Insecticidal potential of a synthetic zeolite against the cowpea weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae)

The insecticidal potential of a synthetic zeolite was evaluated against the cowpea weevil, Callosobruchus maculatus (Fabricius). The synthetic zeolite was applied to concrete surfaces at 0, 2.5, 5, 10 and 20 g/m2, and the mortality of adults was assessed after 1, 3, 6, 9, 12, 24, 36, 48, and 72 h at 28 °C and 65% r.h. The residual efficacy of zeolite applied at 5 g/m2 was evaluated on concrete surfaces at 0, 1, 2, 3, and 4 months post-treatment. Adults of C. maculatus were exposed to cowpeas treated with zeolite at 0, 0.1, 0.5, 1, 2, 3, 4, and 5 g/kg. The number of eggs deposited on cowpea kernels and their hatchability were determined after 7 and 14 d, respectively. The cumulative adult mortality was recorded after 1, 2, 3, and 4 d, and adult progeny production after 42 d. The residual efficacy of zeolite on cowpeas was tested at 0, 1, 2 and 3 months after treatment. On concrete, zeolite applied at ≥ 5 g/m2 resulted in 100% mortality of C. maculatus adults after 24-72 h of exposure. Zeolite at 5 g/m2 exhibited high residual efficacy with 100% mortality of C. maculatus adults after 36 h exposure on treated surfaces for up to 4 months. The mortality of C. maculatus adults exposed to zeolite-treated cowpeas increased with increasing concentration and exposure time. The number of eggs laid by C. maculatus, number of kernels with eggs, and adult progeny production decreased with increasing zeolite concentration. Zeolite applied to cowpeas at 1 g/kg produced 100, 99 and 77% adult mortality at 1, 2, and 3 months post-treatment. Progeny production on zeolite-treated cowpeas was significantly lower than that on untreated cowpeas. These results show that the synthetic zeolite is effective on concrete surfaces and on cowpeas in controlling C. maculatus.