Larval Growth Rates

Research Issue

A phenology model exists for North American gypsy moth but the growth parameters needed to modify the model to predict development of strains from other world areas was not available.  The ability to accurately predict larval instar is critical for timing control or eradication treatments.  Also, knowing when adults will be flying is important to timing mating disruption treatments and pheromone trap deployment.

Our Research

Larval growth rate and adult size were compared for individuals reared from each of the strains on artificial diet under constant 25o C and 60 % RH conditions.  

Expected Outcomes

Biological basis for modifying the gypsy moth phenology model to accurately predict development of strains from other world areas.

Research Results

Growth rates varied between gypsy moth strains; strains from higher latitudes or colder climates compensated for the shorter growing season by completing their development faster.  The number of larval instars that different strains went through also varied.  Strains that developed faster had fewer larval instars and the adults were larger.  A possible explanation for these differences is that over time the local climate of an area has selected for individuals that will survive and reproduce best in that area.  In areas with shorter growing seasons faster growth may be essential whereas in warmer areas protracted development could occur.  Generation to generation changes in growth rate also could occur based on weather conditions, food availability and quality, and maternal nutrition.  

Research Participants

Principal Investigator

• Melody Keena, USDA Forest Service- Northern Research Station Research Entomologist

For further details log on website :
https://www.nrs.fs.fed.us/disturbance/invasive_species/asiangm/biology_ecology/larval_growth_rates/