Interactions of the Whitefly Predator Delphastus pusillus (Coleoptera: Coccinellidae) with Parasitized Sweetpotato Whitefly (Homoptera: Aleyrodidae)

Abstract

Delphastus pusillus (LeConte), an indigenous coccinellid predator of whiteflies, including sweetpotato whitefly, Bemisia tabaci (Gennadius), feeds on all stages of whiteflies. In laboratory tests, fourth-instar and adult female D. pusillus exhibited a marked tendency to avoid fourth-instar B. tabaci parasitized by the aphelinid endoparasitoids Encarsia tmnsvena (Timberlake) and Eretmacerus sp. nr. calif amicus Howard in favor of unparasitized whiteflies. The age of the parasitoid within the whitefly influenced the extent of the avoidance. Whiteflies with first-instar parasitoids were not avoided, hut those containing third instars and pupal parasitoids were significantly avoided. The presumed causes of the avoidance include parasitism-induced hardening of the whitefly cuticle and introduction of air into the whitefly around maturing parasitoids. D. pusillus and parasitoids tend to attack different stages of the whitefly. This attribute increases temporal separation, enhancing the options for the use of D. pusillus in pest management programs in conjunction with parasitoids.

Whitefly population dynamics in okra plantations

“…Although nutritional, chemical and morphological changes in plants have been reported to affect whitefly population in tomato, beans, and zucchini (Noortje & Lindhout, 1992;Hooks et al, 1998;Leite et al, 1998), leaf N and K, chemical compounds analyzed and trichomes were apparently not important in this study. The trichomes (% non-glandular) found in okra were of low density and did not contain toxic compounds, which could affect oviposition and present antibiotic effects.…”

“…in September. These natural enemies have been used to control whitefly population in several plants (Legaspi et al, 1996a(Legaspi et al, , 1996bLiu & Stansly, 1996a and, in some cases, a positive effect was obtained (Hoelmer et al, 1994;Heinz & Nelson, 1996). Hooks et al (1998) reported high populations of coccinellids and syrphids in zucchini plants infested with high populations of aphids and whiteflies.…”

“…These natural enemies have been used to control whitefly population in several plants (Legaspi et al, 1996a(Legaspi et al, , 1996bLiu & Stansly, 1996a and, in some cases, a positive effect was obtained (Hoelmer et al, 1994;Heinz & Nelson, 1996). Hooks et al (1998) reported high populations of coccinellids and syrphids in zucchini plants infested with high populations of aphids and whiteflies. On the other hand, Hagler & Naranjo (1994) observed that Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinellidae) appeared to be capable of locating whitefly present in low density even at the beginning of the season.…”

Conservation and evaluation of natural enemies in IPM systems for Bemisia tabaci

“…Chrysoperla carnea larvae readily fed upon immature E. transvena within 4th instar B. tabaci in laboratory assays (Kapadia and Puri, 1990). Adult Delphastus pusillus did not differentiate between unparasitized B. tabaci and those parasitized with young E. transvena, but both adults and larvae avoided older larval and pupal stages in laboratory studies (Hoelmer et al, 1994). The impact of these examples of intraguild predation on biological control of B. tabaci in the field are largely unknown.…”

Food Relationships

“…The beetles would starve if only scales containing pupae of this parasitic fl y were available (Quezada & de Bach 1973 ). Delphastus pusillus , a predator of all stages of whitefl ies, exhibited a marked tendency to avoid fourth instar Bemisia tabaci containing third instar and pupal aphelinid endoparasitoids (Hoelmer et al 1994 ).…”