Behaviors of Eretmocerus sp. nr. californicus females attacking Bemisia argentifolii Bellows & Perring infesting cotton, Gossypium hirsutum L., and melon, Cucumis melo L., were quantified. Adult female behaviors were described and quantified for Eret. sp. nr. californicus to establish a behavioral time budget analysis. Females readily searched for host whitefly nymphs on cotton leaves with walking speeds averaging 0.5 mm/s. Females remained infrequently on melon leaves; those that did remain and search for hosts averaged walking speeds of 0.33 mm/s. The duration of host assessment by antennation was related to subsequent behaviors. Rejecting a host was a shorter process than accepting it for further evaluation irrespective of plant species or nymphal stage. Probing the margins of the host nymph the ovipositor was repeated less frequently on an individual host on melon leaves than on cotton. Evidence for a behavioral preference for oviposition under early instars was documented for Eret. sp. nr. californicus females on both plant species. Oviposition for the females that remained and searched for nymphs on leaves in 1-h-long laboratory trials on cotton measured 18%, while on melon, oviposition measured 55%; this higher percentage was attributed to oviposition sites being more accessible under nymphs on melon leaves. Superparasitism was not observed on either host plant species. Twenty-six percent of a female's time on cotton leaves was spent in searching, host assessment, probing, and oviposition, while on melon leaves these behaviors accounted for 44% of the total time. The remainder of the time was spent host feeding, grooming, and resting.


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