Elevational Changes in Mormon Cricket Life Histories: Minimum Temperature for Nymphal Growth Declines With Elevation

Area of Science:

• Ecology
• Insect Physiology
• Evolutionary Biology

Background:

• Insect development is temperature-dependent, with shorter growing seasons at higher elevations.
• Mormon crickets' elevational migrations may limit local environmental adaptations.
• Selection for cooler temperature activity could potentially reduce growth rate optimization.

Purpose of the Study:

• To investigate how elevation affects Mormon cricket nymph growth rate and thermal tolerance.
• To determine if adaptations to cooler temperatures impact growth rate.
• To provide data for pest management strategies across different altitudes.

Main Methods:

• Measured nymph growth rates of Mormon crickets from three populations across an elevational gradient (87–2,688 m) in controlled environments.
• Analyzed growth rate responses to varying rearing temperatures (22–30°C).
• Determined critical thermal minimum (base temperature) and degree-day requirements for development.

Main Results:

• Growth rate increased significantly with rearing temperature (22–30°C).
• The base temperature for growth declined with increasing elevation (0.7°C per 1,000 m).
• Higher elevation populations exhibited faster growth rates at given temperatures and smaller body mass.

Conclusions:

• Mormon cricket populations show elevational adaptation in thermal physiology, with higher elevation populations better adapted to cooler conditions.
• Adaptation to cooler temperatures did not compromise growth rate, suggesting a dual adaptation strategy.
• Established base temperatures and degree-day values (509) are applicable for pest management from sea level to 2,700 m.