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Conflicts often exist between the use of pesticides for public health protection and organic farming. A prominent example is the use of insecticides for mosquito control in rice fields designated for organic farming. Rice fields, with static water and other conducive conditions, are favorable mosquito habitats. Best management practices are urgently needed to ensure the integrity of organic farming while addressing the need for public health protection. In this study, we evaluated aerial ultra-low-volume (ULV) applications of two classes of mosquito adulticides, pyrethrins and organophosphates, and their deposition and residues on rice plants throughout an active growing season in the Sacramento Valley of California. Frequent applications of pyrethrin synergized with piperonyl butoxide (PBO) and rotating applications of synergized pyrethrins and naled, an organophosphate, were carried out on two large blocks of rice fields. Aerial ULV application of either synergized pyrethrins or naled was able to generate uniform droplets above the fields with high efficacy for mosquito control. Rice leaf samples were collected before and after a subset of applications, and rice grains were sampled at harvest. Frequent applications of synergized pyrethrins resulted in some accumulation of the synergist PBO on rice leaves, but pyrethrins and naled dissipated rapidly from the leaves after each application with no noticeable accumulation over repeated applications. At harvest, no detectable residues of the pesticides or PBO were found in the rice grains. The absence of pesticide residues in the rice grains at harvest suggested that the ULV aerial application led to deposition of only very low levels of residues on rice plants during the growing season. When coupled with the short persistence and/or poor mobility of the insecticides, such applications resulted in negligible pesticide residues in rice grains.

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BACKGROUND: Al Rabta is a rural area in the North-West of Libya that represents an important focus of zoonotic cutaneous leishmaniasis. This study aimed to evaluate the effect of Ultra Low Volume (ULV) applications in controlling sand flies and its impact on leishmaniasis transmission in this area. METHODS: Two neighboring villages were selected: Al Rabta West (RW) as cypermethrin treated village and Al Rabta East (RE) as check one. The ULV was evaluated through 3 spraying cycles during Apr, Jun and Sep 2013. In the two villages, a number of outdoor sites were selected for sampling of sand flies (twice a month) using the CDC light traps. The cases of CL reported in the two villages during the study period were obtained from Al Rabta health center. RESULTS: The two villages were similar where 9 species of sand flies (6 of Phlebotomu and 3 of Sergentomyia) were collected of which S. minuta and P. papatasi were the abundant species. As compared to the pre- ULV spraying, during the post- spraying periods: i) the reduction in abundance of the different species ranged from 20.85 to 77.52% with 46.69% as an overall reduction for all species altogether and, ii) in significantly (P> 0.05) higher mean ratio of males: females for all species altogether (1:2.41). Moreover, ULV spraying resulted in the absence of CL (Leishmania major) cases (Passive Case Detection). CONCLUSION: The efficiency of ULV spraying in reducing sand fly population, CL cases and consequently limits the disease transmission.