{"id":1453,"date":"2020-10-15T23:06:49","date_gmt":"2020-10-15T20:06:49","guid":{"rendered":"https:\/\/b-ento.com\/ru\/?p=1453"},"modified":"2022-08-11T15:51:07","modified_gmt":"2022-08-11T12:51:07","slug":"kleshh-varroa-varroa-destructor","status":"publish","type":"post","link":"https:\/\/b-ento.com\/en\/kleshh-varroa-varroa-destructor\/","title":{"rendered":"Varroa mite (Varroa destructor)"},"content":{"rendered":"\n

Varroa destructor is the world’s most destructive pest of honey bees, Apis mellifera<\/em>. Although the Varroa complex includes several species, Varroa destructor is the species responsible for the vast majority of damage attributed to mites of this genus.<\/p>\n\n\n\n

Varroa mites are ectoparasites that feed on the hemolymph of immature and adult individuals of Apis mellifera<\/em> honey bees. Apis mellifera<\/em> bee species was originally of European origin and was not the basic host of the pest. In fact, the mite is native to Asia, where it parasitizes another honey bee, Apis cerana<\/em> (Asian or Eastern honey bee). It is believed that Asian honey bees have some natural protection against these mites and, therefore, are rarely negatively affected. It was only when colonies of European Apis mellifera<\/em> bees were introduced to Asia that people began to understand how destructive Varroa mites could be. Host displacement did not occur instantly, and research data suggest that it could have taken 50-100 years. Since then, the mite has spread around the world and become cosmopolitan. In many countries, strict quarantine procedures are followed to reduce the likelihood of accidental mite importation.<\/p>\n\n\n\n

Description<\/strong><\/h3>\n\n\n\n

Adults:<\/strong> adult female mites have an oval shape from reddish-brown to dark brown, measuring from 1.00 to 1.77 mm in length and from 1.50 to 1.99 mm in width. Their curved bodies fit into the abdominal folds of an adult bee and are held there by the shape and location of the ventral bristles. Adult males are yellowish, with light brown legs and a spherical body shape, measuring from 0.75 to 0.98 mm in length and from 0.70 to 0.88 in width. Male chelicerae are modified to transmit sperm.<\/p>\n\n\n\n

Eggs:<\/strong> The eggs are oval and white and are laid singly on the walls of the honeycomb. The eggs are approximately 0.30 mm long and 0.23 mm wide and are almost impossible to see with the naked eye.<\/p>\n\n\n\n

Nymphs:<\/strong> Male and female protonymphs are indistinguishable without dissection. Protonymphs have eight legs, pointed chelicerae (oral apparatus) and have a transparent white colour. The body seems to be round, since they do not acquire an oval shape until the deutonymph stage. After moulting the protonymph, the mite becomes a deutonymph, which resembles adult individuals with reduced bristles. The mite sheds again to move into the last adult stage.<\/p>\n\n\n\n

Life cycle<\/strong><\/h3>\n\n\n\n

An adult female Varroa mite can be found on both adult and immature bees. However, mites reproduce only on the brood of honey bees (developing larvae and pupae). Immature Varroa individuals can only be found on a closed brood.<\/p>\n\n\n\n

Despite its small size, the female Varroa mite is one of the largest ectoparasites known in relation to its host. Since Varroa-related injuries are caused specifically by female mites, the remaining consideration of the life cycle will be aimed at female individuals.<\/p>\n\n\n\n

Adult females go through two phases in their life cycle: the phoretic (a kind of commensalism, the settlement of the organism by means of its transfer to others) and the reproductive phase. During the phoretic phase, female Varroa mites feed on adult bees and are passed from bee to bee as they pass each other in the colony. During this phase, the female parasite feeds on adult bees and, usually, they can be found between the abdominal segments of bees. Varroa pierce soft tissues between segments and feed on hemolymph through punctures.<\/p>\n\n\n\n

Anatomically, Varroa females are well-adapted bee parasites. Their flattened shape allows them to fit between the segments of the abdominal cavity. In addition, they have claws that allow them to grab the bee, and abdominal bristles that allow them to stay attached to it. The mite cuticle has a chemical pattern similar to the bee cuticle, this probably allows the pest to remain unidentified by the bee while parasitizing. In addition, the cuticle is strongly sclerotized, which sometimes protects the mite from bee aggression.<\/p>\n\n\n\n

Varroa can also be transmitted between colonies when infected bees move to another colony. This often happens when growing honey bees, when individual bee colonies are located a few meters from each other. In this situation, bees typically return (drift) to the wrong colony. Interestingly, bees from families heavily infected with Varroa drift more than bees from healthy ones.<\/p>\n\n\n\n

Varroa can also be transmitted between colonies in other ways. Firstly, beekeepers often help weak families by adding bees or a brood from a healthier family, and this practice helps spread the mite. Secondly, beekeepers can move families from one area to another, facilitating the spread of Varroa in the region. Thirdly, individual colonies can form a swarm, moving to a new location and simultaneously spreading Varroa. Finally, mites can spread between colonies when bees from colonies rob (steal honey) from each other. Strong colonies frequently rob weaker ones during periods of nectar shortage. In these cases, mites easily move from one bee to another. All these methods have contributed to the global spread of Varroa as a pest of honey bees.<\/p>\n\n\n\n

The phoretic period of the mite, apparently, contributes to its reproductive ability. Although mites artificially transferred to the brood cells immediately after they mature are capable of reproduction, their reproduction rate is lower than that of mites undergoing a phoretic period. The phoretic period can last from 4.5 to 11 days when there is a brood in the hive, or from five to six months in winter when there is no brood in the hive. Consequently, female mites living when a brood is present in the colony have an average life expectancy of 27 days, but in the absence of brood they are able to live for many months.<\/p>\n\n\n\n

For reproduction, phoretic mites must penetrate into the honeycombs of the brood of bees. Honey bees create a wax matrix in which they form hexagonal cells. Queen bees lay eggs in these cells, and after three days the bee larva comes out of the egg and begins to develop. When the larva reaches a certain age, worker bees in the colony construct a wax curtain over the entrance to the chamber. The larva develops into a pre-pupa, and then into a pupa under a conditional \u201croof\u201d. After the egg is laid, an adult worker, drone, or queen bee leaves the cell after 21, 24 or 16 days, respectively.<\/p>\n\n\n\n

Female Varroa mites must enter the breeding cell before the bees seal it. In families of honey bees, they can get into a working or drone cell, but mites are more attracted to the drone brood. Ready to reproduce, the mite leaves the adult bee, which it feeds on, and crawls along the wall of the honeycomb to the larva at the bottom. For a mite, only larvae that are ready to close are attractive. Crawling under the larva, the female mite plunges into the brood feed under the larva, where it remains until the cell is closed by other worker bees.<\/p>\n\n\n\n

As soon as the worker bees close the cell, the larva eats the remaining food of the brood, thereby freeing the mite. The released mite climbs onto the larva and begins to feed. The mite defecates on the top of the cell wall, feeding on the bee. Soon after, the mite lays its first egg on the surface of the wall. The egg is not fertilized and develops into a male. Subsequent fertilized eggs are laid by the female mite in the direction of the back of the cell of the honeycomb, approximately every 25-30 hours. These eggs hatch into females.<\/p>\n\n\n\n

The newly minted protonymphs join their mother on the ventral side of the developing bee pupa around the 5th segment of the abdomen. Here, the mother and offspring alternate periods of bee feeding and defecation. Developing protonymphs turn into deutonymphs, and then into adult mites. The whole process from egg to adult mite takes from 6 to 7 days for both sexes.<\/p>\n\n\n\n

Taking into account mortality in brood cells and improper mating, the average female mite gives about one generation for each working cell it enters, and about two for a drone cell. Drones need more time to develop, so more mites form in their honeycombs. Thus, in an average temperate climate, mite populations can increase 12 times in families breeding every six months, and 800 times in families in which a brood is created all year round. This makes it difficult to control the mite, especially in warmer climates, where colonies support brood all year round.<\/p>\n\n\n\n

Economic significance<\/strong><\/h3>\n\n\n\n

The Varroa mite has negatively affected beekeeping in all countries where it has been registered. It is difficult to find accurate estimates of the impact of Varroa on beekeeping, but it is safe to assume that the mites have killed hundreds of thousands of colonies around the world, resulting in billions of dollars in economic losses. Varroa mites have led to an increase in production costs, which has reduced the profitability of beekeeping.<\/p>\n\n\n\n

Varroa weakens and eventually kills the colonies. As a rule, the peak of the bee population falls at the end of spring \/ mid-summer, while a steady decline in the population occurs in mid-late summer. The increase in the Varroa population is similar to the growth of bees, but varies by several weeks. Thus, the Varroa population begins to reach its peak when the populations of bee colonies begin to decline. This factor creates serious problems with mites.<\/p>\n\n\n\n

Varroa rarely hits adult bees, but shortens their lifespan and can even change behaviour. Varroa can kill immature bees, and their ability to do so correlates with the number of mites that enter the brood cell before it is closed. The more mites there are in the honeycomb, the less likely it is that an immature bee will successfully develop and grow into an adult.<\/p>\n\n\n\n

Honey bees are known to carry a number of viruses. There is evidence that some of these viruses are associated with the presence of Varroa mites in the colony. It is currently believed that Varroa can transmit several viruses to its hosts, and that these viruses, and not the mites themselves, cause most of the damage that bees experience as a host of mites.<\/p>\n\n\n\n

To illustrate this point, one of the most striking signs of Varroa’s presence in the colony is the appearance of newly emerged adult bees with deformed wings. A virus called deformed wing virus is responsible for this symptom and is present in immature bees. Bees with this virus cannot use their wings and will die or be killed by other workers within a few days of emergence. The wing deformity virus can be so common in maturing bees that they may appear without wings at all. Researchers suspect that other viruses also play an important role in the relationship between the Varroa mite and the honey bee, but the role of these viruses has not been sufficiently studied.<\/p>\n","protected":false},"excerpt":{"rendered":"

Varroa destructor is the world’s most destructive pest of honey bees, Apis mellifera. Although the Varroa complex includes several species, Varroa destructor is the species responsible for the vast majority of damage attributed to mites of this genus. Varroa mites are ectoparasites that feed on the hemolymph of immature and adult individuals of Apis mellifera …<\/a><\/p>\n","protected":false},"author":74,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"single-enciklopedia.php","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-1453","post","type-post","status-publish","format-standard","hentry","category-vrediteli"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/posts\/1453","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/users\/74"}],"replies":[{"embeddable":true,"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/comments?post=1453"}],"version-history":[{"count":0,"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/posts\/1453\/revisions"}],"wp:attachment":[{"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/media?parent=1453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/categories?post=1453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/b-ento.com\/en\/wp-json\/wp\/v2\/tags?post=1453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}