Developing attractants and repellents for ticks: promises and challenges.

Historically, some of the most effective tools to counter vector-borne diseases have been those directed against the vectors. Ticks are undergoing a population explosion as evidenced by the recent expansion of their distribution range. Tick control has traditionally relied heavily on pesticides. However, sustained use of acaricides is resulting in resistant tick populations. Multipronged management strategies that build and expand upon innovative control methods are sorely needed. Behavior-modifying chemicals, referred to as semiochemicals, such as pheromones and repellents, offer a first line of personal protection against ticks. We review the current understanding of tick semiochemicals, and how such understanding is leading to the identification of novel chemistries that are effective and safe.

Chemical Ecology of Oviposition Dynamics in Drosophila suzukii (Diptera: Drosophilidae).

Massive economic damage by spotted-wing drosophila (SWD), Drosophila suzukii, results from their unique egg laying behavior wherein a gravid fly pierces a ripening fruit to lay a number of eggs. Gravid SWD flies employ a complex suite of behaviors to find a fruit with the optimum firmness and chemistry. We investigated chemosensory cues potentially contributing to the oviposition behavior of SWD. In a series of experiments, we studied how the fruit ripeness and the underlying volatile chemistry influence oviposition. We tested the comparative attraction of three common fruits implicated in oviposition and determined raspberries to be most attractive in the trap choice assays that strictly measured olfactory preference. Since SWD oviposit in ripening fruits and appear to avoid the overripe fruit, we further evaluated the effect of ripeness on gravid fly attraction. Overripe fruits were significantly more attractive compared to the ripe fruits. The trap choice assays were repeated in an olfactory T-maze paradigm that provided a complex odor environment, potentially experienced by the gravid flies, and the results were mostly comparable. Since our behavioral paradigms indicated a clear olfactory preference for specific ripeness stages (ripe and overripe), we analyzed the constituent volatile odorants from the three ripening stages, revealing discrete odor profiles. Finally, we quantified the total soluble sugars and carbon dioxide concentrations from field-collected raspberries in underripe, ripe, and overripe conditions, revealing that the overripe stage is the most sugar-rich. Together, our results indicate unique chemosensory adaptations in gravid SWD flies for successfully exploiting optimal oviposition resources.

Evaluation of a Novel User-Friendly Arthropod Repellent Gel, Verdegen.

Hand sanitizers are developed as alcohol-based liquid gel formulations, generally used to decrease the amount of infectious agents on human hands. Verdegen, LLC proposed to prepare an arthropod repellent gel for public use when the recent outbreaks of Zika infection vectored through Aedes mosquitoes in the American continents prompted multi-faceted emergency measures. Four different gel formulations were developed, comprising two of the most efficacious commercial arthropod repellent active ingredients, N,N-diethyl-3-methyl benzamide (deet) and 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester (picaridin), each at different concentrations (20 and 33% deet, or 20 and 33% picaridin). Compliance with the use of topical arthropod repellents remains an issue among military personnel. One of the most common complaints by Soldiers is that they do not like how the repellents applied on their skin leave behind an oily or greasy residue. These new gel formulations offer a user-friendly alternative for commonly used arthropod repellents formulations for the military and civilian personnel. We tested the efficacy and protection time of these new gel formulations in comparison with the commercially available cream formulations of deet and picaridin at similar concentrations. Our data show that gel formulations have better topical attributes, and offer equal or better biting protection for up to 48 h against host-seeking Aedes aegypti (L.) (Diptera: Culicidae) female mosquitoes.