Bioactivity of aqueous extracts of Melia azedarach L. and Azadirachta indica A. Juss (Meliaceae) on tomato pinworm Tuta absoluta (Meyrick, 1917) (Lep.: Gelechiidae) reared on different tomato genotypes

Author(s)

Rogério Brunherotto

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2000-10-27
• Advisor: José Djair Vendramim

Abstract

The effects of aqueous extracts of chinaberry (Melia azedarach L.) and neem ( Azadirachta indica A. Juss (Meliaceae) and three tomato genotypes (Santa Clara and IPA-5, Lycopersicon esculentum and LA 444-1, L. peruvianum) on tomato pinworm Tuta absoluta (Meyrick) were investigated under laboratory conditions. First, the trials were carried out with three concentrations of leaves extracts (0.1, 1.0 e 5.0%) and four different plant structures (Ieaves, branches, raw and ripe fruits) of M. azedarach, in order to determine the most appropriate concentration for bioactivity studies and the most active plant structure. Following, the effects of aqueous extracts (neem seeds and chinaberry leaves, at 0.1%) were evaluated on the development, oviposition and egg mortality of tomato pinworm. Finally, the associated effects of the three tomato genotypes and the two previously referred aqueous extracts were also examined on the insect development and reproduction. The conclusions were: a) the chinaberry leaves extract at 5% concentration had insecticide activity on T. absoluta, causing more than 90% larval mortality; b) the chinaberry extract at 0.1% concentration were suitable for bioactivity studies on tomato pinworm; c) ali tested chinaberry structures (0.1 %) affected the insect development, mainly the leaves, followed by raw fruits, branches and ripe fruits; d) the neem extract showed more insecticide activity rather than chinaberry extract; e) the two Meliaceae extracts inhibited the oviposition but not had ovicidal effect; f) the accession LA 444-1 affected negatively the development and reproduction of T. absoluta; g) the tomato pinworm had equal development and reproduction on IPA-5 and 'Santa Clara' (the susceptible standard); h) the association of tomato genotypes and extracts of chinaberry and neem did not result in synergistic or antagonistic effects on T. absoluta (AU)