Field captures of wild melon fly (Diptera: Tephritidae) with an improved male attractant, raspberry ketone formate.

Field-trapping evaluations of the new male attractant, formic acid 4-(3-oxobutyl) phenyl ester (raspberry ketone formate [RKF]) were conducted in Hawaii with wild populations of melon flies, Bactrocera cucurbitae Coquillett (Diptera: Tephritidae), to determine its activity in the field and to evaluate new plastic matrix formulations. All tests were compared with the standard melon fly attractant 4-(4-acetoxyphenyl) -2-butanone (cuelure [CL]), which is the attractant of choice for detection programs aimed at melon fly and other cuelure-responding Bactrocera fruit flies. Results of these tests over a range of doses on cotton wicks showed that at a 1-g dose raspberry ketone formate was 1.5-2 times more attractive compared with cuelure for up to 11 wk in the field. Lower doses applied on cotton wicks were less active, presumably due to hydrolysis of RKF to raspberry ketone. Raspberry ketone formate embedded in a plastic plug formulation also was field tested, and it was shown to be more attractive to male melon fly compared with cuelure. The use of this new attractant in control and detection programs is discussed.

Field response of Mediterranean fruit fly (Diptera: Tephritidae) to ceralure B1: evaluations of enantiomeric B1 ratios on fly captures.

(-)-Ceralure B1 (ethyl-cis-5-iodo-trans-2-methylcyclohexane-1-carboxylate), a male attractant for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), is significantly more attractive than trimedlure (tert-butyl esters of 4(5)-chloro-2-methylcyclohexane-1-carboxylate), the current standard male attractant used in detection programs. This article reports studies that compare the effectiveness of racemic ceralure B1, mixtures of racemic ceralure B1 and pure (-)-ceralure B1, and trimedlure in field tests conducted in Hawaii, Africa, and Spain with wild Mediterranean fruit flies and in Florida with sterile released Mediterranean fruit fly. Trapping results showed that doses of (-)-ceralure B1 of 87.5 and 75% are just as effective as the 98% (-)-ceralure B1 and the racemic form to be almost as attractive. In nearly all studies, the racemic ceralure B1 was significantly better than trimedlure. These studies suggest that the racemic ceralure B1 could be a viable replacement for trimedlure in areawide detection programs for Mediterranean fruit fly. Synthesizing racemic ceralure B1 instead of a specific stereoselective enantiomer of ceralure B1 would likely be more cost-effective to produce and also might be useful in control as well as detection of this pest.

Efficacy of lufenuron as chemosterilant against Ceratitis capitata in field trials.

Two field trials in citrus orchards in Turis (Valencia, Spain) and Denia (Alicante, Spain) were performed in order to test the sterilant effect of the insect growth regulator lufenuron against wild medfly Ceratitis capitata (Wiedemann) populations. Two application methods for lufenuron were tested: spraying, in spots, an emulsion of lufenuron in a protein bait, and hanging delta traps that contained a proteinaceous gel with lufenuron (solid bait). The sterilant effect was measured as medfly population reduction, reduction of fruit damage in treated fields, and the number of eggs hatching in punctured fruits. In order to assess the efficacy of lufenuron treatments, we recorded results obtained from two different zones in both trial fields: an outer zone, close to untreated fields, and an inner zone, in the centre of lufenuron treated fields. We observed a minimum sterilant effect in the outer zone and a maximum sterilant effect in the inner one. The maximum sterilant effect was in the inner zone, where a reduction of medfly population of 80.4% in the sprayed field and a reduction of 77.6% in the solid bait field was observed. In addition, the greater the distance from the untreated zones of the treated orchard (inwards), the lower the fruit damage and medfly population level. In this inner zone, fruit punctured by medfly developed significantly fewer larvae (38.8%) than punctured fruits from the outer zone (68.6%). In addition, we recorded the decline in the activity of the lufenuron treatments with time. Lufenuron activity persisted in field for at least 2 weeks with spray applications, and for 3 months with bait gels.