Effect of pheromone blend components, sex ratio, and population size on the mating of Cadra cautella (Lepidoptera: Pyralidae)

Authors: SAMMANI, A.M. - Rajarata University Of Sri Lanka; DISSANAYAKA, D.M.S. - Rajarata University Of Sri Lanka; WIJAYARATNE, WOLLY L. - Rajarata University Of Sri Lanka; Morrison, William - Rob

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2020
Publication Date: 11/30/2020
Citation: Sammani, A.P., Dissanayaka, D.K., Wijayaratne, W.K., Morrison III, W.R. 2020. Effect of pheromone blend components, sex ratio, and population size on the mating of Cadra cautella (Lepidoptera: Pyralidae). Journal of Insect Science. 20(6). Article ieaa128. https://doi.org/10.1093/jisesa/ieaa128.
DOI: https://doi.org/10.1093/jisesa/ieaa128

Interpretive Summary: Mating disruption is a key alternative management approach for stored product insects, whereby a large amount of a species' sex pheromone is released in the air, which confuses males and prevents them from finding and mating with females. Thus, the life cycle may be broken. In stored products, there are mating disruption systems for indianmeal moth, Mediterranean flour moth, and the almond moth. For the almond moth, the two sex pheromones used are the main pheromone for the species ((Z, E)-9,12-tetradecadienyl acetate or ZETA for short) and a pheromone synergist ((Z)-9-tetradecadien-1-yl acetate or ZTA). While the natural emissions ratio of these compounds is known, there has been no systematic study evaluating how different ratios of each relative to each other under different population sizes of almond moth impact the efficacy of mating disruption. We found that the most effective ratio of these compounds to each other was 5:1 or 3.3:1 ZETA:ZTA, which reduced mating by 87.5% compared with controls without pheromone present. This information may be used to help lure manufacturers to increase the potency of mating disruption tools for food facility managers, thereby increasing adoption of alternative integrated pest management tactics in the post-harvest supply chain.

Technical Abstract: The tropical warehouse moth Ephestia cautella, a key pest of storage facilities, is difficult to manage using current control measures. Pheromone-based management methods remain a high priority due to advantages over conventional management practices which use insecticides. Ephestia cautella females release a blend of pheromone including (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA). The effect of these components on mating of E. cautella and how response varies with the population density and sex ratio still remain unknown. In the current study, the mating status of Ephestia cautella was studied inside wind tunnel cubicles under different ratios of ZETA and ZTA diluted in hexane and at different population sizes either with equal or unequal male:female ratio. The lowest percentage of mated females, roughly 12.5% (highest MD) was produced by a 5:1 and 3.3:1 ratio of ZETA:ZTA. Populations with equal sex ratio showed the lowest percentage of mated females, at 20% and 12.5% under lower and higher density, respectively. When the sex ratio was set to 0.4:1 and 1:0.4 male:female, this produced the lowest percentage of mated females apart from when the sex ratio was equal, with just 25% and 22.5% of moths mated, respectively. This study shows that mating status of E. cautella is influenced by ZETA:ZTA ratio, sex ratio, and population size, and may have implications for mating disruption programs.