Reduction in egg hatch after a sublethal dose of chlorfluazuron to larvae of the common cutworm, Spodoptera litura

Abstract

Reduction in egg hatch after a sublethal dose of chlorfluazuron to larvae of the common cutworm, Abstract. The effects of a sublethal dose of chlorfluazuron on egg hatching in Spodoptera litura are examined under laboratory conditions. When LD 10 of chlorfluazuron is topically applied to newly moulted fifth-instar larvae of either sex, a significant reduction in both the number of eggs laid and subsequent hatching is observed after mating but no significant differences in daily of oviposition are observed when compared with the controls. In addition, examination of the unhatched eggs reveals that the number of unfertilized eggs is greater than those that were fertilized but there are significantly more unfertilized eggs laid by treated insects. Interference by chlorfluazuron, transferred by copulation through sperm fluids or ova, appears improbable. All the fertilized unhatched eggs in the treated crosses die at an earlier stage than those of the controls. In the female-treated crosses, the egg size is significantly reduced compared with the control or male-treated crosses. During mating, the treated-males transferred significantly lower-weight spermatophores into the females. The weight of spermatophores transferred by untreated males is the same to both treated and untreated females. The duration of mating is not affected by chlorfluazuron treatment.

Biochemical Analyses of Action of Chlorfluazuron as Reproductive Inhibitor in Spodoptera litura

“…Chlorfluazuron had been used as chitin synthesis as well as reproductive inhibitor (Perveen, 2006). Toxicity and effects of chlorfluazuron on reproduction and viability of S. litura had been examined.…”

Effect of the insect growth regulator diflubenzuron on the predator Podisus nigrispinus (Heteroptera: Pentatomidae)

“…Diflubenzuron inhibits the synthesis of chitin, resulting in abnormal cuticle deposition which causes abortive mounting and death and, also has ovicidal activity, causing a reduction in reproduction (Mommaerts et al 2006). Studies have demonstrated the impact of IGRs on reproductive organs (Perveen 2000b(Perveen , 2006Desneux et al 2007) and on embryogenesis and spermatogenesis in insects (Sauphanor et al 1998). The transovarian transfer of diflubenzuron to the eggs of P. nigrispinus may affect the development of the embryo, and explain the reduction in egg viability at the beginning of the reproductive stage, in a similar way to that observed in Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) exposed to diflubenzuron (Medina et al 2002) and, Aedes albopictus (Skuse) and Ochlerotatus triseriatus (Say) (Diptera: Culicidae) exposed to the growth regulator insecticide pyriproxyfen (Chism and Apperson 2003).…”

Effects of sublethal doses of chlorfluazuron on insemination and number of inseminated sperm in the common cutworm, Spodoptera litura (F.) (Lepidoptera: Noctuidae)

“…A significant reduction in the fecundity, fertility and hatchability of the eggs of S. litura has been observed under laboratory conditions (Perveen 2000a). These sublethal doses of chlorfluazuron also disrupt ovarian development, oogenesis (Perveen & Miyata 2000), testicular development and spermatogenesis (Perveen 2000b), and cause reductions in egg hatch (Perveen 2006) and embryogenesis (F. Perveen, unpublished data) in the same insect.…”