Reproductive Dormancy in Boll-Weevil From Populations of the Midwest of Brazil

Abstract

The boll weevil (Anthonomus grandis Boheman) (Coleoptera: Curculionidae) is an introduced pest in Brazil, which in 30 yr has successfully expanded to various eco-regions and became the most important pest of cotton (Gossypium hirsutum, Malvaceae). Given the limited knowledge about the adaptive mechanisms that allowed successful establishment of the pest population in a tropical region, in this work we studied the potential of the Midwest population of boll weevils to enter a reproductive dormancy and identified the importance of the feeding source for induction of dormancy. We investigated morphological and physiological characters as indicators of the dormancy. We also investigated the occurrence of reproductive dormancy in boll weevils populations from cotton farms of the Midwestern region of Brazil during the cotton and noncotton seasons of 2009 and 2010. The studies revealed that boll weevils entered facultative reproductive dormancy; however, unlike what has been observed for boll weevils from temperate and subtropical regions, the hypertrophy of fat body and hexamerin levels did not straightly correlated to reproductive dormancy. The food source and field conditions during early adult development were decisive factor for the induction of reproductive dormancy. The incidence of reproductive dormancy increased progressively as the phenology of cotton plant advanced, reaching approximately 90% at the end of the crop season. During the noncotton season, the boll weevil was predominantly found in reproductive dormancy, especially females; however, there is evidence of use of multiple adaptive strategies to colonize the next harvest.

Boll weevil within season and off-season activity monitored using a pheromone-and-glue reusable tube trap

“…Adult boll weevils off-season extend their stay in the site feeding on cotton regrowth, volunteer plants and, according to Ribeiro et al (2010), on the pollen of at least 19 different plant families, which can be abundant during the intercropping periods. In addition, larger adults emerge from bolls at the end of the season and when combined with low expenditure in energy, due to restrained reproduction in some proportion of the population (Paula et al, 2013), may be enhancing adult survival during offseason period.…”

Trinta anos do bicudo-do-algodoeiro no Brasil

“…O bicudo-do-algodoeiro é uma praga introduzida no Brasil, que em 30 anos se disseminou com sucesso para várias regiões se tornando a principal praga do algodoeiro no país (Paula et al, 2013).…”

Survival and preference of cotton boll weevil adults for alternative food sources

“…These populations during the winter, when cotton is not available, present only reproductive dormancy (Paula et al, 2013), remains active and feeding on pollen from other plants such as Compositae (Asteraceae), Solanaceae, Euphorbiaceae, Amaranthaceae, Leguminosae and Smilacaceae (Ribeiro et al, 2010;Cuadrado, 2002). These plants apparently serve only for feeding and shelter, not being used for boll weevil reproduction (Cross et al, 1975;Gabriel, 2002).…”