Repellents effectively disrupt the olfactory orientation of Sitophilus granarius to wheat kernels

Abstract

Sitophilus granarius (L.) (Coleoptera: Dryophthoridae) is one of the most important pests of stored cereals worldwide. Sustainable control means of this pest are urgently needed mainly owing to legislative limits to the commonly used fumigants and broad-spectrum contact insecticides. The effectiveness of one alcohol and seven aliphatic aldehydes, previously identified as repellents, to disrupt adult granary weevils orientation towards wheat grains were assessed in two-choice olfactometer bioassays. In the dose range tested, all compounds effectively reduced wheat grains attractiveness and inhibited the preferential orientation of adult weevils towards the host substrate. Moreover, at the highest doses the three aldehydes butanal, (E)-2-hexenal, and (E,E)-2,4-nonadienal, their binary (1:1) and the ternary (1:1:1) blends induced a significant preferential orientation of insects to the control, indicating actual repellence. Among all repellent stimuli, the ternary blend and the binary blends of butanal plus (E)-2-hexenal and (E)-2-hexenal plus (E,E)-2,4-nonadienal were the most effective. At certain doses, the observed insect response to these blends was more intense than that expected from individual compounds, demonstrating synergistic interactions between the blend components. Repellent aldehydes and their mixtures were effective in disrupting the olfactory orientation of adult granary weevil to a highly attractive oviposition and food substrate. Future development of proper formulations of these bioactive compounds is promising to set up semiochemical-based control means for this pest.

Fumigant toxicity of eugenol and its negative effects on biological development of Callosobruchus maculatus L

“…In addition to the good toxicity of eugenol, fumigant application of this compound also resulted in a significant inhibition of the offspring emergence even at sublethal doses. Negative effects on biological traits including rates of growth, grain consumption and progeny emergence of C. maculatus can be the results of direct mortality of adults, repellency, oviposition or progeny deterrence and growth inhibition (Athanassiou et al, 2014;Germinara et al, 2015). Similar effects have been reported in Sitophilus zeamais when exposed to other essential oils or their monoterpenes constituents (Nattudurai et al, 2017;Silva et al, 2017).…”

Exposure to cyantraniliprole causes mortality and disturbs behavioral and respiratory responses in the coffee berry borer (Hypothenemus hampei)

“…Various insect pests show altered behavioral responses when exposed to insecticides; insects are reported to leave toxic environments as soon as they detect toxic compounds . Studies show that synthetic insecticides can disrupt recognition of the host substrate, influencing the olfactory orientation and walking behavior of insects . Volatile insecticides may enter insects through the spiracles and tracheae during respiration .…”

Acute Toxicity and Sublethal Effects of Lemongrass Essential Oil and Their Components against the Granary Weevil, Sitophilus granarius

“…Some insect pests alter their locomotion when exposed to lemongrass essential oil and its components and avoided the toxic environments after the detection of the chemical components [ 21 , 22 , 42 ]. Plant essential oils have been claimed to disrupt the recognition of the substrate, which impairs the orientation and locomotor activity of insects [ 29 , 44 , 64 ]. According to the results here obtained, the odor of essential oil and its components is repulsive to S. granarius .…”