Environment and Local Substrate Availability Effects on Harem Formation in a Polygynous Bark Beetle.

Area of Science:

• Ecology
• Behavioral Ecology
• Entomology

Background:

• Polygyny, specifically harem polygyny, is common in animals.
• Environmental factors and habitat availability can influence harem formation.
• The bark beetle, *Ips grandicollis*, is a suitable model for studying harem polygyny.

Purpose of the Study:

• To investigate the impact of the surrounding environment (harvested vs. unharvested pine plantations) on *Ips grandicollis* harem formation.
• To determine how local substrate availability affects beetle aggregation and harem size.
• To analyze female distribution patterns within male galleries and assess influencing factors.

Main Methods:

• Field study comparing *Ips grandicollis* populations in harvested and unharvested pine plantations.
• Quantification of beetle population density and harem size (females per male).
• Assessment of local substrate availability (log piles) and its correlation with beetle attraction and harem size.
• Analysis of female gallery distribution patterns around the male nuptial chamber.

Main Results:

• Significantly higher number of females per male observed in harvested plantations compared to unharvested ones.
• Local substrate availability (number of logs) positively influenced beetle attraction to logs and individual harem size.
• Female distribution within galleries was random, not clumped or evenly spaced, and unaffected by other females or environmental conditions.

Conclusions:

• Habitat availability, particularly in harvested pine plantations, significantly enhances harem polygyny in *Ips grandicollis*.
• Local resource availability is a key driver for beetle aggregation and harem establishment.
• Female distribution patterns suggest a lack of direct interaction or influence from neighbors or external conditions during gallery construction.