Evidence for Reduction of Native Mosquitoes With Increased Expansion of InvasiveOchlerotatus japonicus japonicus(Diptera: Culicidae) in the Northeastern United States

Abstract

Ochlerotatus japonicus japonicus (Theobald) is an invasive mosquito native to Japan, Korea, and eastern China. The species was first detected in the northeastern United States in 1998 and has rapidly spread throughout much of eastern North America. In addition to used tire casings, Oc. j. japonicus develops in a wide variety of artificial and natural container habitats, especially rock pools along stream beds. In an effort to evaluate the invasion success and impact of Oc. j. japonicus on populations of native container dwelling species, waste tire disposal sites and natural rock pool habitats were sampled for mosquito larvae throughout Connecticut in 2005, and data were compared with results from prior surveys made in 1987 and 1999. Oc. j. japonicus was the predominant species collected at the waste tire disposal sites regardless of surrounding landscape features, accounting for 55.9% of all larvae. A comparison with collections from prior surveys revealed a 90% reduction in the relative abundance of larval populations of Oc. triseriatus (Say) and significant reductions among larval populations of Oc. atropalpus (Coquillett) and Culex restuans Theobald. Oc. j. japonicus was also the most abundant mosquito collected in rock pool habitats, accounting for nearly 80% of all collected larvae, except where water temperatures exceeded 30 degrees C. This was concomitant with significant declines in the relative abundance of Oc. atropalpus and Cx. restuans. We conclude that Oc. j. japonicus is a potentially effective competitor in rock pool and tire environments and may be responsible for reducing populations of several native species occupying these habitats through interspecific competition for limited resources. The exclusion of Oc. j. japonicus from warm water pools further suggests that a temperature barrier may exist for Oc. j. japonicus and that populations may not be able to colonize southern regions of the United States with relatively high summer temperatures.

Invasion Biology ofAedes japonicus japonicus(Diptera: Culicidae)

“…j. japonicus is a cold-tolerant species that overwinters primarily in the egg stage (for egg surface characteristics, see 34), but sometimes in the larval stage (4, 5, 41, 50, 93). Bartlett-Healy et al (10) observed that Ae.…”

“…Ae. j. japonicus larval abundances in the newly expanded range are often particularly high in rock pools and tires, with the invasive species dominating the mosquito fauna at many locations and/or within a habitat category (5, 8, 11, 15, 50, 89). …”

“…atropalpus in rock pools and tires after the introduction of Ae. j. japonicus (4, 5, 8, 11, 15, 94). In some cases, an absence of Ae.…”

“…atropalpus has suffered a similar decline in relative abundance or has disappeared entirely from these habitats in some locales as Ae. j. japonicus has established (5, 10, 50). …”

“…j. japonicus is numerically dominant in tires and has increased its abundance in these habitats in many parts of North America at the expense of Ae. triseriatus (5, 11, 15, 45, 50). Although the invasive subspecies colonizes tree holes, sometimes in relatively high abundance (11), there is little evidence to indicate that it will displace the native species in these ancestral habitats.…”