Host plants and relative abundance of fruit fly (Diptera: Tephritidae) species in the Solomon Islands.
Tephritid fruit flies were surveyed using male lure Steiner traps and by collection of host fruits over a 4-year period (June 1994-June 1998) throughout the nine provinces of the Solomon Islands. The purpose of the survey was to determine which species were present, which were most abundant, and which commercial and non-commercial fruits were hosts for fruit flies. A total of 1 051 493 fruit fly specimens were collected in 1726 trap collections from 117 sites. Sixty-three per cent of trap collections were made on the island of Guadalcanal. Overall, 37 fruit fly species were recovered from trap samples, with 79% and 21% of specimens from cuelure and methyl eugenol traps, respectively. The species most common in cuelure traps were Bactrocera frauenfeldi (Schiner) (mango fly), B. moluccensis (Perkins), B. simulata (Malloch), Dacus solomonensis Malloch and B. redunca (Drew). The species most common in methyl eugenol traps were B. umbrosa (Fabricius), B. froggatti (Bezzi) and B. pepisalae (Froggatt). With the exception of B. cucurbitae (Hendel), all common species were recovered in all provinces. B. cucurbitae was the only non-indigenous fruit fly species collected. The number of fruit fly species recovered in each island group was significantly and positively related to trapping intensity. A total of 2527 fruit samples were collected to determine host relationships for fruit flies. Tephritid fruit flies were reared from fruits of 25 of the 67 commercial plant species sampled. However, fruit-survey data indicated that there were only four economic species in the Solomon Islands: (i) B. frauenfeldi; (ii) B. umbrosa; (iii) B. cucurbitae; and (iv) D. solomonensis. Bactrocera frauenfeldi was identified as the only generalist fruit fly species present, and many potential export crops were not hosts for any fruit fly species. These facts emphasise the importance of effective quarantine measures to prevent the accidental introduction of exotic fruit fly pests that might limit or complicate the development of an export industry for fruits and vegetables.