Susceptibility of different kinds of powdered milk to the attack of Pyralid moths

Test were carried out to determine the susceptibility of four different kinds of powdered milk, used in human nourishment to attack by Cadra cautella (Walk.), Corcyra cephalonica (Staint.), Ephestia kuehniella (Zell.) and Plodia interpunctella (Hbn.). One hundred eggs, 24-48 h old, were placed on substrates (50g) in a thermostatic room (26±1°C; 70±5% r.h.; 16:8 L:D). For each substrate, three replicates were carried out. At the end of each test the mean adult number emerged, the mean developmental period and the mean susceptibility index was calculated. Results were subjected to ANOVA and to the Duncas’ multiple range test (SPSS 11.5 for Windows). Test species were able to complete their development on soya milk. On this substrate, emergence of 50-60 individuals were observed except for C. cephalonica where there were 19.0±1.00 emerged adults. C. cautella, E. kuehniella and P. interpunctella were not able to complete their development on the human nourishment milk (powdered whole milk, powdered reconstituted milk and powdered baby milk). C. cephalonica adults were observed not only on powdered soya milk but also on whole milk, numbers of adults that emerged were: 17.0±1.21 from powdered baby milk: 40.7±3.84 from reconstituted milk: 32.0±2.00). C. cephalonica showed the ability to use lactose, as an energetic source. This sugar, in fact, for the most part is toxic to the moths and beetles of stored products.