Effect of insect growth regulators on hatching of eggs of three vector mosquito species

Abstract

Hatchability of eggs of Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi was studied by exposing freshly laid (0-1 h) and older (12-18 h) eggs to varying concentrations ((}-()()()1-1{) mg/l) of 6 insect growth regulators viz. OMS 3019, OMS 3007, OMS 2015, OMS 3031, OMS 3013 and OMS 3009. In all the 3 species, dosage dependent response was observed. The response was also dependent on the age of eggs. Among the 6 IGR compounds OMS 3031 was found highly active resulting in maximum reduction in hatching of freshly laid eggs of Anopheles stephensi (99·95%) followed by Aedes aegypti (89'9%) whereas 50% inhibition in hatching occurred in older eggs of Culex quinquefasciatus exposed to OMS 3009 at the same dosage. Dose, age and dose and age dependent hatching was evident in eggs of the 3 test species exposed to insect growth regulators OMS 3019, OMS JOB and OMS 2015. Higher proportion of unhatched eggs with varying abnormalities was noticed in test species. Percentage mortality observed was higher in first instar larvae hatched from treated eggs reared in untreated water. Therefore, insect growth regulators have great potency in suppressing the population by affecting hatching of mosquito eggs in addition to inhibition of adult emergence, thus providing a useful tool for integrated vector management.

The effects of sublethal doses of hexaflumuron on the feeding behaviour of mosquitoes (Diptera: Culicidae)

“…Control of agricultural insects through sublethal effects of IGRs have already been demonstrated (Robb & Parella, 1984;Hejazi & Granett, 1986). Similar studies on the sublethal effects of IGRs on egg hatching (Vasuki, 1990), immature development time (Wijeyaratne, 1976) and adult reproductive potential (Darriet, 1989) of vector mosquitoes have also been reported.…”

Potential Use of Pyriproxyfen for Control of <I>Aedes aegypti</I> (Diptera: Culicidae) in Iquitos, Perú

“…Pyriproxyfen has been shown to have limited effects on eggs. Vasuki (1990) exposed eggs (0 Ð1 and 12Ð18 h old) to concentrations of 0.1 to 1000 ppb pyriproxyfen. At 1000 ppb, 90% of Ae.…”

“…Pyriproxyfen is not an adulticide nor are there many reports on any direct ovicidal effect in mosquitoes (but see Vasuki 1990). In addition to its larvicidal activity, it has been reported as decreasing the fertility and fecundity of Ae.…”