Radioisotope 32P for assessment of host-preference of the brown plan hopper (Nilaparvata lugens stahl)

Radioisotope 32P was used a tool in the assessment of host-preference of the brown plant hopper. Brown hoppers (biotype 1) are fed with rice seedlings (IR5) containing 32P. The host plants chosen for these experiments were IR26, IR28, IR30, IR32, IR34, IR36, IR38, IR40, IR5 and Pelita 1/1. Individual radioactive hopper was kept in a glass vial containing individual host plant or combination of host plants. After 48 hours the hopper were killed. The assessment of host preference was done by autoradiographing the seedlings on x-ray films. White spots on the film, which were the location of hopper punctures on the seedlings, were classified into 5 groups according to the diameter. Counts were made on the roots, leaves and stems of each seedling. The result of individual trials (one seedling one hopper) showed, that Mudgo group had more punctures than IR5 for BPH biotype 1. Grouped screening produced the opposite results, where the susceptible varieties are punctured more than the resistant ones (autoradiographing as well as radioactivity counting). (author)