Evaluation of the chinaberry Melia azedarach extract against the tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae) in vitro

The South American tomato leaf miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is an important pest of tomato, potato and other solanaceous species of economic relevance. Pest management of TLM based on the use of conventional insecticides can be problematic due to various causes, among them, the reduced economical profits from high insecticide costs, the destruction of natural enemies' populations, the presence of insecticide residues on tomato fruits and the rapid development of insecticide resistance, especially when high levels of infestation are reached. The search for less-persistent active compounds would benefit horticultural production, as well as the environment and consumers. In the current study, we evaluated the toxicity of a hexane extract at different concentrations obtained from the chinaberry tree Melia azedarach L. (MA) fresh fruits, on TLM eggs, 2nd instar larvae and pupae by means of contact tests in the laboratory. Results indicated that with increasing concentrations, mortality of eggs, larvae and pupae also increased. Analysis of probit data showed that LC50 for MA extract in TLM eggs, 2nd instar larvae and pupae were 948.93, 346.72 and 1.75 mu l/ml, respectively. We conclude that this extract has potential for controlling T. absoluta but further ecotoxicological studies should be carried out to conclude on its safety in other organisms and the environment.