Optimized composite microspheres containing insecticide and attractant for control of Rhagoletis batava obseuriosa Kol. (Diptera: Tephritidae)

Abstract Ammonium carbonate is used as an attractant for many fruit flies since it releases ammonia in humid atmospheres, which is attractive to them. For integrated pest management in the field, and as part of an ‘attract‐and‐kill’ strategy, it is necessary to prolong the release period of ammonia from the ammonium carbonate and combine it with an insecticide. To achieve this, we combined ammonium carbonate with spinosad in slow‐release microspheres. The microspheres were prepared using gelatin and polylactic acid as capsule materials. An orthogonal test was used to optimize the parameters needed for production. Particles produced using the optimal parameters were uniform in size (55.5 μm diameter), the spinosad encapsulation rate was 98.1%, the encapsulation concentration of ammonium carbonate was 2.6 mg/g, and they had a longer release period than when the components were not encapsulated. In a field experiment, rates of damage to sea buckthorn by Rhagoletis batava obseuriosa Kol. (Diptera, Tephritidae) (RBO) were 16.05 ± 1.15% in the treatment subplots compared with 81.75 ± 1.50% in the control subplot; the mean number of RBO trapped per trap per day was 21.2 ± 6.3 (SE) in the treatment subplots and 130.8 ± 27.5 (SE) in the control subplot, respectively. Therefore, using composite microspheres has potential as an effective method for control of RBO.