Nutrition induced direct fitness for workers in a primitively eusocial wasp

Eusocial insects are characterised by a reproductive caste differentiation such that egg-laying is restricted to a small number of queens. The majority of the colony members function as non-reproducing workers and gain indirect fitness by rearing the offspring of the reproductives. In primitively eusocial species, some workers can also get direct fitness by sneaking in some eggs in the presence of the queens, replacing the queens and becoming new queens, or initiating new nests. Here we aimed to understand the factors that permit some workers to gain direct fitness and alter the number of workers doing so, using the primitively eusocial wasp Ropalidia marginata. We transplanted 12 naturally occurring colonies into large laboratory cages where there was adequate space for the workers to leave their natal nests and initiate new colonies. We compared six control colonies that we provided with ad libitum food placed near the nest to six test colonies in which we hand-fed the wasps in addition to the ad libitum food. Wasps in test colonies consumed more food, showed more aggression, replaced their queens, and initiated new nests significantly more often than those in control colonies. When considering all 12 colonies, the rates of queen replacement and nest foundation were significantly positively correlated with food consumption rates. The additional nutrition gained by hand-fed wasps appears to help workers in test colonies to develop their ovaries and lay eggs, implying that they are nutritionally castrated in control colonies.

An Economic Approach to Assess the Annual Stock in Beekeeping Farms: The Honey Bee Colony Inventory Tool

For beekeepers, the beehive stock represents a fundamental means of ensuring the continuity of their activity, whether they are professionals or hobbyists. The evaluation of this asset for economic purposes requires knowledge of the rhythms and adaptations of honey bee colonies during the annual seasons. As in any breeding activity, it is necessary to establish the numerical and economic size of the species bred. Beekeepers are interested in this evaluation to monitor beehive stock. For keeping economic accounts of stock, a specific tool has been developed and proposed, here called the “Honey Bee Colony Inventory (HBCI)”. The HBCI can be used as either a final or preventive scheme to assess the numbers of honey bee colonies and nuclei, and the mortality rate, in order to calculate the monetary value. This tool allows the strength of honey bee colony stocks to be monitored, including fluctuations throughout the year, and will prove useful for determining solutions to maintain or increase how long stocks last. Data can be registered in countries such as Italy where the veterinary authorities request data on the stock owned and its variations. Due to widespread Varroa mite infestations, in recent years, beekeepers have experimented with a range of different biotechniques that have included queen caging as well as drone and total brood removal. To verify its effectiveness for gathering honey bee colony data, the HBCI was used in nine beekeeping farms applying different biotechniques to control Varroa mites: chemical treatment, total brood removal, queen caging and old queen replacement by royal cell insertion. The results are compared and discussed. Out of the nine farms, seven showed negative monetary value according to the HBCI, as expected, due to multiple factors such as the unfavorable climate trend of 2017 in the studied area. The positive aspect is that the application of this tool will allow farmers to monitor, manage and maintain their beehive stocks.

Overt Infection with Chronic Bee Paralysis Virus (CBPV) in Two Honey Bee Colonies

Chronic Bee Paralysis Virus (CBPV), a widespread honey bee RNA virus, causes massive worker bee losses, mostly in strong colonies. Two different syndromes, with paralysis, ataxia and flight incapacity on one hand and black hairless individuals with shortened abdomens on the other, can affect a colony simultaneously. This case report presents two Apis mellifera carnica colonies with symptoms of paralysis and hairless black syndrome in 2019. Via RT-PCR, a highly positive result for CBPV was detected in both samples. Further problems, such as a Nosema infection and Varroa infestation, were present in these colonies. Therapy methods were applied to colony 1 comprising queen replacement, shook swarm method and Varroa control, whereas colony 2 was asphyxiated after queen loss and colony weakening. After therapy, colony 1 was wintered without symptoms. Beekeeping and sanitary measures can save a CBPV-infected colony, while further complications result in total colony loss.

Honey Bee Queen Replacement: An Analysis of Changes in the Preferences of Polish Beekeepers through Decades

We conducted a survey on honey bee (Apis mellifera) queen management. Data were collected every year from 1980 to 2018. In total, 2964 questionnaires were collected from all over Poland. We examined the trends by decade timeslot, apiary size, and geographical location. Regardless of the decade and the size of the apiary, on average, above 90% of Polish beekeepers replace old queens with new ones in their colonies. In general, during the observed period, beekeepers replaced almost 52% of their queens, 21% of which were purchased. In the last decade, there was an upward trend in the percentage of beekeepers replacing queens throughout the country. The involvement of purchased queens in colony management is associated with the size of the apiary, and it significantly grows with the number of colonies in the apiary. The percentage of purchased queens went up in all the voivodeships over time. Research and education in this area are needed in order to track the trends and further improve Polish beekeepers’ practices.

Моніторинг втрат колоній медоносних бджіл (Apis mellifera L.) в Україні після зимівлі 2015-2016 рр.

Increasing of honey bee colony losses is considered to be a global threat to the planet's ecosystems, food security and global economy (Neumann & Carreck, 2010; van der Zee et al., 2012; van der Zee et al., 2014; Chauzat et al., 2016). A large-scale study of this phenomenon using the standard protocol is conducted by the international honey bee research association COLOSS. Ukraine has been providing the data since 2015. Honey bee (Apis mellifera L.) colony losses in Ukraine after the winter of 2015-2016 have been analyzed according to the physiographic zones of the country. It has been established that the total loss (the sum of the dead colonies and the colonies lost due to the unsolvable queen problems) after the winter of 2015-2016 was 9.9%, which is 1.5 times lower compared to the winter of 2014-2015 (14.9%). The losses due to colonies death decreased (6.3% after the winter of 2015-2016; 13.4% after the winter of 2014-2015), while the losses due to the unsolvable queen problems increased (3.6% after the winter of 2015-2016; 1.6% after the winter of 2014-2015). The overall loss rate of 12.0% was recorded for the countries participating in the international COLOSS monitoring after the winter of 2015-2016, therefore Ukraine is considered to be the region with the comparatively low risk. Small apiaries had a significantly higher loss rate than medium and large ones. The highest loss rate was noticed in the zone of mixed forests, whereas it was the lowest in the deciduous forest zone. The majority of the respondents (44.4%) from the mixed forest zone, where the loss due to the unsolvable queen problems reached the largest scale, noted that the problems with the queens after this winter were more serious than usual, and wintering of the colonies with new queens was better, than with the old ones (83.3%). 64.4% of respondents conducted monitoring of Varroa infestation level of their colonies, and 82.5% treated the colonies against Varroa. The correlation between the use of some chemical and biotechnical methods against Varroa (lactic acid, amitraz, formic acid, hyperthermia, etc.) and losses due to both colonies death and unsolvable queen problems was revealed. It has been shown that queen replacement before winter contributes to lowering winter mortality (r = -0.18).