Tachinids in conservation biological control of phytophagous Pentatomidae

Abstract

Several stink bugs species constitute an important pest complex in soybean worldwide. Tachi-nidae parasitoids are an important tool to be exploited in conservation biological control programs. We evaluated parasitism of pentatomids in diferent periods of their life-history: diapause (late autumn and winter), start of activity (spring) and full activity (late summer and early autumn). During the growing seasons 2017–2018 and 2019–2020, we collected stink bugs from soybean, alfalfa and wheat crops and natural vegetation, of three species (Nezara viridula, Edessa meditabunda and Diceraeus furcatus) and reared them in laboratory until pupal formation and adult emergence of tachinid. We examined the relationship among pentatomid abundance and multiple measures of parasitism: through observation of tachinid eggsexternally attached to stink bugs body upon feld col lection and through further verifcation of parasitism in the laboratory. We also examined the preference of tachinids regarding host sex. Seven tachinid species were detected. Neobrachelia cf. edessae parasitizing E. meditabunda was recorded for the frst time in Argentina. Only in two periods of N. viridula life history (diapause and start of activity period) the presence of tachinid eggs externally attached to the stink bugs cuticle was a reliable estimation of successful parasitism. Parasitism was highest on N. viridula, followed by E. meditabunda and lower on D. furcatus. Parasitism of stink bugs was highest during the start of activity and during diapause. During the full activity period in 2017–2018 male hosts were more para-sitized than females. This work provides feld results valuable for designing tools for pentatomid conservation biological control programs.