Prey stage preference of Dicrodiplopsis manihoti Harris (Dip., Cecidomyiidae) in response to different stages of Phenacoccus solenopsis Hem., Psedococcidae
پذیرفته شده برای پوستر
عنوان دوره: سومین کنگره بین المللی حشره شناسی ایران
نویسندگان
1Department of Plant Protection, Faculty of Agriculture, Ramin Agriculture and Natural Resources University of Khuzestan, Ahwaz, Iran
2Date Palm and Tropical Fruits Research Center, Horticultural Science Research Institute, AREEO, Ahwaz, Iran,
چکیده
The invasive cotton mealybug Phenacoccus solenopsis Tinsley is one of the most injurious melybugs with economic importance in field crops in warm regions of south-western Iran, including Khuzestan. The predatory gall midges, Dicrodiplopsis manihoti Harris is an important predator associated with mealybugs and frequently reported from plant infested by P. solenopsis. In this study, the prey stage preference of 1st, 2nd and 3rd instar larvae of D. manihoti was studied on 1st, 2nd and 3rd instar nymphs and adult female of P. solenopsis under laboratory condition (32 ± 1°C, 65 ± 5% RH, and 14:10 h L:D). At first, based on preliminary tests, 50% of the consumption demand of each predator stage was placed on Hibiscus rosa-sinensis L. leaves. Afterwards, one single predator (1 day old) was released individually in each arena and allowed to feed (n=20). After 24 h, the predators were removed and the number of each prey stages consumed was counted. The preference index of P. solenopsis for each predator stage was evaluated using Manly’s β preference index and means were separated by Tukey's honest significance test (HSD). The mean Manly’s β preference indexes were evaluated as 1st (0.22, 0.15, 0.13 and 0.48), 2nd (0.51, 0.25, 0.16 and 0.06) and 3rd instar larvae (1.96, 0.56, 0.22 and 0.16) on different stages of D. manihoti. Comparison of means showed the most preference of 2nd and 3rd instar larvae of D. manihoti to 1st instar nymphs of P. solenopsis (a small and active stage) and the lowest preference to adult female of P. solenopsis (the biggest stage). However, 1st instar larvae of D. manihoti showed a high preference to adult female of P. solenopsis and low tendency to the 1st instar nymphs of P. solenopsis. Our findings suggest that 1st instar nymphs of P. solenopsis are more profitable prey stage for larger larval stages of D. manihoti than other stages especially adult female of prey with regard to nutritional benefit, searching efficiency and handling time. The first-instar nymph is the most active stage of the mealybug, and its distribution on plants occurs in this stage, therefore, as D. manihoti feeds more on this stage, it could prevent primary infestations of mealybugs and making it as a good candidate for the biological control of the pest.
کلیدواژه ها