Efficacy of Active Ingredients From the EPA 25(B) List in Reducing Attraction of Aedes aegypti (Diptera: Culicidae) to Humans


Mosquitoes of the Aedes genus are vectors for dengue, chikungunya, Zika, and yellow fever viruses. Mosquito repellents are an effective way to prevent mosquito bites and reduce the spread of mosquito-borne diseases. In the early 90s, the U.S. Environmental Protection Agency (EPA) published a list of active ingredients that pose minimum risk to human health that can be used as pesticides or repellents without passing the EPA registration process. The present study examined the efficacy of 21 of the active ingredients listed by the EPA 25 (B) exempt list and five commercially available sprays that only contained active ingredients from the EPA 25(B) list in repelling female Aedes aegypti (L.) females. We performed choice bioassays in a controlled laboratory environment, using a Y-tube olfactometer to determine attraction rates of humans to female Ae. aegypti in the presence of one of the 21 active ingredients and five commercially available repellent sprays. We found that cinnamon oil, peppermint oil, spearmint oil, lemongrass oil, and garlic oil reduced mosquito attraction to human odor. Of the five commercial repellent sprays, only one reduced mosquito attraction for up to 30 min in our assay. The EPA 25 (B) list contains active ingredients that under the conditions of our assay repel Ae. aegypti.

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Lyme Disease in Ohio Continues to Increase

By: Sarah Short and Spencer Blankenship (OSU Biology Undergraduate)

As the 2019 season wraps up, reports indicate that occurrences of Lyme disease continue to increase in Ohio.  From 2009 to 2018, the number of cases has increased over 500%! (Figure 1)


Data from the Ohio Department of Health https://odh.ohio.gov/wps/portal/gov/odh/know-our-programs/zoonotic-disease-program/resources/lyme-disease

Lyme has been expanding westward across Pennsylvania and occurrences in Ohio are primarily in the Eastern half of the state (Figure 2). 2019 reports indicate the worst year yet for Lyme, with 371 cases reported as of October 21st.


Data from the Ohio Department of Health https://odh.ohio.gov/wps/portal/gov/odh/know-our-programs/zoonotic-disease-program/resources/lyme-disease 

Lyme disease is caused by the bacterium Borrelia burgdorferi and is most commonly contracted through a bite from a nymph (an immature tick), however, adult ticks can spread the disease as well. Nymphs are only about 2 millimeters in size, leaving many people unaware that they were bitten. The tick that spreads the disease, Ixodes scapularis (more commonly referred to as the blacklegged tick or deer tick) is increasing in number and expanding its range. It is important that Ohioans be aware of the situation and take steps to prevent infection. See the resources here for information on how to protect yourself outdoors.