Susceptibility of Field-Collected Mosquitoes in Central New Jersey to Organophosphates and a Pyrethroid

Insecticide resistance alleles in wetland and residential populations of the West Nile virus vectorCulex pipiensin New Jersey

“…Although recent studies did not observe significant resistance to Temephos (an organophosphate) and Sumithrin (a synthetic pyrethroid) in Cx. pipiens in central New Jersey, our results stress the need for continued monitoring to confirm whether selection is occurring and to understand better the stability of resistant alleles in these populations.…”

“…In spite of the absence of L1014S, the wide distribution of the L1014F mutation is concerning, as pyrethroids have surpassed OPs as the most common class of insecticide in use in the United States after the US Environmental Protection Agency restrictions on OPs were enacted from 2000–2001 . The low frequency of the L1014F mutation indicates that pyrethroids are still an effective class of insecticides in New Jersey, which is supported by recent bioassays . However, although the frequency of homozygous individuals was low, it is important to recognize that the observed deviations from Hardy–Weinberg equilibrium in the small wetland and New Brunswick populations suggest that selection for resistance is occurring.…”

“…To the best of our knowledge, the last statewide evaluation of the presence of resistance to OPs in Cx. pipiens in New Jersey was published in 1981, and there have been only a few published assessments of resistance to pyrethroids …”

Biting Deterrence, Repellency, and Larvicidal Activity of <I>Ruta chalepensis</I> (Sapindales: Rutaceae) Essential Oil and Its Major Individual Constituents Against Mosquitoes

“…Several other studies have used a 24 h holding period before recording mortality (Juntarajumnong et al 2012;Marcombe et al 2014), although Sun et al (2014) described 100% mortality in only 40 min at a higher dose. The test dosage (200 µg/bottle) could be another reason for the lack of mortality we observed, but preliminary testing at a range of doses as high as 500 µg/bottle and 1,000 µg/bottle showed no increased mortality at dosages above 200 µg/bottle.…”

“…Initial bottle assays showed no difference in mortality at concentrations greater than 200 µg/bottle (data not shown), therefore, we used lower doses of 100 and 200 µg/bottle (Table 1), which are above the CDC recommendation of 50 µg/bottle for Aedes (Brogdon & Chan 2010). However, the CDC recommendation is suggested as a starting point, others have tested concentrations up to 474 µg/bottle (Sun et al 2014). Complete (100%) mortality was not achieved for any of the 4 strains tested at these doses within the 2-h duration of the study, although it was most effective against the ELKTON strain (50 µg/bottle 98 ± 1.8%, 100 µg/bottle 98 ± 1.5%, and 200 µg/bottle 98 ± 1.7%), compared with the other strains.…”