Engytatus varians as agent for dispersal of Spodoptera exigua nucleopolyhedrovirus

摘要

The interaction between the mirid predator Engytatus varians (Distant) and a Mexican isolate (SeSIN6) of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) was examined under laboratory conditions. In a choice test, E. varians females and males demonstrated no preference for virus-infected Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae) second instar compared with non-infected at two different post-inoculation times (48 and 72 h). Similarly, prey search time (5-6 h) did not differ significantly for each type of prey. Bioassays were performed to confirm the viability of occlusion bodies (OBs) from predator's faces collected at 48, 96, and 144 h after exposure to virus-infected S. exigua larvae. The proportion of larval mortality was between 0.20 and 0.62 across all times and both E. varians sexes. Another experiment was performed to evaluate the dispersal of SeSIN6 OBs by physical contact with E. varians adults on tomato (Solanum lycopersicum Miller) leaflets treated with the pathogen. Engytatus varians adults were exposed to OB-treated tomato leaflets during 24 or 48 h using a clip cage. After each exposure time, these adults were removed and placed on clean uncontaminated leaflets for periods of 4-48 h. These leaflets were then exposed to groups of S. exigua second instars in clip cages. The proportion of virus-induced larval mortality of S. exigua (ranging from 0.45 to 1.0) was significantly affected by the duration of exposure of E. varians adults on OB-treated or untreated tomato leaflets. Our results reveal the potential of E. varians as an agent for the dispersal of SeMNPV OBs.