Ayuka T. Fombong

Monitoring Aethina tumida (Coleoptera: Nitidulidae) With Baited Bottom Board Traps: Occurrence and Seasonal Abundance in Honey Bee Colonies in Kenya

ABSTRACT The population dynamics of the honey bee pest Aethina turida 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.

Aethina tumida (Coleoptera: Nitidulidae) and Oplostomus haroldi (Coleoptera: Scarabaeidae): Occurrence in Kenya, Distribution Within Honey Bee Colonies, and Responses to Host Odors

ABSTRACT Aethina tumida Murray (Coleoptera: Nitidulidae) is considered a minor parasitic pest of African honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies, but little information is available on other coleopteran pests. We surveyed for A. tumida and other beetles in honey bee colonies at four major beekeeping locations: Watamu, Chawia-Taita, Matuu, and Nairobi in Kenya and compared their distribution within the colonies. The presence of A. tumida was confirmed in all the colonies surveyed, whereas Oplostomus haroldi Witte (Coleoptera: Scarabaeidae) was found for the first time to be associated with honey bee colonies in varying numbers at all the sites, except that none were found in colonies in Nairobi. More than 90% of A. tumida and O. haroldi were found in Watamu and Chawia, located within the coastal province of Kenya. Although A. tumida was found mostly on the bottom board of the hives, consistent with previous reports, O. haroldi was found on the frames. Laboratory bioassays using a two-choice olfactometer showed that both beetle species were significantly attracted to worker honey bee volatiles and commercial pollen dough inoculated with the yeast Kodamaea ohmeri associated with A. tumida. Based on these findings, we report for the first time O. haroldi as a pest of African honey bee colonies in Kenya, We propose that differences in their densities recorded in the colonies may be due to dissimilarities in the colony environments in the areas surveyed and that odor-baited traps that have been successfully been used to manage populations of A. tumida also will be suitable for use against O. haroldi.

Standard methods for chemical ecology research in Apis mellifera

Summary This paper describes basic methods essential in elucidating chemically-mediated behavioural interactions among honey bees, and between honey bees and other arthropods. These range from bioassay methods used to demonstrate the role of specific behaviours, techniques and equipment used to collect and analyse semiochemicals (both volatiles and non-volatiles e.g. cuticular hydrocarbons) from individual honey bees, groups of bees or an entire colony in its native environments. This paper covers: collection and analysis of honey bee volatiles in the natural environment, collection and analysis of bee volatiles out of their natural environment and their antennal detection, collection and analysis of non-volatile cuticular hydrocarbons, bioassays with queen pheromone and finally a section focusing on in vitro bioassays as a tool for elucidation of mechanisms regulating pheromone gland activity.

Occurrence, diversity and pattern of damage of Oplostomus species (Coleoptera: Scarabaeidae), honey bee pests in Kenya

Several arthropod pests including the hive beetles Aethina tumida and Oplostomus haroldi and the ectoparasite Varroa destructor have recently been identified as associated with honey bee colonies in Kenya. Here, we report the first documentation of Oplostomus fuligineus in Kenya, a related scarab of O. haroldi, and distribution, diversity and pattern of damage of the two scarab species on honey bee colonies. Sequence analyses of mitochondrial cytochrome oxidase I gene revealed that there was sufficient sequence divergence to separate both Oplostomus beetles. The same molecular marker separated O. haroldi according to place of origin in Kenya. We further show from analysis of feeding behavioural patterns that the two scarab species damaged honey bee combs similarly causing the most damage on brood through feeding; O. haroldi (80%), with O. fuligineus (100%). We discuss our results in relation to the threats these scarabs may pose to bee health in Kenya.

An Inventory of Documented Diseases of African Honeybees

Current trends in global honeybee population changes have been linked to drastic declines in honeybee populations caused by complex interactions between pathogens, arthropod pests such as Varroa, pesticides, honeybee stress and habitat loss. Although substantial information exists for this sudden decline in honeybee populations in Europe and North America, in Africa the effect of this threat continues to draw debate. Despite recent reports showing the presence of V. destructor mites across the continent, knowledge on pathogens associated with bees and this mite in various parts of the continent is scanty. This review provides a comprehensive update on the documented diversity and geographic distribution of honeybee pathogens and points to the need of further information on these constraints of honeybee health.

Life history of Oplostomus haroldi (Coleoptera: Scarabaeidae) under laboratory conditions and a description of its third instar larva

The life history of Oplostomus haroldi (Witte), a recently reported pest of honeybee colonies in East Africa, was studied for the first time under laboratory conditions. Adult O. haroldi collected from beehives in the coastal part of Kenya were reared on a mixture of moist sterilized soil and cow dung. At 25 ± 2 °C, 50 ± 5% relative humidity and a 10h light-14h dark photoperiod, the laid eggs took 11.9 ±1.3 days to hatch into a curved pear-shaped scarabaeiform larva with a well-developed head and thoracic legs. The first, second and third larval instars lasted 14.6 ± 2.6, 17.5 ± 2.4 and 34.6 ± 2.4 days, respectively. The pupal stage, which was marked by formation of a mud cocoon, lasted 31.1 ± 6.7 days with the adults surviving for 2–6 months under laboratory conditions, suggesting that the beetle is multivoltine. A detailed taxonomic description of the external morphology of the third instar larva is provided.

Estimating Reproductive Success of Aethina tumida (Coleoptera: Nitidulidae) in Honey Bee Colonies by Trapping Emigrating Larvae

ABSTRACT 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.

The Biology and Control of the Greater Wax Moth, Galleria mellonella

The greater wax moth, Galleria mellonella Linnaeus, is a ubiquitous pest of the honeybee, Apis mellifera Linnaeus, and Apis cerana Fabricius. The greater wax moth larvae burrow into the edge of unsealed cells with pollen, bee brood, and honey through to the midrib of honeybee comb. Burrowing larvae leave behind masses of webs which causes galleriasis and later absconding of colonies. The damage caused by G. mellonella larvae is severe in tropical and sub-tropical regions, and is believed to be one of the contributing factors to the decline in both feral and wild honeybee populations. Previously, the pest was considered a nuisance in honeybee colonies, therefore, most studies have focused on the pest as a model for in vivo studies of toxicology and pathogenicity. It is currently widespread, especially in Africa, and the potential of transmitting honeybee viruses has raised legitimate concern, thus, there is need for more studies to find sustainable integrated management strategies. However, our knowledge of this pest is limited. This review provides an overview of the current knowledge on the biology, distribution, economic damage, and management options. In addition, we provide prospects that need consideration for better understanding and management of the pest.

Hygienic and grooming behaviors in African and European honeybees - new damage categories in Varroa destructor

Varroa destructor is an ectoparasitic pest of honeybees, and a threat to the survival of the apiculture industry. Several studies have shown that unlike European honeybees, African honeybee populations appear to be minimally affected when attacked by this mite. However, little is known about the underlying drivers contributing to survival of African honeybee populations against the mite. We hypothesized that resistant behavioral defenses are responsible for the survival of African honeybees against the ectoparasite. We tested this hypothesis by comparing grooming and hygienic behaviors in the African savannah honeybee Apis mellifera scutellata in Kenya and A. mellifera hybrids of European origin in Florida, USA against the mite. Grooming behavior was assessed by determining adult mite infestation levels, daily mite fall per colony and percentage mite damage (as an indicator of adult grooming rate), while hygienic behavior was assessed by determining the brood removal rate after freeze killing a section of the brood. Our results identified two additional undescribed damaged mite categories along with the six previously known damage categories associated with the grooming behavior of both honeybee subspecies. Adult mite infestation level was approximately three-fold higher in A. mellifera hybrids of European origin than in A. m. scutellata, however, brood removal rate, adult grooming rate and daily natural mite fall were similar in both honeybee subspecies. Unlike A. mellifera hybrids of European origin, adult grooming rate and brood removal rate did not correlate with mite infestation levels on adult worker honeybee of A. m. scutellata though they were more aggressive towards the mites than their European counterparts. Our results provide valuable insights into the tolerance mechanisms that contribute to the survival of A. m. scutellata against the mite.

Behavioral Evidence for Olfactory-Based Location of Honeybee Colonies by the Scarab Oplostomus haroldi

The Afro-tropical scarab Oplostomus haroldi (Witte) is a pest of honeybees in East Africa with little information available on its chemical ecology. Recently, we identified a female-produced contact sex pheromone, (Z)-9-pentacosene, from the cuticular lipids that attracted males. Here, we investigated the kairomonal basis of host location in O. haroldi. We used coupled gas chromatography/electroantennographic detection (GC/EAD) and GC/mass spectrometry to identify antennally-active compounds from volatiles collected from honeybee colonies. Antennae of both sexes of the beetle consistently detected seven components, which were identified as 3-hydroxy-2-butanone, 2,3-butanediol, butyl acetate, isopentyl acetate, butyl butyrate, hexyl acetate, and methyl benzoate. In olfactometer bioassays, both sexes responded to the full seven-component synthetic blend over solvent controls, but chose honeybee colony odors over the blend. These findings suggest that the seven compounds are components of a kairomone from honeybee colonies used by O. haroldi.