Lewis W. J. and H. R. Gross. 1989. COMPARATIVE STUDIES ON FIELD PERFORMANCE OF HELIOTHIS LARVAL PARASITOIDS MICROPLITIS CROCEIPES AND CARDIOCHILES NIGRICEPS AT VARYING DENSITIES AND UNDER SELECTED HOST PLANT CONDITIONS. Fla. Entomol.72: 6-14.

ABSTRACT

Field performance of the Heliothis (Lepidoptera: Noctuidae) larval parasitoids
Microplitis croceipes (Cresson) and Cardiochiles nigriceps (Viereck) (Hymenoptera:
Braconidae) was assessed at various parasitoid densities and on different plants. I,abo-
ratory-reared M. croceipes were released in field plots of soybeans and peanuts at levels
of ca. 400 and 1,350 ha. Observed and calculated data indicate that over a 4-day period
parasitism levels of 45 and 96%, respectively, would be obtained with M. croceipes at
these levels on soybeans. Performance of M. croceipes on peanuts was less consistent,
but in one study, 71% parasitism was obtained during a 2-day interval after releases of
1,344 females ha.
The searching behavior and efficiency of C. nigriceps females were studied on the
hyacinth bean (Doliclos lablab L.) and Florida beggarweed (Desmodium purpureum
(Mill.)). Observed and calculated data indicate that populations of 2,622 and 6,371
females ha on the hyacinth bean and beggarweed, respectively, would yield 80%
parasitism, as compared to earlier studies showing that 988-1,142 females ha yield this
level of parasitism on cotton.
These findings show that the efficiency of the parasitoids varies considerably on
different host plants. The distribution of searching parasitoids within the experimental
plots and the distribution of their eggs among the host larvae did not differ significantly
from a random (Poisson) pattern.