AbstractThe effects of sublethal doses (LD10: 1.00 ng/larva; LD30: 3.75 ng/larva) of chlorfluazuron on the biochemical constituents of eggs of the tobacco cutworm, Spodoptera litura (F.), are described. Chlorfluazuron was applied topically to fifth-instar larvae and the subsequent adults were allowed to mate according to larval treatment (LD10-treated female × LD10-treated male and LD30-treated female × LD30-treated male). Biochemical constituents of eggs resulting from these pairings were analyzed at various stages of embryonic development. Compared with controls, LD10 or LD30 reduced egg constituents as follows: protein (min.–max.) by 32.8%–34.5% or 62.0%–67.3%, lipid by 33%–34% or 62%–67%, carbohydrates by 30%–39% or 60%–67%, DNA by 33%–40% or 60%–69%, RNA by 31%–34% or 59%–67%, and ecdysteroid by 22%–83% or 28%–92%, respectively. The relative proportions of constituents in control eggs were as follows: protein > lipid > carbohydrate, and RNA > DNA. Three low and three high peaks in ecdysteroid titres were observed. Compared with controls, all peaks were reduced in LD10 or LD30 eggs as follows: low peaks: 1st (at 8 h): 32% or 66%; 2nd (at 16 h): 33% or 67%; 3rd (at 52 h): 35% or 65%; high peaks: 1st (at 32 h): 83% or 92%; 2nd (at 64 h): 65% or 82%; 3rd (at 84 h): 84 h, 36% or 63%, respectively. In addition, the first two high peaks were delayed by 4 h in LD10 eggs and by 8 h in LD30 eggs compared with controls. Sublethal doses of chlorfluazuron reduced the amounts of biochemical constituents of eggs during embryogenesis in S. litura.
Mode of Action of Antifeeding Compounds in Larvae of the Tobacco Cutworm, Spodoptera litura (F.) (Lepidoptera : Noctuidae) IV. Effect of Topical Application with Chlordimeform and Clerodin on the Movement of the Head Appendages
