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Observations on host plant selection in a pentatomid bug, Eurydema pulchrum Westwood were made using olfactometer techniques. The response of the bug to different plant species such as Brassica oleracea, Raphanus sativus and Solanum lycopersium in different forms (intact plant/macerated) and different varieties of B. oleracea (B. o. capitata/B. o. botrytis) has been shown. The results indicated that secondary metabolites present in B. oleracea play an important role in selection of host plant by the bug.
Intensive surveys conducted at Samaru and its environs in the northern Guinea Savanna of Nigeria between October 2000 and September 2002, indicated that Bemisia tabaci (Genn.) infests forty two (thirty three cultivated and seven wild) species of plants. Twenty nine of the plants were found in upland, two in the lowland and eleven in both upland and lowland (fadama) areas. Heavily infested plants were distorted, chlorotic and stunted. Symptoms of virus infection were associated with some of the infested plants. This is the first comprehensive report of hosts of B. tabaci in Nigeria.
The performance of the pea aphid, Acyrthosiphon pisum Harris (Homoptera: Aphididae) was studied on several Fabaceae species including: pea (Pisum sativum), broad bean (Vicia faba), alfalfa (Medicago sativa), bean (Phaseolus vulgaris) and red clover (Trifolium pratense). Alfalfa, bean and red clover were less accepted by the pea aphid than pea and broad bean. The pea aphid fed on the alfalfa, bean and red clover showed longer pre-reproductive, and shorter reproductive and post-reproductive periods. Alfalfa, bean and red clover also shortened and decreased fecundity of the pea aphid. Mean survival of the pea aphids fed on red clover and bean plants was reduced in comparison to pea aphid fed on pea and broad bean. The other studied population parameters: intrinsic rate of natural increase (rm), net reproduction (R0) and mean generation time were also reduced in the case of the pea aphid on alfalfa, red clover and bean. The study of aphid development and reproduction demonstrated that pea and broad bean are suitable host plants for A. pisum while alfalfa, red clover and bean are not. It is likely that the rejection of alfalfa, red clover and bean by A. pisum was caused by chemical factors in these hosts.
An evaluation of the effect of four host plants on biological parameters of Maconellicoccus hirsutus and efficacy of Anagyrus kamali was conducted in the laboratory. Hibiscus rosa-sinensis and Hibiscus sabdariffa produced M. hirsutus with life cycles which were 1-2 days shorter than those of M. hirsutus reared on Solanum tuberosum, and Cucurbita pepo L. Egg to adult M. hirsutus survival was lowest in C. pepo (8.8%) and highest for H. sabdariffa (21.8%). C. pepo, H. rosa-sinensis and H. sabdariffa produced a more female biased M. hirsutus sex ratio from single ovisacs, than S. tuberosum. Although adult M. hirsutus females exhibited variation in size and longevity on the host plants tested, total fecundity was not significantly different. Life cycle of both sexes and offspring sex ratio of A. kamali emerging from M. hirsutus cultured on the four host plants were statistically similar. M. hirsutus infested H. rosa-sinensis and H. sabdariffa produced A. kamali with significantly higher fecundity (post emergence adult counts) and lower longevity compared to the other host plants. Females with largest femur (Mean length = 0.2950 ± 0.0053 mm) were produced by M. hirsutus infested H. rosa-sinensis. A. kamali efficacy measured by percent parasitization and percent adult eclosion was statistically similar for all M. hirsutus infested host plants tested.
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