DOI: 10.57755/fqqg-p483
title: Increasing heat waves – a potentially problematic factor for honey bee reproduction

description: <p style="text-align:justify"><span style="color:rgb( 0 , 0 , 0 );font-size:14px"><span style="font-family:&#39;tahoma&#39; , &#39;geneva&#39; , sans-serif"><span style="color:rgba( 0 , 0 , 0 , 0.87 );font-family:&#39;arial&#39; , &#39;helvetica&#39; , sans-serif;font-size:14px">The dataset contains data of the research evaluated potential effects of short heat waves on honey bee drone semen quality and the fertility of queens inseminated with their semen. Drones were reared in two series (I and II). During </span></span></span><span style="font-size:14px">two fallowing days, drone brood of the selected age</span><span style="letter-spacing:0px;font-size:14px"> was subjected (experimental group, Ht, 39°C) or not subjected (control group, Nt, 35°C) to a 3-hour thermal shock. After both days of thermal treatments, the brood combs were placed back in the colony of origin until the adults emerged. After emergence, drones from each group (Ht/Nt) were marked and returned to the colonies until sexual maturity was reached. Then, mature males were collected and used for analysis. Semen motility: the original sperm suspension was incubated at least 60 min at 35°C (max.2h). After incubation, 8μL were transferred onto a slide and covered with a coverslip, and cells were counted using phase contrast microscopy. Cells were rated as either motile, presenting any type of active movement, or non-motile. Semen viability: 100 µl of semen suspension&#43;2 µl of propidium iodide (PI) solution (1 mg/ml, P4864, Sigma–Aldrich Chemie, Germany)&#43;1 µl of Hoechst 33342 (H33342) solution (1 mg/ml, B2261, Sigma–Aldrich Chemie, Germany) were used. After 30 min. incubation, 8μl of the sperm suspension were transferred onto a microscope slide and covered with a coverslip. Next, cells showing PI- or H33342-fluorescence were counted using a microscope equipped with appropriate filter cubes. For analysis of the fertility of queens</span><span style="letter-spacing:0px;font-size:14px">, two groups of queens </span><span style="letter-spacing:0px;font-size:14px">were artificially inseminated</span><span style="letter-spacing:0px;font-size:14px"> </span><span style="letter-spacing:0px;font-size:14px">according to standard procedures. </span><span style="letter-spacing:0px;font-size:14px">One received</span><span style="letter-spacing:0px;font-size:14px"> semen from Nt-drones, and the other from drones of the Ht group (n&#61;9 and n&#61;10, respectively). After insemination they were reintroduced into their micro-colonies. </span><span style="letter-spacing:0px;font-size:14px">Egg hatching: the hatching ratio of the eggs produced by queens inseminated with semen from the Ht or Nt group was assessed by noting the number of eggs laid. Then, after 96 h incubation of eggs, larvae present were checked and unhatched eggs were counted. </span><span style="letter-spacing:0px;font-size:14px">Semen amount: honey bee drones used for semen collection were counted, and the semen per drone was calculated by dividing the total volume collected from each treatment group by the number of drones that had been used to collect this volume. </span><span style="letter-spacing:0px;font-size:14px">Sperm in the spermatheca:To determine the number of spermatozoa inside the spermatheca, queens were dissected and the prepared spermathecae were crushed and washed in diluent. Then, two subsamples of the suspension were diluted 1:5, and a Neubauer counting chamber was used to count the number of sperm. </span></p>