Behavior, infestation, and molecular characterization of Cryptophlebia spp. (Lepidoptera: Tortricidae) associated with macadamia nut in Hawai'i

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2023-12
Authors
de Rocquigny, Nathalie Brigitte Marie
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Arancon, Norman Q.
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Tropical Conservation Biology & Environmental Science
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Abstract
Macadamia nut (Macadamia integrifolia Maiden & Betche, 1899), one of Hawai'i’s largest agricultural commodities, is susceptible to attacks by several insect pests that reduce yield and profit. Among these pests are two species of Tortricid moths, Cryptophlebia illepida and C. ombrodelta, which cause significant damage to the husk and kernel of macadamia nuts. Currently, growers in Hawai'i have limited options for managing these pests. This limitation is due to their feeding behavior that renders insecticide applications ineffective, their persistence in the orchards year-round due to the phenology of macadamia nut and presence of alternative hosts, and the lack of comprehensive research on these pests. This study aims to investigate Cryptophlebia’s spatial and temporal trends across the macadamia nut growing season to facilitate the development of pest management strategies. Delta traps baited with sex pheromone mixture were utilized to assess male Cryptophlebia populations within and around two macadamia nut orchards in Kea'au and Kapa'au, Hawai'i. Immature nuts were collected and examined from the tree and mature nuts from the ground were sampled to assess for oviposition and injury during the 2022 macadamia nut growing season, spanning from May to October. The numbers of hatched eggs, injury per nut, and total injury of nuts were greater in the exterior of the orchards, than the interior of the orchard. Moreover, male moths and eggs were more abundant in May, June, and July, suggesting that Cryptophlebia mating occurs mostly during the flowering stage of macadamia and egg laying happens shortly thereafter. Furthermore, molecular analysis using DNA barcoding was conducted on collected larvae to determine the species composition of Cryptophlebia in Hawaiian macadamia nut orchards. The species composition was compared to the proportion of adult C. ombrodelta and C. illepida moths caught in delta traps to determine if populations of the endemic C. illepida had decreased since the last time Cryptophlebia were assessed in the field, approximately 30 years ago. These findings provide valuable insights that will guide producers to adhere to a timely and focused integrated pest management (IPM) plan to decrease production inputs such as cost of labor and application of chemicals.
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Agriculture, Entomology, Horticulture, DNA Barcoding, Integrated Pest Management, Koa Seedworm, Litchi Fruit Moth, Sex pheromone
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107 pages
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