Effects of thiamethoxam on brain structure of Bombus terrestris (Hymenoptera: Apidae) workers.

Neonicotinoids are the most widely used pesticide compared to other major insecticide classes known worldwide and have the fastest growing market share. Many studies showed that neonicotinoid pesticides harm honeybee learning and farming activities, negatively affect colony adaptation and reduce pollination abilities. Bumblebees are heavily preferred species all over the world in order to ensure pollination in plant production. In this study, sublethal effects of the neonicotinoid insecticide thiamethoxam on the brain of Bombus terrestris workers were analyzed. Suspensions (1/1000, 1/100, 1/10) of the maximum recommended dose of thiamethoxam were applied to the workers. 48 h after spraying, morphological effects on the brains of workers were studied. According to area measurements of ICC's of Kenyon cells, there was a significant difference between 1/10 dose and all groups. On the other hand, areas of INC's of Kenyon cells showed a significant difference between the control group and all dose groups. Neuropil disorganization in the calyces increased gradually and differed significantly between the groups and was mostly detected at the highest dose (1/10). Apart from optic lobes, pycnotic nuclei were also observed in the middle region of calyces of mushroom bodies in the high dose group. Also, the width of the lamina, medulla and lobula parts of the optic lobes of each group and the areas of the antennal lobes were measured and significant differences were determined between the groups. The results of the study revealed that sublethal doses of thiamethoxam caused some negative impacts on brain morphology of B. terrestris workers.

Sublethal effects of thiamethoxam on immune system cells in the workers of Bombus terrestris (Hymenoptera: Apidae).

Neonicotinoids harm especially bumblebees and other species in agricultural areas all over the world. The toxic effect of thiamethoxam from the neonicotinoid group has been little studied especially on bees. This research aimed to evaluate the effects of thiamethoxam on the immune system cells of Bombus terrestris workers. Different ratios of 1/1000, 1/100 and 1/10 of the recommended maximum application dose of thiamethoxam formed the experimental groups. Ten foraging workers were used for each dose and control groups. Contamination was ensured by spraying the prepared suspensions at different ratios to the bees for 20 s at a pressure of 1 atm. The effects of thiamethoxam on the structures of immune system cells of bumblebees and the amount of these cells were investigated after 48 h of exposure. In general, anomalies such as vacuolization, cell membrane irregularities and cell shape changes were detected in prohemocyte, plasmatocyte, granulocyte, spherulocyte and oenocytoid in each dose group. Hemocyte area measurements in all groups were examined comparatively between groups. In general, granulocyte and plasmatocyte sizes were decreased, while spherulocyte and oenocytoid were increased. It was also determined that there was a significant decrease in the amount of hemocytes in the 1 mm3 hemolymph as dose increased. The results of the study revealed that sublethal doses of thiamethoxam negatively affected hemocytes and their amounts of B. terrestris workers.

Does Nosema ceranae Wipe Out Nosema apis in Turkey?

BACKGROUND: The aim of this study was to determine the prevalence of the Nosema ceranae and Nosema apis among apiaries using both spore counts and multiplex PCR and the replacement of N. apis by N. ceranae in some regions of Turkey. METHODS: A hundred honey bee samples were collected from 99 apiaries in 11 different locations in 2011-2012 in Turkey. Nosema infection degree from collected samples was determined using light microscope and molecular detection of Nosema spp. (N. ceranae and N. apis) was performed using specific primers by multiplex PCR. RESULTS: N. ceranae was only found spores in sampling areas using molecular diagnosis. N. apis was not detected in whole sampling areas using both techniques. There are no Nosema spores detected in Konya one location using two techniques. The nucleotide sequences from amplification products of the Nosema infested honeybee samples were (98%) identical with the sequence of N. ceranae for many countries deposited in the GenBank database in this study. CONCLUSION: The present study illustrated that N. ceranae is the only spores for sampled areas in 2011-2012. The study could also indicate that N. ceranae has been replaced instead of N. apis in Turkey. In addition, the prevalence of N. ceranae and two microsporodia spores effects on honey bee colonies in Turkey were needed to determine with intensive sampling, periodically.