Defensive Behavior Of Honeybees Research Articles

The Process and Outcome of the Africanization of Honey Bees in Mexico: Lessons and Future Directions

The Africanization of honey bees (Apis mellifera L.) in the Americas is among the most extensive insect invasions in the world, with large-scale effects on the economy and ecology of a whole continent. Africanized honey bees (AHBs) are a distinctive lineage of A. mellifera, resulting of the extensive admixture between African subspecies (A. m. scutellata and A.m. adansoni) with resident European stocks of honey bees introduced into the Americas. Despite its great importance, to date, the outcome of Africanization of honey bees has not been evaluated in detail. In this article we use the case of Mexico, one of the top beekeeping countries in the world, to assess the effects of Africanization of honey bees and its outcome. There is evidence of African genes in honey bee populations across Mexico, with prevalence in the tropical areas and less so in temperate ones. The Africanization of honey bees resulted in lower honey yields per hive in temperate climates of Mexico, but this has not been assessed in the tropical regions. Mexico’s total honey production and exports at the start of the Africanization process decreased, but today, they have partially rebounded and have remained stable. As in all countries where Africanization has occurred, the defensive behavior of honey bees in Mexico increased but notably, stinging incidents involving humans have been relatively insignificant (0.23 fatalities per million people). Ecologically, AHBs seem to have posed limited impact on the native apifauna and have contributed to pollination of major economic crops, but more studies are needed to evaluate the overall effect. AHBs can be potentially more resistant to parasites and diseases and worth of note is that AHBs in Mexico resulted in a new generation of beekeepers that propelled management and selective breeding. In general, the evidence suggests that the Africanization of honey bees in Mexico has had a less severe impact than originally predicted. We suggest some lines for future directions that may help to better understand the effects, make sustainable use and ameliorate the negative characteristics of AHBs.

Smoke Conditions Affect the Release of the Venom Droplet Accompanying Sting Extension in Honey Bees (Hymenoptera: Apidae).

Honey bees (Apis mellifera) (Hymenoptera: Apidae) are social insects that have evolved a coordinated defensive response to ensure colony survival. Their nests may contain valuable resources such as pollen and nectar that are attractive to a range of insect and mammalian intruders and need protecting. With sufficient provocation, honey bees will mobilize and sting intruders, who are likely to incur additional stings. To inspect and manage their colonies, beekeepers apply smoke to decrease the likelihood of being stung. The use of smoke is a ubiquitous beekeeping practice, but the reasons behind its efficacy remain unknown. In this study, we examined the effects of smoke on honey bee defensive behavior by assessing individual sting extension responses under smoke conditions. We applied a brief voltage to the bee, ranging from a mild to a strong perturbation, and assessed four components of the sting extension reflex using two types of smoke. We found that smoke did not influence the probability of sting extension, but it did affect whether a venom droplet was released with the stinger. The venom droplet was more likely to be released at higher voltage levels, but this effect was significantly reduced under smoke conditions. Based on these results, we propose that the venom droplet coincides with greater agitation in individual bees; and smoke reduces the probability of its release. We speculate that the venom droplet serves to amplify the sting alarm pheromone, and smoke, in its ability to reduce droplet formation, may indicate that less alarm pheromone is released.

Effects of cold anaesthesia on the defensive behaviour of honeybees

Cold anaesthesia is commonly used to temporarily immobilise honeybees and other insects for a wide range of experimental investigations. Although cold-narcosis is widely regarded as non-invasive and non-damaging for neural structures, it has been shown that it can influence the bees’ subsequent behaviour in various ways. While we do have some understanding of the effect of cold treatment on handling stress, memory, locomotion and foraging in bees, it remains to be tested whether their defensive behaviour is affected. We investigated the response of foragers to a leg pinch applied before, during or after cold-anaesthesia. As expected, bees pinched at the hive entrance all responded defensively, while anaesthetised bees showed no response. When the pinch was applied after the bees recovered from cold-narcosis, all individuals were defensive, suggesting that previous cooling had not impaired nociception. We then subjected two groups of bees to a continuous pinch, commencing either before or during cold anaesthesia. Interestingly, most of these bees did not show defensive behaviour once awake, even though the clip was still attached to their leg. Chilling only lead to a diminished defensive response if the nociceptive stimulus was continuous rather than momentary, which suggests that it is not the chilling on its own, but the duration of the pinch in combination with cold narcosis that is critical. Our findings highlight the subtle ways in which treatment of insects during narcosis can affect their subsequent behaviour, and point to new ways in which narcosis can interact with sensory perception and adaptation.

Chemical communication in the honeybee (Apis mellifera L.): a review

An important area of physiology of the honeybee (Apis mellifera) is chemical communication between individuals and castes in the swarm, which maintains its integrity and function. The highly complex social organization of honeybees is mediated through pheromones. Releaser pheromones cause rapid changes in the behaviour of the recipient, while primer pheromones have relatively slow and long-term effects on the physiology and behaviour of the recipient. Queen retinue pheromone (QRP) is a blend of the nine compounds (9-oxo-(E)-2-decenoic acid, (R)- and (S)-9-hydroxy-(E)-2-decenoic acid, methyl p-hydroxybenzoate, 4-hydroxy-3-methyoxyphenylethanol, methyl oleate, coniferyl alcohol, palmityl alcohol, and linolenic acid) and acts as a releaser pheromone by attracting worker bees to the queen. QRP also acts as a primer pheromone by physiologically inhibiting the ovary development of worker bees. An essential component of QRP, 9-oxo-(E)-2-decenoic acid, acts as a long-distance sex pheromone. Defensive behaviour of honeybees is induced and modulated by alarm pheromones. The essential alarm pheromone component is isopentyl acetate (IPA). The unsaturated derivative of IPA, 3-methyl-2-buten-1-yl acetate, was found in colonies of Africanized honeybees. The Nasanov gland of worker bees produces a pheromone (a blend of nerol, geraniol, (E)- and (Z)-citral, nerolic acid, geranic acid and (E,E)-farnesol) that acts as an attracting signal. This pheromone is used for aggregation (during swarming). Adult worker bees also produce a substance, ethyl oleate, that has a priming effect. Ethyl oleate is produced by adult forager bees and acts as a chemical inhibitory factor to delay age at onset of foraging (the presence of older worker bees causes a delayed onset of foraging in younger individuals). Chemical cues on the surface of larvae called a brood pheromone (ethyl and methyl esters of palmitic, linoleic, linolenic, stearic, and oleic acids, E-β-ocimene) are important in the communication between brood and worker bees. This pheromone modulates the feeding behaviour of worker bees, inhibits the activation of the worker ovary, induces worker bees to cap brood cells, increases the activity of the hypopharyngeal glands of nurse bees and modulates the behavioural maturation of worker bees.

Paternal Effects on the Defensive Behavior of Honeybees

The defensive behavior of 52 hybrid honeybee (Apis mellifera L.) colonies from four sets of crosses was studied and compared with that of European and Africanized bee colonies. Colonies containing F(1) hybrid workers were obtained through reciprocal crosses between European and Africanized bees. The total number of stings deposited by workers in a moving leather patch in 1 min was recorded. In each of the four sets of crosses, bees from hybrid colonies of Africanized paternity left more stings in leather patches than bees from hybrid colonies of European paternity. Results strongly suggest paternal effects of African origin increasing the defensive behavior of hybrid colonies. Although some degree of dominance was observed for high-defensive behavior in one of the four sets of crosses involving European paternity, most of the dominance effects reported in the literature appear to be the result of paternal effects. Several hypotheses to explain this phenomenon, as well as the implications of these effects on the fitness and breeding of honeybees are discussed.

Relative reliability of four field assays to test defensive behaviour of honey bees (Apis mellifera)

SUMMARYMany assays for measuring defensive behaviour of honey bee (Apis mellifera) colonies are reported in the literature, but their reliability in most cases has not been assessed. This study was conducted to determine the reliability and convenience of four field assays: (1) a test to score behavioural traits that differ between defensive and gentle bees (ratings assay), (2) two stinging tests in which a leather patch is presented to the bees above the brood chamber (flag assay), or (3) in a confined space (box assay), and (4) a test to measure the numbers of bees recruited at the hive entrance in response to a chemical stimulus (pheromone assay). Six colonies each of three different bee types known to vary in their defensive responses (European, Africanized, and hybrid) were established and tested with the assays. To determine the reliability of the assays, coefficients of variation (CV) among trials for single colonies were calculated. Additionally, colonies were ranked according to their degree of defensiveness and their rankings compared for each and between the different assays. The mean CV for the ratings assay was 17.0%, vs. 71.8, 90.4, and 67.3% for the flag, box, and pheromone assays, respectively. The pursuing behaviour of the experimental bees was the component of the field assays that best separated gentle and defensive colonies. The mean number of pursuing Africanized bees was > 81 times higher than that of pursuing European bees. No significant interactions between day of test and colony were found. Rankings for all colonies were comparable and similar across all assays, except the box assay. All assays were able to separate gentle from defensive bee types, but the ratings assay was the most reliable, economical and practical.

Evaluation of the defensive behavior of two honeybee ecotypes using a laboratory test

Honeybee defensive behavior is a useful selection criterion, especially in areas with Africanized honeybees (Apis mellifera L). In all genetic improvement programs the selected characters must be measured with precision, and because of this we evaluated a metabolic method for testing honeybee defensive behavior in the laboratory for its usefulness in distinguishing between honeybee ecotypes and selecting honeybees based on their level of defensive responses. Ten honeybee colonies were used, five having been produced by feral queens from a subtropical region supposedly colonized by Africanized honeybees and five by queens from a temperate region apparently colonized by European honeybees. We evaluate honeybee defensive behavior using a metabolic test based on oxygen consumption after stimulation with an alarm pheromone, measuring the time to the first response, time to maximum oxygen consumption, duration of activity, oxygen consumption at first response, maximum oxygen consumption and total oxygen consumption, colonies being ranked according to the values obtained for each variable. Significant (p < 0.05) differences were detected between ecotypes for each variable but for all variables the highest rankings were obtained for colonies of subtropical origin, which had faster and more intense responses. All variables were highly associated (p < 0.05). Total oxygen consumption was the best indicator of metabolic activity for defensive behavior because it combined oxygen consumption and the length of the response. This laboratory method may be useful for evaluating the defensive behavior of honey bees in genetic programs designed to select less defensive bees.

Confirmation of QTL effects and evidence of genetic dominance of honeybee defensive behavior: results of colony and individual behavioral assays.

The stinging and guarding components of the defensive behavior of European, Africanized, hybrid, and backcross honeybees (Apis mellifera L.) were compared and analyzed at both colony and individual levels. Hybrid and Africanized backcross colonies stung as many times as Africanized ones. European backcross colonies stung more than European bees but not as many times as Africanized or Africanized backcross colonies. The degree of dominance for the number of times that worker bees stung a leather patch was estimated to be 84.3%, 200.8%, and 145.8% for hybrid, backcross European, and backcross Africanized colonies, respectively. Additionally, both guards at the colony entrance and fast-stinging workers of one European backcross colony had a significantly higher frequency of an Africanized DNA marker allele, located near "sting1," a QTL previously implicated in stinging behavior at the colony level. However, guards and fast-stinging bees from a backcross to the Africanized parental colony did not differ from control bees in their frequency for the Africanized and European markers, as would be expected if large genetic dominance effects for sting1 exist. These results support the hypothesis that genetic dominance influences the defensive behavior of honeybees and confirm the effect of sting1 on the defensiveness of individual worker bees.

A comparison of two assays to test the defensive behaviour of honey bees ((Apis mellifera)

SUMMARYThe reliability of a traditional leather-patch assay to measure the stinging behaviour of honey bees was compared with that of a temper detection apparatus developed to electronically measure and record defensiveness. Colonies were tested with the two different assays during morning and afternoon hours. The traditional assay was more reliable than the automated electronic assay. Afternoon trials were more reliable than morning trials. Significant variation was observed among colonies with both methods, suggesting that these assays may separate highly defensive from gentle colonies. However, variation among trials within colonies may result in misclassifying colonies with intermediate degrees of defensiveness. The need for the development of more reliable assays is stressed.

Honey Bee (Hymenoptera: Apidae) Behavioral Response to Primary Alfalfa (Rosales: Fabaceae) Floral Volatiles

One potential method to increase honey bee, Apis mellifera L., pollination in alfalfa, Medicago sativa L., seed fields is to develop populations that emanate greater quantities of honey bee attractive floral volatiles. Our study was designed to determine the concentrations for five antennally perceived alfalfa floral volatiles- cis -3-hexenyl acetate, linalool, methyl salicylate, ocimene, and 3-octanone-that optimize honey bee behavioral response, and relative attraction of the alfalfa floral volatiles to honey bees. Studies were conducted in a screened flight chamber and used a single colony of Italian honey bees. Linalool was the only Cornpound attractive to honey bees at the optimized concentration. Two other Cornpounds, 3-octanone and methyl salicylate, were repellent. The remaining two Cornpounds, cis -3-hexenyl acetate and ocimene, were neither attractive nor repellent when Compared with the blank sample. Honey bee defensive behavior was observed when bees were exposed to cis -3-hexenyl acetate. Behavioral response to Cornbinations of these floral volatiles was not determined. Present data suggest that plant breeders should simultaneously select for increased relative concentration of linalool and decreased relative concentration of both 3-octanone and methyl salicylate in the floral aroma to enhance honey bee visitation of alfalfa.

Effects of meteorological factors on defensive behaviour of honey bees

The defensive behaviour of honey bee colonies (Apis mellifera L.) was quantitated in the field throughout a three month season by the use of a standardized test in which numbers of stings in a leather target were counted after single colonies were opened and exposed to alarm pheromone. The main results show how the defensive behaviour of honey bees is highly dependent on weather factors. Eliminating genetic variance, the following meteorological variables account for 92.4% of the variation in defensive behaviour: air temperature, solar radiation intensity, wind velocity, relative humidity, and barometric pressure.

Effect of empty comb on defensive behavior of honeybees

Honeybees in colonies with 6.36-m(2) surface area of empty comb responded faster to moving targets and stung the targets more often than bees from colonies with 3.18-m(2) surface area of empty honeycomb. The two groups did not differ significantly in speed of response to alarm pheromone or in number of bees defending the colony. Volatiles from the comb are suggested as primer pheromones for defensive behavior.

Defensive Behavior of Honey Bees Toward Ants

This article has no abstract.