In vitro effects of thiamethoxam on larvae of Africanized honey bee Apis mellifera (Hymenoptera: Apidae)

Abstract

Several investigations have revealed the toxic effects that neonicotinoids can have on Apis mellifera, while few studies have evaluated the impact of these insecticides can have on the larval stage of the honeybee. From the lethal concentration (LC50) of thiamethoxam for the larvae of the Africanized honeybee, we evaluated the sublethal effects of this insecticide on morphology of the brain. After determine the LC50 (14.34 ng/μL of diet) of thiamethoxam, larvae were exposed to a sublethal concentration of thiamethoxam equivalent to 1.43 ng/μL by acute and subchronic exposure. Morphological and immunocytochemistry analysis of the brains of the exposed bees, showed condensed cells and early cell death in the optic lobes. Additional dose-related effects were observed on larval development. Our results show that the sublethal concentrations of thiamethoxam tested are toxic to Africanized honeybees larvae and can modulate the development and consequently could affect the maintenance and survival of the colony. These results represent the first assessment of the effects of thiamethoxam in Africanized honeybee larvae and should contribute to studies on honey bee colony decline.

Consumption of the neonicotinoid thiamethoxam during the larval stage affects the survival and development of the stingless bee, Scaptotrigona aff. depilis

“…It corroborates earlier findings about high toxicity of thiamethoxam on honey bee larvae (Tavares et al 2015). Tomé et al (2012) also reported adverse effects of neonicotinoid on stingless bees, showing significant reduction on survival rates of larvae of M. quadrifasciata anthidioides , when exposed to imidacloprid.…”

“…At the highest doses (T2 and T3), our study revealed significant acceleration and delay in larval and pupal development times, respectively. In this context, Tavares et al (2015) showed that sublethal doses of thiamethoxam for honey bees can cause atypical progression of larval development stages. In addition, Wu et al (2011) reported delay in the development of A. mellifera workers exposed to pesticide residues, including neonicotinoids, and suggested that it could have negative consequences in the long term, e.g.…”

“…Studies on the exposure of bees during the larval stage through in vitro rearing tests also focus on this species (Aupinel et al 2007;Hendriksma et al 2011;Wilkins et al 2013;Tavares et al 2015). However, Kremen et al (2002), Del Sarto et al (2005) and Tomé et al (2015) highlighted the importance of native pollinators in the context of insecticide use in agriculture.…”

The ontogenetic saga of a social brain

“…The morphogenetic field of the MBs is thus formed by concentric layers of proliferative cells. Knowledge of the development of the MBs and other honeybee brain regions such as the optic lobes (Marco Antônio and Hartfelder 2016) has broad scientific interest given that, for example, pesticides used in agriculture to control insects target the brains of larval bees (Tomé et al 2012;Tavares et al 2015). The ontogenetic saga of a social brain Using phalloidin and DAPI staining of wholemount brains, Moda et al (2013) showed clear peduncular organisation in worker larvae in the L5F phase.…”

Honeybee health in South America

“…In Brazil, de Almeida Rossi et al (2013) reported that sublethal doses of imidacloprid induced negative effects on malpighian tubules of Africanized bees. Moreover, Brazilian researchers reported that thiamethoxam, also a neonicotinoid, was toxic for bee larva in lower doses which alter bee development (Tavares et al 2015).…”