Influencing factors for natural populations of Lycorma delicatula in different habitats

Abstract

To explore the differences between growth and population dynamics of natural Lycorma delicatula in the plantations and semi-natural forests, the susceptible stages and major suppression factors were determined to provide basis for the prediction and controlling the pest. The development duration and life table of L. delicatula in different habitats were established by using tracking method. The index of exclusion effect for lethal factors and the K-value in each development stage were calculated. The population trends were analyzed through the survival curve and key drivers of population change. The results showed that the development duration of L. delicatula in the plantation habitat and semi-natural habitat was significantly different, with thelatter being 25.7 d longer than the former. There were significant differences in the development duration of 1st-3rd-instars nymphs and pre-oviposition period of adults between these two habitats, but no significant difference in the 4th-instar nymphs. The total mortality rate in the plantation habitat and semi-natural habitat was 83.6% and 98.6%, respectively. The index of population trend in the plantation habitat was significantly higher than that in the semi-natural habitat. The population of L. delicatula increased sharply in the plantation habitat, but showed a decline trend in the semi-natural habitat. All of the survival curves of L. delicatula were Deevey-Ⅲ type, and the EIPCs of the "parasitic natural enemies" in egg stage were the highest in both habitats as 1.3 and 1.6, and the total K values were 0.2 and 0.3, respectively. The regression slopes of K-value of natural enemies were the highest (both 0.6). These findings revealed that the semi-natural habitat played an important role in the natural regulation of L. delicatula.