Current Project 3
The Potential Role of Broad-scale Acaricide Applications in Integrated Programs to Control Ixodes scapularis.
- Phase 1. Suppression of Ixodes scapularis Following Annual Broad-scale Acaricide Applications Against Fall Populations of Adults.
- Phase 2. Non-target Effects on Late Season Acaricide Applications Against Ixodes scapularis Adults.
The success of any Lyme disease intervention program is reducing exposure to infected ticks. Chemical control efforts are generally directed against nymphal ticks, the stage epidemiologically linked to the vast majority of cases, and have proven to be the most reliable means of suppressing populations of ticks. The use of habitat-targeted acaricides is generally viewed by the public as having undesirable environmental impacts, particularly adverse effects on non-target organisms. We hypothesized that annual habitat-targeted acaricide applications directed at black-legged tick adults in the fall, when most non-target arthropods are inactive, might suppress tick populations over time, while having minimal adverse effects on other litter-dwelling arthropods.
The objectives of these linked studies are:
- To demonstrate that single, large-scale acaricide applications against adult ticks in the fall for 3 consecutive years will significantly reduce all post-embryonic stages of this important tick vector;
- To demonstrate that broad-scale acaricide applications against ticks in the fall have minimal impact on non-target terrestrial arthropods and that used in conjunction with host-targeted strategies, may accelerate the effectiveness off an integrated tick control strategy.
A section of Naval Weapons Station (NWS) Earle, Colts Neck Township, Monmouth County, New Jersey, serves as the study site. The study site for Phase 1 included treatment and untreated control plots, each at least 2 ha in area. Phase 2 incorporated 2 treatment and 2 untreated control plots, each 1-ha in area. Populations of host-seeking ticks are monitored by a combination of walking and drag sampling methods throughout the study during adult, nymphal and larval activity periods. Non-target arthropods were be sampled using a combination of pitfall traps and sweep netting shrub layer vegetation. Deltamethrin (Suspend SC, 4.75% [AI], Bayer Environmental Science, Montvale, NJ) was applied according to labeling recommendations to the shrub layer of the treatment block using a high pressure hydraulic sprayer.
The fall 2004 and 2005 acaricide applications resulted in 97.1% and 100% control, respectively, of I. scapularis adults. Following 2 consecutive years of control of the reproductive stage of I. scapularis, the abundance of host-seeking nymphs, larvae, and adults was reduced by 100%, 84.8%, and 93.7%, respectively, during the in 2006 field season. The fall 2006 application resulted in 100% control of I. scapularis adults in treated plots compared to untreated areas. Initial analysis indicates no significant decline in the numbers of nontarget arthropods after the initial acaricide application.
The data collected thus far suggest that single acaricide applications directed at populations of I. scapularis adults each fall may have significant impacts on subsequent life stages of this vector tick. Analysis to date suggests that fall applications of acaricides have minimal adverse effects on other arthropods inhabiting the forest leaf litter. This research project is on-going.