Susceptibility of Brazilian Populations of Anastrepha fraterculus, Ceratitis capitata (Diptera: Tephritidae), and Drosophila suzukii (Diptera: Drosophilidae) to Selected Insecticides

Neotropical Flora's Contribution to the Development of Biorational Products for Drosophila suzukii Control

Essential oils (EOs) produced by aromatic plants belonging to different families, such as Asteraceae, Lamiaceae, Lauraceae, Myrtaceae, and Piperaceae, are generally suggested as potential sources of new molecules with insecticidal activity. The EOs are constituted bioactive molecules that may have to control Drosophila suzukii (Matsumura), a serious economic invasive pest of small fruits worldwide. Currently, the control strategy against D. suzukii depends especially on treatment with synthetic insecticides. Due to impacts to human health and the environment, efforts have been made to seek efficient insecticides in chemical pest control. Thus, sixty-five oils extracted from plants were selected to find new alternative types of insecticides active against D. suzukii. The monoterpenes, such as limonene, α-pinene, 1,8-cineole, linalool, menthol, geranial, and neral, were the most representative, which stand out for their insecticidal efficiency. The OEs demonstrated to be used in the management of D. suzukii, thus being an effective strategy to control this pest, ensuring crop protection and agricultural sustainability. Therefore, the substitution by natural products or eco-friendly pesticides instead of synthetic pesticides represents a notable option to mitigate harmful effects on human health and the environment.

Essential Oils as a Source of Ecofriendly Insecticides for Drosophila suzukii (Diptera: Drosophilidae) and Their Potential Non-Target Effects

The spotted wing drosophila (Drosophila suzukii) is one of the main invasive pests of small fruits in the world. Thus, 19 essential oils (EOs) were selected to analyze the effects through toxicity and repellency on oviposition and D. suzukii adults. In addition, their lethal and sublethal effects on the pupal endoparasitoid Trichopria anastrephae were evaluated. The EOs of C. flexuosus and Mentha spp. had the highest toxicity observed in the topical application bioassay for D. suzukii. In contrast, the EOs of C. verum, C. citratus QT citratus, and C. winterianus showed the highest toxicity in the ingestion bioassay for D. suzukii. The dry residues of C. verum and C. citratus QT citratus reduced the oviposition of D. suzukii. In the repellency bioassays, the 19 EOs analyzed repelled ≅ 90% of the D. suzukii females. All EOs evaluated using the LC₉₀ values of the products provided mortality of less than 20% of T. anastrephae adults and did not cause a reduction in the parasitism of surviving T. anastrephae females. We conclude that the EOs evaluated have the potential to be used in the management of D. suzukii. They can also serve as selective active ingredients for the formulation and synthesis of new biopesticides.

Toxicity and Transgenerational Effects of Insecticides on Trichopria anastrephae (Hymenoptera: Diapriidae)

Trichopria anastrephae Costa Lima, 1940 (Hymenoptera: Diapriidae) is a pupal endoparasitoid of Drosophila suzukii Matsumura, 1931 (Diptera: Drosophilidae) in Brazil. This species is of great agricultural importance and is almost exclusively managed by organophosphate, spinosyn, pyrethroid, neonicotinoid, and avermectin insecticides. However, frequent application of insecticides can have negative effects on the parasitoid. The objective of this study was to evaluate the lethal and transgenerational toxicity of five insecticides on T. anastrephae adults during the F₀, F₁, and F₂ generations. Drosophila suzukii puparia were sprayed prior to their exposure to T. anastrephae for 24 h. Parameters evaluated in generation F₀ were mortality and rate of parasitism. After the emergence of the F₁ generation, the emergence rate and sex ratio were analyzed. Then, pairs of parasitoids were selected from F₁ and pupae; the host was offered to evaluate parasitism, emergence, and sex ratio of the F₂ generation. In the F₀ generation, malathion was the only insecticide that caused 100% mortality of adults of T. anastrephae. However, all insecticides tested affected the parasitism rate, being classified as moderately to slightly harmful. In F₁, the emergence of T. anastrephae was also affected, making the insecticides moderately to slightly harmful. However, there were no significant differences in the sex ratio and parasitism rate or the parameters evaluated in F₂, which means that all products were classified as harmless. These results are important for the development of Integrated Management programs for D. suzukii and for the conservation of natural populations of T. anastrephae in the field.