Behaviors of Eretmocerus sp. nr. californicus Howard females on Bemisia argentifolii Bellows & Perring infesting sweet potato, Ipomoea batatas (L.) Lain, were described and quantified. Walking speeds of up to 1.3 mm/s were calculated for females searching for host whitefly nymphs on sweet potato leaves. Females encountered all host stages during searching with approximately the same relative frequency as their relative abundance (average of 17.03% of hosts available were encountered). Females also arrested and antennated all of the host stages with the same relative frequency as their encounter rate (62.8%). Females showed a clear and significant preference for probing second instars over all other stages. Of the hosts probed, females chose all stages for oviposition with the same relative frequency. Successful exsertion of the ovipositor under a host nymph occurred after initial probes 12 times and after repeated probing attempts 15 times. Oviposition occurred under 13.5% of the hosts assessed by antennation; however, 20 of the 27 (74%) nymphs under which the ovipositor was exserted received an egg. Females spent 41% of the total time in searching, host assessment, probing, and oviposition: the remainder of the time (59%) was spent host feeding, grooming, and resting.


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