Invasive tephritid fruit flies collectively pose a significant economic challenge to agricultural pest management globally. Insecticide resistance to a number of previously effective chemical classes has increased the risk these pests pose as management options become limited. We evaluated the efficacy of a novel class of peptide-based biorational insecticides containing the active ingredient, GS-omega/kappa-Hxtx-Hv1a (Hv1a), against four of tephritid species, oriental fruit fly (Bactrocera dorsalis), melon fly (Zeugodacus cucurbitae), Mediterranean fruit fly (Ceratitis capitata, “Medfly”), and Malaysian fruit fly (B. latrifrons). This assessment aimed to determine whether Hv1a has the potential for effective management of tropical tephritids, particularly in regions where insecticide resistance has developed to other products. We conducted two sets of screening assays with different methods of exposure, oral and topical, and compared survival over time in response to increasing concentrations of Hv1a up to 3.86 mg/ml. We found that efficacy was species dependent: Ceratitis capitata was susceptible following topical exposure, while the other species of fruit fly were not. While Medfly was susceptible following oral ingestions as well, the dose required to achieve mortality was greater than topical. We observed that mortality continued to decline up to 72 hours after exposure, indicating a delayed effect similar to other reduced-risk insecticidal products such as fipronil. For this reason, Hv1a may be useful as a horizontal transfer tool in conjunction with C. capitata male pheromone lures.

All data analysis was performed using R version 4.1.3 “One Push-Up”, R Core Team (2021). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria; https://www.R-project.org/). Probit analysis using the package “ecotox” (Hlina et al., 2021) was used to calculate LC50 values for each tephritid species. Survival analysis was conducted using Cox proportional hazards models with the packages “survival” (Therneau, 2022; Therneau & Grambsch, 2000) and “survminer” (Kassambara et al., 2021). Posthoc analysis was conducted using the package “emmeans” (Lenth, 2022) to determine pairwise differences in significance between concentrations for each species.