Interaction ofAnthonomus grandisand cotton genotypes: biological and behavioral responses

Abstract

The boll weevil, Anthonomus grandisBoheman (Coleoptera: Curculionidae), is a key pest of cotton, Gossypium hirsutumL. (Malvaceae). Knowledge about boll weevil feeding and oviposition behavior and its response to plant volatiles can underpin our understanding of host plant resistance, and contribute to improved monitoring and mass capture of this pest. Boll weevil oviposition preference and immature development in four cotton genotypes (CNPA TB90, TB85, TB15, and BRS Rubi) were investigated in the laboratory and greenhouse. Volatile organic compounds (VOCs) produced by TB90 and Rubi genotypes were obtained from herbivore‐damaged and undamaged control plants at two phenological stages – vegetative (prior to squaring) and reproductive (during squaring) – and four collection times – 24, 48, 72, and 96 h following herbivore damage. The boll weevil exhibited similar feeding and oviposition behavior across the four tested cotton genotypes. The chemical profiles of herbivore‐damaged plants of both genotypes across the two phenological stages were qualitatively similar, but differed in the amount of volatiles produced. Boll weevil response to VOC extracts was studied using a Y‐tube olfactometer. The boll weevil exhibited similar feeding and oviposition behavior at the four tested cotton genotypes, although delayed development and production of smaller adults was found when fed TB85. The chemical profile of herbivore‐damaged plants of both genotypes at the two phenological stages and time periods (24–96 h) was similar qualitatively, with 30 identified compounds, but differed in the amount of volatiles produced. Additionally, boll weevil olfactory response was positive to herbivory‐induced volatiles. The results help to understand the interaction between A. grandis and cotton plants, and why it is difficult to obtain cotton genotypes possessing constitutive resistance to this pest.

Influence of multiple- and single-species infestations on herbivore-induced cotton volatiles and Anthonomus grandis behaviour

“…In a previous study, the boll weevil did not respond (positive chemotaxis) to volatiles from cotton plants herbivory damaged by E. heros or S. frugiperda, (Magalhães et al 2012). However, volatiles induced by conspecifics were highly attractive and were preferred over constitutive cotton volatiles (Magalhães et al 2012;Silva et al 2015). Therefore, A. grandis appears to recognize the presence of conspecifics and heterospecifics in the plant, and this configuration is important for regulating its attraction.…”

“…(Coleoptera: Curculionidae) presented different quantitative volatile profiles, even though no qualitative differences were observed (Magalhães et al 2012). Moreover, HIPVs from individual attacks of E. heros and S. frugiperda did not elicit movement towards these volatile sources in the boll weevil, which was only attracted by HIPVs from conspecifics attack (Magalhães et al 2012;Silva et al 2015). The objective of this study was to investigate the effect of simultaneous and sequential multiple-species attack of E. heros, S. frugiperda and A. grandis in the cotton cultivar Delta Opal, comparing it to the individual induction profile of each of these insects.…”

“…Most studies on HIPVs emission have focused on the effects of these volatiles on the behaviour of the third trophic level, showing a positive effect for the plant by attracting the herbivore's natural enemies (Turlings et al 1990; de Moraes et al 1998;Moraes et al 2011;Michereff et al 2013). Increased volatiles production due to herbivore damage can, however, distinguish plants from neighbours, introducing risk since herbivores also use these compounds for food localization (Dudareva et al 2006;Szendrei et al 2009;Addesso et al 2011;Magalhães et al 2012;Silva et al 2015).…”

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

“…During the growing season (especially from flowering to boll formation stages), the efficacy of these traps is considerably diminished, both due to competition with suitable plant structures for feeding and oviposition and the abundance of potential mates in the field (Lloyd et al, 1981;Guerra and Garcia, 1982). Cotton plants produce large quantities of organic volatiles during the reproductive stage and after 96 h of boll weevil herbivory (Silva et al, 2015). This suggests the existence of a competition of plant releasing volatiles plus weevils within the plant making the plant more attractive to weevils than the inert trap lured with pheromone.…”

Identification of Volatile Compounds Involved in Host Location by Anthonomus grandis (Coleoptera: Curculionidae)

“…Several studies have shown that cotton volatiles from the reproductive stage have a great influence on boll weevil foraging behavior and that adult males and females prefer herbivoreinduced volatiles over constitutive cotton volatiles (McKibben et al, 1977;Magalhães et al, 2012Magalhães et al, , 2016Silva et al, 2015). Weevil dispersion from natural refuge areas to the crop begins with cotton squaring.…”