Velcro-Like System Used to Fix a Protective Faecal Shield on Weevil Larvae

Area of Science:

• Entomology
• Insect Morphology
• Evolutionary Biology

Background:

• The Ceutorhynchinae subfamily includes numerous leaf-mining weevils with diverse larval adaptations.
• Euonymus europaeus is a common host plant for various insect herbivores.

Purpose of the Study:

• To describe the last instar larva and pupa of Eucoeliodes mirabilis.
• To compare and key these stages with 58 other Ceutorhynchinae taxa.
• To elucidate the unique defensive strategy of E. mirabilis larvae.

Main Methods:

• Detailed morphological descriptions using drawings and Scanning Electron Microscopy (SEM) images.
• Comparative analysis with existing larval descriptions of related taxa.
• Identification of key morphological features for taxonomic differentiation.

Main Results:

• The last instar larva and pupa of E. mirabilis are described and illustrated.
• A unique defensive strategy involving a fecal shield attached by dorsal microtrichia (velcro system) was identified.
• Morphological adaptations for spiracle protection, including dense microtrichia clusters and safety valves, were observed.
• Macrosetae are significantly reduced in larvae and pupae due to the fecal shield strategy.
• The defensive strategy is unique but shares some similarities with certain Chrysomelidae beetles, albeit with distinct morphological adaptations.

Conclusions:

• Eucoeliodes mirabilis larvae exhibit a unique and effective fecal shield defense mechanism.
• Specialized microtrichia and spiracle structures are key adaptations for this strategy.
• The findings contribute to understanding larval diversity and defensive evolution within Ceutorhynchinae.