Effects of Climate and Host Age on Flight Activity, Infestation Percentage, and Intensity by Coptoborus ochromactonus (Coleoptera: Curculionidae: Scolytinae) in Commercial Balsa Plantations of Ecuador

Abstract

Abstract Coptoborus ochromactonus (Smith and Cognato) is one of the most common and important pests of balsa, Ochroma pyramidale (Cav. Ex Lam. Urb.), an economic pillar of the wood industry in Ecuador. Commercial balsa plantations have been expanded from humid to dry climate areas to limit insect damage, but basic knowledge is still lacking on the interaction of C. ochromactonus activity with variation in climate and plantation age. We investigated the effects of climate and host age on the seasonal flight activity of C. ochromactonus and its infestation rate and intensity, as well as the effect of age and individual infestation intensity on balsa dieback. Experiments were conducted in 1-, 2-, and 3-yr-old commercial balsa plantations located in areas of humid or dry climates. Seasonal flight activity (monitored with baited traps) differed between study sites and seasons. Increased flight activity was significantly correlated with higher relative humidity, higher mean temperature, and reduced precipitation during the dry season in the humid site and with increased mean and minimum temperature and increased precipitation during the rainy season in the dry site. Infestation rates by C. ochromactonus significantly increased with plantation age, especially in the humid site. Intensity of individual infestations (measured as number of successful insect entry holes per tree) was significantly influenced by both climate and plantation age, and it was particularly severe on 3-yr-old trees in the dry site. Percentage of foliage loss significantly increased with infestation intensity. Overall, our results can be relevant for devising preventive measures and suitable management strategies for this emerging pest in Ecuadorian wood plantations.