Pesquisa Agropecuária Brasileira
On-line version ISSN 1678-3921
SANTOS, Terezinha Monteiro dos; COSTA, Nivânia Pereira; TORRES, Adalci Leite and BOICA JUNIOR, Arlindo Leal. Effect of neem extract on the cotton aphid. Pesq. agropec. bras. [online]. 2004, vol.39, n.11, pp. 1071-1076. ISSN 1678-3921. http://dx.doi.org/10.1590/S0100-204X2004001100003.
The aphid Aphis gossypii Glover (Hemiptera: Aphididae), a harmful pest on cotton, causes direct damage, reducing plant vigor, and indirect damage by honeydew secretion and transmission of several viruses. Due to the problem of pesticide resistance, alternative techniques for chemical control, such as the use of natural insecticides, have been object of research. The effects of aqueous extracts of neem (Azadirachta indica A. Juss) seed powder on the development, survival and fecundity of A. gossypii were evaluated. Treatments consisted of neem seed powder in the concentrations of 23.8, 122.0, 410.0 and 1,410.0 mg/100 mL of distilled water. Mortality rate during the nymphal development for aphids maintained on cotton leaf discs treated with the two highest concentrations were, respectively, 60.0% and 100.0%. With the exception of the highest concentration (1,410.0 mg/100 mL), neem concentrations did not extend the aphids' development period. The net reproductive rate (R0) was of 35.0 nymphs/female for control aphids and of 0.0 nymph/female when the group of females was exposed to neem seed powder at 1,410.0 mg/100 mL since birth. The aqueous extract of neem seeds is efficient against the aphid A. gossypii, causing nymph mortality and reducing their survival period and fecundity.
Keywords : Insecta; Aphis gossypii; Azadirachta indica; Gossypium hirsutum; aqueous extract.