Field comparison of food-based synthetic attractants and traps for African tephritid fruit flies

Four field trials were conducted on coffee orchards in Ruiru, Central Province, Kenya to compare captures of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae) in Multilure Plastic McPhail type traps and Israeli Shabtiely traps baited with female selective food-based attractants. In trial 1, wet Ammonium Acetate (AA) + Trimethylamine (TMA) + Putrescine (PT), AA+TMA and TMA+PT captured significantly more female flies than the other treatments. In the second trial, both the wet and dry AA+TMA+PT and wet AA+TMA were superior to the other treatments in capturing females. Among the different synthetic food attractants, female C. capitata accounted for 67 to 72% of the total captures while 72 to 74% females were captured using NuLure as attractant in both trials. In trials 3 and 4, treatments containing half patch of AA were equally effective as those treatments containing full patch of AA and in trial 4, both treatments with half patch of AA captured significantly more female C. capitata than the NuLure treatment. In trial 3, all treatments in Multilure traps were selective for female C. capitata with percent female caught ranging from 62-67% across the different treatments while in trial 4, all treatments caught between 56 to 70% female flies. In all the trials, the different treatments generally captured lower number of males compared with female catches. Traps baited with the different three component treatments also captured Ceratitis fasciventris. Two other field trials were also conducted in mango orchards at Nguruman, Rift Valley Province and at Muhaka, Coast Province to compare catches of Bactrocera invadens and Ceratitis cosyra in Multilure trap baited with female selective food-based attractants. At Nguruman, treatment AA+TMA+PT captured significantly more females and males of B. invadens compared with the other treatments while at Muhaka, the NuLure treatment caught more males and females of B. invadens although catches were not significantly different from the AA+TMA+PT treatment. For C. cosyra, the NuLure, however, caught significantly more females compared with the other treatments in the two trials. Similarly, the NuLure captured more male C. cosyra than other treatments at Nguruman but at Muhaka no difference was found among treatments. Results demonstrates for the first time the field responses of mango infesting fruit flies such as C. fasciventris, C. cosyra and B. invadens to odours of synthetic food attractants and possibility of using the AA+TMA+PT (Biolure) or AA+TMA with full or reduce doses of AA for monitoring of these fruit flies. All treatments captured non-target insects with dipterans and ants predominating in all the trials. Overall, these potent synthetic food attractants offers a new facet in fruit fly detection and monitoring in Africa and possibly suppression through mass trapping. (author)