The Asian tiger mosquito, Aedes albopictus (Skuse), is an invasive species with substantial biting activity, high disease vector potential, and a global distribution that continues to expand. New Jersey, southern New York, and Pennsylvania are currently the northernmost boundary of established Ae. albopictus populations in the eastern United States. Using positive geographic locations from these areas, we modeled the potential future range expansion of Ae. albopictus in northeastern USA under two climate change scenarios. The land area with environmental conditions suitable for Ae. albopictus populations is expected to increase from the current 5% to 16% in the next two decades and to 43%–49% by the end of the century. Presently, about one-third of the total human population of 55 million in northeastern USA reside in urban areas where Ae. albopictus is present. This number is predicted to double to about 60% by the end of the century, encompassing all major urban centers and placing over 30 million people under the threat of dense Ae. albopictus infestations. This mosquito species presents unique challenges to public health agencies and has already strained the resources available to mosquito control programs within its current range. As it continues to expand into areas with fewer resources and limited organized mosquito control, these challenges will be further exacerbated. Anticipating areas of potential establishment, while planning ahead and gathering sufficient resources will be the key for successful public health campaigns. A broad effort in community sanitation and education at all levels of government and the private sector will be required until new control techniques are developed that can be applied efficiently and effectively at reasonable cost to very large areas.

The newly introduced mosquito Aedes japonicus has expanded from its original range in Northeastern Asia to 29 US states (including Hawaii) plus Canada and northern Europe. Our objectives were to test an earlier hypothesis of multiple introductions of this species to the Northeastern US and evaluate putative temporal changes in genetic makeup. Using a panel of seven microsatellite loci, we confirmed the existence of two abundant genetic forms in specimens originally collected in 1999-2000 (F(ST) value based on microsatellite data = 0.26) that matches the disjunctive distribution of mitochondrial haplotypes. To examine the distribution of the two genetic 'types' across Pennsylvania we created a fine-scale genetic map of Ae. japonicus using 439 specimens collected from 54 Pennsylvania counties in 2002-2003. We also made direct comparisons between collections in 1999-2000 and new collections made in 2004-2005 obtained from the same areas in the northeastern US. We observed that the strong association between mtDNA haplotype and microsatellite signature seen in 1999-2000 had weakened significantly by 2002 across Pennsylvania, a trend continued to some extent in 2004-2005 in PA, NJ, and NY, indicating that once easily distinguishable separate introductions are merging. The two expanding genetic forms create a complex correlation between spatial and genetic distances. The existence of multiple introductions would be obscured without sampling early and across time with highly polymorphic molecular markers. Our results provide a high-resolution analysis of the spatial and temporal dynamics of a newly introduced disease vector and argue that successive introductions may be a common pattern for invasive mosquitoes.

The etiological agents responsible for Lyme disease (Borrelia burgdorferi), human granulocytic anaplasmosis (Anaplasma phagocytophilum), and babesiosis (Babesia microti) are primarily transmitted by the blacklegged tick, Ixodes scapularis Say. Despite Pennsylvania having in recent years reported the highest number of Lyme disease cases in the United States, relatively little is known regarding the geographic distribution of the vector and its pathogens in the state. Previous attempts at climate-based predictive modeling of I. scapularis occurrence have not coincided with the high human incidence rates in parts of the state. To elucidate the distribution and pathogen infection rates of I. scapularis, we collected and tested 1,855 adult ticks statewide from 2012 to 2014. The presence of I. scapularis and B. burgdorferi was confirmed from all 67 Pennsylvania counties. Analyses were performed on 1,363 ticks collected in the fall of 2013 to avoid temporal bias across years. Infection rates were highest for B. burgdorferi (47.4%), followed by Ba. microti (3.5%) and A. phagocytophilum (3.3%). Coinfections included B. burgdorferi+Ba. microti (2.0%), B. burgdorferi+A. phagocytophilum (1.5%) and one tick positive for A. phagocytophilum+Ba. microti. Infection rates for B. burgdorferi were lower in the western region of the state. Our findings substantiate that Lyme disease risk is high throughout Pennsylvania.

Ixodes scapularis, the black-legged tick, harbors multiple organisms and transmits several pathogens to animals and humans. To determine the presence of tick-borne microorganisms carried by I. scapularis in Pennsylvania, 299 adult I. scapularis ticks were collected from across the state and tested with a multiplex bead panel targeting 20 microorganisms. The Luminex bead-based xMAP Ò MultiFLEX Mega Tick Panel detected microorganisms in these ticks, including Anaplasma spp. (1.7%), Borrelia spp. (45.8%), Babesia spp. (16.1%), and Rickettsia spp. (22.1%) at the genera level and identified Anaplasma phagocytophilum (1.7%), Babesia microti (0.7%), Borrelia burgdorferi sensu stricto (45.5%), Borrelia miyamotoi (0.3%), and Rickettsia parkeri (0.7%) at the species level. Babesia spp. reactivity was found to be due to Ba. odocoilei, and Rickettsia spp. reactivity was mainly due to rickettsial endosymbionts.

Although Pennsylvania has recently reported the greatest number of Lyme disease cases in the United States, with the largest increase for PA occurring in its western region, the population biology of the blacklegged tick (Ixodes scapularis Say) has not been adequately characterized in western PA. We studied the seasonal activity of host-seeking I. scapularis larvae, nymphs, and adults in mid-western PA over the course of a year, including a severe winter, and determined their absolute densities and collection efficiencies using replicated mark-release-recapture or removal methods. Our results are compared to those from similar studies conducted in the highly Lyme disease endemic Hudson Valley region of southeastern New York State. The seasonal activity of I. scapularis was intermediate between patterns observed in the coastal northeastern and upper Midwestern United States. Only one peak of larval activity was observed, which was later than the major peak in the Midwest, but earlier than in the northeast. Seasonal synchrony of larvae and nymphs was similar to the northeast, but the activity peaks were much closer together, although not completely overlapping as in the Midwest. Pre- and postwinter relative densities of questing adult I. scapularis were not significantly different from one another. The absolute densities and collection efficiencies of larvae, nymphs, and adults were comparable to results from classic research conducted at the Louis Calder Center in Westchester County, NY. We conclude that the population biology of I. scapularis in mid-western PA is similar to southeastern NYS contributing to a high acarological Lyme disease risk.