Showing papers on "Varroa sensitive hygiene published in 1994"

Population dynamics of Varroa Jacobsoni: a model and a review

Abstract: (1994) Population Dynamics of Varroa Jacobsoni: A Model and a Review Bee World: Vol 75, No 1, pp 5-28

Ontogenesis of the mite Varroa jacobsoni Oud. in worker brood of the honeybee Apis mellifera L. under natural conditions

Abstract: A study carried out during the summer of 1994, in southern England, investigated the developmental times and mortality ofVarroa jacobsoni inApis mellifera drone cells. The position and time of capping of 2671 naturally infested drone cells were recorded. Six hours after the cell was capped, 90% of the mites were free from the brood food to start feeding on the developing drone. The developmental time of the mite's first three female offspring (133±3 h) and the male offspring (150 h) and the intervals between egg laying (20–32 h) were similar to those found in worker cells. However, the mortality of the offspring was much lower in drone cells than worker cells. The mode numbers of eggs laid were six and five in drone and worker cells, respectively. All offspring had ample time to develop fully in drone cells with the sixth offspring reaching maturity approximately 1 day before the drone bee emerged. Normal mites (those which lay five or six viable eggs) produced on average four female adult offspring but since only around approximately 55% of the mite population produced viable offspring the mean number of viable adult female offspring per total number of mother mites was 2 to 2.2 in drone cells.

Non-reproducing Varroa jacobsoni Oud. in honey bee worker cells—status of mites or effect of brood cells?

Abstract: The parasitic mite Varroa jacobsoni Oud. reproduces in sealed honey bee brood cells. Within worker cells a considerable fraction of the mites do not produce offspring. It is investigated whether variation in the ratio of cells without reproduction is caused by properties of the worker brood, or by the state of the mites entering cells. Pieces of brood comb were taken from colonies of 12 different bee lines and were placed simultaneously into highly infested colonies. Non-reproduction was independent of the origin of the brood pieces, indicating a minor role of a variation due to different brood origin. Between colonies used for infestation, however, it differed considerably. A comparison of the proportion of cells without reproduction when infested by one Varroa mite or when infested by two or three Varroa mites showed, that non-reproduction was mainly related to the state of the mites entering cells, and only to a minor degree to an influence of the brood cells. A high ratio of worker cells without reproduction was consistently reported in bee lines which survive the disease without treatment, and a high level of non-reproduction is thus regarded to be a key factor in breeding bees for high Varroa tolerance. The current results indicate, that differences in this trait are only to a minor degree related to differences between bee lines in the ability of the bee brood to induce oviposition. These differences seem rather to depend on other, unknown colony factors influencing the reproductive state of Varroa when they enter cells for reproduction.

Factors influencing host choice of the honey bee parasite Varroa jacobsoni Oud

Abstract: Reproducing Varroa jacobsoni obtained from brood cells of Apis mellifera L. with 13–16 day old bees (pupae) and Varroa mites kept on adult bees for at least 8 days were simultaneously tested for their choice in three host types. Comparisons were made of attractiveness of Varroa jacobsoni to nurse bees, pollen foragers as to larvae from nearly capped brood cells. Host choices were observed in Petri dishes and in an Y-shaped olfactometer. Varroa jacobsoni obtained from capped brood cells showed a stronger preference for nurse bees in Petri dish simultaneous choice tests with pollen foragers or larvae than did mites which were previously kept on adult bees. In olfactometer simultaneous choice tests, the two mite test groups showed no clear difference in preferences for bees of different ages. The preference of Varroa jacobsoni for bees of different ages is therefore not only influenced by host factors but also by intrinsic factors in female mites that depend on the mite's reproductive stage.

The Varroa mite, a devastating parasite of Western honeybees and an economicthreat to beekeeping.

Abstract: Beekeepers produce honey and wax, but the most Important aspect of beekeeping is the pollination of crops. Beekeeping with the western honeybee is threatened by the ectoparasite Varroa jacobsoni. w...

Effects on Honey Bees of Insecticides Applied to Snap Beans in Wisconsin: Chemical and Biotic Factors

Abstract: Studies were conducted to determine the role of snap beans as a food resource for honey bees (Apis mellifera L.), bee mortality resulting from pesticides, and the long-term effects on bees of such insecticide exposure. Aerial application of microencapsulated methyl parathion induced elevated levels of bee mortality and reduced total pollen collection rates, whereas treatment with acephate did not. Honey bees did not forage snap beans for pollen or nectar even under conditions of extreme resource dearth. Bee mortality following application of insecticides was caused by foraging either on blooming weeds in the field or among flowering plants within the spray-drift zone. Thus, such bee losses in snap beans could be avoided almost entirely through clean cultivation. High intercolony variability obscured possible differences in winter survival after exposure and in subsequent honey production.