3.Factors influencing population 4)Host plants Adults prefer to choose plants sown early,that are growing well,with very green leaves to oviposit; Variety resistance:Corn contains certain substances,called anti--borertin(抗螟素)，resistant to insects.These include:anti-borertins A,B and C.Of which,anti-borertin A and anti-borertin C,called "Dimboa",are the most effective in resistance.4) Host plants ‰ Adults prefer to choose plants sown early, that are growing well, with very green leaves to oviposit; ‰ Variety resistance: Corn contains certain substances, called anti-borertin (抗螟素), resistant to insects. These include: anti-borertins A, B and C. Of which, anti-borertin A and anti-borertin C, called “Dimboa”, are the most effective in resistance. 3. Factors influencing population 3. Factors influencing population