Evaluation of the Boll Weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) Suppression Program in the State of Goiás, Brazil

Abstract

The boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae) is the most important cotton pest in Brazil. A large-scale field-testing of a Boll Weevil Suppression Program (BWSP) was implemented to assess its technical and operational feasibility for boll weevil suppression in the state of Goiás, Brazil. The pilot plan focused on 3,608 ha of cotton during the 2006/2007 and 6,011 ha in the 2007/2008 growing seasons; the areas were divided into four inner zones with an outer buffer zone. We analyzed data on boll weevil captures using pheromone traps installed in the BWSP fields, on the detection of the first insect and the first damaged floral bud, greatest damage, and number of insecticide applications. The nonparametric Mann-Whitney U test was used to evaluate the differences between presuppression and suppression years. Fourteen pheromone-baited trapping evaluations were used to compare the weevil populations from 2006/2007 and 2007/2008 growing seasons. The BWSP regime reduced in-season boll weevil captures from 15- to 500-fold compared to presuppression levels in the preceding year. The low capture rates were related to delays in infestation and damage by weevils. The smaller population size measured by trapping and field monitoring reduced the number of required insecticide treatments. The BWSP strategy was efficient in suppressing populations of this pest and is a viable program for cotton production in subtropical and tropical regions, with long-term economic and environmental benefits.

Survival pattern of the boll weevil during cotton fallow in Midwestern Brazil

“…At the end of the crop cycle, the adults search for alternative food sources and shelter in order to survive the fallow period. This mass egress, both during and after the harvesting procedures, has been reported in the state of São Paulo, in the Distrito Federal, and in the state of Bahia by Campanhola et al (1988), Ribeiro et al (2010), and Macêdo et al (2015), respectively, and has been confirmed in monitoring studies using traps baited with pheromone, carried out in cotton-producing areas in the state of Goiás (Lima Jr. et al, 2013).…”

“…This may explain the high number of adults captured in the traps, as noted at the end of the cotton cycle (Showler, 2003;Lima Jr. et al, 2013).…”

“…However, for the structures that contained fifth-stage larvae, pre-pupae, and pupae, the incubation times were shorter than five days. The act of removing the dry bolls from the cotton plant and keeping them in the laboratory may have been a mechanical stimulus for the emergence of adults from these structures, as happens during harvest on farms (Showler, 2003;Lima Jr. et al, 2013). These results are indicative that the crop management at the end of the cycle, with desiccant application and harvesting, could disturb the adults and force them to leave the cotton structures.…”

Investigating Engineered Ribonucleoprotein Particles to Improve Oral RNAi Delivery in Crop Insect Pests

“…The Cotton boll weevil ( Anthonomus grandis ) is an economically important crop insect pest that attacks cotton fields, particularly in South America (de Lima et al, 2013). The larvae live and feed off the cotton flowers and buds, causing serious damage to cotton yields.…”

Rational Practices to Manage Boll Weevils Colonization and Population Growth on Family Farms in the Semiárido Region of Brazil

“…Boll weevil immature stages exhibit low natural mortality from natural enemies [ 9 , 10 ] and are difficult to control with insecticides, because they are partially protected inside cotton fruit bodies. Current insecticide-based practices require 5–6× sequential sprays at ~5-day intervals, with the intent of killing adults emerging from fallen fruiting bodies before they are able to oviposit [ 11 ]. Technologies such as transgenic cotton also have no impact on boll weevils [ 12 ].…”