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Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 5/1/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Studies quantified predation by generalist predators on parasitized and unparasitized Bemisia tabaci in cotton. Adult females of Geocoris punctipes, Orius insidiosus and Hippodamia convergens were provided equal numbers of parasitized (Eretmocerus emiratus) and unparasitized early 4th instar whiteflies in petri dish arenas and allowed to forage for 24 h. Studies were conducted with early instar parasitoids (displaced mycetomes) and with pupal-stage parasitoids. All three predator species displayed a significant preference for parasitized hosts. Preference was consistently strongest for pupal-stage parasitoids. H. convergens exhibited the strongest bias for parasitized hosts; responses by G. punctipes and O. insidiosus were similar to one another. Early 4th instar whitefly are flat and translucent on the leaf surface. In contrast, once the immature parasitoid is large enough to displace the host's mycetomes the host begins sto swell and become opaque. Thus, parasitized hosts may be more apparent to predators foraging on the leaf surface. This hypothesis was tested by presenting parasitized host along with late-stage 4th instar whitefly. Both G. punctipes and O. insidiosus showed no preference in these arenas supporting the hypothesis that preference for parasitoids may be based on visual cues. In contrast, H. convergens still showed a preference for parasitized hosts suggesting that other factors are involved in prey choice by this beetle. |
