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Exposure of freshly laid eggs (<24 h old) of Earias vittella Fabricius (Lepidoptera: Noctuidae) and Dysdercus koenigii (Fabricius) (Hemiptera: Pyrrhocoridae) to volatiles from bulbs of Allium sativum significantly reduced their hatchability. Eggs of Spodoptera litura (Fabricius) (Noctuidae) treated likewise, failed to hatch. Eggs of Helicoverpa armigera (Hübner) (Noctuidae) were more tolerant and showed only a slight decrease in mortality. None of the immature stages of D. koenigii and H. armigera and only 30% of those of E. vittella that hatched from treated eggs managed to complete their metamorphosis. A few larvae of H. armigera developed to the pupal stage but their pupal weights were markedly low. These findings are interpreted as the chronic effects of volatiles affecting larvae/nymphs following developmental defects sustained during embryonic development. The known chief constituents such as allicin, 2-propene sulfenic acid, 2-propene thiol, propylene, thioacrolein and ajoene present in the volatiles were presumed to be responsible for the adverse consequences reported here.

Postembryonic development and adult emergence ofCorcyra cephalonica (Stainton) were adversely affected in varying degrees when individuals were reared for the first 2 weeks of larval life or for a similar duration from the sixteenth day of their lives in an environment of eucalyptus oil volatiles. This was, however, not so in the progeny of parents exposed to these volatiles for only 5 min. Exposure of this pest to neem oil volatiles during larval stages for similar periods failed to produce such adverse effects. A marked decline in the reproductive potential, in terms of egg output and egg hatchability, of the moth was observed when the larvae were reared for the first 15 days in the presence of eucalyptus oil volatiles or when the parents were exposed for 5 min to such an environment during adult life. Thus, a "carry over" of the detrimental effect of the volatile(s) of this oil on the reproductive potential of the pyralid was indicated.

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