Some factors affecting the susceptibility of four stored garlic cultivars to infestation with Cryptoblabes gnidiella Milliere.

The honey dew moth Cryptoblabes gnidiella Milliere is one of the most important insect pests of stored garlic. Data revealed that, Egyptian (Baladi) cultivar was the least susceptible to attacke by this insect . After four months of storage, the infestation percentages were 21.68% for Egyptian (Balady) cultivar as compared to 32.39% for Sids 40, 44.88% for American and 70.99% for Chinese cultivar. The oil content of the four garlic cultivars were measured along four months of storage. Data showed that the four cultivars were differed significantly in this respect. The highest weight of volatile oils, 436.8 mg/100g was fined in the Egyptian cultivar whereas the Chinese cultivar had 340.6 mg/100g. The correlation coefficients “r” values showed highly significant and negative relationship between infestation percentages and volatile oils weight (mg) . The main components of the volatile oils of the tested four garlic cultivars were separated by GC- MS analysis. Nine sulfur compounds were separated and identified, the major compound was Diallyl trisulfide (i.e. 49.82, 46.23, 46.17 and 44.89%) for Egyptian, Sids 40, Chinese and American cultivars, respectively. Allyl methyl trisulfide ranged from 11.40 to 23.15%. On the other hand percentage of total soluble solids (TSS%) for the four cultivars were almost the same trend during the storage period extended for four months or slightly increased. These data indicate the importance of the type and quantity of volatile oils and its component in protection of stored garlic from infestation by C. gnidiella.