Andean Flora as a Source of New Repellents against Insect Pests: Behavioral, Morphological and Electrophysiological Studies on Sitophilus zeamais (Coleoptera: Curculionidae)

Abstract

Sitophilus zeamais (Motschulsky) is considered as one of the most destructive foodstuff pests. Due to their efficiency, low toxicity for mammalians and low environmental impact, plant-derived essential oils (EOs) are promising tools for pest control. In particular, the OEs extracted from Lamiaceae are considered among the most bioactive in terms of repellent and/or insecticidal effect. Here, we investigated the repellence of the EOs extracted from two aromatic plant species typical of the flora of the Ecuadorian Andes, Clinopodium tomentosum and C. nubigeum, against adults of S. zeamais. The behavioral assays carried out at concentrations ranging from 0.7 to 23.9 μL L−1 air in a two-way static olfactometer showed a significant repellent effect starting from the concentration of 8.4 mL L−1 air both for the EO of C. nubigenum and C. tomentosum. We also carried out a complete structural analysis of the antenna of S. zeamais using scanning (SEM) and transmission electron microscopy (TEM), in order to characterize the olfactory sensilla equipment. In this species, there is no sexual dimorphism also as regards to the antennal morphology and the sensilla type and distribution. We identified six type of sensilla, among which at least three types (Sensillum Trichoideum 1, Sensillum Trichoideum 2 and Grooved Peg Sensillum) can be considered as olfactory. Electroantennography (EAG) recordings carried out on S. zeamais revealed a positive dose-response to both EOs, without differences between the two sexes.

Allium sativum, Rosmarinus officinalis, and Salvia officinalis Essential Oils: A Spiced Shield against Blowflies

“…In our experiments, the A. sativum EO elicited an overall stronger EAG response than the other two EOs tested. Nevertheless, there was not a clear concentration dependent response, as observed in other dose response experiments, using EOs as stimuli [34]. Compared with the solvent, A. sativum and S. officinalis EOs determined significant antennal responses from the concentration of 10 µg µL −1 , while EAG responses at 1 µg µL −1 were similar to the solvent, which indicates a threshold of perception for these EOs concentrations.…”

Essential Oils as Post-Harvest Crop Protectants against the Fruit Fly Drosophila suzukii: Bioactivity and Organoleptic Profile

“…After each bioassay, the Plexiglas arena and the glass lid were first washed for about 30 s with hexane, then with warm water at 35–40 °C. The arena was then cleaned in a water bath with mild soap for about 5 min, rinsed with hot water for about 30 s, and finally rinsed with distilled water at room temperature [ 45 ].…”

“…The repellence/attractiveness of both EOs towards D. suzukii adults was evaluated in a two-choice bioassay olfactometer, a Plexiglas unit (15 × 15 × 3 cm) according to Romani et al [45] with minor changes. In the centre of the unit, a circular chamber (i.e., the specimen release chamber, diameter 4 cm) was connected to two identical chambers by means of two linear paths (length, 2 cm; width, 1 cm), forming a 90 • angle.…”

Attractant Effect of Eucalyptus globulus (Labill) and Foeniculum vulgare (Mill.) Essential Oils on Aegorhinus superciliosus (Guérin) (Coleoptera: Curculionidae)

“…Semiochemical properties of essential oils (EOs) and their constituents are increasingly used for integrated pest management programs in order to reduce the application of chemical pesticides (Isman 2000;Isman and Machial 2006;Koul et al 2008;van Tool et al 2012). EOs are natural extracts composed of a wide variety of volatile compounds, such as monoterpenes, sesquiterpenes, aromatic phenols, alcohols, ethers, esters, aldehydes, and ketones, which determine the characteristic aroma of the plant (Tripathi et al 2009;Romani et al 2019). They occur as secondary metabolism products in several plant groups and play an important protective role against several pathogens, such as bacteria, fungi, and insects (Bakkali et al 2008;Gols 2014).…”