The mechanisms and host plant responses that are indicative of tolerance to the African rice gall midge, Orseolia oryzivora Harris & Gagne were investigated in four promising donor rice cultivars, Cisadane, Bw 348-1, Tox 4093-17-1 and ITA 306 (local check), in a screen house at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Results indicated that Cisadane was tolerant to infestations on the basis of higher (P 0n05) percentage seedling survival, production of significantly higher number of fertile tillers, productive panicles and significantly higher grain yield per infested plant than the control. Both single infestation at one larva per plant and adult infestation once at 14 days after seeding were positively correlated to higher fertile tiller production per infested plant (at 80 days after transplanting) and higher grain yield per infested plant at maturity. The grain yield per infested plant was significantly higher (P 0n05) in the tolerant variety (Cisadane) than in the control.

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Dry artificial diet pellets prepared with maize, cassava chips, and amino acid supplements (lysine and methionine) were evaluated for mass culture of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), a highly polyphagous pest of many stored grains. Evaluation was done in the laboratory at temperature 26 ± 2 °C, 60–70% RH, 12:12 L:D photoperiod. The artificial diet was compounded from different proportions of maize (M) variety TZPB-SW-R, cassava (C) variety TMS-2110, and amino acid supplements, and was pelletized into 6 mm diameter pellets on which five pairs of one—day—old S. zeamais were bioassayed. The diet M9C1 (90% M and 10% C) was the most suitable diet with comparatively shorter developmental period (34.8 days) and the highest F1 emergence of progeny (145.4) compared to the control, M10C0 (100% M and 0% C).

The maize weevil,Sitophilus zeamaisMotschulsky (Coleoptera: Curculionidae), is one of the most destructive pests of stored cereals. Knowledge of the life history and biology is important to the development of an integrated pest management program. Investigation was carried out on developmental biology ofS. zeamaison four main cereal crops, maize, rice, sorghum, and millet, under laboratory conditions. Egg incubation, oviposition periods, and larval instar development were not different significantly among the food hosts. Number of eggs laid varied significantly among the cereal grains; mean fecundity was highest on maize (67.2±3.16) and lowest on millet (53.8±0.17). Number of immature (larva and pupa) and adult stages varied significantly among the cereal grains. There exist four larval instars with a varied mean head capsule width, with a mean total instar larval developmental period of 23.1, 22.2, 22.2, and 21.6 d on maize, rice, sorghum, and millet, respectively. There was linear relationship and significant correlation between the stages of larval development and head capsule width. The mean developmental period from egg to adult varied, being highest on maize (34.7 d) and lowest on sorghum (33.5 d).

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The sweet orange, Citrus sinensis L. is an important fruit crop in Nigeria and its production is seriously constrained at maturity by attack of the fruit fly, Ceratitis capitata which results in severe yield loss. Effects of attack by C. capitata on fruit morphology and nutritional characteristics of C. sinensis from selected sites in southwest Nigeria were investigated. Twenty five mother citrus trees with >45 cm diameter at breast height (DBH) were randomly selected at two plantation sites: Ede (Osun state) and Olodo (Ogun state) in southwestern Nigeria. Ten mature fruits, plucked randomly from four cardinal sections of each tree were classified based on levels of infestation. Effects of attack on fruit morphometrics were assessed by standard measurements while the effects on fruit quality were determined by proximate and mineral analyses. Results indicated that attack by C. capitata was characterized by oviposition punctures which predisposed the fruit to secondary infection by Penicillium notatum. Fruits were attacked at any point on the surface but significantly more at about 2 cm from the fruit stalk scar. Multiple attacks did not follow a regular pattern. Fruit attack by C. capitata significantly decreased moisture content of fruit by 79% and mineral content; calcium, phosphorous, copper, zinc and iron while percentage dry matter, crude protein and crude fiber decreased significantly (P<0.50) with increased infestation. Fruit infestation also caused significant decrease in the vitamin C content by about 50% but increased saccharose, maltose and glucose content of attacked fruits by about 10%.

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