Effects of recombinant baculoviruses on three nontarget heliothine predators

Genetically engineered baculoviruses, relative to their wild-type progenito rs, have successfully improved the time-to-kill of these arthropod-specific biopesticides. Beneficial arthropods that prey on targeted pest insects ar e likely the first nontarget organisms to be adversely affected by the appl ications of such biopesticides. The goals of this project were to assess po tential risks of the recombinant baculoviruses on Solenopsis invicta, Geoco ris punctipes, and Hippodamia convergens, all of which are common predators of heliothines in Texas cotton. Four recombinant Autographa californica nu clear polyhedrosis viruses (AcNPV), one Helicoverpa tea nuclear polyhedrosi s virus (HzNPV), and two corresponding wild-type NPVs were used in this ris k assessment study. Risks associated with these baculoviruses were determin ed by possible shifts in predator life history traits (rate of food consump tion, travel speed, fecundity, and survival) when fed prey infected with re combinant viruses compared to prey infected with wild-type viruses or to he althy prey. We also tested for possible transmission of these viruses by pr edators using the polymerase chain reaction (PCR). No significant shifts in life history characteristics were detected in predators fed Heliothis vire scens larvae infected with any of the seven viruses. Viral DNA was discover ed using PCR in 2.3% of fire ant workers, but not from any of the queens or eggs. In G. punctipes, 13.4% of adults and 0.5% of eggs scored positive fo r viruses. Twelve percent of H. convergens adults were found PCR positive. Residency in all three predators tested provides a pathway which could incr ease the persistence of recombinant viral particles in the environment and thus may produce an indeterminable amount of risk associated with their ina dvertent movement. (C) 1999 Academic Press.