Behavioral responses (time budgets) of bollworm (Lepidoptera: Noctuidae) larvae for three cotton cultivars

A greenhouse study was conducted to determine the effects of three cultivars, varying in resistance, on the behavior of first-, third-, and fifth-instar larvae of Heliothis zea (Boddie) using time budgets. Behavioral observations of individual larvae were made at 10-min intervals for 10 h (time budgets). Third- and fifth-instar larvae were observed feeding more frequently than resting on the glandless isoline of "Stoneville-213" and on "TAMCOT CAMD-E." All three larval instars tended to feed more frequently on squares than on other plant parts of all three cultivars. The next most frequent feeding site was the terminal (position of placement) for first instars and the bloom for third and fifth instars. Boll feeding was greatest among fifth instars. Antixenosis in CAMD-E was expressed as decreased feeding of first instars on terminals and of fifth instars on bolls. Distinct differences in frequency of feeding on squares, blooms, and bolls were found among the cultivars. More larvae were observed dropping off CAMD-E plants than off glandless plants. Observations of larval behavior using time budgets could be a useful method in screening cotton germplasm for resistant genotypes