Apis mellifera africanized queens tolerant to the neonicotinoid thiamethoxam

Abstract

Interaction between bees and plants ensured success in cross-pollination crops, increasing the vigor of the species, as the production of fruits and seeds. Bees are the main pollinators of angiosperms and several crops. Among the factors related to the disappearance of bees in agricultural areas is the excessive or improper use of insecticides. However, agriculture is extremely dependent on pesticides for pest control and the neonicotinoid thiamethoxam is one of the most used insecticides. The use of these chemicals affects the pollinating bee Apis mellifera. Thus, the aim of the study was to select Africanized A. mellifera queens tolerant to thiamethoxam, producing four generations of bees kept in chronic contamination and perform tests to validate tolerance. Colonies of A. mellifera were subjected to chronic contamination by contact with thiamethoxam at a sublethal concentration of 1.65 mg a.i./L. From the surviving colonies, four generations of new queens were produced, kept in chronic contamination with thiamethoxam. Chronic contamination caused changes in the workers' behavior for 25 days. Validation of selection and tolerance was performed in vitro bioassays to verify mortality and critical electrolyte concentration (CEC). In vitro bioassays showed that there was low mortality after contamination for 24 hours by contact with thiamethoxam at 82.5 mg a.i / L. The analyzes of CEC indicate that there was an increase in gene expression in brain cells, probably as an attempt to detoxify the workers' organism by contamination with thiamethoxam. New tests need to be carried out with colonies tolerant to the neonicotinoid thiamethoxam, but these initial results indicate that these queens have potential to tolerate this neonicotinoid.

Toxicological, morphological and cytochemical effects caused by the agrochemical Fastac Duo in africanized Apis mellifera tolerant to neonicotinoid thiamethoxam

“…These same changes were observed in S. bipunctata bees also contaminated orally with Fastac Duo, highlighting the degenerative effects of this agrochemical (Diniz et al, 2020). Although all concentrations and periods of exposure resulted in some type of change in the middle intestines of F4 bees that were tolerant to thiamethoxam after treatment with Fastac Duo, we can see that this damage becomes more severe at higher concentrations and, mainly, after a longer period of exposure to the agrochemical, as observed by Pizzaia et al (2021). This probably occurs because at low concentrations and/or exposure to the agrochemical for a shorter period, the activation of detoxification mechanisms contributes more efficiently to the metabolization of a large part of these contaminants, and, thus, a smaller amount of the agrochemical entering into contact with the epithelium, allows regenerative cells to divide and differentiate into new digestive cells, replacing those that have been damaged or lost.…”

“…Located at latitude 23º 25' S; 51º 57' W, and 550 meters altitude. Pizzaia et al, (2021) previously selected bees from specific swarms for the agrochemical Thiamethoxam (Fluka). In the study, natural bee colonies were collected in urban and rural areas during the months of February, March and April 2015.…”

“…These F4 workers came from the same nest as the workers analyzed by Pizzaia et al (2021). In this study, the author exposed bees to the agrochemical thiamethoxam and, subsequently, carried out oral exposure of the insects for a period of 24 hours.…”

“…Due to high exposure by agrochemicals, genetic improvement seeks to select individuals that are resistant to these elements as well as present desirable characteristics for humans. The present study aimed to analyze the toxicity and occurrence of crosstolerance effects of worker bees of Africanized A. mellifera F4 selected for tolerance to the neonicotinoid thiamethoxam in relation to Fastac Duo Basf®, which has active ingredients Acetamiprid 100 g/L (neonicotinoid) and Alpha-Cypermethrin 200 g/L (pyrethroid) (Pizzaia et al, 2021).…”