Abstract :
Leaves from the invasive tree Melaleuca quinquenervia containing a range of nitrogen levels were fed to neonate and adult Oxyops vitiosa to determine the influence of plant nutrition on insect survival, growth, development, and fecundity. Larvae fed the low-fertilizer leaves (30 g/11.4-liter pot; 15–9–12, N–P–K) had less than one half the survival (30±5.0%) of larvae fed the high-fertilizer (90 g/pot) leaves (65±10.4%). Additionally, the biomass of prepupae, pupae, and adults was each significantly greater (each 1.15-fold) in larvae fed leaves from the high-fertilizer level. However, fecundity was not influenced by these fertilizer treatments. The effect of five fertilizer treatments (30, 90, 135, 180, and 225 g/pot) applied to M. quinquenervia on O. vitiosa larval survival, growth, development, and feeding efficiency was determined in a second experiment. These results indicated that slight increases occurred in food consumption and biomass when larvae were fed leaves from the lowest and highest fertilizer treatments, respectively. Little if any evidence of compensatory feeding or increased food utilization efficiency was found on the low-nitrogen leaves. The results suggest that in mass rearing activities increased production of weevils will occur in high-fertilized (90 g/pot) treatments due to increased larval survival. However, adult fecundity will not be affected by fertilizer treatment. Several qualities of this species contribute to its success as a biological control, namely the adults are long-lived, which enables individuals to bridge periods when suitable leaves are available, and both larval and adult performance are apparently little affected by a wide range of nitrogen levels.
