Control of potato tuber moth Phthorimaea operculella with sex pheromones in Peru

Abstract

The potato tuber moth (PTM), Phthorimaea operculella (Zeller), is one of the most damaging pests of potatoes in field and storage and is generally of greatest importance in warmer climates. The sex pheromone of this pest consists of two substances. The first is trans-4, cis-7, tridecadien-1-ol acetate (also called PTM 1) and the second active substance is trans-4, cis-7, cis-10-tridecatrien-1-ol acetate (also called PTM 2). Results on monitoring, mass trapping and mating disruption using this pheromone are reported. Of the trap designs tested, no significant differences ( P>0.05) in trap capture were observed between the water-pan trap and the funnel trap set at ground level and at 40 and 80 cm of elevation. Of the eight ratios of PTM 1 and PTM 2 tested, all were significantly superior to the use of virgin-female traps. Highest captures were obtained by using a 9:1 or 1:1.5 ratio of PTM 1:2. The attractiveness of 9:1 ratio appears to drop after 90 days of field use. The 1:1.5 ratio remained attractive for 90 days and beyond. Storage at −5°C for 2 months did not diminish the attractiveness of this pheromone blend. The presence of impurities EZ 4,7–13: OH or EZZ 4,7,10–13: OH reduced trap captures. Unpurified pheromone 1:1.5 at 15-mg loading was as effective as the pure pheromone. In monitoring studies, tuber damage of clone DTO 33 was related to trap catches. Mass trapping demonstrated the feasibility of direct control in field and stores. In field studies, the presence of synthetic pheromones reduced the catch in surrounding water-pan traps baited with virgin females by 97%. Trap densities of one funnel trap per 225 m 2 reduced tuber damage by 45% when compared with plots receiving normal insecticidal application with no pheromones. In storage trials, both water-pan and funnel trap were effective in reducing tuber damage. Microencapsulated pheromone spray significantly reduced larval infestation in stored tubers.