Amitraz or coumaphos efficacy tests in Guatemala for control of Varroa jacobsoni Mesostigmata : Varroidae in honey bees?

Field studies in southwestern Guatemala demonstrated that plastic strips im pregnated with either amitraz or coumaphos controlled Varroa jacobsoni Oude mans in colonies of honey bees, Apis mellifera L. In the spring of 1997, fo ur groups of 12 colonies each were given two plastic strips in the broodnes t containing one of four concentrations of amitraz (5, 7.5, 10 or 12.5%). A fifth group was untreated. All four amitraz treatments were highly effecti ve (97 to 99% mite mortality) in reducing numbers of varroa over a 47-day t reatment period. In the fall of 1997, a similar study was done with coumaph os-impregnated plastic strips placed in the broodnest or attached to the hi ve entrance. Four groups often colonies each received treatment, and the re maining six colonies were untreated controls. Broodnest treatments were one , 10% strip; or two, 10% strips; or two, 1% strips per colony. Two 10% stri ps were attached to the hive entrance in the fourth group. One or two 10% s trips were effective against varroa (91-97% reduction) when placed in the b roodnest or across the hive entrance. The 1% strips and controls were ineff ective and failed to reduce the mire population.