Showing papers on "Varroa sensitive hygiene published in 2006"

Drift of Varroa destructor-infested worker honey bees to neighbouring colonies

Abstract: (2006). Drift of Varroa destructor-infested worker honey bees to neighbouring colonies. Journal of Apicultural Research: Vol. 45, No. 3, pp. 155-156.

An easy dissection technique for finding the tracheal mite, Acarapis woodi (Rennie) (Acari: Tarsonemidae), in honey bees, with video link

Abstract: Since the introduction of varroa mites (Varroa destructor Anderson and Trueman, 2000), the impact of tracheal mites on bees has been largely overshadowed or ignored. Tracheal mites are still present in bees, and may be responsible for some unexplained colony losses. If they cause bee mortality, it is important to be able to identify their presence and at what levels. This paper illustrates a quick and easy technique for dissecting bees for tracheal mites. Hopefully, the video link will be a useful training tool for researchers, beekeepers or regulatory personnel who need to test bees for the mite's presence. Tracheal mites are still present in some areas and can be introduced through the sale of bee packages or purchased queens. The presence or absence of these mites can also help determine or eliminate the cause of unexplained colony losses, especially in overwintered colonies.

Varroa destructor virus 1: A new picorna-like virus in Varroa mites as well as honey bees

Abstract: Proefschrift ter verkrijging van de graad van doctor op gezag van de rector magnificus van Wageningen Universiteit

Biological control of Varroa destructor by fungi

Abstract: The mite Varroa destructor is a pest in bee colonies (Apis mellifera). The mites feed on haemolymph of the bees and their larvae and they can transmit viruses. Little work has been done on biological control of this mite. Only in the last few years the effect of insect pathogenic fungi on Varroa mite is investigated. Literature shows that several insect parasitic fungi are able to infect and kill Varroa without being a threat to honey bees. In this paper three products based on the fungi Metarhizium anisopliae and Lecanicillium lecanii, which are currently sold in The Netherlands for the control of insect pests, were tested in bee hives for their effect on Varroa. Neither of them was effective against Varroa, at least not in the currant formulation. For the control of Varroa we should search for fungi that work under bee hive circumstances, high temperature and low humidity, and a good application method.

Reproduction of Varroa destructor in sealed worker bee brood cells of Apis mellifera carnica and Apis mellifera syriaca in Jordan

Abstract: The reproduction of the honey bee mite, Varroa destructor in sealed worker bee brood cells represents an important factor for the population development of this parasite in honey bee colonies. In this study, the relative infestation levels of worker brood cells, mite fertility (mites that lay at least one egg) and reproductive rate (number of viable adult daughters per mother mite) of Varroa mite in worker brood cells of Apis m. carnica and Apis m. syriaca were compared in fall 2003 and summer 2004 at two locations in Jordan. The relative infestation levels in sealed worker brood cells ranged from 23 - 32 % in fall and 19 - 28 % in summer. The average fertility of Varroa mite ranged between 90 - 98% in colonies of A. m. carnica and between 88 - 96 % in A. m. syriaca with minor differences between colonies and locations. The number of total progeny of fertile mites in worker brood cells was 4.0 in both bee races. The reproductive rate was high with 2.7 and 2.6 in both honey bee races. The post-capping period of the worker brood cells differs only slightly between both bee races and between locations (284.4 h on average, n = 4,000). Our data reveal surprisingly high mite fertility and reproductive rates in both honeybee races under Mediterranean conditions of Jordan. The possible physiological background of Varroa reproduction and the impact of mite fertility on the development of Varroa tolerance are discussed.

Swarm prevention and spring treatments against Varroa destructor in honey bee colonies

Abstract: In 2004 and 2005 experiments were carried out to test the efficacy and efficiency of Varroa control combined with swarm prevention methods in spring. Honey bee colonies were split in an artificial swarm and a brood carrier. Hereafter the swarms were treated with oxalic acid and the brood carriers either with formic acid (2004) or Thymovar (2005). Both the oxalic acid and the formic acid were very effective, resulting in an average efficacy of 97% and 96%, respectively. There was some worker bee mortality in both treatments. Thymovar was less effective (71%), but did not cause any worker bee mortality. The results show that the combination of Varroa control and swarm prevention can effectively be used in spring.

Attractiveness of brood cells from different honey bee races (Apis mellifera) to Varroa mites

Abstract: Reproduction of the Varroa mite only occurs inside capped brood cells of honey bees. Therefore, invasion into brood cells is crucial for the mite’s reproduction and the rate of invasion will affect the growth of the mite population. We investigated the invasion response of the mites to drone or worker larvae of different honey bee races, because selection for less attractive brood may help Varroa mite control. We compared attractiveness of brood cells in 3 or 6 hour intervals before cell capping, because invasion response of the mites increased strongly with the age of both worker and drone larvae. The results suggest that not the racial origin of the worker brood, but the distance between the larva and the cell rim affected the invasion response of the Varroa mites to worker brood cells. Possibilities to obtain less attractive brood via selection seem to be limited.

Toxicity of some new pesticides to honey bees and their residues in honey and pollen

Abstract: The problem of pesticide toxicity to honey bees- the primary pollinator of crops requiring cross pollination is an area of prime concern as pesticide use in such crops result in high bee mortality. Some times it exceeds 90 per cent in some apiaries (Wedberg and Erickson. 1986). In India, only about 10 lakh bee colonies are available at present as against an estimated need of 737 lakh owing to extensive agriculture. deforestation and use of pesticides (Ramarethinum, 1998).

Bees and Pesticides

Abstract: Honey bees (Apis mellifera L.) are the main pollinating agents for numerous plants and fruit trees and hence, play a key role in agriculture and more generally in the maintenance of ecological biodiversity. They are mostly affected farm animals by pesticides. Indeed, pesticides work in two ways to reduce bee populations. First, many pesticides used in crop production are highly toxic to these social insects. Second, the use of herbicides can reduce the acreages of useful plants for the bee activity. Pesticides damages to honey bee colonies take different forms. Honey bees may be poisoned when they feed on nectar or pollen contaminated by pesticides. Bees may also be poisoned when they fly through a cloud of pesticide dust or spray or walk on treated parts of plant. Sometimes, colonies in the hives can be directly affected, but most commonly only field bees are killed or have their physiological functions altered. Toxicity and hazards of 158 pesticides to Apis and non-Apis bees are well reviewed in a study of Devillers et al. (2003). Honey and bee products have the image of being natural, healthy and clean. However, today bee products are produced in a environment, polluted by different sources of contamination. The contamination sources can be roughly divided into environmental and apicultural ones. Environmental contaminants are pesticides, heavy metals, bacteria, GMO and radioactivity, contaminants from beekeeping practice includes acaricides used for parasitic mites (mainly Varroa) control, bee repellents used at honey harvest, pesticides for wax moth and small hive beetle control and antibiotics used against foul brood disease. There are very few special residue limits for honey, making it difficult to discuss the toxicological importance of residues. Honey makes a minimal contribution to the acceptable daily intake (ADI) of pesticides. The most common insecticides that have been examined in European honeys include organochlorines, organophosphorous pesicides and carbamates. In a recent study using 50 honey samples from Spain and Portugal, residues of 42 different pesticides were examined (Blasco et al., 2003). Most of the pesticides found in honey were organochlorines. Among them, gamma-HCH was found in 50% of the samples and was the most frequently detected substance, followed by HCB in 32% of the samples and other isomers of HCH. The values found varied between 0,03 and 4,31 mg/kg, but most of them were bellow 0,5 mg/kg. There are several other European studies with no measurable residues of insecticides in honey found above the detection limit, which varied between 0,005 and 0,050 mg/kg. (Bogdanov, 2006). Similar situation is in Slovakia, monitoring of 20 honey samples for the presence of 14 insecticides showed no detectable residues of insecticides (see the presentation). The effect of imidacloprid (known under the name of Gaucho) on bee health is highly controversial, even just very small residues were found in honey. (Bogdanov, 2006). SUMMARY

Infestation levels of Varroa destructor in local honey bees of Jordan.

Abstract: To determine Varroa mite infestation levels in Jordan, a survey covering 180 colonies of two bee types (Apis m. syriaca and Apis m. syriaca hybrids) from six locations of 4 climatic zones was conducted during August, 8 month after the last treatment. Sampled colonies had 8-10 frames covered with bees and 3-4 brood frames. Levels of infestation were determined on both adult worker bees and in sealed worker brood cells. Two-way ANOVA showed no significant differences due to bee type with average adult bee infestation of 10.9 % and 13.1 % on hybrid and local bee types, respectively. Average infestation levels in sealed brood worker cells were 37.6 % and 32.5 % in hybrid and local bee types, respectively. Differences in infestation levels on adult bees were significant due to location and ranged between 6.9 - 18.6 % in Daba'a (Desert climate) and Jerash (Dry Mediterranean), respectively. In sealed worker brood cells infestation levels ranged between 15.7 - 84.7 % in Baqa (Dry Mediterranean) and Jerash, respectively. This indicates clearly that the usual scheduled Varroa control practice by a single chemical treatment in autumn could be insufficient. Therefore, to prevent damages or even losses of colonies, including diagnosis of infestation rates as part of integrated Varroa management is highly recommended.