MOVEMENT AND ESTABLISHMENT OF SUGARCANE BORER (LEPIDOPTERA, PYRALIDAE) LARVAE ON RESISTANT AND SUSCEPTIBLE SUGARCANE

The movement and establishment of sugarcane borer, Diatraea saccharali s (F.), larvae was studied on resistant and susceptible sugarcane. A f ield study was conducted over three years on the cultivars 'CP 74-383' (susceptible), 'CP 65-357' (intermediate), and 'CP 70-321'(resistant) . Stalks of each cultivar were artificially infested with neonate suga rcane borer larvae and sampled at 10, 20, and 30 days after infestatio n. Larval movement, entrance holes, and plant growth were mapped and r ecorded for each cultivar and sample date. Larval recovery at 30 days after infestation was low and varied among cultivars totalling 10.2% o n CP 74-383, 7.0% on CP 65-357, and 3.5% on CP 70-321. Larvae entered stalks of CP 74-383 earlier than those of CP 65-357 and CP 70-321; at 10 days after infestation, 48% of the larvae on CP 74-383 had entered the stalk, but only 19% on CP 65-357 and CP 70-321. Larvae generally m oved up the stalk before entering, indicating that young internodes we re preferred to older internodes for entry sites. Larvae feeding on CP 74-383 were also more likely to damage multiple internodes. This stud y suggests that a major component of sugarcane's resistance to sugarca ne borer is reducing the frequency of the establishment of young larva e in the stalk.