Food Intake in Relation to the Growth of Dysdercus koenigii (Heteroptera)

Abstract

The feeding activity of fifth-instar nymphs of Dysdercus koenigii (Fabricius) at different time intervals after the fourth molt can be expressed in terms of duration of feeding per individual in 4-hour periods, and on the basis of percentage of individuals showing a feeding response during a 30-minute or a 4-hour period. Fifth-instar nymphs began to feed about 16 hours after the molt. Their feeding activity reached the maximum level between 24 and 32 hours after ecdysis, then declined until about the 80th hour, after which there was no more feeding on cotton seeds until the nymphs had become adults. Feeding on cotton leaf or on water alone remained uniformly low throughout the instar, and was significantly less than feeding activity on cotton seeds during the active phase from the 17th to the 80th hour after the preceding molt. In nature the insects probably use the cotton leaf largely or wholly as a source of water. Individuals allowed continuous access to cotton seeds throughout the first four instars, but deprived of his food during the fifth instar, failed to mature as adults but survived as fifth-instar nymphs for twice the normal duration of the fifth instar. Individuals allowed to feed on cotton seeds for only a restricted period during each nymphal instar suffered higher mortality, but the survivors completed their development from egg to adult in a period only very slightly longer than that required by nymphs given continuous access to the diet.