Bioactivity of Indigenous Melia azedarach Extracts against the Tomato Leafminer, Tuta absoluta

Abstract

Fruit extracts of indigenous Melia azedarach were tested for their insecticidal bioactivity against the tomato leafminer (Tuta absoluta) under laboratory conditions. Tomato plants were exposed to moths, after/before application of treatments. Treatments included: crushed fruit extracts of water (500,000 ppm and 200,000 ppm), methanol and ethyl acetate (200,000 ppm) with and without mineral oil (2%); M. azedarach powder extracts (2,000 ppm) in different solvents: water, methanol, ethanol, ethyl acetate, hexane and chloroform; biorational products: neem oil, mineral oil, micronized sulfur and thyme oil. The released moths were removed from treated/untreated plants at 72 h and effect of treatments on adults, eggs, larvae and pupae were recorded. Results indicated that sulfur caused the lowest number of live moths to be present on treated plants and was not significantly different in its effect from that of M. azedarach extracts and neem oil. Aqueous extracts without and with oil caused the highest % of dry eggs and were comparable to neem oil. Extracts in the two formulations (crushed fruits and/or powder) caused significant direct effects on immature instars: eggs, early larval instars and pupae. M. azedarach extracts and the tested products also caused indirect effect in form of significant decrease in number of developing the 3rd larval instars and new emerging moths compared to the control. Consecutive sprays of these extracts against eggs, larvae and pupae on same treated plants lead to very low number of moths for a second generation of the pest which contributes to low buildup of pest population in a tomato crop.

Ovicidal Activity and Phytochemical Analysis of some Spontaneous Plants Extracts Against Ectomyelois ceratoniae (Zeller) Lepidoptera: Pyralidae

“…In the case of Spodoptera litura, the plant extract of Clerodendrum inerme (LC 50 =20.46 mg/ml) and Argemone mexicana (LC 50 =21.82 mg/ml) revealed the highest ovicidal activity [34]. The bioactivity of Melia azedarach extracts was tested to treat the Tomato Leaf miner, Tuta absoluta eggs, which displays a medium yield mortality that vary between 39 to 41% [35]. Recently, an egg mortality rates of 71 to 100 % at 48th hour for 50 μl L -1 air doses of an essential oil of Rosmarinus officinalis L. in the Control of Callosobruchus maculatus [36].…”