Effects of Soybean Mosaic Virus on the Facultative Phytophagous PredatorOrius insidiosus(Heteroptera: Anthocoridae)

Abstract

Orius insidiosus (Say) is an important predator in soybeans, feeding on thrips, aphids, and other small arthropods. This predator also feeds on plant tissues, and can be affected by the plant’s physiological status, which is altered by age of the leaves or diseases such as soybean mosaic virus. This study examined the effects of soybean mosaic virus on longevity and fecundity of O. insidiosus, as a result of feeding on soybean leaves of different ages infected with a mild or a severe strain of the virus. Females provided with prey on uninfected plants and on plants infected with a mild virus strain lived longer than females on plants infected with a severe strain. When caged on leaves without prey, females lived longer on older and younger leaves than on middle-aged leaves. Fecundity and percentage of egg hatch did not differ significantly between leaf ages and virus strains. Leaf hair density appeared to have the greatest effect on longevity and fecundity; when the leaf hairs were sparse enough for O. insidiosus to reach the leaf’s surface readily, other chemical factors, such as amino acid and starch levels, may have influenced the longevity and fecundity of O. insidiosus. This study shows that some plant stresses might negatively effect yield both through direct reduction in plant health and indirectly when the plant stresses reduce the predator population. Because many heteropteran generalist predators are also facultatively phytophagous, we need to consider the dual impact of plant stresses on crop yields and on these important biological control agents.