Effect of aerial spray adjuvant applying on the efficiency of small unmanned aerial vehicle for wheat aphids control

Small unmanned aerial vehicles(UAVs)have been widely used in different aspects of modern farming management,including pest and disease control in China in recent years.In this study,the spray performance of a small plant protection UAV at low volume spray was evaluated by adjusting the pesticide dosage and adding aerial spraying adjuvants.Droplet deposition,droplet density,coverage,control effect and pesticide residue from field trials were assessed.In addition,the residue and control effect of UAV spray were compared to manual knapsack at high volume spray.The results showed that,the adjuvant applying improved the efficiency of UAV spray.Also,the adjuvant applying reduced the dosage of imidacloprid by 20%.However,there was no significant difference on initial residue between UAV spray and knapsack spray.Thus,plant protection UAV spraying pesticide by adding appropriate adjuvant showed the ability of improving the pesticide effectiveness by improving the control efficiency,reducing the pesticide dosage and residue.

Effect of ENSO-driven precipitation on population irruptions of the Yangtze vole Microtus fortis calamorum in the Dongting Lake region of China

The Yangtze vole(Microtus fortis Buechner,1889)is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China.Its population shows strong oscillations during the wet season due to summer precipitation-induced immigration away from the lake into adjacent rice fields.The effect of El Niño-Southern Oscillation-driven precipitation on population abundance and growth of the vole species is not fully understood.We undertook an analysis of the combined data of 4 time series covering 1981–2006 from 4 different sites and a separate analysis on a single time series(1981–2006)from one site.Our results demonstrate that a dual effect of El Niño-Southern Oscillation-driven precipitation on the population abundance of voles is timedependent:precipitation in the current year has a positive effect,whereas precipitation in the previous year has a negative effect.The dual effect of precipitation on vole population is well explained by the unique interactions among vole population,precipitation water level and the lake beach habitat around Dongting Lake.We found that drier than average weather of the previous year benefited voles because their breeding habitats,lake beaches,were exposed for long stretches of time.Wet weather was found to increase the number of voles inhabiting rice fields because as the water level of the lake rose they were forced from beaches into surrounding rice fields.Summer precipitation in the Dongting Lake region was found to be positively associated with the sea surface temperature(SST)of the eastern tropical Pacific Ocean of the previous year and winter SST and spring SST of the current year.Annual rates of increase in the vole population of the reconstructed time series are negatively associated with the vole abundance and autumn precipitation of the previous year and winter precipitation of the current years.These results suggest that both extrinsic and density-dependent intrinsic factors may affect population dynamics of the Yangtze voles.