Impact of controlled burns on the abundance of Ixodes scapularis (Acari: Ixodidae).

Information on the effect of vegetative destruction by controlled burns in reducing the abundance of the blacklegged tick, Ixodes scapularis Say, the vector for the agents of Lyme disease, human babesiosis, and human granulocytic ehrlichiosis, is limited. Therefore, the abundance of nymphal, larval, and adult I. scapularis was monitored by dragging the vegetation at 2 separate 4-ha tracts in Cockaponset State Forest in Connecticut following a single controlled burn on 15 April or 21 May 1992. The burn at the April burn site was rated as light to moderate with a flame height of 0.3 m and consumed approximately 67% of the surface leaf litter. The burn at the May burn site was rated moderate to severe with a flame height of 0.6-0.9 m., which consumed vegetation < 5 cm in diameter and approximately 100% of the surface leaf litter. The impact of the burn was strongly influenced by the intensity and timing of the burn. Burning of the vegetation resulted in a reduction of the abundance of nymphal I. scapularis by 74% at the moderately burned site and 97% at the severely burned site, compared with adjacent unburned woodland. No larvae were recovered later in the summer from the severely burned tract. However, judging by the comparable abundance of adult I. scapularis in the fall at the burned and unburned woodlands, the effect of the burns was temporary. Burning the vegetation for the control of I. scapularis appears limited in effect and could be applied only on a large scale in areas with little or no human habitations.