Abstract
Hawaii has a multitude of scolytine (Coleoptera: Curculionidae: Scolitinae) pests including Hypothenemus hampei, coffee berry borer, which is apest of coffee, Hypothenemus obscurus, tropical nut borer, a significant pest of macadamia nut, and Xylosandrus compactus, black twig borer, a pest of many tropical and ornamental crops. The flat bark beetles, Carthartus quadricollis (Coleoptera: Silvanidae) and Leptophloeus sp. (Coleoptera; Laemophloeidae), are known to predate on coffee berry borer and tropical nut borer but their natural history (feeding habits, reproduction and movement) are poorly understood. Studies were conducted using molecular, field, and laboratory assays to examine 1) flat bark beetle reproduction and movement in coffee and the broader agricultural landscape, 2) establishment of augmentative releases for biological control, and 3) predation rates on H. hampei, H. obscurus and X. compactus. Various life stages of C. quadricollis and Leptophloeus sp. were found in seven different plant species common to the agricultural landscape around coffee farms, suggesting these predators are feeding and reproducing on theses hosts. Molecular analysis indicated that C. quadricollis and Leptophloeus sp. predated on H. hampei, H. obscurus and X. compactus in coffee, macadamia nut, and mixed coffee-macadamia nut farms. Laboratory reared predators were recaptured near release sites on coffee farms at 1, 2, and 7 weeks after augmentative releases. Predation of C. quadricollis on H. hampei eggs placed inside artificial coffee berries in coffee farms was about 40%. Predators C. quadricollis and Leptophloeus sp. are natural enemies of some significant agricultural scolytine pests in Hawaii and have excellent potential for biological control with augmentative releases.
Highlights
Among the most economically important of scolytine pests in Hawaii are the beetles coffee berry borer (Hypothenemus hampei (Ferrari)), tropical nut borer (Hypothenemus obscurus (F.)), and black twig borer (Xylosandrus compactus Eichoff) (Coleoptera: Curculionidae: Scolytinae)
Both H. obscurus and X. compactus are found on all major islands in the state; H. hampei was initially detected on the island of Hawaii where much of the state’s coffee is grown and has since spread to other islands (Messing 2017)
Xylosandrus compactus adults were collected from coffee laterals and verticals; H. obscurus adults were collected from macadamia nut sticktights; and H. hampei adults were collected from infested coffee berries
Summary
Among the most economically important of scolytine pests in Hawaii are the beetles coffee berry borer (Hypothenemus hampei (Ferrari)), tropical nut borer (Hypothenemus obscurus (F.)), and black twig borer (Xylosandrus compactus Eichoff) (Coleoptera: Curculionidae: Scolytinae). Hypothenemus hampei, a recent invasive species discovered in 2010 in Hawaii, bores into the blossom end of ripening coffee (Coffea arabica L.) and if left unmanaged, can damage90% of the crop (Follett et al 2016). Hypothenemus obscurus causes significant damage to macadamia nut Xylosandrus compactus attacks >200 host plants, including coffee and macadamia nut, as well as other tropical crops such as cacao (Theobroma cacao L.), avocado (Persea americana Mill), and a variety of nursery, ornamental and native Hawaiian plants Both H. obscurus and X. compactus are found on all major islands in the state; H. hampei was initially detected on the island of Hawaii where much of the state’s coffee is grown and has since spread to other islands (Messing 2017)
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