Resumo:
Aqueous solutions of neem oil and aqueous extracts of neem seeds and leaves were sprayed on coffee fruits for laboratory evaluation of their efficiency in reducing infestation of the coffee borer, Hypothenemus hampei (Ferrari), in multi-choice preference assays in laboratory. Neem oil and extracts reduced infestation of fruits in a dose-dependent manner, acting as a repellent. At 0.5%, 1% and 1.5%, the oil reduced fruit infestation by 30.2%, 42.5% (P > 0.05), and 58.6% (P < 0.05), respectively, as compared with the control. Seed extracts at 1%, 2% and 4% (w/v) reduced infestation by 30.9%, 38.3% (P > 0.05) and 70.2% (P < 0.05), respectively; seed extracts at 0.15%, 1.5% and 15% (w/v) reduced fruit infestation by 16.5%, 38.5% (P > 0.05) and 56.9% (P < 0.05), respectively. Spraying the emulsifiable oil at 1% on coffee fruits and adult borers was compared with spraying on fruits or adults only. Adult-only spraying caused low mortality (P > 0.05) and low reduction on the number of damaged fruits (P > 0.05). Fruit-only spraying significantly reduced insect survival rates and the number of damaged fruits (P < 0.05). However, spraying on adults and fruits caused the greatest reduction in adult survival (55.6%; P < 0.05) and in fruit infestation (78.7%; P < 0.05), probably due to insect mortality and neem oil repellence acting together
