Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 1996
Publication Date: N/A
Interpretive Summary: Fruit flies are among the world's most important agricultural pests. As such, they have been targeted for suppression or eradication by government agencies almost everywhere that fruit is grown on a commercial scale. Traps that attract the flies are used universally to detect the presence of fly populations and determine if population sizes warrant corrective actions. During the last 10 years, agricultural agencies have greatly increased funding of research to develop more powerful lures for the traps because of skyrocketing costs of eradicating fly populations if they are not discovered soon enough and left to grow too long. Much of the recent work has pointed to a class of chemicals that is notoriously difficult to analyze chemically as the best hope for new attractants. In this report, we developed a method that can be used to analyze these difficult chemicals. The method was used to determine rates of emission of chemicals from a lure that is known to be highly attractive to the Mexican fruit fly, a potentially important pest of citrus and other fruits in tropical and subtropical fruit growing regions throughout the world. The information gained from such analyses can be used to develop more potent lures for the Mexican fruit fly. The method should also aid development of better lures for other species of fruit flies by allowing faster technology transfer from laboratory results showing that certain chemicals are attractive to lures that can be put into traps. Better lures result in earlier detection of pest populations and less expensive control programs.
Technical Abstract: A method was developed to analyze ammonia, methylamine and putrescine emanating from a lure for the Mexican fruit fly (Anastrepha ludens). Lures were put into closed glass vessels containing 2% phosphoric acid to trap the basic volatiles. The phosphoric acid solution was then made basic and solid-phase microextraction (SPME) was used to sample the dissolved chemicals and load them without solvent onto a thick-film GC column. Calculated emissions from the lures at 35 deg C were 234-373 ug/h of ammonia, 25.8-61.3 ug/h of methylamine, and 15.0-19.4 ng/h of putrescine during the first 48 h after opening the tubes. 1- Pyrroline, a chemical not present in the lures by design, emanated at about 20 ng/h. Flame thermionic detection aided analysis of putrescine and 1-Pyrroline. Experiments with standards indicated that determination errors of + 50% could be expected due to inherent problems associated with the analytical methods.