Effect of cotton cultivars on the oviposition preference of pink bollworm (Lepidoptera: Gelechiidae)

The effect of four cotton cultivars on the oviposition behavior of the pink bollworm Pectinophora gossypiella (Saunders) was studied under laboratory and semi-field conditions. Young plants and bolls from four commercial upland cotton cultivars (Lachata, Macnair-220, Midas and Sandra) cultivated in the area of Thessaloniki were used. The four cultivars had palmate leaves, and nectaries on both leaves and bolls. Differences were observed in the trichome density and the length of leaf petiole among the cultivars. The typical shape of bolls was either round or ovate. Differences were observed among the cultivars tested in boll size and bract's length. In a series of experiments we recorded the number of eggs oviposited in no-, two-, three-, and four-choice tests using either young plants or bolls. Although the four cotton cultivars exhibited a variation in morphological characteristics, the mean number of eggs oviposited on young plants and bolls did not differ among them in two-, three-, and four-choice experiments. Substantially higher number of eggs were oviposited on either young plants or bolls of Midas in no-choice experiments. Eggs were oviposited mainly on newly developed unfolded leaves of the young plants and under the calyx of the bolls. In a semi-field experiment, we found a clear oviposition preference for bolls compared with plant terminals in all the cultivars tested. Females oviposited similar number of eggs in the four cultivars. We discuss the effect of morphological characteristics of cotton cultivars on the oviposition behavior of pink bollworm.