Insecticidal properties of neem (Azadirachta indica), annona (Annona squamosa) and castor (Ricinus communis) seed extracts against tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Abstract

Laboratory bioassays were conducted to investigate the insecticidal effects of seed extracts of neem (Azadirachta indica), annona (Annona squamosa) and castor (Ricinus communis) on the larvae of tomato leaf miner, Tuta absoluta. Six different concentrations of the seed extracts were tested on the second instar larvae of T. absoluta. The mean per cent mortality of the larvae revealed a significant toxic effect of all seed extracts that were tested. The seed extracts of annona showed highest mortality (75.1%) of T. absoluta followed by neem (70.1%) and castor (52.5%). Based on bioassay and probit analysis, more toxic effect on T. absoluta was from annona (LD50 656.21mg/l), and therfore annona seed extract would be a alternative to chemical insecticides in managing T. absoluta.