RESUMO
Transgenerational experience can affect a range of natural enemies' life-history traits and can be involved in the control of developmental plasticity. As a major egg parasitoid of the spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae), the wasp Anastatus orientalis (Hymenoptera: Eupelmidae) is effective at suppressing its host populations. The reproductive and developmental traits of A. orientalis is known to depend on photoperiod conditions, but transgenerational photoperiodic effects have yet to be evaluated. To evaluate the transgenerational photoperiodic effects on A. orientalis, we assessed wasp adult longevity, female fecundity, sex ratio, and diapause rate over three consecutive generations under different experimental photoperiods (L16:D8, L12:D12, and L8:D16), using Antheraea pernyi (Lepidoptera: Saturniidae) eggs as hosts. The results suggest that transgenerational experience significantly impacts several biological parameters of progeny. All parasitoids entered a diapause under the long photoperiod condition (i.e., L16:D8), after which the number of female parasitoids and fecundity of the 2nd and 3rd generations increased significantly as compared to the 1st generation. With the long photoperiod conditions, the female ratio rose from 68.1% (1st generation) to 86.0% (3rd generation) and the progeny per females increased from 35.8 to 75.7. However, adult longevity of females and males were shortened significantly. With the intermediate photoperiod (L12:D12) conditions, fecundity and sex ratio of the 2nd and 3rd generations increased significantly as compared to the 1st generation. With the short photoperiod (L8:D16) conditions, there were no significant differences in fecundity among three generations, but sex ratio of the 2nd and 3rd generations increased significantly as compared to the 1st generation. These results on transgenerational photoperiodic effects can be applied to improve laboratory rearing efficiency of parasitoids and to better understand population dynamics in the field across a latitudinal gradient.
RESUMO
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-â ¢ 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.
