A STUDY ON ENERGETICS OF PODISUS MACULIVENTRIS (HEMIPTERA: PENTATOMIDAE)

Abstract

Based on bomb calorimeter determinations, the calorific values of four sizes of larvae of Galleria mellonella (L.) fed to nymphs and adults of the predator Podisus maculiventris (Say) increased with increase in larval size. Correspondingly, these values for P. maculiventris nymphs in fourth and fifth instars and adults, male and female, increased when the predator fed on larger larvae. Increases in energy consumption resulted in increases in energy loss due to respiration and egestion for nymphs and adults of the predator. For unfed males and females, calorific values decreased with age, i.e., as initial body energy reserves were used up.No significant differences in mean calorific values were observed for fertile and infertile eggs laid by females reared at each of the four diet levels. This suggests that the amount of energy utilized by females in the production of eggs is fairly constant, irrespective of the amount of energy consumed at each diet level.Energy budgets for nymphs of P. maculiventris showed that gross efficiency of growth for second- and third-instar nymphs was inversely proportional to energy consumed; however, no such relationship was observed for fourth and fifth instars. For males, energy budgets showed that at all diet levels little growth took place during adult fife, with gross efficiency at diet levels 1 to 4 ranging from 0.88 to 2.20%. For females, some growth occurred at all levels of diet during the first 35 days of adult life, mainly as a result of the production of eggs. Gross efficiency during this period ranged from 5.5 to 13.6%. Efficiency of reproduction at diet levels 1 to 4 ranged from 37.26 to 45.35% during the first 35 days of adult life and from 39.46 to 51.16% for the next 20 days.