Interactions between soil‐dwelling arthropod predators and Ixodes scapularis under laboratory and field conditions

Abstract

AbstractThe primary vector for Lyme disease and several other medically significant tick‐borne diseases, Ixodes scapularis (blacklegged tick), spends over 95% of its two‐year life cycle exposed to the soil environment. However, the effect of soil‐dwelling arthropod predator populations on I. scapularis survival either in the laboratory or under field conditions is unclear. We collected soil‐dwelling obligate arthropod predators from the field, representing 13 taxonomic families, and investigated whether they would target two I. scapularis life stages (nymph/engorged larva) under laboratory conditions. After 48 h, 30.6% of the predator species targeted I. scapularis nymphs, while 41.3% targeted engorged larvae. One spider species, Schizocosa ocreata, targeted both I. scapularis life stages reliably under laboratory conditions. We used this species to test whether an arthropod predator would affect I. scapularis survival in field microcosms which contained alternative prey items and a complex soil environment. We also investigated the direct and indirect effects of surface litter on I. scapularis survival by removing the leaf litter layer from half of the microcosms. Predator addition reduced the number of nymphs recovered from the microcosms after 21 d by 32.9%. Litter removal also had a negative effect on tick survival, and interacted weakly with the addition of a predator further decreasing tick survival. Additionally, we found that when leaf litter was removed, I. scapularis survival was positively correlated with the organic matter content of the soil within the microcosms. Naturally occurring arthropod predators may play an important role in regulating population dynamics of I. scapularis and show potential as biological control agents for use in integrated pest management protocols.