Semiochemicals from Herbivory Induced Cotton Plants Enhance the Foraging Behavior of the Cotton Boll Weevil, Anthonomus grandis

Abstract

The boll weevil, Anthonomus grandis, has been monitored through deployment of traps baited with aggregation pheromone components. However, field studies have shown that the number of insects caught in these traps is significantly reduced during cotton squaring, suggesting that volatiles produced by plants at this phenological stage may be involved in attraction. Here, we evaluated the chemical profile of volatile organic compounds (VOCs) emitted by undamaged or damaged cotton plants at different phenological stages, under different infestation conditions, and determined the attractiveness of these VOCs to adults of A. grandis. In addition, we investigated whether or not VOCs released by cotton plants enhanced the attractiveness of the aggregation pheromone emitted by male boll weevils. Behavioral responses of A. grandis to VOCs from conspecific-damaged, heterospecific-damaged (Spodoptera frugiperda and Euschistus heros) and undamaged cotton plants, at different phenological stages, were assessed in Y-tube olfactometers. The results showed that volatiles emitted from reproductive cotton plants damaged by conspecifics were attractive to adults boll weevils, whereas volatiles induced by heterospecific herbivores were not as attractive. Additionally, addition of boll weevil-induced volatiles from reproductive cotton plants to aggregation pheromone gave increased attraction, relative to the pheromone alone. The VOC profiles of undamaged and mechanically damaged cotton plants, in both phenological stages, were not different. Chemical analysis showed that cotton plants produced qualitatively similar volatile profiles regardless of damage type, but the quantities produced differed according to the plant's phenological stage and the herbivore species. Notably, vegetative cotton plants released higher amounts of VOCs compared to reproductive plants. At both stages, the highest rate of VOC release was observed in A. grandis-damaged plants. Results show that A. grandis uses conspecific herbivore-induced volatiles in host location, and that homoterpene compounds, such as (E)-4,8-dimethylnona-1,3,7-triene and (E,E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene and the monoterpene (E)-ocimene, may be involved in preference for host plants at the reproductive stage.

Attractiveness of Host Plant Volatile Extracts to the Asian Citrus Psyllid, Diaphorina citri, is Reduced by Terpenoids from the Non-Host Cashew

“…aphids, leafhoppers, stinkbugs (Hegde et al 2011; Moraes et al 2009; Oluwafemi et al 2011; Sobhy et al 2017), and in indirect defence via recruitment of natural enemy parasitic wasps (Bruce et al 2008; Li et al 2017; Moraes et al 2009; Tamiru et al 2011). Furthermore, Magalhães et al (2012) suggested that cotton boll weevils, Anthonomus grandis recognize the physiological stage of host cotton plants via information on the amount of DMNT and TMTT released by cotton plants. Male and female A. grandis prefer plants that produce lower amounts of DMNT and TMTT, allowing discrimination between plants at the reproductive and vegetative stages (Magalhães et al 2016).…”

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

“…Showler (2002) demonstrated that the boll weevil is less inclined to use kaolin-coated cotton plants for feeding and oviposition, indicating that visual stimuli are important for the recognition of cotton plants by cotton boll weevil. However, a study that characterized boll weevil responses to the volatiles released by cotton in different growth stages and herbivorous conditions in olfactometer, showed that A. grandis uses conspecific herbivore-induced volatiles enriched with the aggregation pheromone to locate host cotton plants and that terpenic compounds may be involved in their attractiveness (Magalhães et al, 2012). This result suggests that the olfactory stimulus is also important probably at short distance.…”

Effect of the postfeeding interval on olfactory responses of thrips to herbivore‐induced cotton plants

“…Here we also report that F. occidentalis showed very different responses to damage by H. armigera or T. urticae; it preferred undamaged plants to those damaged by H. armigera, but preferred plants damaged by T. urticae over undamaged plants. types of feeding damage (i.e., chewing vs. sucking) inflicted (Magalhães et al, 2012). This suggests that the attractiveness of the HIPVs induced by T. urticae damage was able to overcome the "repellency" of the HIPVs induced by H. armigera damage but only for 2 d (compared with 4 d of attraction to T. urticae damage alone).…”