Efficiency of host utilisation by coleopteran parasitoid

Area of Science:

• Entomology
• Insect Physiology
• Ectoparasitoid Biology

Background:

• Optimizing food utilization is key for insect larval development and adult fitness.
• Solitary idiobiont ectoparasitoids are important model organisms for studying insect feeding ecology.
• Understanding food conversion efficiency (ECI) provides insights into insect growth and survival.

Purpose of the Study:

• To investigate food utilization, body size, mortality, and development time in the solitary idiobiont ectoparasitoid Brachinus explodens.
• To determine the efficiency of conversion index (ECI) in B. explodens reared on Amara pupae.
• To analyze the relationship between host mass, larval growth, and development time under different temperatures.

Main Methods:

• Laboratory rearing of Brachinus explodens larvae on Amara pupae.
• Measurement of food intake, assimilation, and biomass gain (W(gained)).
• Analysis of mortality and larval development time at varying host masses and temperatures (20.3°C, 23.7°C, 26.9°C).

Main Results:

• The average efficiency of conversion index (ECI) was 54.1%, with a wide range (26.9%–81.6%).
• Females exhibited a higher rate of biomass gain from hosts compared to males.
• Larval development time increased with host mass at 20.3°C and 23.7°C, while mortality increased below 20°C.

Conclusions:

• Brachinus explodens demonstrates high food conversion efficiency, among the highest recorded in insects.
• Host mass influences biomass gain differently between sexes, with females benefiting more.
• Temperature significantly impacts larval development time and mortality, highlighting environmental influences on ectoparasitoid fitness.