MORTALITY OF CARIBBEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE) IMMATURES IN COATED FRUITS

The fruit coatings Primafresh 31, Sta-Fresh 360HS, Sta-Fresh 600, and Nature Seal were studied for their ability to kill Caribbean fruit fly, Anastrepha suspensa (Loew), larvae infesting fruits. Mortality in grapefruits ranged from 33% (Primafresh 31) to 100% (Sta-Fresh 600). Methyl cellulose and shellac, known to restrict gaseous exchange, were identified as substances in Nature Seal that reduced survival of Caribbean fruit fly; Nature Seal with 4% methyl cellulose and 17% shellac caused 99.2% mortality in grapefruits. Coating of cold-stored mangoes and carambolas did not increase Caribbean fruit fly mortality. Hot-air treatment of Nature Seal (2% methyl cellulose plus 10% shellac)-coated grapefruits increased Caribbean fruit fly mortality compared with uncoated fruits; when both were exposed to hot air at 48-degrees-C for 60 min, no larvae survived treatment of coated grapefruits, whereas 24% survived treatment of uncoated grapefruits. Carambolas immersed in 46-degrees-C Nature Seal heated slower than those immersed in 46-degrees-C water. Also, more damage occurred to carambolas immersed in Nature Seal than in water at 46-degrees-C. Carbon dioxide and alcohol levels were higher in coated grapefruits, and oxygen levels were lower compared with uncoated grapefruits. Coatings may have potential as possible quarantine treatments of interior pests, if not alone then in combination with other treatments. Coatings might also be considered as part of an integrated pest management system of fruit pests.