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The repellency and toxicity of a CO2-derived cedarwood oil (CWO) was evaluated against actively questing unfed nymphs of four species of hard ticks: Amblyomma americanum (L.), Dermacentor variabilis (Say), Ixodes scapularis Say, and Rhipicephalus sanguineus (Latreille). Using a vertical climb bioassay for repellency, nymphs of these species avoided a CWO-treated filter paper in proportional responses to treatment concentrations. At 60 min of exposure, I. scapularis nymphs were most sensitive with 50% repellency concentration (RC50) of 19.8 µg cm−2, compared with RC50 of 30.8, 83.8 and 89.6 µg cm−2 for R. sanguineus, D. variabilis and A. americanum, respectively. Bioassays determined the lethal concentration for 50% (LC50) and 90% (LC90) mortality of nymphs exposed to CWO in treated vials after 24- and 48-h exposure. After 24 h exposure, the LC50 values were 1.25, 3.45 and 1.42 µg cm−2 and LC90 values were 2.39, 7.59 and 4.14 µg cm−2 for D. variabilis, I. scapularis and R. sanguineus, respectively, but had minimal effect on A. americanum. After 48 h exposure, the LC50 values were 4.14, 0.78, 0.79 and 0.52 µg cm−2, and LC90 values were 8.06, 1.48, 1.54 and 1.22 µg cm−2 for A. americanum, D. variabilis, I. scapularis and R. sanguineus, respectively. The repellency of CWO on tick species decreased with time. The repellency and toxicity bioassays demonstrated concentration-dependent responses of tick nymphs to the oil, indicating the potential of the CO2-derived cedarwood oil be developed as an eco-friendly repellent and/or acaricide. [ABSTRACT FROM AUTHOR]

We evaluated the potential of a granular formulation of Metarhizium brunneum F52 containing microsclerotia (MbMSc granules) for control of Aedes aegypti by targeting eggs. MbMSc granules produced infective conidia within 14 days after application to 2.5 g moist potting soil, producing 5.9 × 105, 2.08 × 106 and 6.85 × 106 conidia from 1, 5 and 25 mg MbMSc granules, respectively. Application of MbMSc triggered premature eclosion of eggs (EC50 = 12 mg) with percentages as high as 31 ± 2.9% and 67 ± 4.3% of the eggs treated with 5 and 25 mg MbMSc granules, respectively, after 14 days on moist filter paper. Premature eclosion of eggs started at 3 days subsequent to MbMSc granule application and survival of larvae was significantly reduced for granule treated eggs (74 ± 2.2%, 39 ± 2.0% and 23 ± 4.9% larvae survived for 1, 5 and 25 mg granule treatments, respectively, EC50 = 4.9 mg). When MbMSc granules were applied in moist potting soil with mosquito eggs, rates of 1, 5 and 25 mg of MbMSc granules significantly reduced adult emergence with only 81 ± 2.1%, 47 ± 1.9%, and 34 ± 2.1% emergence, respectively (EC50 = 7 mg). Eggs treated with increasing concentrations of fungal conidia enhanced premature eclosion of eggs with an EC50 = 1.6 × 106 conidia/mL. Our results demonstrate that MbMSc granules are a promising candidate for control of A. aegypti and that fermentative production of Mb F52 microsclerotia as the active propagule has the potential for use for mosquito control. [ABSTRACT FROM AUTHOR]