Varroa sensitive hygiene

About: Varroa sensitive hygiene is a research topic. Over the lifetime, 714 publications have been published within this topic receiving 24928 citations. The topic is also known as: VSH.

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.

Invasion of Varroa mites into honey bee brood cells

Abstract: Invasion behaviour of Varroa jacobsoni into honeybee brood cells was studied using an observation hive. The mites were carried close to a suitable brood cell by the bees. Subsequently, the mites moved from the bees to the rim of the cell, walked quickly inside, crawled between the larva and the cell wall, and moved onto the bottom of the cell. Varroa mites were never seen walking across the comb, and entering and leaving brood cells as has been described for Tropilaelaps clareae. Differences in invasion strategies between V. jacobsoni and T. clareae are discussed. Introduction The parasitic mite Varroa jacobsoni is currently the most important pest of Apis mellifera, worldwide. Varroa mites parasitize both adult bees and bee brood. They feed on the haemolymph of adult bees and additionally use the bees as transport vehicles within the colony as well as for dispersal from colony to colony. Reproduction of the mites only takes place while residing on honeybee brood. Consequently, the mites have to leave the bees and invade the brood cells (Ritter, 1981; Ifantidis & Rosenkranz, 1988). Since invasion into brood cells is indispensable for reproduction, knowledge about invasion behaviour and the factors affecting this behaviour may provide a basis for development of new control methods. For example, the finding that Varroa mites invade drone cells in larger numbers than worker cells (e.g. Fuchs, 1990), prompted a biotechnical control method in which mites are trapped in drone cells and subsequently removed from the colony (Schulz et al., 1983; Rosenkranz & Engels, 1985). Invasion has been studied primarily at the population level. Studies have been done on the distribution of mites over different types of brood cells (e.g. Ruijter & Calis, 1988; Buchler, 1989; Fuchs, 1990), and on the distribution of mites over adult bees and brood cells (e.g. Woyke, 1987; chapters 2,3). In these studies the resulting distribution was studied, whereas the underlying behaviour was reconstructed indirectly by inference. Direct studies on behaviour of individual mites have been carried out in artificial settings (e.g. Otten & Fuchs, 1988; Le Conte et al., 1989; Rickli et al., 1992) because manipulations to see individual mite behaviour are difficult in a bee hive. Such studies are useful to provide answers to specific questions, e.g. whether mites react to certain odours (Le Conte et al., 1989; Rickli et al., 1992), but the relevance of these observations to the behaviour of mites under realistic conditions is not immediately obvious. In this study mite behaviour was observed in a more realistic setting to identify which factors and conditions may play a role during invasion of mites, and to help interpretation of observations in artificial settings.

Varroa destructor resistance of honey bees in Hawaii, USA, with different genetic proportions of Varroa Sensitive Hygiene (VSH)

Abstract: Apis mellifera, Varroa destructor, honey bees, genetic resistance, integrated pest management, bee breeding Journal of Apicultural Research 51(3): 288-290 (2012) © IBRA 2012 DOI 10.3896/IBRA.1.51.3.13 The Big Island of Hawaii, USA, supports an important honey bee (Apis mellifera) queen rearing industry that supplies queens worldwide. This industry now is threatened by Varroa destructor, as the mite was detected on the Big Island in 2008. Mite parasitism is now high in queen production operations because of the extended brood rearing season in the tropics, the deliberate production of large numbers of drones in many colonies, and invasion of mites from dying feral colonies. Mites can currently be managed with acaricides, and beekeepers typically treat colonies at two to four month intervals (compared to at six to twelve month intervals on the USA mainland). Acaricides may be problematic for queen producers, however, because they can interfere with queen rearing and sperm production (e.g., Haarman et al., 2002, Rinderer et al., 1999). An alternative management strategy might employ bees bred for mite resistance. Bees with Varroa Sensitive Hygiene (VSH) offer good resistance to V. destructor (Harbo and Harris, 2009). This trait could be used for breeding in Hawaii through importations of semen, as queens cannot be imported into the state. We sought to determine what proportion of VSH genetics can confer useful honey bee resistance to V. destructor in queen production operations in Hawaii. In July 2010, a cooperating queen breeder established 30 colonies (without sealed brood) that were assigned to three treatment groups. Groups were created so that initial mite density was equal for the groups (0.10-0.11 ± s.d. 0.09-0.12 mites per 100 adult bees). Instrumentally inseminated queens were added to each colony. The queens were created so that their workers had either 0%, 50% or 75% of the genetics for VSH. Genetic groups were as follows: 0% VSH = commercial Hawaiian X commercial Hawaiian; 50% VSH = commercial Hawaiian X VSH; and 75% VSH = 50% VSH X VSH. Mated queens were produced from five colonies of the operation. VSH semen was from drones from Glenn Apiaries and our USDA laboratory. Previously inseminated queens (commercial Hawaiian X VSH) produced hybrid daughter queens that were inseminated to make the 75% VSH group. We initiated testing with two other queen producers, but their colonies became unusable; in one case there was inadvertent treatment with acaricide, and in the other case colonies became unviable because of small size, poor nutrition and high mite populations (which increased from July to September from 1.1 to 14.7 mites per 100 bees). Beginning in September when experimental populations of workers were fully established, the colonies were sampled every two months to monitor the density of mites and to measure the population of brood. Mite densities were measured by sampling ca. 300 adult bees from the broodnest, shaking the sample in 70% ethanol to wash off phoretic mites, and counting bees and mites. Brood populations were measured by using a grid to estimate the area of sealed brood on each side of each comb to the nearest 1/6 of the side, and summing these counts to get the number of comb equivalents covered with brood. Colonies were managed initially without treatment against V. destructor; later, individual colonies that reached a density of 10 mites per 100 bees were treated with fluvalinate (Apistan

Control of honey bee mites in Vietnam without the use of chemicals.

Abstract: In Vietnam, various biotechnical methods are used by professional beekeepers to control Varroa jacobsoni and Tropilaelaps clareae. For control of tropilaelaps, a broodless period has to be created. Varroa is controlled by trapping methods. The methods suffice to successfully control both mite species without the use of chemicals.

Host-parasite adaptations and interactions between honey bees, Varroa mites and viruses

Abstract: The ectoparasitic mite, Varroa destructor, has become the largest threat to apiculture and honey bee health world-wide. Since it was introduced to the new host species, the European honey bee (Apis mellifera), it has been responsible for the near complete eradication of wild and feral honey bee populations in Europe and North America. Currently, the apicultural industry depends heavily on chemical Varroa control treatments to keep managed colonies alive. Without such control the mite populations in the colony will grow exponentially and the honey bee colony will succumb to the development of overt virus infections that are vectored by the mite typically within three years. Two unique sub-populations of European honey bees (on Gotland, Sweden and in Avignon, France) have adapted to survive for extended periods (over ten years) without the use of mite control treatments. This has been achieved through a natural selection process with unmanaged mite infestation levels enforcing a strong selection pressure. This thesis reveals that the adaptation acquired by these honey bee populations mainly involve reducing the reproductive success of the parasite, that the different populations may have evolved different strategies to do so, and that this mite-resistant trait is genetically inherited. In addition, results of this thesis demonstrate that chemical mite control treatments used by beekeepers to inhibit the mite population growth within a colony can actually worsen bee health by temporarily increasing the bee's susceptibility to virus infection. The results of this thesis highlight the impact that apicultural practices otherwise have on host-parasite interactions and the development of disease in this system. Possible solutions to the threat of Varroa are discussed such as the potential to breed for mite-resistant honey bees, which may offer a sustainable long-term solution, and the need for better general beekeeping techniques that reduce the use of chemical treatments and inhibit the spread of disease.