Neonicotinoids can cause arrested ecdysis in Coleoptera

Area of Science:

• Insect Physiology
• Toxicology
• Entomology

Background:

• Neonicotinoids are insecticides targeting nicotinic acetylcholine receptors.
• Previous research indicates neonicotinoids affect insect behavior and physiology.
• Ecdysis is a critical developmental process in insects.

Purpose of the Study:

• To investigate the effects of neonicotinoids on ecdysis in three coleopteran species.
• To determine if neonicotinoids impact molting at sublethal doses.
• To explore the role of nicotinic acetylcholine receptors in regulating insect ecdysis.

Main Methods:

• Topical application of neonicotinoids to pupae and larvae of Tenebrio molitor, Tribolium castaneum, and Leptinotarsa decemlineata.
• Doses were chosen to avoid direct paralytic effects.
• Observation of ecdysis progression and adult development.

Main Results:

• Neonicotinoid application arrested ecdysis in all three beetle species.
• Adult beetles developed under the pupal cuticle but failed to shed it completely.
• Molting impairments included unexpanded wings and failure of ecdysial lines to break.
• Arrested ecdysis was also observed in larval stages.
• Four neonicotinoids implicated nicotinic acetylcholine receptors in ecdysis regulation.

Conclusions:

• Neonicotinoids disrupt coleopteran ecdysis, even at sublethal doses.
• Nicotinic acetylcholine receptors appear to play a role in regulating insect molting.
• Neonicotinoids may disrupt crustacean cardioactive peptide producing neurons, impacting ecdysis across insect orders.