Insecticidal and Synergistic Potential of Three Monoterpenoids against the Yellow Fever Mosquito, Aedes aegypti (Diptera: Culicidae), and the House Fly, Musca domestica (Diptera: Muscidae)

Abstract

As resistance to the limited number of insecticides available for medical and veterinary pests becomes more widespread, there is an urgent need for new insecticides and synergists on the market. To address this need, we conducted a study to assess the toxicity of three monoterpenoids—carvone, menthone, and fenchone—in comparison to permethrin and methomyl against adults of two common pests: the yellow fever mosquito (Aedes aegypti) and the house fly (Musca domestica). We also examined the potential for these monoterpenoids to enhance the effectiveness of permethrin and methomyl when used together. Finally, we evaluated the ability of each monoterpenoid to inhibit acetylcholinesterase, comparing them to methomyl. While all three monoterpenoids performed relatively poorly as topical insecticides (LD50 > 4000 ng/mg on M. domestica; >6000 ng/mg on Ae. aegypti), they synergized both permethrin and methomyl as well as or better than piperonyl butoxide (PBO). Carvone and menthone yielded synergistic co-toxicity factors (23 and 29, respectively), which were each higher than PBO at 24 h. Currently, the mechanism of action is unknown. During preliminary testing, symptoms of acetylcholinesterase inhibition were identified, prompting further testing. Acetylcholinesterase inhibition did not appear to explain the toxic or synergistic effects of the three monoterpenoids, with IC50 values greater than 1 mM for all, compared to the 2.5 and 1.7 µM for methomyl on Aedes aegypti and Musca domestica, respectively. This study provides valuable monoterpenoid toxicity and synergism data on two pestiferous insects and highlights the potential for these chemistries in future pest control formulations.

Adult Mosquito and Butterfly Exposure to Permethrin and Relative Risk Following ULV Sprays from a Truck-Mounted Sprayer

“…Permethrin risk to adult butterflies and mosquitoes following ULV sprays was evaluated by comparing cumulative frequency distributions of measured exposures and available toxicity data. Toxicity data for five different mosquito species (Aa, Cq, Aedes albopictus , Anopheles gambiae and Anopheles quadrimaculatus ) include those reported in the literature (Pridgeon et al 2008 ; Chansang et al 2018 ; Estep et al 2018 ; Baker et al 2023 ) and determined in the present study. Toxicity data for adult butterflies ( Heliconius charitonia , Eumaeus atala , Junonia coenia , Vanessa cardui , Anartia jatrophae ) also include those reported in the literature (Salvato 2001 ; Hoang et al 2011 ).…”

“…A risk comparison for butterflies and mosquitoes requires data on toxicity and exposure for both insect groups. Several studies have reported 24-h LD50s for adult mosquitoes exposed to permethrin (Pridgeon et al 2008 , Agramonte et al 2017 , Chansang et al 2018 , Estep et al 2018 , Taylor-Wells et al 2018 , Tak et al 2020 and Baker et al 2023 ). The toxicity values reported in those studies ranged from 49 to 6960 ng/g for five different species ( Culex quinquefasciatus Say, Anopheles quadrimaculatus Say, Aedes aegypti Linnaeus, Anopheles gambiae Giles and Aedes albopictus Skuse).…”

Insecticidal Activity of Essential Oils and Their Synergistic Effect on Improving the Efficacy of β-Cypermethrin against Blattella germanica

“…The synergistic effects of these compounds on other compounds have also been reported in various insects. 45,46 Notably, there was no positive correlation between the concentration of the compounds and their synergistic effect on the insecticides; instead, the synergistic effect of most of the compounds decreased with an increasing concentration. Among all of the EOs tested, wormseed oil had the best synergistic effect on βcypermethrin against B. germanica.…”

Point Protection with Transfluthrin against Musca domestica L. in a Semi-Field Enclosure

“…The CAR21 susceptible strain of M. domestica (susceptibility confirmed by Baker et al [11]) and WHF strain of M. domestica used in this study were reared at the USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology (CMAVE), using the protocols outlined in Geden et al [12]. The "wild" house flies (WHF) were originally collected from dairy farms in Florida, Minnesota, California, and Nebraska in 2014-2015.…”