Prey Preference by Delphastus Catalinae (Coleoptera: Coccinellidae) on Bemisia Argentifolii (Homoptera: Aleyrodidae): Effects of Plant Species and Prey Stages

Plant species and insect stages were studied for their effects on feeding by predator Delphastus catalinae (Horn) (Coleoptera: Coccinellidae) on the silverleaf whitefly (Bemisia argentifolii Bellows and Perring) (Homoptera: Aleyrodidae). To study the influence of plant species, immature whitefly prey were presented simultaneously to starved predator adults on leaf cuttings of five different plant species: cotton (Gossypium hirsutum L.), tomato (Lycopersicon esculentum Miller), hibiscus (Hibiscus rosa-sinensis L.), cowpea (Vigna unguiculata [L.], Walpers ssp. unguiculata), and collard (Brassica oleracea var. acephala DC). Percentage predation over 24 h was significantly highest on cotton, followed in rank order by collards, cowpea, tomato, and hibiscus. Different predation rates may have been caused by differential response to volatile secondary compounds released by the leaf cuttings. Host stage preference was studied by presenting individual adult predators with equal numbers of prey (200 per replicate) in three aggregate life stages: eggs, small nymphs (1st to 3rd instars) and large nymphs (4th instar to pupae). Adults consumed significantly higher numbers of eggs in a 24-h predation period compared with small or large nymphs. These findings suggest that among the plant species tested, Delphastus catalinae may be most effective on early-season cotton or immediately after whitefly infestation when eggs are predominant.