Evaluation of new insecticides in selected peanut cultivars: Effects on thrips (Frankliniella fusca Hinds) feeding behavior and transmission of tomato spotted wilt virus (TSWV)

Peanut varieties that display field resistance to Tomato spotted wilt virus are critical for management of TSWV. However, planting of TSWV-resistant cultivars alone is not enough for suppressing virus incidence. Chemical management still plays a major role in TSWV management. Older insecticides such as aldicarb and phorate are still used extensively. Both aldicarb and phorate exhibit broad-spectrum toxicity, and the usage of the former will be phase out soon. In this study, several new insecticides as alternatives to aldicarb and phorate were evaluated against thrips and transmission of TSWV on two peanut cultivars (GA-Green and GA-06G) under greenhouse conditions. Feeding and transmission assays indicated that majority of the selected insecticides reduced thrips feeding and TSWV transmission (<40%). These results are in accordance with the results obtained from the field trials. Selected alternative insecticides were also compatible with the commonly practiced cultural tactics involving row and tillage patterns, and seeding rates. TSWV incidence prior to harvest in plots treated with candidate insecticides (≤8%) was comparable to TSWV incidence in phorate and aldicarb treated plots (≤5%). TSWV reduction with selected alternative insecticides was more pronounced in GA-06G than in Georgia Green. GA-06G is more recently released cultivar (2006) with greater magnitude of field resistance to TSWV than Georgia Green. Almost all the newly released peanut cultivars possess a greater degree of field resistance to TSWV than Georgia Green. Thus, these new cultivars might provide us with more flexibility in transitioning from using older insecticides to newer insecticides with narrow non-target effects and without compromising on yields.