Determination of sublethal effects of some insecticides on tomato leafminer, tuta absoluta (meyrick)(lepidoptera:gelechiidae)

This study aimed at gathering data on the efficient and conscious use of insecticides applied against tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) which was shown as an important pest of tomatoes recently in Antalya province, one of the most important tomato growing regions in Turkey. The larvae of T. absoluta were exposed to a sublethal dose (LC30) of 4 insecticides registered for use in the control of the pest in Turkey, namely, chlorantraniliprole+abamectin, indoxacarb, azadirachtin and spinosad. The effect of the insecticides on the development, survival, reproduction and feeding of T. absoluta was investigated. The effect on the following parameters were studied: Developmental time and survival of eggs, larvae and pupae, duration of total development and overall survival, fecundity, preoviposition, oviposition and postoviposition periods, longevity, generation time, sex ratio and pupal weight. The developmental time of the eggs, larvae and pupae, and total develomental time were significantly longer compared to the control in those treated with indoxacarb, chlorantraniliprole+abamectin and azadirachtin, while in those treated with spinosad the developmental time of larvae and pupae was significantly shorter. Survival of the eggs, larvae and pupae, and overall survival were reduced in those treated with spinosad, indoxacarb, azadirachtin and chlorantraniliprole+abamectin. Fecundity (eggs per female) was reduced in those subjected to spinosad, indoxacarb, azadirachtin and chlorantraniliprole+abamectin. Preoviposition, oviposition and postoviposition periods were shorter in those treated with azadirachtin while preoviposition and postoviposition periods were longer in those subjected to, chlorantraniliprole+abamectin and indoxacarb. Chlorantraniliprole+abamectin led to an increase in the longevity of females and males while azadirachtin led to a decrease in the same. Generation time was longer in those treated with spinosad, indoxacarb, azadirachtin and chlorantraniliprole+abamectin. Sex ratio was not effected from exposure to spinosad, indoxacarb and chlorantraniliprole+abamectin. The female pupal weight was significantly lower t in those exposed to spinosad, indoxacarb, azadirachtin and chlorantraniliprole+abamectin which suggest an anti-feeding effect. The male pupal weight was not affected. The insecticides registered for use in T. absoluta control, namely spinosad, indoxacarb, azadirachtin and chlorantraniliprole+abamectin inhibited development, survival, reproduction and feeding of the pest. Thus the insecticides appeared to be effective also in those survived the sprays. A significant reduction in the development and reproduction can be expected in those individuals survived the sprays and their offsprings. Therefore immediate control actions against the survived individuals should be avoided. Such a policy is usefull from the point of reducing pest control costs, delaying insecticide resistance in the pest and addressing the health and environmental concerns.