Quantifying dispersal of a non-aggressive saprophytic bark beetle

Area of Science:

• Ecology
• Entomology
• Forestry

Background:

• Long-distance dispersal is crucial for bark beetle population dynamics.
• Dispersal behavior of aggressive bark beetles is well-studied, but less is known about non-aggressive species using host volatiles (kairomones).

Purpose of the Study:

• To investigate the dispersal patterns of the saprophytic bark beetle Hylurgus ligniperda.
• To differentiate dispersal behavior between flight-experienced and flight-naïve adults.

Main Methods:

• A mark-recapture experiment was conducted in a New Zealand pine forest.
• Adult H. ligniperda (flight-experienced and flight-naïve) were marked and released.
• A circular grid of 170-200 panel traps baited with kairomones (alpha-pinene and ethanol) was used to recapture beetles up to 960 m.

Main Results:

• Of 18,464 released beetles, 49.9% flew, and 1.04% were recaptured.
• Recaptures occurred at all distances, with a decline for flight-experienced beetles as distance increased.
• A diffusion model estimated 46% of flight-experienced beetles disperse > 1 km and 1.6% > 5 km.
• Flight-naïve beetles showed no declining recapture pattern with distance.

Conclusions:

• Emerging H. ligniperda may need a flight period to develop chemotropic orientation behavior.
• Understanding dispersal is key for managing phytosanitary risks and estimating pest pressure in timber sites.
• Dispersal estimates aid in predicting the spread of H. ligniperda, a species with establishment capabilities in new regions.