Study on resistance of Aquilaria sinensis against Heortia vitessoides

Objective  Heortia vitessoides is an important defoliator attacking the precious tree species of Aquilaria sinensis. The goal was to screen potential insect-resistant plants by surveying A. sinensis victimization in a large area of forest, and provide a basis for the scientific prevention of H. vitessoides and the breeding of insect-resistant plants.

Method  In the harmful period of H. vitessoides, regular surveys on large area of A. sinensis forests were conducted. In the seriously damaged A. sinensis forests, plant appearances and leaf physical structures at different levels of victimization were observed, and leaves from different insect-resistant plants were collected to feed the newly-hatched larvae of H. vitessoides. Whether the leaves from different insect-resistant plants were chosen or rejected by the larvae was observed. The differences in larva survival rate, growth and development, pupation and feathering by feeding on different resistant A. sinensis leaves were tested.

Result  There were two undamaged A. sinensis plants in the severely damaged A.sinensis forests, showing good resistance to insect pests (anti-1 and anti-2). There were significant differences in leaf length and thickness between the insect-resistant plants (anti-1 and anti-2) and susceptible plants(P<0.05), while the ratio of leaf length to width had no significant difference. As for leaf physical structures, the leaf upper epidermis cuticle thickness of anti-2 was significantly higher than that of the susceptible plant. The antifeedant rate ofH. vitessoides larvae against anti-2 plant was significantly higher than that against anti-1 plant, and both were above 44.81%. Larvae fed on resistant leaves had significant lower survival rate, adult emergence rate, pupal weight and shorter adult longevity, but longer duration of pupa compared to larvae fed on normal A. sinensis leaves.

Conclusion  A. sinensis plants with tender green leaves are more susceptible to H. vitessoides, while the plants with thick, yellow or dark green leaves have strong resistance to H. vitessoides. Resistant A. sinensis plants have a higher inhibitory effect on feeding activity of H. vitessoides larvae and hinder larval development.