Coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae) is a serious pest of coffee worldwide and a new invasive pest in Hawaii. Adult flat bark beetles, mainly Leptophloeus sp. (75%) and Cathartus quadricollis (21%) (Coleoptera: Laemophloeidae and Silvanidae, respectively), were found inside CBB-infested coffee beans on the tree and molecular marker studies confirmed feeding on CBB. Research was conducted to better understand the ecology of these predators and explore ways to increase their role in suppressing CBB populations in coffee. Laboratory feeding assays demonstrated the capacity for adult and larval flat bark beetles to feed on all CBB life stages. The predators are widely distributed in the coffee growing areas on the island of Hawaii, but feed mainly in dried coffee on the tree rather than in ripening berries where initial crop damage occurs. Berlese funnel extraction of flat bark beetles from dried beans on the tree indicated that predator numbers can be relatively high (up to 23 adult predators per 150 bean sample). C. quadricollis was not susceptible to infection by the fungal biopesticide Beauveria bassiana which is used for field control of CBB in coffee. Leptophloeus sp. and C. quadricollis can be raised easily on a diet of cracked corn and cornmeal. Augmentative releases of generalist flat bark beetle predators like Leptophloeus sp. and C. quadricollis may be a useful component of integrated pest management programs against coffee berry borer and other scolytine pests.
Coffee is one of the most economically valuable specialty crops for which Hawaii is famous. It is produced commercially on >6,900 acres across six islands by more than 1,470 growers. It has a raw crop value of $55.9 million, while the value-added benefits of coffee-related industries exceed $148.5 million (USDA, 2021). In addition to high product quality, Hawaii also has the distinction of being the last major coffee growing region that is free of coffee leaf rust (CLR), a highly damaging disease caused by the obligate parasitic fungus Hemileia vastatrix Berk. & Broome. On October 21, 2020, a coffee grower in Maui County, Hawaii reported the presence of coffee leaf rust-like symptoms on coffee plants (var. ‘Typica’) at their farm with many trees heavily defoliated. Foliar symptoms consisted of yellowish-orange, circular lesions that often coalesced. On abaxial surfaces, these lesions appeared powdery. Urediniospores were mostly reniform, (25)27-34(36) × (17)18-28(29) µm, strongly echinulated on the upper (convex) surface and smooth on the lower (concave) surface, with hyaline to pale yellow-orange walls. Urediniospores incubated in molecular grade water for 10 min at 95 oC served as template for PCR targeting the internal transcribed spacer region of fungi using primers ITS1/ITS2, ITS3/ITS4, and ITS1/ITS4 (White et al., 1990). Amplification products underwent direct Sanger-based sequencing. Following primer sequence trimming, the sequence reads were assembled using CAP3 (Huang and Madan, 1999) and deposited in GenBank (Accession MW228837). Blastn analysis revealed > 99% nucleotide identity with isolates of H. vastatrix from Mexico (eg. KX260251) and Brazil (eg. MF627828). A voucher material from which both the morphological and molecular assays were performed was deposited in the National Fungus Collection (BPI 924818). Subsequent surveys on the islands of Hawaii, Lanai, and Oahu revealed the presence of coffee plants with symptoms of coffee leaf rust. To confirm pathogenicity, urediniospores from a symptomatic plant growing in Holualoa, Hawaii, were collected in gelatin capsules using a G-R Electric Manufacturing Portable Vacuum Pump with a mini cyclone spore adapter. The concentration of spores was adjusted to 1 x 105 spores/ml in sterile water using a Brightline Hemocytometer. The spore suspension was brushed onto the abaxial side of leaves from two C. arabica var. ‘Typica’ plants using a camel hair paintbrush. Two control plants were mock-inoculated with sterile water. Plants were placed in a dark humid chamber set at 22 oC for 48 hours, after which it was adjusted to 12 hours light under cool white fluorescent lighting. After 20 days small, chlorotic spots were visible on the adaxial leaf surface and a few spots contained orange urediniospores on the abaxial surface. Lesions expanded by day 34, followed by necrosis of the center area of several leafspots and leaf abscission was observed at day 70. The experiment was conducted twice. H. vastatrix was confirmed by both morphological and molecular examination of urediniospores recovered from the observed lesions. All mock-inoculated control plants remained asymptomatic. To our knowledge, this is the first report of CLR on coffee in Hawaii. This discovery is of great concern since CLR threatens not only the yield and quality of Hawaii-grown coffee, but also the economic viability of this historic and culturally important industry. Statewide monitoring for CLR continues and further work is needed to mitigate the impact of this discovery through the development of short- and long-term management strategies.
Integrated pest management strategies were adopted to combat the coffee berry borer (CBB) after its arrival in Hawaii in 2010. A decision tree framework is used to model the CBB integrated pest management recommendations, for potential use by growers and to assist in developing and evaluating management strategies and policies. The model focuses on pesticide spraying (spray/no spray) as the most significant pest management decision within each period over the entire crop season. The main result from the analysis suggests the most important parameter to maximize net benefit is to ensure a low initial infestation level. A second result looks at the impact of a subsidy for the cost of pesticides and shows a typical farmer receives a positive net benefit of $947.17. Sensitivity analysis of parameters checks the robustness of the model and further confirms the importance of a low initial infestation level vis-a-vis any level of subsidy. The use of a decision tree is shown to be an effective method for understanding integrated pest management strategies and solutions.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.