Assessment of Navel oranges, Clementine tangerines and Rutaceous fruits as hosts of Bactrocera cucurbitae and Bactrocera latifrons (Diptera: Tephritidae)

Authors: McQuate, Grant; Follett, Peter; LIQUIDO, NICANOR - Animal And Plant Health Inspection Service (APHIS); Sylva, Charmaine

Submitted to: International Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2014
Publication Date: 1/29/2015
Citation: Mcquate, G.T., Follett, P.A., Liquido, N.J., Sylva, C.D. 2015. Assessment of Navel oranges, Clementine tangerines and Rutaceous fruits as hosts of Bactrocera cucurbitae and Bactrocera latifrons (Diptera: Tephritidae). International Journal of Insect Science. 7:1-9.

Interpretive Summary: Citrus spp. are now widely cultivated throughout the tropics and subtropics. Throughout their geographic range of distribution, Citrus spp. fruits can be subject to infestation by a range of different tephritid (Diptera: Tephritidae) fruit fly species. Export of Citrus spp. fruits may require risk mitigation measures if infested by locally established tephritid fruit fly species. In order to develop recommendations of regulatory procedures that could be used to permit the export of citrus fruits from Hawaii to the U.S. Mainland, the host status of citrus fruits to the four established tephritid fruit fly species of economic importance in Hawaii is needed. Of the four species, it was already known that Ceratitis capitata and Bactrocera dorsalis are serious pests of citrus in Hawaii. However, assessment of the status of Citrus spp. as hosts of Bactrocera cucurbitae and B.latifrons was needed to develop an overall risk mitigation plan to permit citrus export. Here, we present results of laboratory no-choice infestation trials of B.cucurbitae and B.latifrons on Washington navel oranges (Citrus sinensis (L.) Osbeck) and Clementine tangerines (C.reticulata L. var. Clementine). We, also, present summaries of data available in the literature which report on infestation of fruits from plants in the family Rutaceae (which includes Citrus spp.) by B.cucurbitae or B.latifrons. The lab studies showed that fruit fly species were able to infest both fruit species, but B.cucurbitae infestation rates were significantly higher in both punctured and intact Clementine tangerines, and in punctured navel oranges. Data available in the literature suggested that several citrus fruits, e.g., pummelos, oranges, and tangerines, are natural hosts of B.cucurbitae. Comparable data was not found in regards to B.latifrons. Lab results reported here, in combination with published field results, suggest that mitigation measures are needed for B.cucurbitae, but not for B.latifrons. We provide recommendations for potential regulatory procedures, to satisfy the phytosanitary security mandated by USDA-APHIS, which could be used to mitigate the risk of introduction of fruit fly pests in Hawaii grown citrus if shipped into the continental United States, or shipment of Citrus spp. fruits produced in areas having field populations of B.cucurbitae, in general, and shipped to geographic localities where B.cucurbitae is not present.

Technical Abstract: Export of Citrus spp., widely cultivated throughout the tropics and subtropics, may require risk mitigation measures if grown in areas with established tephritid fruit fly (Diptera: Tephritidae) populations capable of infesting the fruits. Two tephritid fruit fly species whose geographic ranges have expanded in recent years are melon fly, Bactrocera cucurbitae (Cocquillett), and B.latifrons (Hendel). Improved knowledge of host range is needed for both species. Laboratory tests were conducted on the infestability of both intact and punctured Washington navel oranges (Citrus sinensis [L.] Osbeck) and Clementine tangerines (C.reticulata L. var. Clementine). Both fruit fly species were able to infest both fruit species, but B.cucurbitae infestation rates were significantly higher in both punctured and intact Clementine tangerines, and in punctured navel oranges. Lab results reported here, in combination with published field results, suggest that mitigation measures are needed for B.cucurbitae, but not for B.latifrons.