The behaviors of female Eretmocerus sp. nr. californiens raised from Bemisia argentifolii Bellows & Perring on melon, Cucumis melo L., were analysed on four different host plant species (cotton, melon, sweet potato and Abutilon theophrasti Medic). Comparison with previously published results of similarly treated females reared from sweet potato plants showed performance related differences leading to oviposition. In the present study, the generalized behavioral pathway (walking, host- encounter, antennation, probing and oviposition) did not vary among host plant species for melon- reared parasitoid females. Host assessment by antennation leading to host acceptance for probing varied from 10.5- 12.3 sec among the host plant species with no host stage- related differences in duration. Initial and repeated (multiple probes on the same host nymph) probing events varied from 52.4 to 77.3 sec among host plant species and no stage- related differences were detected. Oviposition occurred under 62 % of the nymphs on cotton, 100 % of the nymphs on melon and 51 % of the nymphs on sweet potato under which the ovipositor was exserted. On cotton, melon and sweet potato proportionally fewer first instar nymphs were encountered than present, a larger proportion of the second instars that were encountered were subsequently antennated, and a larger proportion of second instars on cotton were then subsequently probed. For cotton, melon, and sweet potato, the overall frequency of oviposition was lower than reported in previous studies. Results from these studies showed that the greatest factor in influencing overall parasitism in laboratory experiments was the propensity of females to alight and remain to search for hosts on a particular host plant. The role of “pre- conditioning” parasitoids to be better- suited to a particular host or host plant species is discussed relative to the findings herein.


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