Effects of insect longevity and drought conditions on realized and potential fecundity of aster leafhoppers (Hemiptera: Cicadellidae)

Insect population dynamics profoundly affect the potential for a species to serve as a pest, highlighting the importance of proper quantification and monitoring of insect reproduction. Important measurements of reproduction include individual female egg load and realized fecundity, which can be affected by food quality and insect longevity. Water deficit in plants can lead to higher amino acid and sugar concentrations, which can render plants more palatable and nutritious for insect herbivores. To examine the relationship between water deficit and reproductive potential, aster leafhoppers (Macrosteles quadrilineatus Forbes) were reared on water-stressed and non-stressed barley plants until adult emergence. Pairs with all possible combinations of leafhoppers from each water stress condition were caged onto plants for seven days, after which they were removed, and plants were kept for further analysis. Individual female egg load was determined prior to the start of the experiment (parental generation, F0), following the seven-day mating period (F0), and following adult emergence of the new generation (F1). Offspring numbers and nymphal development were determined for all crosses. Amino acid and sugar concentrations were quantified in water-stressed and non-stressed plants. Moreover, previous work on age-specific fecundity seems to indicate that fecundity decreases over time. To evaluate this using aster leafhoppers, pairs of newly emerged females and males were caged onto plants, and egg and nymph numbers were determined on a weekly basis until females died. Altogether, findings provide insight into how two important factors (age and abiotic stress on plants) can shape aster leafhopper reproduction and population dynamics.