The impact of a parasitic nematode,Thripinema fuscum, on the feeding behavior and vector competence ofFrankliniella fusca

Frankliniellafusca (Hinds) (Thysanoptera: Thripidae) is the predominant thrips species found inhabiting and reproducing in peanut, Arachis hypogaea L. (Fabaceae), and is one of at least seven thrips species reported to transmit Tomato spotted wilt virus (TSWV). The entomogenous nematode Thripinema fuscum Tipping & Nguyen (Tylenchida: Allantonematidae), a natural enemy of F. fusca, parasitizes larval and adult populations under field conditions. All known Thripinema species render the host female thrips sterile and have the potential to suppress pest populations to near extinction. As a result, secondary spread of TSWV in peanut is reduced. Reduction of the virus under field conditions may also be due to lower transmission rates caused by parasite-induced alterations in host feeding behavior. Therefore, the feeding rates of healthy and parasitized F. fusca male and female cohorts on leaf discs were recorded daily for 10 days and digital images were subjected to image analysis and viral transmission rates were compared daily using double antibody sandwich enzyme-linked immunosorbent assay. Thripinema fuscum reduced the feeding of female F. fusca by nearly 65%, and the ability of females to transmit TSWV by 50%. Potential mechanisms underlying the parasite-induced alterations in feeding behavior and transmission are discussed. Parasitism by T. fuscum significantly reduced male longevity, but female longevity was not affected. These results provide further evidence that T. fuscum aids in regulating viruliferous F. fusca pest populations and suggests its potential as a biological control agent for inoculative release in peanut.