Insecticidal and oviposition deterrent effects of essential oils of Baccharis spp. and histological assessment against Drosophila suzukii (Diptera: Drosophilidae)

Abstract

The diverse flora of the Atlantic Forest is fertile ground for discovering new chemical structures with insecticidal activity. The presence of species belonging to the genus Baccharis is of particular interest, as these species have shown promise in pest management applications. The objective of this study is to chemically identify the constituents expressed in the leaves of seven species of Baccharis (B. anomala DC., B. calvescens DC., B. mesoneura DC., B. milleflora DC., B. oblongifolia Pers., B. trimera (Less) DC. and B. uncinella DC.) and to evaluate the toxicological and morphological effects caused by essential oils (EOs) on the larvae and adults of Drosophila suzukii (Diptera: Drosophilidae). Chemical analysis using gas chromatography-mass spectrometry (GC–MS) indicated that limonene was the main common constituent in all Baccharis species. This constituent in isolation, as well as the EOs of B. calvescens, B. mesoneura, and B. oblongifolia, caused mortality in over 80% of adults of D. suzukii at a discriminatory concentration of 80 mg L−1 in bioassays of ingestion and topical application. These results are similar to the effect of spinosyn-based synthetic insecticides (spinetoram 75 mg L−1) 120 h after exposure. Limonene and EOs from all species had the lowest LC50 and LC90 values relative to spinosyn and azadirachtin (12 g L−1) in both bioassays. However, they showed the same time toxicity over time as spinetoram when applied to adults of D. suzukii (LT50 ranging from 4.6 to 8.7 h) in a topical application bioassay. In olfactometry tests, 92% of D. suzukii females showed repellent behavior when exposed to the EOs and limonene. Likewise, the EOs of B. calvescens, B. mesoneura, and B. oblongifolia significantly reduced the number of eggs in artificial fruits (≅ 7.6 eggs fruit−1), differing from the control treatment with water (17.2 eggs fruit−1) and acetone (17.6 eggs fruit−1). According to histological analyses, the L3 larvae of D. suzukii had morphological and physiological alterations and deformations after exposure to treatments containing EOs and limonene, which resulted in high larval, pupal, and adult mortality. In view of the results, Baccharis EOs and their isolated constituent, limonene, proved to be promising alternatives for developing bioinsecticides to manage of D. suzukii.

Essential Oil Content and Chemical Composition in 14 Selected Species From a Stretch of Restinga in Southern Brazil

“…Limonene was the only common constituent in all the species analyzed, with a concentration ranging between 4.9% and 13.0% (Table 2). This similarity may be associated with the role of limonene as a precursor of monoterpene biosynthesis (Trombin-Souza et al, 2017;de Souza et al, 2021). Limonene was only the most abundant constituent in Schinus terebinthifolius, accounting for 10.2% of the essential oil.…”

Atividade larvicida do óleo essencial de Rosmarinus officinalis e seu composto majoritário contra Drosophila suzukii

“…Para mitigar esses efeitos, os óleos essenciais (OEs) podem ser uma alternativa ambientalmente segura frente aos sintéticos, pois possuem múltiplos modos de ação, como inibidores da acetilcolinesterase e do ácido gama-aminobutírico e ligantes dos receptores de octopamina (JANKOWSKA et al, 2017). Isso pode diminuir ou evitar a evolução da resistência, assim como uma alta volatilidade que reduz a presença de resíduos nos frutos (SOUZA et al, 2020b(SOUZA et al, , 2021.…”

“…A análises histológicas seguiram o protocolo descrito por Souza et al (2021). Para isso, duas horas após o contato com OE de R. officinalis e eucaliptol, as larvas de D. suzukii (n = 20) foram fixadas em 10% de formalina tamponada para evitar a autólise dos tecidos.…”

“…Cinco seções longitudinais foram incluídas em parafina, e as larvas foram seccionadas em série (4 μm de espessura) e coradas com hematoxilina-eosina. Os danos microscópicos em D. suzukii foram analisados com auxílio de um microscópio estereoscópico (40× de ampliação) e realizadas as análises descritivas (SOUZA et al, 2021).…”

Essential Oil Variation in Brazilian Varronia curassavica Jacq. in Response to Drying and Edaphoclimatic Conditions

“…The Atlantic Forest is one of 25 recognized biodiversity hotspots globally; it is home to more than 19,000 species, of which 35% are endemic (Oliveira et al, 2019;Souza et al, 2021). Despite the remarkable endemism levels that make the Atlantic Forest one of the most distinct regions in the Neotropics (Ribeiro et al, 2011;Souza et al, 2020), little is known about the aromatic plants' potential genetic resources in this biome.…”