Effectiveness of botanical compounds for controlling Tuta absoluta and Bemisia tabaci

G. GUTIÉRREZ, A. REINOSO, M. HARAMBOURE, S. PALACIOS, M. FOGEL, G. REBOREDO & M.I. SCHNEIDER

Ghent

Simposio; 65th International Symposium on Crop Protection; 2013

Faculty of Bioscience Engineering Ghent University

The tomato leaf miner Tuta absoluta (Lepidoptera: Gelechiidae) and the whitefly Bemisia tabaci(Hemiptera: Aleyrodidae) are two important pests of horticultural crops worldwide, for tomato andsweet pepper respectively.Both species have been controlled by chemical broad‐spectrum pesticides during decades causingcontrol failures due to insecticides resistance development in insects? populations Botanical insecticides could be an alternative to replace the broad‐spectrum for controlling pests. In this sense, the plant family Meliaceae was identified as a promising source of compounds with insectcontrol properties. From this family, the most known compound has been azadirachtin from Azadirachta indica Just, commonly called ?The Neem tree?. Therefore, the Chinaberry tree, Melia azaderach L. is an other source of tetranortriterpenoid compounds with similar structures and insecticidal activities than azadirachtin. The objectives of this work were to evaluate the toxicity of a formulation of azadirachtin (NeemAzal®) and an ethanolic extract from ripe fruits of M. azaderach on eggs, larvae and pupae of T. absoluta and eggs, nymphs and adults of B. tabaci. The full field concentration of NeemAzal®(48 mg/L a.i) and 2%,w/w of Melia extract (obtained by the CEPROCOR, Cordoba‐Argentina) were employed for toxicological bioassays. The exposure methods were by immersion for eggs, larvae, nymphs and pupae and topical for pupae. The solutions were prepared using distilled water or acetone as solvent and a tensioactive (Tween 20®) for immersion and topical application respectively. The bioassays were carried out in the laboratory under controlled conditions: 23±0.5 °C temperature, 75±5% RH and 16:8 (L:D) photoperiod. Mortality, hatching, hervibory (for T. absoluta), development time and adult emergence were the endpoints evaluated. Moreover, repellence and antifeedant effects of both botanical compounds were checked for old larvae and adults of T. absoluta and for adults of B. Tabaci at 2, 4 , 6 and 24h post‐exposure. Azadirachtin was more toxic than Melia extract for both species. Although none disruption was recorded in egg stage of two phytophagous but early neonate larvae of T. absoluta and crawlers of B.tabaci died after hatching or inside the mines in the case of T. absoluta. The development time of the survivors of both species was longer than those registered in controls. Melia extract showed a high repellence effect in two species whereas azadirachtin had a strong antifeedant effect on larvae of T.absoluta. Key words: Key words: Tuta absoluta, Bemisia tabaci, botanical insecticides, toxicity