VIPOSITIONAL BEHAVIOR OF THE PARASITOID PALEXORISTA LAXA (DIPTERA: TACHINIDAE) ON HELIOTHIS ZEA (LEPIDOPTERA: NOCTUIDAE) LARVAE

Abstract

The distribution and number of eggs deposited by the tachinid parasitoid Palexorista laxa (Curran) on instars of Heliothis zea (Boddie) were studied. Significantly more eggs were deposited on the thoracic segments of instars 2–5 than on the head or abdominal segments. This may be an adaptation by the parasitoid to avoid removal of the eggs by the host's mandibles. This selectivity of egg placement was not observed on first instars or prepupae. Significantly more eggs were deposited on fourth instars than on any other host developmental stage, suggesting that this may be the preferred host stage for parasitization.