# Non-Host Status of Green Lemon Fruit (Citrus × limon (L.) Burman f. cv. Lisbon) to Oriental Fruit Fly, Mediterranean Fruit Fly, and Melon Fly (Diptera: Tephritidae) in Hawaii

## TL;DR

Green lemons in Hawaii are not a natural host for three major fruit fly pests, making them safe for export without quarantine treatments.

## Contribution

Demonstrates that undamaged green Lisbon lemons are non-hosts for three economically significant fruit fly species in Hawaii.

## Key findings

- Oriental, Mediterranean, and melon fruit flies did not infest undamaged commercial-quality green lemons.
- Over 58,000 field-collected lemons showed no natural infestation by these fruit flies.
- Lemon fruit flies only infested artificially damaged lemons in controlled experiments.

## Abstract

Tephritid fruit flies are major economic and quarantine pests of fresh fruits and an impediment to international trade. Fruits differ in their susceptibility to infestation by fruit flies. International regulatory standards that delineate host status categorize fruits as a natural host, conditional host, or non-host. If a fruit fly cannot completely develop to form viable adults, the fruit is a non-host and may not require a quarantine treatment or other phytosanitary measures. Lemon cv. Lisbon is a new crop in Hawaii, with approximately 800 ha recently planted on the island of Maui. Currently, the fruit is being sold locally, but harvest volumes may eventually surpass local demand, and therefore, export options would be needed. Host status testing was conducted using no-choice laboratory and field cage tests in addition to field collection of fruit. Oriental fruit fly (Bactrocera dorsalis [Hendel]), Mediterranean fruit fly (Ceratitis capitata [Wiedemann]), and melon fly (Zeugodacus cucurbitae [Cocquillett]) oviposited and developed in artificially damaged green lemons in cage tests but did not infest undamaged commercial-quality fruit. Field-collected and processed commercial-quality green Lisbon lemons (total of >58,000 fruits) were not naturally infested by Oriental fruit fly, Mediterranean fruit fly, or melon fly under local conditions. Green Lisbon lemons are naturally a non-host for these three pests and pose a negligible risk of moving these fruit flies during overseas export.

We investigated the host status of harvest-ready green lemons, Citrus × limon (L.) Burm. F. cv. Lisbon (Rutaceae), to Oriental fruit fly (Bactrocera dorsalis), Mediterranean fruit fly (Ceratitis capitata), and melon fly (Zeugodacus cucurbitae) (Diptera: Tephritidae) in Hawaii using laboratory and field studies. In forced-infestation small-cage exposures (using 25 × 25 × 25 cm screened cages with 50 gravid females), punctured lemons were infested by Oriental fruit fly, Mediterranean fruit fly, and melon fly, whereas undamaged lemons were not infested. Field collection, packing, and incubation of approximately 58,420 mixed-grade fruit (commercial export quality and off grades) found no natural infestations and resulted in no fruit fly emergence. Field studies enclosing fruit on trees in sleeve cages that were stocked with 50 gravid females per cage resulted in no infestations. Commercial export-grade green Lisbon lemon fruit should, therefore, be considered a non-host for Oriental fruit fly, Mediterranean fruit fly, and melon fly.