Development of heat treatments for two species of Samoan fruit flies (Bactrocera spp., Diptera: Tephritidae)

Abstract

Of the seven species of Bactrocera fruit flies found in Samoa, only two (B. kirki (Froggatt) and B. xanthodes (Broun)) are of economic importance. These species attack a range of fruit, including papaya (Carica papaya), breadfruit (Artocarpus altilis), eggplants (Solanum melongena) and guava (Psidium guajava). The presence of these two species limits export market access for Samoan produce. Eggplants and breadfruit infested with the eggs of B. kirki and B. xanthodes, respectively, were treated using a high-temperature forced-air (HTFA) protocol to heat the fruits to core temperatures of 40oC, 42oC, 44oC or 46oC. No B. xanthodes pupae emerged from fruit treated at 42oC or greater. Pupae of B. kirki were found from fruit treated at temperatures up to 44oC, but failed to survive treatments at 46oC. The HTFA protocol previously approved for treatment of other Pacific fruit flies (fruit core temperature to 47.2oC for 20 min) works without modification for treatment of the two combinations of fruit flies and commodities tested. However, less intense HTFA treatments are worth investigating, if required to enhance fruit quality.