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Нозематоз, парвовирусы и прочая гадость у сверчков


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#1 Mikhail F. Bagaturov

Mikhail F. Bagaturov

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  • Интересы:Пауки-птицееды, рептилии, птицы и др., а также блюз

Отправлено 24 Июль 2007 - 16:45

Вот, привожу статью, если кому интересно...==========Cricket Virus Wipes Out Growers in UK & Europeby Jon CooteCricket Growers in Europe and the UK have been seriously impacted by a species-specific parvovirus, presumed to be a densovirus. Commonly known in the UK as ‘cricket paralysis virus’ first appearance in the UK from mainland Europe was in early 2002. All five major commercial cricket growers in the UK were infected before the end of 2002. This virus specifically attacks only the Common Brown or House cricket (Acheta domesticus), previously the core species in European trade, and the only species in trade in the USA. In Europe, commercial growers regularly raise three alternative species of cricket, Banded cricket, also known as the Tropical House cricket (Gryllodes sigillatus), African Black Field cricket (Gryllus bimaculatus), and Silent Brown cricket, also known as Jamaican Field cricket (Gryllus similis), so the impact of loosing the Brown House cricket is not as serious as it would currently be in the USA.Infected crickets die without any visible symptoms and at all stages of development, but death rates are heaviest at the pre-wing stage just before adult size. The effect is also cumulative. At first death rates are tolerable and many growers believe that they simply have a husbandry problem. Within as little as six weeks death rates become catastrophic and all viable commercial production is lost. Though a few adults may still survive, they are in too low numbers to support continued commercial production. There is no known treatment and, being a virus, probably none will be found. Prevention is the only viable solution at this time. Experiments are being conducted to try to establish the vectors of this virus. I’ve arranged for one UK grower to conduct an experiment to see if the Dermestes beetles (commonly called Fuzzy Bugs) that infest most growers’ colonies are primary vectors of this virus. Other UK growers are trying to determine if any individuals can be found that are resistant to this virus. Imported crickets from the USA have proved to be particularly susceptible. Where this virus came from is open to speculation, but it apparently first appeared in Germany, were commercial production of this species has now effectively ended. It may ultimately prove to have mutated from a similar virus that infects Wax Moth larvae (Galeria mellonella). These larvae are routinely used in research establishments to maintain a wide variety of insect viruses injected into them that researchers want to study. So this insect species is clearly especially adept at carrying insect viruses of many types and maintaining them in a viable form. It is possible that a mutation could have occurred in this way to ultimately infect Brown House crickets.My position in both the UK and USA reptile industry, working with T-Rex Products, provides me with a unique opportunity to be able to talk candidly to both reptile breeders and insect growers, as our products complement theirs rather than compete. As a result I was able to call a meeting of all interested parties, including most of the largest US cricket growers, last August, at Wayne Hill’s Reptile Expo in Daytona Beach. Also present was one of the principal US reptile vets and a UK cricket grower, who was able to share his direct experiences with this virus. From that meeting I’ve continued an e-mail correspondence with the group to enable them to better understand this virus and what measures are likely to prevent it impacting on the US. I’ve been able to establish a likely protocol to clean up after an infection, if that ever occurs, and locate a UK based researcher who would be interested in studying this virus. This researcher is currently working on baculoviruses for insect pest control and is intrigued by our problem. Much of her work focuses on trying to elucidate the ecology of insect diseases (persistence, transmission, etc.) in addition to pest control, which is the sort of study that is required. No one anywhere currently works on insect parvovirus ecology and biology, which does mean that some basic biology needs to be done to start with. If it is a parvovirus, it is presumed to be a densovirus, one of which has been previously reported from the Brown House cricket in a single report in the 1970s, in Montpellier in France. This researcher considers that my idea that it might be passively dispersed by Dermestes beetles is intriguing and perhaps a good place to start, hence the experiment described above.During my investigations into this subject I came upon another researcher who was raising pathogen-free crickets, i.e. free of bacteria, etc., in special isolator systems. This is a very costly operation producing perhaps the most expensive insects reared worldwide! It could however provide an opportunity to re-colonize with disease free crickets if effective cleanup after this virus proves to be possible. Experiments are underway. A well known parvovirus infects dogs. Believed to have mutated from feline parvovirus, also known as feline distemper virus, it first appeared in 1978 in the USA. It soon crossed the Atlantic to infect dogs in Europe. It is hoped that strict measures are voluntarily adopted to ensure that this cricket virus does not cross the ‘pond’ in the opposite direction. All contact with European commercially grown insects should be avoided and imports of these into the USA should cease with immediate effect. It is known that the largest commercial producer of Wax Moth larvae in the UK has shipped surplus stock to the USA in the recent past. This should no longer be considered viable. It may be wise to establish from your supplier if insects are USA home grown or not. The Brown House cricket is commercially extinct in Europe. It would currently be a tragedy if the same situation were to occur in the USA, whilst prevention remains possible. Jon Coote is a professional herpetologist, trained at the University of Nottingham in the UK. He is Director of Research & Development for T-Rex Products Inc. He is Chairman of the Livestock Advisory Panel, of the UK’s industry association, the Pet Care Trust, and Chairman, and past President, of the International Herpetological Society.===============




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