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

Abstract

ABSTRACT:The boll weevil colonizes cotton fields as early as cotton squaring, causing significant losses due to feeding and protected development inside fruiting structures throughout crop phenology. Successful control depends on control of adults and their accurate detection when they colonize the crops. The commercial trap and boll weevil attract-and-control tubes (BWACT) are the only available tools to monitor and attract-and-kill boll weevil, despite limitation in efficacy, and insecticide in BWACT is not allowed in organic production. A grandlure-and-glue reusable and insecticide-free tube (GGT) made with polyvinyl chloride tube, smeared with entomological glue, and lured with pheromone was tested to detect boll weevil activity across various seasons. Boll weevil showed activity during growing season and off-season from 2009 to 2012 in the Semiarid and with higher numbers captured in GGT in comparisons to commercial traps. GGT was able to detect early weevils in the field right after planting. Further, the overall averages resulted in 34-, 16.8-, and 7.5-times more weevils captured in GGTs compared to the traps during stalk destruction in the Semiarid 2011 and Cerrado season 2012/13 and during the harvesting period in the Cerrado season 2011/12, respectively. Therefore, boll weevils were captured actively during season and off-season and early captures obtained in GGT compared to traps showed a better correlation between captures and square damage.

Colonization and Spatial Distribution of Boll Weevil in Commercial Cotton Fields

“…The whole season monitoring showed that even though farmers adopted their control practices, such as spraying borders early in the season along with insecticide application in the total area later, boll weevil reached high density at the end of the season. A similar outcome was observed by Neves et al (2018) during the 2010/2012 and 2011/2012 seasons in the Cerrado (Rondonópolis, Mato Grosso); despite all the farmers' control practices, boll weevil was detected during the early crop stage in Rondonópolis (< 35 DAE) and resulted in large populations in these fields late in the season corroborating our results. This is likely due to colonizing weevils escaping control from treated border plus weevils not targeted at the center of the field during this early crop stages.…”

“…This survey can be done by direct plant inspection or with pheromone traps. During the early stage, the pheromone traps often have greater efficacy in detecting areas infested with weevil (Neves et al 2018), helping control decisions. Proper survey data for each field will ensure a judicious decision about insecticide application either only in the field border or in whole field area promoting reduction in control cost and biological control action by conserving natural enemies (Machado et al 2019).…”

“…Literature data suggest that high dispersal activity of boll weevil takes place throughout the flowering stage of cotton plants (arrival) and during the harvest period (departure) (Braga Sobrinho & Lukefahr 1983, Leggett 1986, Degrande 1991, Busoli et al 1994, Neves et al 2018. Thus, controlling boll weevil requires attention during the flowering-fruiting stages of cotton plants, which is when plants become susceptible to both adult feeding and reproduction, causing direct crop loss.…”

“…Thus, controlling boll weevil requires attention during the flowering-fruiting stages of cotton plants, which is when plants become susceptible to both adult feeding and reproduction, causing direct crop loss. Data from literature also report about plant colonization (Showler 2006, Spurgeon 2016) and maintenance in the field (Fernandes et al 2001, Grigolli et al 2015, Neves et al 2018, Silva et al 2018, but information is lacking about how commercial cotton fields are colonized by boll weevil as a function of the crop phenology and their bordering vegetation in the Brazilian Cerrado. The knowledge about the spatial distribution of the boll weevil occurrence might help control decisions such as delimiting the area to deploy the BWACT and areas to be treated with insecticides (i.e., field borders instead of spraying the whole field).…”

Integration of Cotton Plant Resistance With Selected Organic Boll Weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae) Control Tactics

“…Previous studies determined that increasing dosages of grandlure usually captures more weevils (Legget, 1980) and that the combination of the pheromone with some plant volatiles increases trap captures (Magalhäes et al, 2012(Magalhäes et al, , 2016. The relatively low late-season numbers of A. grandis grandis where colored cotton cultivars are grown with BRS Aroeira is likely because there were fewer susceptible (attractive) cultivar buds in the BRS Aroeira-associated plots (Showler, Greenberg, Scott Jr., & Robinson, 2005;Neves, Torres, Barros, & Vivan, 2018). While it is possible to capture large numbers of adult A. grandis grandis in grandlure-baited large capacity traps (Showler, 2003), trapping has not been shown to reduce adult A. grandis grandis populations in commercial cotton fields (Showler, 2009b).…”