1Department of Entomology, Sugarcane Research Station, Cuddalore-607 001, Tamilnadu (India).
2Centre for Plant Protection Studies, Tamilnadu Agricultural University, Coimbatore-641 003, Tamil Nadu (India).
An improved method for screening and grading of egg plant accessions (Solanum melongena L.) against the spotted beetle, Henosepilachna vigintioctopunctata (Fab.) was developed. The screening procedure combined both the incidence and intensity of damage in the field. This method has both the advantages of field screening and cage screening in the field itself as it takes into account the plant leaf damage (per cent leaf damage indicating incidence and leaf area damage in 24 h by one beetle (intensity of leaf damage in unit time). The damage index (D.I) was calculated by multiplying incidence and intensity/100. Then grading was done in three categories as resistant (R) (D.I:0.0–0.10), moderately resistant (MR) (D.I:0.11–0.30), and susceptible (S) (D.I:> 0.31). With this technique, 78 accessions of S. melongena, 15 hybrids and 10 wild Solanum spp. were screened during 1993–94. Among the hybrids, EP 24x65 alone was moderately resistant (MR). All the wild accessions were resistant except Solanum macrocarpum (BE-046/EP 154) which was moderately resistant. Among the 78 cultivable accessions screened, none was resistant, but 15 accessions were moderately resistant to spotted beetle.
