Trapping of Aethina tumida Murray (Coleoptera: Nitidulidae) from Apis mellifera L. (Hymenoptera: Apidae) colonies with an in-hive baited trap

The effectiveness of two lures for trapping the small hive beetle, Aethina tumida, by means of in-hive traps was tested by field trials in apiaries located in Florida, Delaware, and Pennsylvania during 2003-2005. Both lures included a mixture (pollen dough) consisting of bee pollen and commercial pollen substitute formulated with or without glycerol and honey. Before it was used in the traps, the dough was conditioned either by the feeding of adult small hive beetles or by inoculation with the yeast Kodamaea ohmeri (NRRL Y-30722). Traps baited with conditioned dough captured significantly more beetles than unbaited traps, and traps positioned under the bottom board of a hive captured significantly more beetles than traps located at the top of a hive. In fact, baited in-hive bottom board traps nearly eliminated the beetles from colonies at a pollination site in Florida. However, when these honey bee colonies were moved to an apiary, trap catch increased markedly over time, indicating a resurgence of the beetle population produced by immigration of beetles from nearby hives or emerging from the soil. In tests at three Florida apiaries during 2006, yeast-inoculated dough baited bottom board traps captured significantly more beetles than unbaited traps, showing the effectiveness of yeast-inoculated dough as a lure and its potential as a tool in managing the small hive beetle.     

Evaluation of an upper hive entrance for control of Aethina tumida (Coleoptera: Nitidulidae) in colonies of honey bees (Hymenoptera: Apidae)

This investigation was conducted to test whether an upper hive entrance may result in reduced Aethina tumida Murray (Coleoptera: Nitidulidae) population buildup in newly established honey bee, Apis mellifera L., colonies over an 8-mo period. The upper hive entrance consisted of a 3.5-cm-i.d. polyvinyl chloride pipe positioned 20 cm above the hive bottom. Sixteen bee colonies were established using five-frame nucleus hives with a 0.9-kg (2-1b) package of bees with queen. Eight colonies were placed in each apiary, and each colony received one of two treatments: 1) conventional hive lower entrance and 2) modified upper hive entrance. This investigation was conducted in two distant apiaries where A. tumida had been a major problem to local beekeepers for a minimum of 2 yr. Results showed no overall differences between treatment effects on A. tumida counts over the test period, but there was a reduction in bee brood measured in colonies having an upper hive entrance. We conclude that the upper pipe entrance is not recommended in areas where A. tumida are well established and have become problematic. The expected reduction of brood in colonies as a result of using an upper hive entrance will lead to less productive units for honey production and pollination activities. Other control measures will be necessary to maintain tolerable levels of A. tumida in honey bee colonies at high pest densities.     

Olfactory responses of Aethina tumida murray (Coleoptera: Nitidulidae) to some major volatile compounds from hive materials and workers of Apis mellifera

The small hive beetle (Aethina tumida Murray) is an invasive pest affecting honey bee colonies. The beetles are known to be attracted to volatiles from hive products and honey bees like Apis mellifera L. Previously we reported the presence of five major compounds from the volatile extracts of hive materials; ethyl linolenate and ethyl palmitate from pollen dough, oleamide and tetracosane in fermenting honey, and oleamide and 5-methyl-2-phenyl-1H-indole from A. mellifera worker bees. This study tested the attractiveness of the aforementioned five volatile organic compounds to small hive beetles (SHB) by Y-tube olfactometric bioassay. Ethyl linolenate was highly attractive to both male and female adults of SHB. Ethyl palmitate was attractive to SHB only at higher concentration (0.01–01 mg/ml). Interestingly, tetracosane, 5-methyl-2-phenyl-1H-indole and oleamide were repellent for SHB of both sexes, but ethyl linolenate and ethyl palmitate as components of honey bee brood pheromone attracted SHB. The results highlight that SHB differentially utilizes volatile chemicals from hive materials and honey bees as cues to locate honey bee hives.     

Intraspecific competition effects on Aethina tumida (Coleoptera: Nitidulidae)

Two kinds of experiments were conducted with Aethina tumida Murray larvae over four temperatures: "consumption" experiments, in which larvae and diet were weighed to determine food consumption rates under conditions of unlimited food and few conspecifics; and "competition" experiments, in which varying numbers of larvae were presented with the same amount of honey and pollen diet, and larval weight at final instar was used to determine competition effects. In consumption experiments temperature, diet and their interaction all had significant effects on the ratio of larval weight to the weight of food consumed, which was higher at 24 degrees C than at any other temperature. In competition experiments, three relationships were examined and modeled: that between the number of larvae per experimental unit and the average weight of those larvae; that between average larval and adult weights; and that between average adult weight and survivorship to adult (emergence rate). An exponential decay function was fit to the relationship between number of larvae per experimental unit and their average weight. Average adult weight was linearly correlated with larval weight. Likewise, emergence rates for adults < 11.6 mg in weight were linearly correlated with adult weights, but no significant relationship was observed for heavier adults. Using these relationships, the reproductive potential for A. tumida were estimated for a frame of honey and pollen. Information on resource acquisition by A. tumida will be useful in evaluating the impact of different factors on beetle population dynamics, such as bee hygienic behavior or control strategies used by the beekeeper.     

An ecological digest of the small hive beetle (Aethina tumida), a symbiont in honey bee colonies (Apis mellifera)

The small hive beetle (Aethina tumida Murray) is an endemic scavenger in colonies of western honey bee subspecies (Apis mellifera L.) inhabiting sub-Saharan Africa where it only occasionally damages host colonies. Such damage is usually restricted to weakened/diseased colonies or is associated with after absconding events (all bees, including the queen, leave the hive) due to behavioral resistance mechanisms of its host. In sharp contrast, the beetle has proven deleterious to honey bee colonies in introduced ranges of the United States and Australia. With this review we synthesize the existing data in a manner that allows us to discuss the beetle’s natural history from an ecological perspective. A thorough exploration of beetle ecology allows us to 1) illuminate the unique symbiotic relationship it and its host share and understand how this relationship is fostered, 2) place this relationship in context with those of other arthropods inhabiting social insect colonies, 3) understand its natural reliance on honey bee colonies, 4) predict its spread outside its native range, and 5) predict its effects on non-African honey bees and non-target species. Here we present an amalgamation of information that will contribute to a more thorough and appropriate understanding of not only small hive beetles as symbionts, but of social insect symbionts in general. Received 4 April 2005; revised 15 October 2005; accepted 18 October 2005.     

Susceptibility of small honey bee colonies to invasion by the small hive beetle,Aethina tumida (Coleoptera,Nitidulidae)

Weak and small honey bee colonies are supposed to be more susceptible to infestations by the small hive beetle [Aethina tumida, small hive beetle (SHB)]. To test this, we established 24 nucleus colonies [12 with and 12 without previous SHB removal (= screening)]. Four weeks later, we compared beetle numbers and the occurrence of SHB reproduction to the corresponding full‐sized colonies. Full‐sized colonies with no screening were infested with significantly more SHBs than all other groups (mean ± standard deviation = 46.9 ± 26.7). Regardless of this, none of the full‐sized colonies showed damage or evidence of SHB reproduction. In contrast, five nucleus colonies collapsed and SHB larvae were found in an additional seven colonies. Our study demonstrates that SHB infestation levels which are harmless to full‐sized colonies may have a negative impact on small nucleus colonies.     

Monitoring Aethina tumida (Coleoptera: Nitidulidae) with baited bottom board traps: occurrence and seasonal abundance in honey bee colonies in Kenya

The population dynamics of the honey bee pest Aethina tumida Murray (small hive beetle) have been studied in the United States with flight and Langstroth hive bottom board traps baited with pollen dough inoculated with a yeast Kodamaea ohmeri associated with the beetle. However, little is known about the population dynamics of the beetle in its native host range. Similarly baited Langstroth hive bottom board traps were used to monitor the occurrence and seasonal abundance of the beetle in honey bee colonies at two beekeeping locations in Kenya. Trap captures indicated that the beetle was present in honey bee colonies in low numbers all year round, but it was most abundant during the rainy season, with over 80% trapped during this period. The survival of larvae was tested in field releases under dry and wet soil conditions, and predators of larvae were identified. The actvity and survival of the beetle were strongly influenced by a combination of abiotic and biotic factors. Larval survival was higher during wet (28%) than dry (1.1%) conditions, with pupation occurring mostly at 0-15 cm and 11-20 cm, respectively, beneath the surface soil during these periods. The ant Pheidole megacephala was identified as a key predator of larvae at this site, and more active during the dry than wet seasons. These observations imply that intensive trapping during the rainy season could reduce the population of beetles infesting hives in subsequent seasons especially in places where the beetle is a serious pest.     

Susceptibility of adult Aethina tumida (Coleoptera: Nitidulidae) to entomopathogenic fungi

Aethina tumida Murray (Coleoptera: Nitidulidae) is an invasive parasite species in populations of honey bees, Apis mellifera L. Aiming toward substitution of chemical control, we here identified a naturally occurring fungal pathogen of adult A. tumida from its endemic range in South Africa [Metarhizium anisopliae (Metschnikoff) Sorokin variety anisopliae strain FI-203]. The susceptibility of adult beetles (n = 400) to this fungus and to three other generalist entomopathogenic fungal isolates [Metarhizium anisopliae, Beauveria bassiana (Balsamo) Vuillemin, and Hirsutella illustris Minter & Brady] was assessed using spore suspension bioassays. The data revealed significantly increased mortality in the B. bassiana (74.00 +/- 8.94%) and M. anisopliae variety anisopliae (28.00 +/- 16.43%) tests but not in the H. illustris (2.00 +/- 4.47%) and M. anisopliae (12.00 +/- 8.37%) groups. The results indicate a potential for entomopathogenic fungi as an alternative control of A. tumida.     

Estimating reproductive success of Aethina tumida (Coleoptera: Nitidulidae) in honey bee colonies by trapping emigrating larvae

The small hive beetle (Aethina tumida Murray) is a scavenger and facultative predator in honey bee colonies, where it feeds on pollen, honey, and bee brood. Although a minor problem in its native Africa, it is an invasive pest of honey bees in the United States and Australia. Adult beetles enter bee hives to oviposit and feed. Larval development occurs within the hive, but mature larvae leave the hive to pupate in soil. The numbers leaving, which can be estimated by trapping, measure the reproductive success of adult beetles in the hive over any given period of time. We describe a trap designed to intercept mature larvae as they reach the end of the bottom board on their way to the ground. Trap efficiency was estimated by releasing groups of 100 larvae into empty brood boxes and counting the numbers trapped. Some larvae escaped, but mean efficiency ranged from 87.2 to 94.2%. We envision the trap as a research tool for study of beetle population dynamics, and we used it to track numbers of larvae leaving active hives for pupation in the soil. The traps detected large increases and then decreases in numbers of larvae leaving colonies that weakened and died. They also detected small numbers of larvae leaving strong European and African colonies, even when no larvae were observed in the hives.     

蜂巢奇露尾甲幼虫龄期的划分

为了明确蜂巢奇露尾甲Aethina tumida Murray幼虫的龄期和最佳分龄指标,本研究分别对不同发育阶段幼虫的头壳宽进行测量,根据各指标的频次分布结果初步确定龄期,并运用Crosby生长法则和线性回归方法进行验证分析。结果表明：蜂巢奇露尾甲幼虫可分为4龄,1~4龄头壳宽度平均值分别为0.1842 mm、0.2942 mm、0.4613 mm、0.7280 mm;此外,本文还对蜂巢奇露尾甲幼虫的形态特征进行描述。本文为研究蜂巢奇露尾甲的发生规律、生物学特性及制定防治措施等提供参考。     

蜂巢小甲虫OBP4的克隆及表达谱分析

本研究克隆获得了一个新的蜂巢小甲虫Aethina tumida的气味结合蛋白(odorant-binding proteins, OBPs)基因,并对其序列特征、表达情况、系统发育进行研究。该蜂巢小甲虫气味结合蛋白基因命名为AtumOBP4(GenBank登录号：ON813082),开放阅读框全长465 bp,编码154个氨基酸,预测其分子量大小为17.4 kDa,理论等电点为5.07。N末端有23个氨基酸组成的信号肽,具有6个保守的半胱氨酸位点,属于Classical OBP亚家族,系统进化树分析表明其与黄粉虫Tenebrio molitor OBP8亲缘关系最近。qRT-PCR结果显示AtumOBP4在雄性成虫中表达量显著高于雌性成虫且在头部(包含触角)特异性高表达,羽化后第7天达到最高值。推测AtumOBP4在蜂巢小甲虫嗅觉识别一般气味或性信息素过程中发挥重要作用。此外,成功构建了pET32a(+)/AtumOBP4重组表达载体并通过原核表达获得了重组蛋白,为后期深入研究AtumOBP4蛋白功能奠定了基础,也为进一步研究OBP家族基因在蜂巢小甲虫寻找寄主蜂箱的嗅觉机制中提供了丰富...     

Longevity and reproductive success of Aethina tumida (Coleoptera: Nitidulidae) fed different natural diets

The longevity and reproductive success of newly emerged, unfed adult Aethina tumida Murray assigned different diets (control = unfed; honey-pollen; honey; pollen; empty brood comb; bee brood; fresh Kei apples; and rotten Kei apples) were determined. Longevity in honey-fed small hive beetle adults (average maximum: 167 d) was significantly higher than on other diets. Small hive beetles fed empty brood comb lived significantly longer (average maximum: 49.8 d) than unfed beetles (average maximum: 9.6 d). Small hive beetle offspring were produced on honey-pollen, pollen, bee brood, fresh Kei apples, and rotten Kei apples but not on honey alone, empty brood comb, or in control treatments. The highest reproductive success occurred in pollen fed adults (1773.8 +/- 294.4 larvae per three mating pairs of adults). The data also show that A. tumida can reproduce on fruits alone, indicating that they are facultative parasites. The pupation success and sex ratio of small hive beetle offspring were also analyzed. Larvae fed pollen, honey-pollen, or brood had significantly higher pupation success rates of 0.64, 0.73, and 0.65 respectively than on the other diets. Sex ratios of emerging adults fed diets of pollen or brood as larvae were significantly skewed toward females. Because small hive beetle longevity and overall reproductive success was highest on foodstuffs located in honey bee colonies, A. tumida are efficient at causing large-scale damage to colonies of honey bees resulting in economic injury for the beekeeper. Practical considerations for the control of A. tumida are briefly discussed.     

Evolution of starvation resistance in an invasive insect species,Aethina tumida (Coleoptera: Nitidulidae)

Starvation resistance, or the ability to survive periods without food, can shed light on selection pressure imposed by food scarcity, including chances to invade new regions as a result of human transport. Surprisingly, little information is known about starvation resistance for invasive insect species. Given that native and invasive populations differ in starvation resistance, this would suggest different selection scenarios and adaptive shifts fostering invasion success. Here, we show striking differences in starvation resistance of adult small hive beetles Aethina tumida (SHB) between native and invasive populations. In the laboratory, starvation resistance of freshly emerged laboratory‐reared and field‐collected adult females and males was evaluated in the beetle's native African range and in their invasive North American range. SHB in their native African range survived longer than SHB in their invasive North American range. Across ranges, females survived longer than males. Field‐collected SHB survived in Africa longer than freshly emerged ones, but not in the invasive range. This suggests no selection for starvation resistance in the invasive range, possibly due to differences between African and European‐derived honey bee hosts facilitating a trade‐off scenario between reproduction and starvation resistance. The ability of adult females to survive up to two months without food appears to be one factor contributing to the invasion success of this species. Assuming food availability is usually high in the invasive ranges, and trade‐offs between starvation resistance and fecundity/reproduction are common, it seems as if selection for starvation resistance during transport could set up potential trade‐offs that enhance reproduction after invasion. It would be interesting to see if this is a possible general pattern for invasive insect species.     

Effect of height and color on the efficiency of pole traps for Aethina tumida (Coleoptera: Nitidulidae)

Olfactory cues released by adult bees, brood, pollen, and honey from a honey bee, Apis mellifera L., colony are the primary stimuli that guide the beetle Aethina tumida Murray (Coleoptera: Nitidulidae) to host colonies. To investigate the response of adult A. tumida to visual stimuli, we tested the influence of color and height on trap efficiency. Two pole trap colors (black and white) were evaluated at three heights (46 cm, 1 m, and 3m) from October 2008 to December 2009. A. tumida were trapped in the greatest numbers between 17 April and 15 May 2009. The lowest numbers were captured during the winter and fall. The trapping results showed that both color and trap height significantly influenced capture. The average catch in the white traps (mean +/- SE, 2.47 +/- 0.30) was significantly higher than that of the black traps (1.53 +/- 0.29) probably because white is more reflective than black. Among the heights evaluated, there were more beetles caught when traps were positioned at 46 cm (the same height as the entrance of the hives) with 3.07 +/- 0.51 beetles compared with beetles captured at 1 m (1.88 +/- 0.30) or 3 m (1.06 +/- 0.18) high. Male and female beetles exhibited similar responses to trap color and height. The relationship between the numbers of beetles in colonies and capture rates in traps was very poor and did not provide a basis to evaluate trap efficiency. In addition, because capture rates seemed generally low in relationship to the number of beetles in the apiary, substantial improvements to the trap may be necessary.     

Resistance to Chalkbrood disease in Apis mellifera L. (Hymenoptera: Apidae) colonies with different hygienic behaviour

Chalkbrood disease affects the larvae of honeybees Apis mellifera L. and is caused by the fungus Ascosphaera apis. Infected larvae die when they are stretched in the cap cell and suffer a gradual hardening that ends in a very hard structure (mummie). Several studies have demonstrated that colonies that express an efficient hygienic behaviour (uncapping of cell and subsequent removal of dead brood) exhibit a higher resistance to the disease. However, it remains unclear whether the advantage of hygienic colonies over less hygienic ones lies in the ability to remove mummies or in the early detection of infected larvae and its cannibalization before they harden. To elucidate this aspect, the hygienic behaviour of 24 colonies, which were subsequently provided with pollen cakes containig A. apis, was evaluated. The number of mummies and the number of partially cannibalized and whole larvae in uncapped cells were recorded. The most hygienic colonies controlled the disease better. These colonies also had a higher tendency to uncap cells that contained infected larvae and cannibalize them. The presence of A. apis in partially cannibalized and whole larvae in uncapped cells indicate that the advantage of hygienic colonies over less hygienic ones lies in the early detection of infected larvae death and their quick removal from the cell before they become mummies.     

Multiple mating by both sexes in an invasive insect species,Aethina tumida (Coleoptera: Nitidulidae)

Multiple mating by both sexes is common among sexually reproducing animals. Small hive beetles (SHB), Aethina tumida, are parasites of bee nests endemic to sub-Saharan Africa and have become a widespread invasive species. Despite the considerable economic damages they can cause, their basic biology remains poorly understood. Here we show that male and female small hive beetles can mate multiple times, suggesting that costs for mating are low in this species. In an invasive A. tumida population in the United States, a combination of laboratory experiments for males and paternity analysis with eight polymorphic DNA microsatellite markers for field-caught females were used to estimate the number of mating by both sexes. The data show that females and males can mate multiple times—females mated with up to eight males, whereas males mated with at least seven females. The results also showed that A. tumida displayed a skewed paternity, although this was not consistent among the tested females. Thus, first or last male advantage seem to be unlikely in A. tumida. Our observations that individuals of both sexes of A. tumida can mate multiple times opens new research avenues for examining drivers of multiple mating and determining the role it may play in promoting biological invasions.     

氯虫苯甲酰胺亚致死剂量对蜂巢小甲虫生长发育和繁殖的影响

氯虫苯甲酰胺是我国蜂农防治蜂巢小甲虫Aethina tumida的主要杀虫剂。本研究旨在探讨氯虫苯甲酰胺对蜂巢小甲虫生长发育和繁殖的亚致死效应,为氯虫苯甲酰胺的合理使用提供一定的理论依据。本文采用饲料混毒法测定了氯虫苯甲酰胺对蜂巢小甲虫的毒力以及亚致死剂量LC10和LC25对蜂巢小甲虫生长发育和繁殖的影响。结果表明,氯虫苯甲酰胺对蜂巢小甲虫3龄初幼虫的LC50、LC25、LC10分别为5.193 μg/g、1.678 μg/g和2.865 μg/g。以氯虫苯甲酰胺亚致死剂量处理蜂巢小甲虫3龄初幼虫后,幼虫发育历期、雌预蛹期+蛹期、雄预蛹+蛹期均显著延长,且分别延长了3.38%和4.50%、10.51%和21.92%、5.26%和12.20%。LC10和LC25处理组幼虫的存活率均降低,尤其LC25处理组与对照组存在显著差异。LC10和LC25处理组漫游期幼虫重、初羽化雌虫重和初羽化雄虫重相比于对照均显著降低,且分别减轻了15.45%、21.54%、17.26%和13.47%、16.47%、16.46%。LC10和LC25处理组的产卵前期分别为7.96 d和7.47 d,比对照组显著缩短12.36 d和12.85 d;60 d内单雌产卵总量与对照组间无显著性差异,但在产卵期5~7 d时,LC25处理组的单雌产卵量显著增加。LC10和LC25处理组蜂巢小甲虫种群趋势指数低于对照组,但其种群趋势指数均远大于1,表明蜂巢小甲虫种群仍呈增长趋势,因此应加强蜂巢小甲虫的防控以及对氯虫苯甲酰胺的抗性监测。     

Bombus impatiens (Hymenoptera: Apidae): an alternative to Apis mellifera (Hymenoptera: Apidae) for lowbush blueberry pollination.

The pollination effectiveness of the commercially reared bumble bee Bombus impatiens Cresson, was compared in field studies to the honey bee, Apis mellifera L., for lowbush blueberry, Vaccinium angustifolium Ait. A preliminary study indicated that B. impatiens had potential as an alternative pollinator. In a 3-yr study, percentage fruit set, percentage harvested berries, berry weight, and seeds per berry were compared in blueberry fields stocked at 7.5 A. mellifera hives per hectare to 5, 7.5, or 10 B. impatiens colonies per hectare. Percentage of harvested berries (yield) was significantly higher in fields stocked with B. impatiens at 10 colonies per hectare. No other parameters measuring pollinator effectiveness were significantly different at 5, 7.5, or 10 colonies per hectare. Flower handling time was significantly faster for B. impatiens and it more frequently collected blueberry pollen. All parameters of pollinator effectiveness were similar for B. impatiens, A. mellifera, and native wild bees in a follow-up study. Overall, B. impatiens was a suitable alternative to A. mellifera.     

Invasion pathway of the honeybee pest,small hive beetle,Aethina tumida (Coleoptera: Nitidulidae) in the Republic of Korea inferred by mitochondrial DNA sequence analysis

The small hive beetle (SHB), Aethina tumida, is native to the Sub-Saharan region of Africa, but it became invasive in many countries after its first introduction to the USA in 1996. The SHB is a destructive pest of the honey industry and can cause damage in apiaries due to feeding on the honey, pollen, honey bee brood and honey fermentation. SHB was recently found infesting honeybee colonies in the South-Eastern part of Korea, Miryang city in 2016. No inference of the origin or the pathway of the invasion into Korea has been made, so far. We analyzed partial cytochrome oxidase I gene of mitochondrial DNA to unveil the possible source of the invasive populations of SHB in South Korea. A Bayesian inference tree and median joining haplotype network revealed a strong relationship between South Korean and North American populations suggesting that the SHB in South Korea came from the USA. Low genetic variation among Korean populations suggests that the invasion might have occurred in a single event with small number of founders. In addition, a new global distributional map of SHB is provided.     

Effect of entomopathogens on Africanized Apis mellifera L. (Hymenoptera: Apidae)

This study aimed to evaluate the effect of commercially used entomopathogens on Africanized Apis mellifera L. (Hymenoptera: Apidae). Four bioassays were performed: 1) pulverized entomopathogens on A. mellifera; 2) entomopathogens sprayed on a smooth surface; 3) entomopathogens sprayed on soy leaves; and 4) entomopathogens mixed with candy paste (sugar syrup). Five treatments were prepared: sterile distilled water (control), distilled water sterilized with Tween^® 80 (0.01%), and the commercial entomopathogens Metarhizium anisopliae E9 (1.0 × 10⁹ conidia mL^?1), Beauveria bassiana PL63 (1.0 × 10⁸ conidia mL^?1) and Bacillus thuringiensis var. kurstaki HD-1 (3.0 × 10⁸ spores mL^?1). Each treatment consisted of five repetitions, with 20 workers per repetition, which were stored in a plastic box and, later, in a biological oxygen demand (B.O.D.) incubator (27 ± 2 °C, RH of 60% ± 10%, 12-h photophase). The mortality of the workers was evaluated from 1 h to 240 h, and the data were analyzed using Bayesian inference. The workers killed by the ingestion of candy paste contaminated with the pathogens (products) were randomly separated and selected for the removal of the midgut. Each midgut was fixed in Bouin's solution and prepared for histology. B. bassiana was verified to reduce the survival of A. mellifera workers in all bioassays. Moreover, M. anisopliae reduced the survival of A. mellifera workers directly sprayed, on a smooth surface and mixed with candy. B. thuringiensis reduced A. mellifera survival on a smooth surface and mixed with candy paste. However, its effects were lower than that observed by B. bassiana. The treatments with the biological products did not induce morphometric alterations in the midgut of A. mellifera.