This study assessed the effects of different protein levels on the development of the mandibular gland (MG) in six-day-old worker bees (Apis mellifera) during the dearth period. Twenty colonies were randomly assigned to one of four experimental diets containing 0%, 23%, 25%, or 27% crude protein (CP), with five replicates each. The experimental diets were composed of feed meal and honey sirup. Each colony was provided with 30 g of formulated feed every 3 days over a 36-day period. At the end of the experimental period, ten six-day-old worker bees were collected from each treatment for the morphological analysis of their MGs. The area of the MG was significantly larger in the bees fed protein-enriched feeds than in the controls. The height of the secretory cells in the MG was also significantly greater in all colonies fed protein-enriched feed than in the control group. However, the group that received the feed with 23% CP had significantly taller secretory cells than the other groups. Based on regression analysis, the ideal level of protein in the diet for the development of the MG was 22.2% CP. Thus, the use of protein-enriched feed promotes greater increases in the area and height of secretory MG cells in six-day-old honey bee workers.

In this study, we analyzed Apis mellifera royal jelly proteome alterations induced by supplementation with different concentrations of dietary organic zinc (0, 25, 50, and 75 ppm). Proteins extracted from royal jelly were separated by electrophoresis and isoelectric focusing, and zinc-containing protein spots were identified by tandem mass spectrometry. Organic zinc-containing diets modified total royal jelly protein content and altered the expression of five major royal jelly proteins (MRJP1, MRJP2, MRJP3, MRJP5, and MRJP8). While the diet with the lowest tested zinc content (Zn25) increased total royal jelly protein content and expression of MRJP1, diets with higher zinc contents (Zn50 and Zn75) decreased MRJP expression. Our results demonstrate that important proteins and metabolic processes are modified in royal jelly produced by honey bees supplemented with different concentrations of organic zinc source, affecting nutrition and maintenance of colonies.

In this study the effects of inorganic iron (Fe) supplementation on the morphology of mandibular glands in Apis mellifera were investigated. We randomly assigned 12 beehives to four treatment groups (with three hives in each group), as follows: Fe0 (no Fe supplementation), and Fe25, Fe50, and Fe100 (supplemented with 25, 50, and 100 ppm Fe, respectively). Ferrous sulfate heptahydrate (containing 33.10% Fe), diluted in sugar syrup (1:1 water and sugar), was used as the iron source, and the treatment was done for 3 months. The morphology of glands collected from six-day-old nurse bees from each group was analyzed after sectioning them and visualizing the sections under a microscope. The results were compared by ANOVA followed by the Tukey test (P < 0.05). The area and height of the secretory cells of mandibular glands were observed to be significantly reduced. We conclude that the supplementation of inorganic Fein the feed of bees, at concentrations used in this study negatively modulates their development.

Animal models have been essential for advancing research of fetal alcohol spectrum disorder (FASD) in humans, but few animal species effectively replicate the behavioural and clinical signs of FASD. The honey bee (Apis mellifera) is a previously unexplored research model for FASD that offers the distinct benefit of highly social behaviour. In this study, we chronically exposed honey bee larvae to incremental concentrations of 0, 3, 6, and 10% ethanol in the larval diet using an in vitro rearing protocol and measured developmental time and survival to adult eclosion, as well as body weight and motor activity of newly emerged adult bees. Larvae reared on 6 and 10% dietary ethanol demonstrated significant, dose-responsive delays to pupation and decreased survival and adult body weight. All ethanol-reared adults showed significantly decreased motor activity. These results suggest that honey bees may be a suitable social animal model for future FASD research.

Antibiotics have been widely used in North American beekeeping for the last 70 yr, contributing to the emergence of antimicrobial resistance (AMR). European foulbrood (EFB) is a stress-associated, reportedly self-limiting, bacterial disease of honey bee larvae, caused by Melissococcus plutonius (ex-White 1912) Bailey and Collins 1983 (Lactobacillales: Enterococcaceae). Although oxytetracycline (OTC) is the only antibiotic approved for EFB, its continued use in North America requires evidence to justify it, given concerns about AMR despite no confirmed resistance in M. plutonius. Moreover, if AMR emerges in M. plutonius, the efficacy of alternative antimicrobials for treatment of EFB should be determined, such as tylosin (TYL) and lincomycin (LMC), which are approved in North America for managing American foulbrood. Therefore, in this study, we evaluated the effectiveness of OTC, TYL, and LMC in treating colonies affected by a natural outbreak of EFB during spring 2024 in Saskatchewan, Canada. Forty-eight infected colonies were split into 4 groups of 12: 1 sham-treated and 3 treated with either OTC, TYL, or LMC per label instruction. Colony strength and EFB symptoms were monitored over 1 mo, and M. plutonius bacterial load was quantified via Quantitative polymerase chain reaction (qPCR) pretreatment, 1- and 4-wk posttreatment. We found that all antimicrobial-treated colonies had significant improvement in colony strength relative to pretreatment. Adult bees from antimicrobial-treated groups also had a significant reduction in bacterial load 1-mo posttreatment. However, we also observed a spontaneous recovery in sham-treated colonies. Our findings support the clinical efficacy of OTC and highlight the potential of TYL and LMC as effective alternatives for managing EFB.