Kairomones for the Management of Anastrepha Spp. Fruit Flies
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Proceedings of 6th International Fruit Fly Symposium 6–10 May 2002, Stellenbosch, South Africa pp. 335–347 Kairomones for the management of Anastrepha spp. fruit flies H.N. Nigg1*, S.E. Simpson2, R.A. Schumann1, E. Exteberria1 & E.B. Jang3 1Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, U.S.A. 2Division Plant Industry, Florida Department Agricultural and Consumer Services, 3027 Lake Alfred Road, Winter Haven, FL 33881, U.S.A. 3Agricultural Research Service, Pacific Basin Agricultural Research Center, United States Department of Agriculture, PO Box 4459, Hilo, Hawaii, U.S.A. Current worldwide methods for fruit fly management include bait/pesticide combinations. These combinations are not necessarily tested for attractiveness and consumption for any particular fruit fly and, consequently, tend to be generic for fruit flies. On the other hand, kairomones tend to be organism specific. Kairomones are defined as attractants, arrestants, excitants (elicit biting, pierc- ing, oviposition) and phagostimulants. Kairomones hold the promise of fly-specific baits, lower pesticide use,fruit fly management in the urban setting,and environmentally acceptable technolo- gies. The best kairomone example in current science is the Cucurbitaceae Diabrotica spp. beetles, used here to describe the ideal approach to kairomone research. Examples of kairomones used for Anastrepha suspensa (Loew), Caribbean fruit fly, and Anastrepha ludens (Loew), Mexican fruit fly, are detailed.Our current kairomone research with sugars for A.suspensa management indicated that Caribbean fruit fly exhibits preferences for specific sugars.A consumption technique is a critical component for development of kairomone-based baits and a technique for the quantification of food consumption of individual flies is presented. INTRODUCTION ted cucumber beetle) and Diabrotica virgifera Kairomones are a subset of plant-produced LeConte (western corn rootworm). Beetles may be allelochemicals. If an allelochemical confers an directly observed coming from downwind to the adaptive advantage to the producer plant, it is bait,anobservationsimilartothatofHowlett(1912, defined as an allomone.If an adaptive advantage is 1915) with oriental fruit fly attracted to methyl to the insect, the chemical is termed a kairomone eugenol. Once they arrive at the bait, the bitter (Metcalf & Metcalf 1992 and references therein). and highly toxic cucurbitacins are powerful Kairomones are defined as: phagostimulants for these beetles. In fact, the Attractants – orient insects toward plants. cucurbitacins are sequestered by the Diabrotica Arrestants–slowdownorstopinsectmovement. spp. and protect these beetles from predators by Excitants – elicit biting, piercing, or oviposition. making them unpalatable (Metcalf & Metcalf 1992). We expand this definition to include attractants This is a nice, complete example of kairomones. from any food or host source and phagostimulants: Fruit flies constitute one of the most destruc- chemicals which increase the ingestion of a food tive and economically important insect groups source. worldwide (Tan 2000 and references therein; Perhaps the best example of a kairomone use is Economopoulos 1987 and references therein; the technology associated with Diabrotica spp. McPheron & Steck 1996 and references therein). In beetles. These beetles are attracted to volatile the American tropics and subtropics, fruit flies compounds found in flowers of their cucurbit of the genus Anastrepha compose one of the hosts. Once they arrive at the host, these beetles largest and most economically important insect are arrested and stimulated to feed by the cucurbi- groups that infest both cultivated and native fruit tacins found in the host fruit (Metcalf & Metcalf crops (Aluja 1994; Stone 1942). The majority of 1992). As a result of the observation that adults of Anastrepha species found on the American conti- most Diabrotica species are found on blossoms, nent occur in Central and South America, with the blossom volatiles were isolated and identified. greatest number of species recorded in Brazil, After laboratory and field bioassays, a three- Costa Rica, Panama and Venezuela (Hernandez- component lure was devised,TIC,1,2,4-trimethoxy- Ortiz & Aluja 1993; Jirón et al. 1988). benzene, indole and trans-cinnamaldehyde. This Anastrepha spp. are invasive species in Florida, is by personal experience an effective lure for and Anastrepha suspensa L. has been a particularly Diabrotica undecimpuncata howardii Barber (spot- costly fly for Florida (McAlister 1936; Newell 1936). *To whom correspondence should be addressed. Anastrepha spp. flies can be a limiting factor for E-mail: [email protected] agricultural commodities. For example, guava 336 Proceedings of the 6th International Fruit Fly Symposium production in Florida is limited by A.suspensa (Peña because the bait lasted longer. A variety of other et al.1999).Swanson & Baranowski (1972) recorded protein hydrolysates (cottonseed,food seasonings, 84 hosts in 23 plant families for A. suspensa in meat extract,etc.) were attractive to A.ludens.Borax Florida. There is general agreement that monitor- was used as a preservative with these extracts ing methods for these flies have not been opti- without affecting the catch (Lopez & Spishakoff mized (Calkins 1993; Heath et al. 1993). 1963). A variety of preservatives were tested with SIB 7,but borax,at greater than 1% concentrations, FRUIT FLY CONTROL USING ATTRACTANTS was superior as a preservative although A. ludens Worldwide,the control technology for fruit flies is catch numbers were lowered (Lopez et al. 1968). driven by control of Mediterranean fruit fly These findings led to pelletized lures with borax (Ceratitis capitata (Wiedemann)). Early control and cotton seed protein hydrolysate or PIB 7 (Lopez methods for the Mediterranean fruit fly and the et al. 1968) and a Torula yeast hydrolysate borax Queensland fruit fly employed a bait in an inverted bait (Lopez et al. 1971).The Torula yeast/borax bait glass trap and bait plus pesticide (Gurney 1925). is the bait currently used in McPhail-type traps for The trap used by Gurney (1925) is now called the A. ludens and A. suspensa. McPhail trap. The bait was a mix of molasses, fruit These early attractant studies might loosely be syrup and water. McPhail (1937) used fermenting termed kairomone studies. Most investigators sugar in glass fly traps for A. ludens Loew (Mexican believe kairomones relate to a host. Under this fruit fly). Males were caught earlier and females presumption, one early study attempted to study laterintheday.Greaternumbersofbothsexeswere the attraction of Bactrocera cucurbitae (Coq.), caught at higher temperatures (McPhail 1937). In melon fly, to the blossoms of Dendrobium super- McPhail’s next study (McPhail 1939), we learn that bum Rchb.,an orchid (McPhail 1943).The melon fly the fermenting sugar was probably brown sugar, was known to concentrate on the blossoms of this possibly piloncillo, a very crude product. Piloncillo particular orchid and, consequently, blossoms and was shown to contain protein (McPhail 1939). blossom extracts were used. Linseed oil soap was Anastrephaludens and A.striata Schiner were moni- added to the water in the traps to break the surface tored for attraction to protein (McPhail 1939). tension so flies would drown readily. Linseed oil Anastrepha ludens did not respond to any of the soap solution turned out to be a strong attractant materials tested. Anastrepha striata responded to for melon fly (McPhail 1943). an alcoholic precipitate of piloncillo solution in sodium hydroxide solution, casein with sodium FRUIT FLY KAIROMONES hydroxide, gelatin with sodium hydroxide, cow For control of fruit flies it is important that they hide with sodium hydroxide, cow’s blood with are attracted and feed heavily on a pesticide/bait sodium hydroxide, and wheat shorts with sodium combination. This is a common control or eradica- hydroxide and borax (McPhail 1939). Increasing tion procedure for C. capitata (Mediterranean fruit concentrations of casein and gelatin were more at- fly)andfortheA.suspensafly-freezoneprogramme tractive (McPhail 1939).Glycine (1.5 g/l) was attrac- in Florida (Simpson 1993). These programmes de- tive (McPhail 1939). Ammonia appeared to be pend on aerial and ground application of pesti- attractive to A. striata (McPhail 1939). Starr & Shaw cide/bait combinations, a concept increasingly (1944) investigated pyridine as an attractant for unpopular with the public.Kairomones, as defined A.ludens.Although pyridine improved trap catches, above, are the heart of these control methods. The it was not used as an A. ludens attractant. These attractant (kairomone) bait mixed with a pesticide early studies were empirical, but they did lead to is applied at a very low rate of the mixture.The bait fruit fly control methods which used a protein attracts the fly which then ostensibly consumes a bait/pesticide combination (Steiner 1952a,b; mortal dose of the bait/pesticide. Steiner&Hinman1952), amethodstillinusetoday. Within the tephritid flies,we have a good example Lopez & Spishakoff (1963) extended the early of the use of a kairomone with methyl eugenol and work with A. ludens. They discovered that an acid oriental fruit fly. The original observation was hydrolysate of corn protein with corn steep water made by Howlett (1912) in a screening experiment (Staley’s Insecticide Bait No. 7; SIB 7) was a consis- with essential oils.Citronella oil