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.

We examined the host status of the Australian finger lime, Citrus australiasica F. Muell. (Rutaceae), to Hawai’i’s tephritid fruit fly pests using laboratory and field studies. In high-density (500 flies, 1;1 males and females) no-choice cage exposures (25 × 25 × 25-cm cage size), both undamaged and punctured finger limes were infested by Ceratitis capitata and Zeugodacus cucurbitae at a low rate compared to papaya controls, whereas Bactrocera dorsalis did not infest undamaged fruit, suggesting finger lime is a nonhost. In low-density (50 females) no-choice cage exposures, C. capitata and Z. cucurbitae readily oviposited in undamaged fruit but individuals rarely developed to the pupal or adult stage. For C. capitata, 274 finger limes exposed to 2000 gravid females, which laid an estimated 14,384 eggs, produced two pupae and no adults. For Z. cucurbitae, 299 fruit exposed to 2000 gravid females, which laid an estimated 4484 eggs, produced four pupae and one adult. Field sampling of undamaged fruit from the tree and off the ground from commercial farms produced five C. capitata pupa and one adult from 1119 fruit, for an infestation rate of 0.05 flies per kilogram of fruit; field collections found no natural Z. cucurbitae or B. dorsalis infestation, but the number of fruit available was too low to demonstrate nonhost status with a high degree of confidence.

Avocados are generally poor hosts or nonhosts for tephritid fruit flies, which can influence the type of mitigation measures required by export protocols for trade. We conducted experiments to determine the susceptibility of the avocado, Persea americana, cv. ‘Malama’ to infestation by Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in Hawai’i using laboratory and field no-choice cage tests, together with field sampling. In no-choice cage tests, infestation rates increased with decreasing fruit firmness over time after harvest. Although risk of infestation was negatively correlated with fruit firmness, about 50% of mature hard fruit exposed immediately after harvest became infested. In field cage tests, mature hard fruit on the tree at the 25% purple color stage were not infested, whereas fruit at the 50, 75, and 100% purple color stages were infested at relatively low rates. Field sampling of fallen ‘Malama’ fruit over two seasons showed no natural infestation by B. dorsalis and trap captures in avocado orchards using McPhail traps containing protein bait lures averaged 0.13 ± 0.03 (mean ± SE) flies per trap per week, underscoring the low prevalence of fruit flies in avocado orchards and the poor host quality of this cultivar. A systems approach based on poor host status, low prevalence, and a limited harvest period (October to March) and distribution area (northern tier states) is proposed to export ‘Malama’ avocados from Hawai’i to the continental United States.

Studying the effects of predation in cryptic herbivorous insects is difficult because many spend all or most of their life cycle inside their host plant. Here, we designed and 3D-printed artificial coffee berries to study predation of coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae, Scolytinae), by the flat bark beetle, Cathartus quadricollis (Guerin-Meneville) (Coleoptera: Silvanidae). The 3D-printed berries were tested under laboratory and field conditions and the results confirmed the usefulness of 3D-printed materials to create life-like models for studying predation.