Factors affecting pheromone production by the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and collection efficiency

Authors: Eller, Fred; Palmquist, Debra

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2014
Publication Date: 11/18/2014
Publication URL: http://handle.nal.usda.gov/10113/60533
Citation: Eller, F.J., Palmquist, D.E. 2014. Factors affecting pheromone production by the pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae) and collection efficiency. Insects. 5:909-920.

Interpretive Summary: This research studied several potential factors which might affect pheromone production by male pepper weevils. Two adsorbents for collecting volatile chemicals were compared as well as male pepper weevil age, time of day, male pepper weevil density, and male pepper weevil diet. The porous polymer Super Q was found to be far superior to Tenax in collecting volatiles released by both pepper weevils and weevil-damaged peppers. Male pepper weevils produced the most pheromone at about 15 days old and produced pheromone at the highest rate between noon and 2 pm. Individual male pepper weevils produced the most pheromone on a per male basis and the lowest percentage of geranic acid in the blend. The use of artificial diet was not a good means to collect pheromone from pepper weevils. Feeding fresh peppers to male pepper weevils resulted in very high pheromone production. These results demonstrate several factors which have significant effects on the measured release rates of both the male-produced aggregation pheromone as well as plant-derived compounds. This information provides the basis for designing better lures for this important pest to aid in its effective management.

Technical Abstract: Several factors which might affect pheromone production by male pepper weevils, Anthonomus eugenii Cano (Coleoptera: Curculionidae), were investigated. Included were a comparison of porous polymer adsorbents (Tenax versus Super Q), the effect of male age, the effect of time of day, the effect of male density; and the effect of male diet. Super Q was found to be a far superior adsorbent for the male-produced alcohols and geranic acid as well as the plant-produced E-ß-ocimene. Pheromone production increased with male age up to about age 15 and then tapered off as the weevils approached age 30. Male pepper weevils produced the highest amount of pheromone between noon and 2 pm (i.e., 4 to 6 hours after “lights on”) and were producing ca. 800 ng/hour during this period. Thereafter, pheromone production decreased and was extremely low during the scotophase (i.e., ca. 12 ng/hour). Male pepper weevil density had a definite effect on both release rate and composition. Pheromone production on a per male basis was highest for individual males and the percentage of geranic acid in the blend was lowest for individual males. The significance of this remains to be determined. Male pepper weevils produced only extremely low amounts of pheromone when feeding on artificial diet, however, they produced very high amounts when on fresh peppers. This information will be useful in designing the optimal attractant for pepper weevils.