Effect of environmentally relevant dose of pesticides sulfoxaflor, chlorpyrifos and their combinations on africanized honey bees (Apis mellifera)

• Grant number: 23/14022-8
• Support Opportunities: Regular Research Grants
• Start date: July 01, 2024
• End date: June 30, 2026
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: Ricardo de Oliveira Orsi
• Grantee: Ricardo de Oliveira Orsi
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The pesticides use is a determining factor in the survival of bees, which can become contaminated through the ingestion of contaminated resources or direct contact. These forms of contamination are often acute, and even if contaminated food stores occur inside the nest, this can affect physiological and behavioral functions in the long term. However, the product that remains in the beehive for a longer period is beeswax, which, due to its characteristics, can retain active ingredients for an extended time, directly affecting the bees. Therefore, in this study, we propose to evaluate the effect of two commonly used pesticides observed to beeswax, sulfoxaflor, and chlorpyrifos, as well as their combinations, on the larval development of bees and in two phases of adult bee life (nursing and foraging). For this purpose, colonies without the presence of diseases such as acute paralysis virus (APV), deformed wing virus (DWV), Melissococcus pluton, Nosema apis, Nosema ceranae, and Paenibacillus larvae will be selected. The following treatments, with 5 colonies per treatment, will be conducted: Treatment 1: Control - addition of frames containing uncontaminated beeswax. Treatment 2: Frame containing beeswax with the pesticide Sulfoxaflor (16.97 µg/kg). Treatment 3: Frame containing beeswax with the pesticide Chlorpyrifos (24.95 µg/kg). Treatment 4: Frame containing beeswax with a combination of the pesticides Sulfoxaflor (16.97 µg/kg) and Chlorpyrifos (24.95 µg/kg). The beeswax for each treatment will be prepared using molds and embedded in a brood frame. After the comb construction, the queen will be confined to this frame for standardizing egg-laying. Subsequently, the frames will be marked to monitor the larval development phases. Bee larvae will be collected on the fifth day of development for genetic and intestinal microflora analyses. Nineteen days after egg-laying, one frame containing sealed brood cells will be removed from each experimental colony, wrapped in cheesecloth, and kept in an incubator with controlled temperature and humidity (33±1.0°C and 75% humidity) until the emergence of bees. The newly emerged bees will be marked (approximately 200 bees on the dorsal side of the thorax, from each colony, totaling 2,000 bees) with a non-toxic pen and reintroduced into their original colonies. These marked bees will be captured from their respective hives at seven days of age for gene expression analyses, mandibular and hypopharyngeal gland development, and intestinal microflora. Bees in the foraging phase (21 days) will be retrieved from their respective colonies for gene expression and intestinal microbiota assessment. Bee mortality and colony population development will also be evaluated. It is expected that this project will provide important information on how the exposure of Apis mellifera bees to the studied pesticides can affect their development and adult life. (AU)