Showing papers on "Varroa sensitive hygiene published in 2004"

Altered Physiology in Worker Honey Bees (Hymenoptera: Apidae) Infested with the Mite Varroa destructor (Acari: Varroidae): A Factor in Colony Loss During Overwintering?

Abstract: The ectoparasitic mite Varroa destructor (Anderson & Trueman) is the most destructive pest of the honey bee, Apis mellifera L., in Europe and the United States. In temperate zones, the main losses of colonies from the mites occur during colony overwintering. To obtain a deeper knowledge of this phenomenon, we studied the mites’ impact on the vitellogenin titer, the total protein stores in the hemolymph, the hemocyte characteristics, and the ecdysteroid titer of adult honey bees. These physiological characteristics are indicators of long-time survival and endocrine function, and we show that they change if bees have been infested by mites during the pupal stage. Compared with noninfested workers, adult bees infested as pupae do not fully develop physiological features typical of long-lived wintering bees. Management procedures designed to kill V. destructor in late autumn may thus fail to prevent losses of colonies because many of the adult bees are no longer able to survive until spring. Beekeepers in temperate climates should therefore combine late autumn management strategies with treatment protocols that keep the mite population at low levels before and during the period when the winter bees emerge.

Acaricide (pyrethroid) resistance in Varroa destructor

Abstract: The infamous varroa mite has become one of the most serious pests of European honey bees, causing a worldwide loss of millions of colonies. As the eradication of the mite is impossible, beekeepers have had to rely heavily on a small number of acaricides as their main line of defence against the mite. However, the appearance and rapid spread of mites resistant to some of the most commonly used acaricides is causing a new wave of problems for beekeepers.

The energy and nutritional demand of the parasitic life of the mite Varroa destructor

Abstract: The energy metabolism and nutritional demand of the ectoparasitic mite Varroa destructor Anderson and Trueman was investigated by calorimetry, respirometry and resource utilization rate. Mites from different sexes and developmental stages of the western honeybee Apis mellifera were monitored in the absence of the host. Energy metabolism of the mites, calculated from the rate of heat production, was an insignificant factor in the cause of honeybee colony death. The metabolic rates of mites ranged from 1.1% to 2.4% of that of the bee pupa depending on the infestation level. But the nutritional demand of the mites was very high, owing to their inefficient metabolic machinery, utilizing up to 25% of the nutritional reserves of the pupae accumulated in tissue during the larval stage. The feeding of the mites contributes to the malformation and weakening of the bees and eventually of the colony.

A semiochemical from brood cells infested by Varroa destructor triggers hygienic behaviour in Apis mellifera

Abstract: Hygienic behaviour of bees towards mite infested brood is involved in the tolerance of some bee strains to Varroa destructor. The stimuli triggering hygienic behaviour are olfactory cues emanating from cells containing infested brood but their identity is still unknown. After confirming the capacity of bees to detect and empty mite-infested cells, we studied the volatile chemicals released by artificially infested worker brood cells by means of SPME-GC-MS. The identified chemicals were then bioassayed by comparing the bees' hygienic behaviour towards treated cells into which 1 µg of each compound was injected and control cells which received the solvent alone. Z-(6)-pentadecene significantly increased the number of cells emptied by the bees. Varroa destructor / semiochemicals / hygienic behaviour / removal / hydrocarbons

Cape honeybee ( Apis mellifera capensis Eshscholtz) and varroa mite ( Varroa destructor Anderson & Trueman) threats to honeybees and beekeeping in Africa

Abstract: Honeybees are of critical importance in Africa for both ecological and economic reasons. Their contribution to floral biodiversity and conservation, by virtue of their pollination of indigenous flowering plants is unknown, but certain to be considerable. Economically, honeybees are critical for the pollination of a host of commercial crop plants as well as being the source of energy and livelihood for many thousands of mostly small- scale beekeepers. In the past, honeybee pests and problems have been of limited importance in Africa. More recently, however, an increasing number of exotic diseases and pests as well as home-grown problems threaten honeybees, beekeeping and honeybee- pollination in Africa. Two problems in South Africa, the capensis problem and varroa mites, have severely curtailed beekeeping in that country and may well have impact on bees and beekeeping throughout the continent.

Effect of screen floors on populations of honey bees and parasitic mites (Varroa destructor)

Abstract: SUMMARYThis study compared brood production, honey consumption (in winter only), population growth of honey bees (Apis mellifera), and population growth of parasitic mites (Varroa destructor) in hives with open screen or wood as floor material. Two experiments were conducted in Baton Rouge, Louisiana, USA, one in winter (19 colonies) and one in summer (22 colonies). In both experiments, we established uniform colonies of honey bees by subdividing 30 kg of mite-infested bees. Each colony began with about 11 000 bees, no brood, and uniform populations of mites (127 and 480 mites per colony in winter and summer, respectively). The summer test included a third treatment (8 colonies) where a wooden tray (5 cm deep) closed the space beneath a screen floor. After the first 20 days of the experiments, when no adult bees or mites had yet been produced in any of the colonies, the treatments showed no differences in brood production, honey consumption, or survival of adult bees. At nine weeks, colonies with screen f...

Honey Bee (Hymenoptera: Apidae) Distribution and Potential for Supplementary Pollination in Commercial Tomato Greenhouses During Winter

Abstract: This study examined the use of honey bees, Apis mellifera L., to supplement bumble bee, Bombus spp., pollination in commercial tomato, Lycopersicon esculentum Miller, greenhouses in Western Canada. Honey bee colonies were brought into greenhouses already containing bumble bees and left for 1 wk to acclimatize. The following week, counts of honey and bumble bees foraging and flying throughout the greenhouse were conducted three times per day, and tomato flowers open during honey bee pollination were marked for later fruit harvest. The same counts and flower-marking also were done before and after the presence of honey bees to determine the background level of bumble bee pollination. Overall, tomato size was not affected by the addition of honey bees, but in one greenhouse significantly larger tomatoes were produced with honey bees present compared with bumble bees alone. In that greenhouse, honey bee foraging was greater than in the other greenhouses. Honey bees generally foraged within 100 m of their colony in all greenhouses. Our study invites further research to examine the use of honey bees with reduced levels of bumble bees, or as sole pollinators of greenhouse tomatoes. We also make specific recommendations for how honey bees can best be managed in greenhouses.

Testing a combination of control tactics to manage Varroa destructor (Acari: Varroidae) population levels in honey bee (Hymenoptera: Apidae) colonies

Abstract: Four combinations of strategies to reduce population growth of Varroa destructor Anderson and Trueman were tested in honey bee colonies located at two apiary sites. The strategies were combinations of mite tolerant queen stock, screen inserts, and T-02® strips (AI thymol). The effectiveness of the treatment combinations differed between the apiary sites. Site 1 apiary was in a cleared forest surrounded by secondary growth, while Site 2 was on the top of a hill, exposed to the wind. At Site 2, all but one colony survived the winter, while at Site 1, over-winter mortality of colonies was lowest in those colonies that combined hygienic queens and screen inserts. Mite populations at the end of the study did not differ among treatments or between sites. However, colony populations at Site 2 were significantly larger and overall colony survival was greater than at Site 1. The study demonstrates how the effectiveness of strategies to reduce the impact of Varroa on colony survival might ultimately depend...

Influence of brood, vent screening, and time of year on honey bee (Hymenoptera : Apidae) pollination and fruit quality of greenhouse tomatoes

Abstract: Greenhouse tomatoes, Lycopersicon esculentum Miller (Solanaceae), are autogamous, but facilitated pollination results in increased fruit size and set. Previous research examining honey bee pollination in greenhouse tomato crops established that fruit quality resulting from honey bee visitation is often comparable to bumble bees (Bombus spp.) and significantly better than in flowers that receive no facilitated pollination. However, management alternatives have not been studied to improve tomato fruit quality when honey bees are the only pollination option available for the high-value greenhouse industry. We investigated whether the quantity of brood (eggs, larvae, and pupae) in a honey bee colony in the winter and screening on greenhouse vents in the summer would encourage honey bee foraging on tomato flowers. We also established the influence of time of year on the potential for honey bees to be effective pollinating agents. We constructed small honey bee colonies full of naive forager bees with either two frames of brood ("brood colonies") or two empty frames ("no-brood") and compared total fruit set and the number of tomato seeds resulting from fruit potentially visited by honey bees in each of these treatments to bagged flowers that received no facilitated pollination. There was no significant difference in the quality of fruit resulting from honey bees from "brood" and "no-brood" colonies. However, these fruits produced significantly more seeds than bagged flowers restricted from facilitated pollination. Honey bees from brood and no-brood colonies also resulted in 98% fruit set compared with 80% fruit set in bagged flowers that received no facilitated pollination. During the summer, the number of seeds per fruit did not differ significantly between unbagged flowers potentially visited by honey bees in screened greenhouses and unscreened greenhouses and bagged flowers that received no facilitated pollination. However, time of year did have a significant influence on the quality of fruit produced by honey bees compared with flowers that received no facilitated pollination, because no difference in seed number was observed between the treatments after mid-April. The results from this study demonstrate that the management of brood levels and vent screening cannot be used to improve the quality of fruit resulting from honey bee pollination and that honey bees can be a feasible greenhouse pollination alternative only during the winter.

Number and position of wounds on honey bee (Apis mellifera) pupae infested with a single Varroa mite

Abstract: The wounds inflicted on pupae in capped brood cells of the honey bee, Apis mellifera, infested with a single female of the ectoparasitic mite, Varroa destructor, were investigated after visualisation by vital staining with trypan blue. On average the mites made two integumental perforations for feeding on prepupae and one on pupae. Most of the punctures were on particular ventral sites on the abdomen. Possible reasons for this pronounced preference and the evolutionary aspects of this highly specialised parasite-host relationship are discussed.

Varroa resistance of hybrid ARS Russian honey bees.

Abstract: SUMMARY The varroa resistance2 of several genetic crosses utilizing ARS Russian honey bees was tested in Alabama during 2001. Bee stocks included pure ARS Russian (Russian queens × Russian drones), commercial (commercial queens × commercial drones), Russian hybrids (commercial queens × Russian drones), and SMR-Russian hybrids [(queens bred for the suppression of mite reproduction trait) × Russian drones]. The varroa resistance of Russian hybrids was intermediate to that of pure ARS Russian and commercial stocks. This suggests that Russian hybrids may offer some varroa resistance, but pure ARS Russian stock should be used to achieve the maximum varroa resistance that is currently available in Russian bees. The lowest growth of mite populations occurred in the SMR-Russian hybrids. This may suggest that resistance genes from the two parental types combine in an additive manner, but we cannot be sure because pure SMR bees (SMR queens × SMR drones) were not included in the study.

Population dynamics of Varroa destructor in colonies of Apis mellifera macedonica in Greece.

Abstract: SUMMARYPopulation dynamics of Varroa destructor were studied for two years (April 1999-April 2001) in 12 Apis mellifera macedonica colonies located in Thessaloniki, Greece. Colonies were not treated with acaricide. Mite population development was characterized by: (a) a period of increase from the end of March to mid-summer, followed by (b) a period of stabilization or marginal increase characterized by fluctuations and ending late October/early November, followed by (c) a period of decrease from October to the following March.

Observations of the ectoparasitic bee mite Varroa destructor in honey bee (Apis mellifera) cells infected with chalkbrood (Ascosphaera apis)

Abstract: The mite Varroa destructor is the most problematic pest of honey bees (Apis mellifera) in the world. Current mite control practices rely heavily on a small number of chemical pesticides, an approach that will not be sustainable as mites develop resistance to available chemicals. This is worrisome because agricultural production attributed to honey bee pollination in the USA has been estimated to be $US14.6 billion (Morse & Calderone, 2000). A vigorous beekeeping industry is thus essential to a healthy agricultural economy as a whole.

Prevalence of Varroa destructor in Africanized honey bees (Apis mellifera scutellata Lepeletier) in Lara State, Venezuela.

Abstract: SUMMARY This study was conducted during June-July 2003 and April-May 2004 in colonies of Africanized honey bees distributed in two different communities in the state of Lara, Venezuela. These colonies belonged to the Apicultural Research Station facilities of the Universidad Centroccidental “Lisandro Alvarado” (UCLA). The colonies were maintained in one deep brood chambers and managed to prevent swarming. These colonies had not changed the queens in the last five years and had never been treated for Varroa infestation. Samples of worker bees were collected from brood combs, placed into a plastic jars inside a cooler and taken to the lab. The bees were placed in a detergent solution, shaken for about 5 minutes and strained to separate mites from the bees (De Jong et al. 1982). The worker brood were unsealed, examined for the presence of mites and the number of foundress adult mites was recorded. Infestation prevalence of Varroa was determined as the number of adult female mites per 100 adult bees and 100 worker brood cells respectively. It was found statistical significant differences between the proportions in the colonies under study (P< 0.01). The average Varroa infestation rate in adult worker and brood in both locations decreased from one year to another without treatment of the colonies during these periods. Curiosly, all colonies inspected in this study in both locations the female Varroa was not reproducing. The female was found alone inside the cells, even though there were abundant available cells in the brood nest.