, 20, 25 and 30) at three temperatures (22, 27 and 32°C). Two-day-old adult females were used. The number of oviposition scars on the surface of each egg was determined under a stereomicroscope (Nikon, DS- L3, camera head: DS- Fi2, Japan), 12 h after exposure in photo phase. Values for attack rate and handling time were estimated with using the SAS. Polynomial logistic regression equations and associated parameters revealed a type II functional response at all temperature levels. The parasitization rate was highest at 27°C (10.8 host eggs in 12 hours) and was lowest at 22°C (5.32 host eggs in 12 hours). From the models estimated handling times (Th) were obtained 0.932, 0.849 and 0.878 h-1 for females at 22, 27 and 32 °C, respectively. There was no significant difference between the temperatures. The highest instantaneous attack rate was calculated 1.26 at 27°C. The instantaneous attack rate (a) was no significant difference at 22°C and 32°C temperatures. The data indicated that high parasitization rates for O. egeria at wide range of temperatures, indicating its potential for augmentative releases against these pests. Our results may be of value for biological control applications and in developing mass rearing techniques for O. egeria.
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