Effects of Age and Host Number on Reproductive Biology of<i>Allorhogas pyralophagus</i>(Hymenoptera: Braconidae) Attacking the Mexican Rice Borer (Lepidoptera: Pyralidae)

Abstract

Abstract Laboratory studies were conducted to determine the effects of parasitoid age and number of hosts available on selected attributes of parasitoid reproduction. Newly emerged mated females of the gregarious parasitoid Allorhogas pyralophagus Marsh were divided into groups ranging in age from 5 to 12 d. For each age class, individual females were exposed to one, two, four, and eight hosts of the Mexican rice borer, Eoreuma loftini (Dyar), over a 24-h period. For each age class, number of eggs laid and hosts attacked were fitted to nonlinear oviposition models and type II functional response curves, respectively. Numbers of eggs laid per female per day were highest at ≈20 eggs per day in 6-d-old females, declining to ≈5 per day in 12-d-old females. The functional response curves showed declining attack rates with time, from ≈2.0 hosts per day in 5-d-old females, to ≈1.0 in 12-d-old parasitoids. Percentage of progeny emergence was not affected by either parasitoid age or number of hosts available. Percentage of female progeny also was not affected by parasitoid age, remaining female-biased.