Varroa destructor resistance to miticides in the Middle East

Reza Shahrouzi, International Counsellor for Agriculture & Apiculture, PO Box 34185-451, Qazvin, Iran Amir Mohammad Elmi, Department of Environment Wildlife Bureau, Tehran, Iran Abbas Gerami Sadeghian, Department of Parasitology, Veterinary Medicine Faculty of Tehran, Iran

Keywords: Afghanistan, Apis mellifera, Azerbaijan, Egypt, Iran, Iraq, Kurdistan, Pakistan, pyrethroids, Tajikistan, Turkey, Yemen

The Middle East encompasses the majority of western Asia (excluding the Caucasus) and Egypt. The climate is hot and arid. Several major rivers provide irrigation to support agriculture in limited areas, especially in Mesopotamia and the rest of the Fertile Crescent.

History

Books on bees were written in Roman times, and beekeeping was known in the Middle East centuries before the advent of Islam. By 5,000 BC the people of Iran and Iraq understood the need for pollination of date palms.

Everywhere bees nest in old trees, holes in rocks and caves. Honey is harvested from these wild colonies. Beekeeping using localstyle hives - baked clay, tree trunk, and basket (made from willow branches covered with cow dung to seal) – is practised across the region. In the last 50 years the use of frame hives has increased.

Four countries of the Middle East have over a million bee colonies:

Egypt 2,000,000

Iran 5,613,259

Turkey 4,300,000

Yemen 1,001,022

Varroa

Varroa destructor, first recorded in the Middle East in the 1970s, is still considered a leading cause of death of Apis mellifera honey bee colonies. Research has developed several products that received market authorisation in most countries of the region. The Ministries of Agriculture have undertaken substantial expenditure purchasing different anti-Varroa products to test their effectiveness.

Since 2008 products have been sold on the black market without veterinary authorisation. In Afghanistan, Azerbaijan, Iran, Iraq, Kurdistan, Pakistan and Tajikistan, beekeepers have reported serious problems with the illegal substances including death of colonies. Some flumethrin and fluvalinate products have the same active ingredient of pyrethroids as proprietary products.

Resistance

Varroa mite resistance to miticides is well known and documented. The first cases of resistance to organophosphates were reported in 1947 (Delome & Dacol, 1989), and since 1996 there has been development of resistance to the pyrethroids flumethrin and fluvalinate. Varroa develops resistance to chemicals used in control strategies as a result of prolonged exposure to the acaricide. This is especially true for mites with short life cycles, such as Varroa destructor which has twelve generations per year. This is one of the reasons that manufacturers of products advise users to limit the frequency and period of application. Despite precautionary measures, it is now evident that acaricides such as fluvalinate (Lodesani et al, 1992) accumulate in beeswax, creating conditions for prolonged contact with Varroa, especially inside the brood cells where they reproduce. The ineffectiveness of fluvalinate has been reported in France, Italy and Iran (Faucon 1994; Milani 1995; Shahrouzi 1998). The use of this chemical for Varroa control became widespread because it is easy to apply and relatively cheap. However, the use of Apistan® and Apivar® has often been replaced by wooden strips impregnated with the same active ingredient, made by the beekeepers themselves using Klartan and Mavrik (containing fluvalinate) and Taktic (containing amitraz) that are not authorised for use in beekeeping, and difficulties with dosage have led to loss of effectiveness. Resistance to other acaricides, belonging to different groups of chemicals, has been also reported. Resistance to bromopropylate and chlordimeform was shown to be favoured by under dosing and this has been verified in laboratory tests (Ritter & Roth 1988). The presence in different countries of Varroa destructor populations simultaneously resistant to different pyrethroids highlight the risks of basing control strategies purely on chemical treatment, particularly when the substances used belong to the same chemical family.

Conclusion

After three decades of experience in the Middle East using different treatments against Varroa, I feel that efficacy depends upon local conditions and that care is needed when using these products. The optimal conditions are a high and stable external temperature and the absence of worker brood. The main precautions consist of preventing re-infestation and robbing by treating outside periods of nectar flow or queen rearing, and by checking the effectiveness of the treatment.

The alternative to chemical control needs more than just using a plant extract in place of synthetic acaricide. It is likely that Varroa destructor will still remain for several years as one of the agents for weakening colonies. However it is necessary that we learn to live with it, by identifying and preserving surviving colonies in the apiaries. This may require additional effort and time by beekeepers to look after their bees.

If treatment is to be used, the first application must be carried out in late September or early October. To give overwintering bees the optimum potential for survival, it must be sufficiently effective to ensure that at the end of the treatment there will be fewer than 50 parasites in treated colonies. If colonies are located in an area conducive to the rearing of brood - potential source of development for the mite – a second treatment may be carried out in early spring.

For references see www.beesfordevelopment.org/resources-forbeekeepers