Systemic insecticidal effect of neem-based nanoformulations against Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B in tomato

This study evaluated the systemic insecticidal action and the residual effect of neem-based nanoformulations (Azadirachta indica A. Juss, Meliaceae) on Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) nymphs, a pest of several economic important crops. Colloidal suspensions containing nanocapsules loaded with derived products from A. indica were prepared by using biodegradable polymers such as poly-e-caprolactone (PCL) and poly-beta-hydroxybutyrate (PHB). The encapsulated matrix was a commercial formulation, which contained not only enriched amount of limonoids azadirachtin and 3-tigloilazadiractol, but also in known quantities (Azamax (R) 1.2 CE). Initially, it was estimated the LC50 of solutions containing neem oil, which were applied through irrigation water (soil) in tomato in order to control nymphs of B. tabaci. Afterwards, two lots of nanoformulations, varying in type and amount of polymers and in quantity of commercial oil, were evaluated for systemic action. The nanoformulations NC L5-2 (nanocapules in PCL) and NC L6-1 (nanocapsules in PHB) caused higher mortality among others and for this reason were assayed for residual effect. The estimated value for LC50 was 180.67 mg L-1 of azadirachtin. The results showed that systemic action of oils and nanoformulations containing neem compounds depends on environmental conditions. Azamax (R) did not show either deterrent effect of oviposition or effect on whitefly embryogenesis when applied in soil irrigation at the time of infestation. The nanoformulations selected are bioactives even about 30 days after application and do not differ of commercial product.