EFFECT OF HERBICIDE ON THE SURVIVAL OF STINGLESS BEES IN THE STATE OF RONDÔNIA

Abstract

As the main pollinating agents, bees are responsible for pollinating most of the native plants in Brazil. The objective of this study was to verify the mortality rate of Melipona seminigra seminigra bees through contact and ingestion with different concentrations of the herbicides Reglone® and Trop®. The bees were collected in the inlet tube and placed in glass jars with a volumetric capacity of 1L, capped with voile fabric. The experimental model used was a Completely Randomized Design, the control in three replications, containing 15 bees per replication.  In the experiment, Candy food was provided (a mixture of 40 mL of honey and 70 g of powdered sugar). Inside each jar, food, filter paper, and a container containing cotton soaked in water were placed. For contact contamination, filter paper soaked in 1000 μl of Aqueous Reglone® solution was used, as well as for Trop®, placed at the bottom of the glass flasks and tested at different concentrations (100% and 50%). Contamination by ingestion was used 1000 μl of aqueous solution of Reglone® and also for Trop®, mixed with the food and tested at different concentrations (100% and 50%) of the concentration of active ingredient diluted according to the package insert for use in soybean crops. The flasks were kept at a temperature of 28ºC and 70% humidity, the observations were carried out in 24h, 48h, and 72h. All the bees survived the control experiment. The results of the contaminations for the two herbicides evaluated did not show differences. The contact experiment showed lower lethality potential when compared to ingestion. The highest lethality occurred at 72 hours of the experiment when compared to the rates observed in 24 hours and 48 hours. The highest concentration (100%) was the one with the highest lethality, but the number of dead individuals was low and was only recorded after 48 hours of the experiment. Considering the contamination by contact, the bees of the species Melipona seminigra seminigra did not have their mortality affected by exposure to the herbicide, but more studies are needed.