Fruit Flies and Mango Seed Weevil in Relation to Quarantine

FRUIT FLIES AND MANGO SEED WEEVIL IN RELATION TO QUARANTINE Wallace C. Mitchell Emeritus Professor, Department of Entomology College of Tropical Agriculture and Human Resources University of Hawaii at Manoa I am surprised so many came to this meeting, I shall briefly discuss the mango insect pests in because the commercial value of mangos is not Hawaii. Special emphasis will be given to tephritid very large. In fact, I have always considered it to fruit flies and the mango weevil, Cryptorhynchus be nil as far as Hawaii is concerned. Looking at mangiferae (Fabricius). We have 13 insect and the group here, I will bet that the total value of mite pests that attack mangos in Hawaii. Some of your efforts, salaries, etc. for these three days these and their commodity treatments will be added together is greater than the annual value of discussed by other speakers. The mango shoot commercial production of mangos in Hawaii. In caterpillar is a noctuid moth that is a minor the Hawaii Department of Agriculture'S statistics problem. There are a number of scales for 1991, mangos were included under the tropical (Homoptera). The mango soft scale, Protopul specialty fruit sales, with a farm value of $46,600. vinaria mangiferae (Green), the green scale, The farm price was 73 cents a pound. There were Coccus viridus (Green), the red wax scale, 40 farms totaling 65 acres with 2,750 trees of which Ceroplastes rubens Maskell, and the Cockerell 810 were bearing. So, you see, we have a long way scale (white scale), Pseudaulacaspis cockererelli to go. (Cooley), all attack growing mangos. The green There are a number of factors that have scale has a quarantine regulation against it limited the commercial expansion of this crop. because it is not present on the mainland. We also Other speakers in the conference will cover have the red banded thrips (Thysanoptera), cultivars, propagation, physiology, commercial Selenothrips rubrocinctus (Giard), attacking the production, economics, trade, marketing, and so foliage. Two species of mites (Acari), the mango forth. In the time allotted to me I will attempt to bud mite, Eriophyes mangiferae (Sayed), and the provide information on one of the limiting factors mango spider mite, Oligonychus mangiferus responsible for plant quarantine regulations. (Rahman & Sapra), occasionally cause problems Hawaii's mangos are hosts for plant and are difficult to control for the lack of a pathogens, insects, mites, and other pests that are properly registered pesticide. not present on the U.S. mainland. Tom Davenport In the Diptera (true flies) we have a mango mentioned that the mango seed weevil is not blossom midge, Dasineura mangiferae Felt, that is present in the Americas; neither are fruit flies, quite prevalent at this time of year in the blooms except every once in while they get into California you see on the trees. In addition to the blossom and Florida and create havoc. midge, there are two tephritid species of fruit flies Plant quarantine regulations deter the that attack ripe mangos. accidental introduction and dissemination of mango pests into Hawaii. Tom Davenport also Fruit Flies mentioned a number of insect pests from various There are four species of tephritid fruit flies parts of the world that were discussed at an (Diptera, family Tephritidae) in Hawaii. Two international conference a few months ago. We species, the Oriental fruit fly, Bactrocera dorsalis have enough difficult problems and do not need (Hendel), and the Mediterranean fruit fly, Ceratitis any more. The plant quarantine regulations deter capitata (Wiedemann), are pests of mango. The the possibility of these pests entering into Hawaii egg, larva, and adult stages of development of and also the dissemination of mango pests to the these fruit flies are greatly influenced by air mainland. I wholeheartedly support Hawaii's state temperature. Pupal development is greatly influ quarantine regulations and the U.S. Department enced by soil temperature. of Agriculture's federal regulations. The Eggs. Eggs are deposited by the female quarantine regulations should be maintained and beneath the skin of the host fruit and develop followed to prevent the movement of these serious within two to three days. pests to the mainland. Larvae. The eggs hatch and the larvae begin to - 5 - tunnel out the fruit. Larvae are negatively populations need to survive is effective, especially phototrophic and tend to put their heads down in eradication programs. Fruit of these wild hosts into the pulp of the fruit and their small spiracles provide a source for survival when the cultivated near the surface to obtain air and survive. Larva hosts are absent or not fruiting. development takes place in about six to ten days Paper bagging of fruit. Bagging of fruit to depending on the temperature. The larvae molt prevent fruit fly ovipostion has been used by many twice. There are three stages in the development. backyard growers and small farmers in Hawaii. From the egg comes the first instar, then the larva The bag is removed 24-48 hours prior to harvest to molts twice, producing the second and the third allow the natural color of the fruit to develop. I do instars. The third instar develops into the pupa. not recommend it for commercial farmers. Small Pupae. The pupa is a stage in which the larva holes must be made in the paper bag in order for changes from a maggot to an adult insect. Pupae transpiration to take place. Plastic bags are not are found in the soil, usually in the top 2 in. They used. can be found in the top 2-6 in. of the soil. It takes Chemical control. Bait sprays are the most nine to 10 days for the pupal development to take common method of fruit fly control. The bait spray place and adults to emerge. is mixture of a protein hydrolysate and the Adults. Adults of newly emerged flies must insecticide malathion applied to the mango foliage find a source of protein and carbohydrate for as a spray. Large droplet size is more important maturation of the ovaries and the testes. This than a fine spray or complete coverage. Male and preovipositional period may take one to two weeks female fruit flies are attracted to the protein, feed for wild flies. The length of time for the on it, and the toxicant kills them before they are preovipositional period depends upon the species sexually mature or deposit their full complement of fruit fly and the ambient temperature. of eggs. Under natural conditions the flies will obtain We are gradually losing many of the this source of protein and carbohydrate from plant insecticides, miticides, and fungicides, used as exudations, animal excrement, fruit fly regurgitant, tools in the past. What is going to happen when we honey dew, bacteria, yeasts, and fruit juices. Adult lose the presently registered compounds? We have fruit flies in nature may live from two to six weeks nothing in the developmental stage for fruit fly or longer, again depending upon the temperature, control in the field. You can recall that when humidity, and activity. Rachael Carson published her book, "Silent We have a number of things that we can do to Spring," we lost DDT, and others have followed. reduce popUlations of fruit flies in mango Postharvest treatments. Commodity treat orchards. ments are needed in order to be able to transport Preharvest control. Biological control is the use mangos and other host fruits from areas infested of fruit fly parasites, predators, and pathogens. A with fruit flies through quarantine barriers into number of these beneficial organisms have been areas that are free of the pests. The commodity purposely introduced into Hawaii to reduce the treatments have been developed by researchers in populations of fruit flies. the U.S. Department of Agriculture Fruit Fly Sanitation. Removing unusable fruit in the Laboratory. Dr. Armstrong is going to speak after orchard is important. All infested fruit should be me and will discuss some of the later destroyed. The fruit can be buried, cooked, and developments in commodity treatments. Some of fed to poultry or swine. Cultivating the soil the commodity treatments mentioned here are beneath the trees to expose larva and pupa to ants, effective for fruit fly control but have not been poultry, lizards, and song birds is also a worthwhile approved for fruit flies in mangos. idea. Fumigants. These are chemicals which produce Fruit picking or stripping. Picking all the fruit a gas or vapor that is toxic to insects, bacteria, or from a tree has been used primarily in eradication rodents. Methyl bromide (ME) and ethylene programs. This was used a great deal in California. dibromide (EDB) have been used in the past. As They picked all the fruit from the tree to remove many of you know, the use of EDB was canceled any ovipositional sites that would be available for in 1984. The use of MB is presently on the ropes the continued development of .he fruit fly and we will likely lose it as an effective fumigant. population. Research on new fumigants is scarce. Wild host destruction. Elimination of noneco Lethal temperatures. The use of heat and cold nomic or noncultivated hosts that fruit fly to kill insects is an old remedy. It is based upon - 6 - the thermal tolerance of the insect and the Irradiation is used to sterilize the fruit flies commodity. Mortality is a function of temperature released in eradication programs. Dr. Moy is going and time. We have a number of treatments that to speak on irradiation later this morning and he are concerned with lethal temperatures. will give you the latest information. In my opinion, Vapor-heat treatment.

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