Life History of the Giant Looper Moth Ascotis selenaria (Lepidoptera: Geometridae) in Eucalyptus Plantations and the Effect of Adult Mating Age on Fecundity

<i>Ascotis selenaria</i> has recently shifted hosts to become a major defoliator in Southern China's eucalyptus plantations. To facilitate Integrated Pest Management (IPM), we investigated the genetic origins, life history, and reproductive bio-ecology of this population. Mitochondrial COI analysis revealed that the Southern China population aligns phylogenetically with South Asian clades, distinct from Northern China populations. Life table analysis confirmed six larval instars, with the final instar exhibiting exponential consumption, accounting for 79.68% of total food intake. Reproductive assays demonstrated significant protandry and a novel bimodal ovarian maturation rhythm (peaking on days 3 and 7). Crucially, female fecundity declined sharply after a 3-day mating delay, and mating with older males severely reduced egg hatchability in older females. These findings suggest that control thresholds must shift from visual damage assessment to monitoring early-instar larvae (1st-3rd instars). Furthermore, the combination of protandry and reproductive sensitivity implies that mating disruption strategies must be deployed prior to male emergence. This study provides the biological basis for a dual-window IPM framework targeting this emerging pest.