Alternative food sources and overwintering feeding behavior of the boll weevil, Anthonomus grandis boheman (coleoptera: curculionidae) underthe tropical conditions of central Brazil

Abstract

-The boll weevil causes serious damage to the cotton crop in South America. Several studies have been published on this pest, but its phenology and behavior under the tropical conditions prevailing in Brazil are not well-known. In this study the feeding behavior and main food sources of adult boll weevils throughout the year in Central Brazil was investigated. The digestive tract contents of insects captured in pheromone traps in two cotton fields and two areas of native vegetation (gallery forest and cerrado sensu stricto) were analyzed. The insect was captured all through the year only in the cerrado. It fed on pollen of 19 different plant families, on Pteridophyta and fungi spores and algae cysts. Simpson Index test showed that the cerrado provided greater diversity of pollen sources. In the beginning of the cotton cycle, the plant families used for pollen feeding were varied: in cotton area 1, the weevil fed on Poaceae (50%), Malvaceae and Smilacaceae (25% each); in cotton area 2 the pollen sources were Malvaceae (50%), Asteraceae (25%) and Fabaceae and Clusiaceae (25% each); in the cerrado they were Chenopodiaceae (67%) and Scheuchzeriaceae (33%). No weevils were collected in the gallery forest in this period. After cotton was harvested, the family Smilacaceae was predominant among the food plants exploited in all the study areas. These results help to explain the survivorship of adult boll weevil during cotton fallow season in Central Brazil and they are discussed in the context of behavioral adaptations to the prevailing tropical environmental conditions.

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

“…These laboratory based results corroborate the results from Ribeiro et al (2010), carried out in the field, that has shown that boll weevils can feed on alternative plants that occur in natural fields of the Central Brazil region. However, our results refine the information indicating that these alternative resources are mainly plant species that belongs to the Malvaceae family.…”

“…Boll weevils have an evolutionary history with cotton that originated with the host shift from its Hampea ancestral host to Gossypium, the genera of the wild and domesticated cotton plants, early in the domestication process (Jones, 2001). Both genera, Hibiscus and Abelmoschus, belong to Malvacea family, and indeed several studies have also shown that boll weevil adults primarily feed on plants from the Malvaceae family (Cuadrado, 2002;Cuadrado and Garralla, 2000;Gabriel, 2002;Jones et al, 1993;Showler and Abrigo, 2007;Ribeiro et al, 2010). Probably, hibiscus and okra plants attracted and feed boll weevils because they are likely chemically and structurally more similar to cotton plants.…”

“…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).…”

Infestação de Anthonomus grandis (Coleoptera: Curculionidae) em rebrota de algodoeiro

“…The FM 910 cultivar had the highest number of re-sprout plants, while the DeltaOPAL cultivar showed the highest number of flower buds and adults per plant, as well as the highest percentage of buds damaged by the boll weevil. (Ramalho & Jesus 1988, Cuadrado 2002, Ribeiro et al 2010. Uma das estratégias de manejo do bicudo é a destruição dos restos culturais e o vazio sanitário, que auxiliam na redução de populações dessa praga, ao final do ciclo de cultivo.…”

“…Assim, as fontes de recursos alimentares existentes, como áreas de vegetação de Cerrado, têm papel primordial na sobrevivência de adultos de bicudo, principalmente no período da entressafra. Os sobreviventes do período de escassez alimentar da entressafra influenciarão a taxa de crescimento populacional, durante um novo ciclo do algodoeiro (Barbosa et al 1983, Ribeiro et al 2010.…”