Evaluation of Rearing Factors Affecting Clanis bilineata tsingtauica Mell Larvae Fed by Susceptible Soybean Variety NN89-29 in Spring and Autumn Sowing

Abstract

Clanis bilineata tsingtauica Mell is a nutritious edible insect. In the present study, soybean variety NN89-29 susceptible to leaf-feeding insects was used as the experiment material to evaluate the rearing factors affecting the production of C. bilineata tsingtauica in spring and autumn sowing. We artificially inoculated C. bilineata tsingtauica eggs to soybean plants, and the relevant indexes of larvae and soybean plants were recorded. The main results from spring sowing were as follows: (1) Larval number, single larval weight and plot-larval weight were all higher in the V6 stage (sixth trifoliolate) than those in the R3 stage (beginning pod) of inoculated eggs. (2) Larval number, single larval weight and plot-larval weight significantly decreased under higher planting density. Meanwhile, the soybean plant height and internode length increased, while the main stem node number of soybean decreased under higher planting density. (3) Single larval weight and plot-larval weight were not significantly affected by different numbers of eggs inoculated, but the larval number was significantly affected. Under autumn sowing conditions: (1) The larvae production and soybean plant growth were not significantly affected by covering the top of the net house with plastic film to isolate rainwater. (2) More eggs inoculated were associated with higher plot-larval weight. Conversely, fewer eggs inoculated resulted in a higher proportion of single larvae weight more than or equal to 6 g (≥6 g). Compared to spring sowing, the low biomass of autumn-sown soybean plants did not provide sufficient food for C. bilineata tsingtauica growth, and competition for food resulted in lower larval number, single larval weight and plot-larval weight.