Locomotory and physiological responses induced by clove and cinnamon essential oils in the maize weevil Sitophilus zeamais

Abstract

Plant essential oils have been suggested as a suitable alternative for controlling stored pests worldwide. However, very little is known about the physiological or behavioral responses induced by these compounds in insect populations that are resistant to traditional insecticides. Thus, this investigation evaluated the toxicity (including the impacts on population growth) as well as the locomotory and respiratory responses induced by clove, Syzygium aromaticum L., and cinnamon, Cinnamomum zeylanicum L., essential oils in Brazilian populations of the maize weevil Sitophilus zeamais. We used populations that are resistant to phosphine and pyrethroids (PyPhR), only resistant to pyrethroids (PyR1 and PyR2) or susceptible to both insecticide types (SUS). The PyPhR population was more tolerant to cinnamon essential oil, and its population growth rate was less affected by both oil types. Insects from this population reduced their respiratory rates (i.e., CO2 production) after being exposed to both oil types and avoided (in free choice-experiments) or reduced their mobility on essential oil-treated surfaces. The PyR1 and PyR2 populations reduced their respiratory rates, avoided (without changing their locomotory behavior in no-choice experiments) essential oil-treated surfaces and their population growth rates were severely affected by both oil types. Individuals from SUS population increased their mobility on surfaces that were treated with both oil types and showed the highest levels of susceptibility to these oils. Our findings indicate that S. zeamais populations that are resistant to traditional insecticides might have distinct but possibly overlapping mechanisms to mitigate the actions of essential oils and traditional insecticides.

Insecticidal activity of garlic essential oil and their constituents against the mealworm beetle, Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae)

“…Respiratory rate and body mass of insects can represent the sum of the energy demands of the physiological processes of insects that are necessary to produce defense mechanisms against the essential oils and toxic compounds495051. Thus, low respiration rate is an indicator of physiological stress, and essential oils can compromise insect respiration by impairing muscle activity, leading to paralysis495051. Several studies of plant volatile and their constituents were shown to effectively disrupt the recognition process of the host substrate and influence the walking behavior on insects5253.…”

Sexual Success after Stress? Imidacloprid-Induced Hormesis in Males of the Neotropical Stink Bug Euschistus heros

“…Imidacloprid has distinct pharmacological profiles in diverse subtypes of insect nAChRs [ 34 – 38 ]. Furthermore, such alterations in walking behavior has been shown to be a strategy used by insects to overcome the actions of natural and synthetic insecticides [ 19 , 29 , 48 – 50 , 52 ]. Such higher walking activity in exposed males of E .…”

“…Behavioral bioassays were conducted in arenas that were fully treated either with imidacloprid residues (at 0.042 μg a.i./cm 2 , the equivalent of 1% of the field rate dose), or with deionized water (control), following methods previously described elsewhere [ 48 – 52 ]. Briefly, the filter paper disks were impregnated with 1 mL of insecticide or water solution and, after drying for 20 min, the filter paper was placed in Petri dishes (135 × 20 mm).…”

Deltamethrin toxicity and impaired swimming behavior of two backswimmer species

“…Notably, short‐term exposure to deltamethrin did not affect the swimming activity of M. bentoi or B. tarsalis as a group, which might be the result of a less intense insecticide poisoning per individual. With backswimmers, individual swimming activity is reduced as the density increases , and in general, reduced locomotor activity is apparently a strategy widely used by insects to mitigate the effects of insecticide toxicity .…”