Effect of an anti-juvenile hormone agent (Precocene I) on Sunn pest, Eurygaster integriceps (Hemiptera: Scutelleridae) development and reproduction

Abstract

Sunn pest (Eurygaster integriceps Put.) (Hemiptera: Scutelleridae) is a serious pest of cereals causing severe quantitative and qualitative damage by feeding on leaves, stems and grains. Pesticide application is the main method of Sunn pest control, thus a search for developing new control methods is needed to diminish reliance on insecticides for insect control. So in the current study, the effect of an anti-juvenile hormone agent (precocene I) on the growth, reproductive biology and adult hemolymph proteins of E. integriceps females and males were investigated. The results indicated that precocene I had no acute toxicity to adults and second instars of E. integriceps. The treatment of second instars did not lead to death even in high doses, nor did it induce abnormality. The treatment of the third instar nymphs caused disorder in the physiology and increased mortality. The mortality of third instar was dose dependent (R² = 0.9774). Hemolymph protein concentrations in control males and females were high (2497.95 ± 0.04 and 2088 ± 0.04, respectively), but they decreased with the starting of oviposition. Hemolymph protein concentrations in treated females were lower than the control, at first day after treatment. With passage of time, hemolymph protein concentrations remained constant and decreased near oviposition. Total protein concentration in males and females was nearly equal, and there were no significant differences among them (P > 0.01). Precocene I also affected the number of eggs laid by females and the percentage of hatched eggs. It can be said that the effect of precocene I was stage- and age-specific, that is, its effects were varied with stage of the insect and its age in that stage. When used in early growth stage, its effect was less. However, when used in the late developmental stage its effect was more apparent and increased mortality as well as abnormalities.

Keywords: Eurygaster integriceps Put, precocene I, hemolymph protein concentration, immature development, reproduction

African Journal of Biotechnology Vol. 9(36), pp. 5859-5868, 6 September, 2010