Interspecific competition between Anagyrus pseudococci and Leptomastix dactylopii, parasitoids of the vine mealybug Planococcus ficus

Abstract

Interspecific competition among parasitoids plays a key role in the population dynamics of insect pests and may affect the outcome of biological control programs. The aim of this study was to examine competition between two parasitoids, Anagyrus pseudococci (Girault) and Leptomastix dactylopii Howard (Hymenoptera: Encyrtidae), of the vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) under laboratory conditions. The mealybug was parasitized by both parasitoid species at the same time (within 2 h) or sequentially at 24, 48 or 72 h intervals. When mealybug were parasitized at the same time by both parasitoids, the emergence rate from the host was 68.63 % for L. dactylopii and 31.37 % for A. pseudococci. The emergence rate of females was higher than that for males, but the duration of development of males was shorter than for females in both species. When A. pseudococci had parasitism priority for 24 h, there was no difference between the emergence rates of both parasitoids. When A. pseudococci had parasitism priority for 48 and 72 h, the emergence rates of A. pseudococi were 65 and 77.50 % respectively. Also, the duration of development of A. pseudococci was shorter than that of L. dactylopii for all three time intervals. When L. dactylopii had parasitism priority for 24 and 48 h, there was no difference between the emergence rates of both parasitoids. However, when L. dactylopii had parasitism priority for 72 h, the emergence rate of L. dactylopii was 94.83 %. Only when L. dactylopii had parasitism priority for 48 h, there was a difference between both parasitoids and the duration of development of A. pseudococci was shorter than for L. dactylopii. Consequently, it was found that competition may occur between L. dactylopii and A. pseudococci if they are used together to control P. ficus. Also, it was determined that the A. pseudococci population may be more affected than the L. dactylopii population by this competition.