Study On Feeding Preference For The Larvae Of Euproctis Angulata

Insect and plant is an important part of the terrestrial ecosystem, and they form a complex and special coevolution relationship, the plant giving food for insect is an original ecological relationship. Zhejiang Tiantong National Forest Park is the typical subtropical evergreen broadleaf forest, Schima superba is the main constrctive species and dominant species, the larvae of Euproctis angulata is one kind of the most individual Lepidoptera insect on Schima superba leaves, Euproctis angulata belong to Lymantriinae, Lymantriidae, it is the pest of agriculture and forestry crops, widely distributed in the south of China. In order to know the host plant choice of Euproctis angulata, the studies were carried out in subtropical evergreen broadleaf forest Zhejiang Tiantong National forest Park during March to July in2010and2011, the larvae of Euproctis angulata and the related plant leaves were chosen, through field observation, breeding experiment indoor, realizing the growing development of the Euproctis angulata larvae, feeding different plant leaves to study the feeding preference of Euproctis angulata larvae, discuss the relationship between the larvae to the plants, to give more theory evidence to know the relationship of the plant and the phytophagous insect in subtropical evergreen broadleaf forest. The results showed as follows:1. By field ovservation, there were many larvae of Euproctis angulata which were found on the leaves of Schima superba and Rubus corchorifolius, sometimes they can feed on old leaves of Schima superba, so in this study we discuss the larvae feeding preference to of the young and old leaves of Schima superba, and Rubus corchorifolius leaves by feeding experiments. The results showed that:for single feeding experiment, the larvae fed on Rubus corchorifolius leaves pupated first, the time for3-5larvae instars was the shortest (29days), the average weight of the larvae on pupation is0.2169g; the larvae fed on Schima superba old leaves pupated latest, the time for3-5larvae instars was the longest (57days), the average weight of the larvae on pupation is0.2786g; the larvae fed on Schima superba young leaves pupated and the time for3-5larvae instars (47days) were in the middle, the average weight of the larvae on pupation is0.5345g; the food efficiency of Rubus corchorifolius leaves was the highest in3larvae instar, the food efficiency of Schima superba young leaves was the highest in4larvae instar, the food efficiency of Schima superba old leaves is steal in a low level. Feed on3kind leaves mixture with same weight, the time for3-5larvae instars was41days, the highest weight of the larvae on pupation is0.3256g; in3larvae instar it fed on Rubus corchorifolius leaves most, in4instar it fed on Schima superba young leaves increased, and more than Rubus corchorifolius leaves, fed on Schima superba old leaves increased little in old larvae it, but it is always in a low level. Feed on3kind leaves mixture with same area, the time for3-5larvae instars was40days, the highest weight of the larvae on pupation is0.3516g; the variation of feeding area for3kind leaves is as same as the same weight group. The efficiency of the larvae fed with three different kind leaves, food consumption, body weight of larvae and feeding area is positively correlated with. So the young leaves of Schima superba was the fondest food of Euproctis angulata, and the Raspberry was the second, if there was no leaves of above mentioned, the old leaves of Schima superba would be chosen for the larvae’s host plant.2. In order to know the host plant range of Euproctis angulata larvae in Zhejiang Tiantong National Forest Park,13species of evergreen plants were chosen for feeding study, contain the plant species find the larvae, around the plant, the same family plant species and with the similar growing development plant, they were Schima superba、Cinnamomum camphora、Machilus thunbergii、Castanopsis cuspidate、Cyclobalanopsis gilva、Castanopsis sclerophylla、Camellia fraterna、 Eurya rubiginosa var. attenuat、Symplocos stellaris、Symplocos sumuntia、 Daphniphyllum macropodum、Elaeocarpus decipidns、Photinia glabra. The results showed that:Euproctis angulata larvae fed with multiple plants. In13plant species, the larvae fed on the leaves of Schima superba, Cyclobalanopsis gilva, Castanopsis sclerophylla, Camellia fraternal, Elaeocarpus decipidns, Photinia glabra, little fed on the leaves of Eurya rubiginosa var. attenuate, they didn’t feed on the leaves of Cinnamomum camphora, Machilus thunbergii, Castanopsis cuspidate, Symplocos sumuntia, Daphniphyllum macropodum, Symplocos stellaris. The daily intake of Schima superba is the highest (0.1529±0.0424)g and the selective index is the highest (SI=2.38). The study also shows that a basic positive correlation between the larvae of Euproctis angulat feeding quantity and the selective index for the different plant species. But there are exceptions for Camellia fraternal.3. In order to know the feeding preference of the Euproctis angulata larvae for6plant species in Zhejiang Tiantong National Forest Park, preference experiments of the larvae to6plant species leaves were carried out, by measuring the index of larvae different development stage and physicochemical property, analysing the relation of above two, to discuss the main factors influencing Euproctis angulata larvae, the results showed that:_Relative growth rate and food efficiency of the larvae fed with the leaves of Castanopsis sclerophylla and Schima superba were positive correlated with water content and N content of leaves; Relative growth rate and food efficiency of the larvae fed with the leaves of Elaeocarpus decipiens was_relative with the change of water content of the leaves; Food efficiency of the larvae fed with the leaves of Photinia glabra was relative with the change of water content and N content of leaves; Relative growth rate and food efficiency of the larvae fed with the leaves of Camellia fraternal and Cyclobalanopsis gilva were relative with water content positively, with N content negatively. Relative growth rate and food efficiency of the larvae fed with the leaves of Schima superba were not increased with the declining of N content; but relative growth rate and food efficiency of the larvae fed with the leaves of Elaeocarpus decipidns were consist with the change of leaves condensed tannin content. The physicochemical properties of plant leaves put an effect on the insect feeding behavior, but it is not the single one, there are other impact factors.