EFFECT OF BODY-SIZE AND FEEDING ON FECUNDITY IN THE DAMSELFLY ISCHNURA-VERTICALIS (ODONATA, COENAGRIONIDAE)

We looked for relationships between number of eggs and the independent factors of food availability and body size in lab-reared females of t he damselfly Ischnura verticalis. Multiple regression analysis reveale d a strong positive relationship between number of eggs in the abdomen and both short term and long term food intake. There was no relations hip between body size (wing length or head width) al maturity and numb er of eggs in the abdomen. Larval diet during the final instar affecte d development rate and adult size but not fecundity. Food consumed aft er emergence was negatively correlated with time to sexual maturity. S ignificantly more animals given low food diets died before maturity. F ield data of gut weights suggest that animals in the field frequently have empty guts and we infer that food availability may be an importan t determinant of realized fecundity. Failure to find food on any one d ay will have consequences, not only for clutches laid the next day, bu t also for subsequent clutches, and finally for probability of survivi ng to the next day.