Submitted to: California Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2014
Publication Date: 3/1/2016
Citation: Kuenen, L.P., Siegel, J.P. 2016. Sticky traps saturate with navel orangeworm in a non-linear fashion. California Agriculture. 70(1):32-38.
Interpretive Summary: The use of any trap necessarily means capturing animals for counting, whether for re-release (e.g., undersized fish/shellfish) or retention for monitoring a target population or for subsequent consumption. Regardless of the purpose for trapping, trap saturation presents a problem in that fewer target animals are captured or retained because the trap cannot retain all the individuals that enter. Saturation is rarely an all or none phenomenon, rather traps decrease in efficiency as more and more individuals are captured. As such, the interaction of the target animal with the trap affects the saturation “curve” and typically needs to be evaluated empirically for each trap and animal combination. In this study, after capturing over 300,000 navel orangeworm males in four different sex pheromone-baited trap models, we found that trap saturation effects begin after about 30-to-50 males were captured and can be described by equations that are largely parabolic in nature. Thus, trap capture decreases were not exponential in nature and although corrections to high trap counts will have to be made to account for the saturation affects, even initial readings/counts will give a fairly good assessment of increases or decreases in navel orangeworm populations in the nut orchards where they are being monitored.
Technical Abstract: In order to evaluate saturation thresholds as well as differences among wing-trap types, we used unmated female navel orangeworm (NOW) as sex pheromone baits in wing-traps that varied by color and glue/trapping surface. These results were compared to male capture in red delta and simple water cup traps. In the sticky traps, the accumulation of scales and insect bodies on the traps’ glue surface began to reduce capture efficiency after 30-40 males were caught in a trap. The continued accumulation of trapped insects and scales further reduced trap capture in a non-linear fashion. In contrast, the water cup trap’s efficiency was not affected by accumulation of insects or scales since both readily sank beneath the trapping surface; however, the water cup trap captured fewer moths than the non-saturated sticky traps. Trap capture in the sticky traps was compared to comparable traps that had the bottom replaced at all trap checks, which essentially eliminated saturation. In every instance, these nonsaturating traps captured significantly more moths than saturating traps.