Host Volatiles Potentially Drive Two Evolutionarily Related Weevils to Select Different Grains

Area of Science:

• Agricultural Entomology
• Chemical Ecology
• Stored Product Protection

Background:

• Sitophilus zeamais (maize weevil) and Sitophilus oryzae (rice weevil) cause significant economic losses in stored grains globally.
• Environmentally friendly pest control strategies are urgently needed for these destructive insects.

Purpose of the Study:

• To analyze the olfactory-mediated grain selection preferences of maize and rice weevils.
• To identify key volatile compounds influencing weevil behavior.
• To inform the development of integrated pest management (IPM) strategies, such as pull-push systems.

Main Methods:

• Olfactory-mediated selection bioassays using maize, paddy, and wheat.
• Gas chromatography-mass spectrometry (GC-MS) for volatile compound analysis.
• Y-tube olfactometry to assess weevil responses to specific volatile chemicals.

Main Results:

• Maize weevils showed a preference for maize > paddy > wheat.
• Rice weevils primarily migrated towards wheat.
• Key attractive volatiles identified: 2-ethylhexanol, piperitone, and (+)-Δ-cadiene for both species; limonene attractive only to rice weevils.
• Maize weevils exhibited higher sensitivity to tested volatiles.

Conclusions:

• Differences in grain volatile profiles and weevil sensitivity to these volatiles explain host selection behavior.
• Understanding these olfactory cues is crucial for developing targeted, environmentally benign pest control measures for stored grains.