Location: Pest Management and Biocontrol ResearchTitle: Semiochemical lures reduce emigration and enhance pest control services in open-field predator augmentation Author
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2014
Publication Date: 3/7/2014
Publication URL: http://handle.nal.usda.gov/10113/58583
Citation: Kelly, J.L., Hagler, J.R., Kaplan, I. 2014. Semiochemical lures reduce emigration and enhance pest control services in open-field predator augmentation. Biological Control. 71:70-77. Interpretive Summary: The introduction of predators as biocontrol agents is a commercially viable insect pest management tactic in greenhouses. However, predator augmentation in nature is far less effective because they rapidly disperse from the targeted crop. We examined the possibility of retaining predaceous stink bugs in tomato plots infested with hornworm caterpillars by using predator attractants consisting of: (1) a plant odor that is emitted as the hornworm feeds (methyl salicylate, which smells like wintergreen) on plant tissue and (2) a stink bug aggregation pheromone. Further, potential hornworm prey were protein marked and released in the plots. In turn, released and native stink bugs were collected and then their gut contents were examined for the presence of protein-marked prey to determine the frequency of predation on hornworms. Of the 3600 total predators marked and released, we recaptured ca. 17% of individuals after 36 hrs. Also, we detected behavioral responses of native stink bugs as 97% of all captured adults were found in aggregation pheromone treated plots. Only 24 of 567 (4%) captured stink bugs tested positive for the presence of predation, suggesting that stink bugs do not readily feed on hornworms. However, caterpillars were depleted by predators at a higher rate in stink bug augmented plots on tomato plants occurring near the methyl salicylate and stink bug pheromone lures. These data show that plant and insect odors are capable of increasing predation of an important tomato pest.
Technical Abstract: Augmentation biocontrol is a commercially viable pest management tactic in enclosed glasshouse environments, but is far less effective in open-field agriculture where newly released enemies rapidly disperse from release sites. We tested the potential for behavior-modifying semiochemicals to increase the retention of mass released predatory stink bugs, Podisus maculiventris Say (Hemiptera: Pentatomidae), for enhanced consumption of hornworm caterpillars, Manduca sexta L. (Lepidoptera: Sphingidae), in tomato fields using the herbivore-induced plant volatile (HIPV), methyl salicylate, and P. maculiventris aggregation pheromone. Further, immunomarked prey were deployed to quantify caterpillar predation in the field by augmented and wild stink bugs. Of the 3600 total predators marked and released, we recaptured ca. 17% of individuals after 36 hrs. This retention rate, however, was highly affected by weather (12% vs. 19% recapture in rainy vs. dry weeks, respectively) and semiochemical deployment, but only under optimal weather conditions (19% vs. 26% recapture in control vs. pheromone lure plots, respectively, during dry weeks). Further, we detected behavioral responses of wild P. maculiventris (i.e., those naturally colonizing) to semiochemical treatment with 97% of all captured adults found in aggregation pheromone plots. Only 24 of 567 (4%) captured stink bugs tested positive for the immunomark, suggesting that hornworm predation occurred but at a low frequency. Importantly, we documented that sentinel caterpillar prey were depleted by predators at a higher rate in stink bug augmented plots on tomato plants occurring near (<3 m from) the HIPV and pheromone lures. These data empirically demonstrate that both semiochemicals are capable of increasing pest consumption via attraction of P. maculiventris. Future work should focus on mechanisms of lure attraction and the long-term consequences of predator development in fields with artificially elevated semiochemical emissions.