Examining potential intra-guild predation of Peristenus relictus by Geocoris punctipes, and its effects on the biological control of Lygus lineolaris

Abstract

The generalist predator Geocoris punctipes (Say) and the parasitoid Peristenus relictus (Ruthe) are Lygus bug natural enemies. Augmentative biological control of some Lygus species has been attempted using either the predatory bug, or the parasitoid, but never in combination. In the present study, in laboratory assays, we determined whether G. punctipes engaged in intra-guild predation of P. relictus while developing in nymphs of Lygus lineolaris Palisot de Beauvois. In choice and no-choice experiments, G. punctipes preyed on more first and second instar nymphs of L. lineolaris than third and fourth instar nymphs. In choice and no-choice experiments G. punctipes ate more L. lineolaris nymphs that contained P. relictus eggs than nymphs containing P. relictus larvae; no nymphs containing P. relictus pupae were eaten. In experimental arenas in the laboratory, simultaneous release of G. punctipes and P. relictus achieved an additive effect on the mortality of L. lineolaris, killing 90, 80 and 70 percent of first, second and third instar nymphs, respectively. Although those are encouraging results for pest management, additional research on the interactions between these two natural enemies in commercial strawberry fields is needed before practical recommendations can be made.