Effects of Planting Dates on Boll Weevils (Coleoptera: Curculionidae) and Cotton Fruit in the Subtropics

Abstract

The effects of planting dates 2-3-wk apart on boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), field-level populations, and feeding and oviposition damage to cotton, Gossypium hirsutum L., squares and bolls, were studied during 2002 and 2003 in the Lower Rio Grande Valley of Texas. Squares were 44-56% more abundant in some later planted treatments than in the earlier planted treatments, but mean cumulative numbers of oviposition- and feeding-damaged squares were 2.7 - 4.8-fold greater in some later planted treatments than in earlier treatments. Increased square production in later planted cotton was offset by boll weevil infestations that occurred when squares are most vulnerable and contribute most toward the pest's reproduction. Early planting avoided boll weevil population buildups in the field when large squares were abundant. Lint yields in 2002 did not differ significantly between the planting date treatments, but in 2003, mean yield in the middle treatment was 23% greater than in the early and late-planted treatments. Insecticide sprays in the earliest planted treatment of each year, based on the 10% damaged squares threshold, were >33% and >43% fewer than in the corresponding middle and latest planting treatments, respectively. Delayed planting, relative to the onset of favorable cotton-growing weather, at the field level, even when not applied uniformly on an areawide scale, is more cost-effective than planting too early or too late.

Spatial and temporal distribution of cotton squares and small cotton bolls fallen on ground after damage by boll weevil and the efficiency of the equipment used to collect them

“…In addition, various bolls, especially large-sized ones (>15mm diameter) with punctures of feeding and oviposition produced cotton fibers. These results corroborated those obtained by SHOWLER et al (2005) andSHOWLER (2008), confirming that the punctures by feeding in the cotton squares and small bolls are not associated with your abscission.…”

“…In percent terms, the averages of cotton squares and small bolls damaged by boll weevil and then fallen on the ground at 0.01m to 0.11m; 0.12m to 0.22m; 0.23m to 0.33m, and 0.34m to 0.44m distance throughout the study period were 49.57, 35.63, 11.54, and 3.25%, respectively (Table 1). These results can be attributed to the population growth of the boll weevil with overlapping generations synchronized with the phenological development of cotton Silva et al with increased formation of cotton squares and bolls (SHOWLER et al, 2005).…”

Longevity and egg development of adult female boll weevils fed exclusively on different parts and stages of cotton fruiting bodies

“…Overall, feeding on the reproductive tissue of fruiting bodies promoted more egg production than rinds, squares being nutritionally superior to bolls for that purpose. Once numbers of large squares decline or are no longer available after cut‐out, which is when square populations decline and are replaced by bolls (Guinn, 1986; Cothren, 1999), reduced nutritional quality of bolls and boll weevil egg production when fed bolls is reflected by a leveling of adult weevil populations observed in commercial cotton (Showler et al., 2005).…”

Effects of Fall and Spring Seeding Date and Other Agronomic Factors on Infestations of Root Maggots, <I>Delia</I> spp. (Diptera: Anthomyiidae), in Canola

“…(Wiseman and McMillan 1967); Japanese beetle, Popilla japonica Newman, in corn, Zea mays L. (Woodside 1954); and boll weevil, Anthonomus grandis grandis Boheman, in cotton (Gossypium spp.) (Showler et al 2005).…”