Influence of competition and intraguild predation between two candidate biocontrol parasitoids on their potential impact against Harrisia cactus mealybug, Hypogeococcus sp. (Hemiptera: Pseudococcidae)

Authors: AGUIRRE, MARIA - Fuedei; BRUZZONE, OCTAVIO - Instituto De Clima Y Agua (INTA); TRIAPITSYN, SERGUEI - University Of California, Riverside; DIAZ-SOLTERO, HILDA - Animal And Plant Health Inspection Service (APHIS); HIGHT, STEPHEN - Retired ARS Employee; LOGARZO, GUILLERMO - Fuedei

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2021
Publication Date: 6/28/2021
Citation: Aguirre, M.B., Bruzzone, O.A., Triapitsyn, S.V., Diaz-Soltero, H., Hight, S.D., Logarzo, G.A. 2021. Influence of competition and intraguild predation between two candidate biocontrol parasitoids on their potential impact against Harrisia cactus mealybug, Hypogeococcus sp. (Hemiptera: Pseudococcidae). Scientific Reports. 11:13377. https://doi.org/10.1038/s41598-021-92565-6.
DOI: https://doi.org/10.1038/s41598-021-92565-6

Interpretive Summary: The Harrisia cactus mealybug is a devastating pest of native cacti throughout the Caribbean, Mexico and North America. In its native range, natural enemies maintain control of populations and two parasitoid species selected as potential biological control agents. A USDA-ARS scientist with the Insect Behavior and Biocontrol Research unit in Tallahassee, FL in collaboration with researchers from FuEDEI and INTA, Argentina, APHIS and University of California-Riverside investigated parasitism levels of both species to determine their efficacy. Based on models and laboratory results, it was determined that a multiple release strategy for the two parasitoids would provide more control of the pest than a single species release with one species (Anagyrus lapochosus) being released first. These studies provide the foundation for protocols for the eventual release of these biological control agents.

Technical Abstract: When two or more parasitoid species, particularly candidates for biocontrol, share the same target in the same temporal window, a complex of behaviors can occur among them. We studied the type of interactions (competition and intraguild predation) that existed between the nymphal parasitoids Anagyrus cachamai and A. lapachosus (Hymenoptera: Encyrtidae), two candidate neoclassical biocontrol agents against the Puerto Rican cactus pest mealybug, Hypogeococcus sp. (Hemiptera: Pseudococcidae). The surrogate native congener host in Argentina, the cactus mealybug Hypogeococcus sp., was studied to predict which species should be released; in the case that both should be released, in which order, and their potential impact on host suppression. In the laboratory we conducted experiments where different densities of the host mealybug were exposed to naive females of A. cachamai and A. lapachosus sequentially in both directions. Experiments were analyzed by combining a series of competitive behavioral and functional response models. A fully Bayesian approach was used to select the best explaining models and calculate their parameters. Intraguild predation existed between A. cachamai, the species that had the greatest ability to exploit the resource, and A. lapachosus, the strongest species in the interference competition. The role that intraguild predation played in suppression of Hypogeococcus sp. indicated that a multiple release strategy for the two biocontrol agents would produce better control than a single release; as for the release order, A. lapachosus should be released first.