Progress 08/01/07 to 10/01/09

Outputs
OUTPUTS: Interspecific competition can be an important determinant of community structure. In some instances the outcome of competition between two species may depend on other environmental conditions, one of which is presence of contaminants such as pesticides in the environment. Competitive interactions may facilitate or repel invaders into new communities and the presence of pesticides may modify the invasive potential of exotic species. Malathion, an organophosphate, is widely used in controlling agricultural pests and mosquitoes worldwide. Malathion is sprayed as an adulticide in terrestrial environments but the droplets disperse and also reach water sources. Studies have shown that small amounts of Malathion, previously considered inconsequential, may in fact increase in lethality when combined with ecological factors like predation and competition in aquatic systems. We tested whether small amounts of Malathion affects competition between two invasive mosquito species Aedes albopictus and Aedes japonicus. We also tested if laboratory rearing affects the outcome of survival of A. albopictus in the presence of malathion. There was a significant negative effect of A. japonicus density (interspecific competition) on A. albopictus survival but this effect was eliminated by the addition of malathion. Laboratory rearing did not affect the tolerance of A. albopictus to malathion but did affect their sensitivity to intraspecific competition such that they became tolerant to crowding. Superior competitive ability of A. albopictus has been argued as one of the major traits facilitating its successful invasion. Our results indicate that malathion use could play a role in enhancing invasive potential of A. albopictus. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: This work was initated as a Rapid Response multistate project designated NE-507. A full proposal, with revised objectives, was officially approved in August 2009 and the new designation is NE-1043. Accordingly, this will be the termination report for this project.

Impacts
Malathion is highly toxic to aquatic invertebrates which brings into question whether other biotic interactions may be modified by this ubiquitous environmental contaminant. Aedes albopictus is a superior competitor to native eastern treehole mosquito A. triseriatus but the presence of dipteran predators promotes predator-mediated coexistence between these two species. Further, A. triseritus is known to be more susceptible to malathion than A. albopictus. Future research will investigate whether malathion decreases the probability of predator-mediated coexistence between competing species due to detrimental effects on these dipteran predators, as well as other competing species with invertebrate predators. Our results indicate that synergistic effects of pesticides and competition could not only affect survival of native species but can also potentially alter the invasive potential of exotic species. The knowledge that the very pesticides that are used in control operations to decrease the spread of invasive species can alternately facilitate invasion of some exotic species indicates that currently implemented control strategies need to be revisited.

Publications

• Farajollahi, A, B Kesavaraju, M Nelder, S Crans & R Gaugler. 2009. A unique larval collection and survival of Orthopodomyia signifera in the presence of the predator Toxorhynchites rutilus septentrionalis. J Am Mosq Contr Assoc 25:370-3.
• Bai, X, B Adams, T Ciche, S Clifton, R Gaugler, S Hogenhout, J Spieth, P Sternberg & P Grewal. 2009. Transcriptomic analysis of the entomopathogenic nematode, Heterorhabditis bacteriophora TT01. BMC Genomics 10:205 doi:10.1186/1471-2164-10-205.
• Bartlett-Healy, K, W Crans & R Gaugler. 2009. Vertebrate hosts and phylogenetic relationships of amphibian trypanosomes from a potential invertebrate vector, Culex territans. J Parasitol 95:381-7.
• Williges, E, A Farajollahi, M Nelder & R Gaugler. 2009. Comparative field analysis of rapid analyte measurement platform and reverse transcriptase polymerase chain reaction assays for West Nile virus surveillance. J Vect Ecol 34:324-8.
• Molaei, G, A Farajollahi, J Scott, R Gaugler & T Andreadis. 2009. Human blood feeding by the recently introduced mosquito, Aedes japonicus japonicus (Diptera: Culicidae) and public health implications. J Am Mosq Contr Assoc 25:210-4.
• Farajollahi, A, B Kesavaraju, D Price, G Williams, S Healy, R Gaugler & M Nelder. 2009. Field evaluation of BG-Sentinel and industry-standard traps for Aedes albopictus and West Nile virus surveillance. J Med Entomol 46:919-25.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Standard surveillance traps in North America for adult Aedes albopictus (Skuse) (Diptera: Culicidae), an invasive mosquito with public health implications, are currently ineffective. The BGS with or without lures collected more Ae. albopictus compared to other trap configurations and was more specific for Ae. albopictus. In Camden County, the BGS with lures collected three times more Ae. albopictus than the CDC (with carbon dioxide only) and five times more than the GT. In Mercer County, BGS with lures collected the most mosquitoes, with three times more Ae. albopictus than the CDC with all lures and fifty times more than the GT. The BGS collected more male Ae. albopictus than other traps in both counties, providing further population monitoring. The GT and BGS provided a relative measure of the enzootic activity of West Nile virus in Culex spp. and the potential epidemic activity of WNV in Ae. albopictus. The BGS provides effective chemical and visual cues for host-seeking Ae. albopictus and should be utilized as a part of existing surveillance programs and new iniatives targeting this mosquito. We evaluated a novel method of controlling Ae. albopictus immatures by using two products already available but used in tandem, one with a quick kill and another with a long residual. Specifically, we evaluated a monomolecular film (Agnique) and (S)-methoprene (Altosid) in the laboratory and under field conditions. In the laboratory, combinations of the two products performed better than controls and products on their own for the first 40 d, indicating synergistic or additive effects of the combined products. Agnique alone killed over 95% of larvae in 24 h and over 80% in 20 d in the laboratory, while Altosid/Agnique-containing treatments provided over 95% control for greater than 100 d in the laboratory. Field trials on natural populations of Ae. albopictus, using a single combination of products, provided 100% control for greater than 30 d and significantly more kill than controls for an additional 30 d. Agnique and Altosid, when used together in difficult-to-treat locations, provide long-term control of Ae. albopictus immatures and reduce the number of treatments needed by mosquito control operators. We tracked statewide changes in populations of the Asian tiger mosquito and its association with West Nile virus from 2003-2007. Aedes albopictus abundance has increased in New Jersey since 2003 along the urban corridor between New York City and Philadelphia with expanding populations detected in suburban and rural areas of the state. Aedes albopictus has invaded all counties of New Jersey except for two northwest-rural counties (Sussex and Warren). West Nile virus was detected in Ae. albopictus throughout several foci in NJ during the study, underscoring the public health significance of this mosquito. PARTICIPANTS: Mark Nelder, Faculty research assistant. Banugopan Kesavaraju, Post doctoral research associate. Isik Unlu, Biologist, Mercer County mosquito control. Ary farajollahi, Supervisor, Mercer county mosquito control. Sean Healy, Biologist, Monmouth county mosquito control. Taryn Crepeau, Biologist, Mounmouth county mosquito control. Collaborations with Monmouth county mosquito control and Mercer county mosquito control. TARGET AUDIENCES: Mosquito control personnel in New Jersey and any other region with infestations of Ae. albopictus. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
In urban New Jersey, the BGS trap has improved the ability of mosquito control operations to monitor and react to Ae. albopictus (AF, unpublished observations). The increase in catch with the BGS can provide much needed information on the involvement of Ae. albopictus in WNV ecology and accurate determination of population densities in response to resident complaints. In 2006, 37 travelers returning from India and La Reunion to the northeast U.S. were infected with chikungunya virus, exemplifying the continued threat of exotic pathogens entering and establishing in the U.S. Considering U.S. populations of Ae. albopictus are efficient laboratory vectors of chikungunya virus and Ae. albopictus was the principle vector in a chikungunya outbreak in Italy, an effective means of surveillance is crucial for protecting U.S. public health. Where the Asian tiger mosquito is established in the U.S., the BGS trap should be an integral part of any existing or planned surveillance program and, where Ae. albopictus has not become established, the BGS trap can provide an early warning system for detecting incipient invasion. Current control measures for Ae. albopictus immatures have proven ineffective, labor intensive, and economically infeasible. For effective control of Ae. albopictus immatures, cost-effective and long-acting measures are needed. We tested the duel use of a monomolecular film (Agnique) and an insect growth regulator ((S)-methoprene, Altosid) against immature stages of Ae. albopictus under field and laboratory conditions. In the laboratory, we tested 9 combinations of the products and the products on their own against controls for their efficacy in controlling 4th instar larvae from developing to adulthood over a period of 120 d. We have documented population changes of Ae. albopictus populations in New Jersey with increases in range and relative abundance; trends that could become common across other developed regions in the US where climatic and environmental conditions are suitable for colonization. We have also documented associations between WNV and Ae. albopictus from field collections, further underlining the public health importance of this invasive mosquito. Contributing to population changes of Ae. albopictus is the ubiquitous nature of man-made container habitats within these densely populated regions and the difficulty in either removing refuse or treating artificial containers with conventional biological or chemical insecticides. Mosquito control in New Jersey has traditionally focused on rural mosquito species such as the inland floodwater mosquito Aedes vexans (Meigen) and the Eastern salt marsh mosquito Aedes sollicitans (Walker). In contradistinction, Ae. albopictus is an urban and suburban problem pleading for a paradigm shift in mosquito control. Expanded surveillance for Ae. albopictus and subsequent control are urgently needed within the urban landscape where the potential for introduction of an exotic arbovirus is high.

Publications

• No publications reported this period

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: To ensure public health in the state of New Jersey, the Center for Vector Biology conducted the surveillance of mosquitoes to monitor eastern equine encephalitis virus (EEE) and West Nile virus (WNV). Activities included the collection of mosquitoes from resting boxes (for EEE) and other mosquito traps (for WNV, with the aid of the 21 county mosquito control agencies) to the interpretation and dissemination of testing results from the state's public health labs. In 2007, twenty-one weekly reports were compiled and disseminated to county and state agencies during the mosquito season. Surveillance of EEE indicated activity typical of moderate dissemination in the enzootic vector Culiseta melanura with eleven positive pools found out of 445 pools submitted to the public health labs. No bridge vectors were found positive. Activity began after August first and one horse case resulted. Of the eleven positive pools, eight were from resting boxes monitoring long-term sites and three were from traps used for West Nile surveillance. Chicken flocks maintained by Cape May County were also reported to have converted positive for EEE antibodies. Results from the state program indicated that the abundance of vector population present to detect positive pools can be low (fifty boxes used). Surveillance of WNV used a variety of traps to find most activity in the urban/suburban corridors between New York City and Philadelphia. Of the 331 positive pools from the 6,623 submitted to the state public health lab, the majority of positive pools was found in Culex pipiens (primary enzootic vector) or mixed Culex pools. Potential bridge vectors were also found positive, including Aedes albopictus (4), Aedes japonicus (2), Culex salinarius (8) and Coquillettidia perturbans (1). Two horse cases and one human case developed. WNV activity was similar to the previous year. While dead crows continued to be found, their numbers initially appeared outside the urban/suburban area where most positive mosquito pools were detected. Reports were stored on Rutgers University computers and made permanently available through the Web. Reports included EEE mosquito pool testing results, minimum field infection rates and their significance, population levels and seasonal changes of Culiseta melanura (the enzootic vector of EEE) with interpretations of population changes, concurrent climatic changes in New Jersey, and EEE activity in the US. For WNV, reports included the WNV pool results per species, the number of positive pools and MFIR values per species within each county and the national activity level of WNV. Events included the participation at two annual mosquito control meetings (NJMCA and NMCA). We presented a summation of virus activity for EEE and WNV to an audience that included superintendents, mosquito biologists, and state control agencies. PARTICIPANTS: Dr. Randy Gaugler, PI; Dr. Lisa Reed, Co-PI; Linda McCuiston, Mosquito Identification Specialist; Scott Crans, Office of Professional Continuing Education; Dana Price, Field Coordinator; Audrey McGough, field technician New Jersey Department of Environmental Protection, State Mosquito Control Coordination, partner organization; New Jersey Department of Health and Senior Services, Public Health and Environmental Laboratories, partner organization. TARGET AUDIENCES: County mosquito control agencies, including superintendents, directors, biologists and inspectors. State mosquito control agencies. County public health individuals.

Impacts
Superintendents and directors determined the direction and degree of mosquito control their agency perform. Weekly reports on positive mosquito pools, changes in seasonal vector populations and national perspectives on virus activity were made available to all of the 21 county mosquito control agency superintendents and directors plus the state agency that aids counties in aerial control of mosquitoes. The presence of virus and the population level of vectors provided critical information for agency action. A superintendent or director's change of knowledge based on the surveillance reports, combined with their own mosquito population surveillance efforts, were necessary to effectively manage an integrated control program based on scientific evidence on the level of disease and disease vectors present. When positive mosquito pools were found and programs informed, this change of knowledge effected a change in action that resulted in control of potentially disease-inflicting populations of mosquitoes. Data from this program will be used to model the risk associated with WNV. This model will be part of the arsenal of information that county superintendents and directors can use to further refine their IPM programs in the control of disease vectors.

Publications

• Reed, L. 2007 Vector surveillance of eastern equine encephalitis and West Nile virus in New Jersey, 2006. Proceedings of the New Jersey Mosquito Control Association (in press).