Toxicity and sublethal effects of lead (Pb) intake on honey bees (Apis mellifera).

Heavy metal pollution is becoming a worldwide problem affecting pollinators. The massive use of lead (Pb), the most harmful metal for the biosphere, in industries has increased the risk for honey bees. Pb exerts toxicity on living organisms inducing mainly oxidative stress. We assessed the toxicity and sublethal effects of Pb ingestion on protein content, catalase (CAT) activity, fat content and fatty acid (FA) profile of honey bee workers (Apis mellifera L.) under different nutritional conditions during chronic exposure tests. The LD50 was 15.13 ± 6.11 µg Pb2+/bee, similar to other reports. A single oral sublethal dose of 15 µg of Pb2+ affected the survival of bees fed with sugary food for ten days after Pb ingestion while supplementing the diet with bee bread improved Pb tolerance. The highest protein content was found in bees fed with the sugar paste and bee bread diet without Pb. CAT activity tended to decrease in bees of Pb groups independently of diet. Fat content was not affected by the diet type received by bees or Pb ingestion, but the FAs profile varied according to the nutritional quality of the diet. The results highlight that a single sublethal dose of Pb negatively affected the body proteins of bees despite the nutritional condition but did not disturb the FAs profile of workers. Nutrition plays an important role in preventing Pb-induced toxicity in honey bees.

Effect of Abscisic Acid (ABA) Combined with Two Different Beekeeping Nutritional Strategies to Confront Overwintering: Studies on Honey Bees' Population Dynamics and Nosemosis.

In temperate climates, beekeeping operations suffer colony losses and colony depopulation of Apis mellifera during overwintering, which are associated with biotic and abiotic stressors that impact bees' health. In this work, we evaluate the impacts of abscisic acid (ABA) dietary supplementation on honey bee colonies kept in Langstroth hives. The effects of ABA were evaluated in combination with two different beekeeping nutritional strategies to confront overwintering: "honey management" and "syrup management". Specifically, we evaluated strength parameters of honey bee colonies (adult bee and brood population) and the population dynamics of Nosema (prevalence and intensity) associated with both nutritional systems and ABA supplementation during the whole study (late autumn-winter-early spring). The entire experiment was designed and performed with a local group of beekeepers, "Azahares del sudeste", who showed interest in answering problems associated with the management of honey bee colonies during the winter. The results indicated that the ABA supplementation had positive effects on the population dynamics of the A. mellifera colonies during overwintering and on the nosemosis at colony level (prevalence) in both nutritional strategies evaluated.