the population response of heliothis armigera larvae to nuclear polyhedrosis virus (npv) was investigated. the virus was introduced by permitting the larvae to feed on lettuce leaves. median lethal doses (ld50) were determined. the estimated ld50 values for the first, second, third, early, and late fourth larval instars were 5, 141, 1226, 5168 and 24553 polyhedra per larva respectively. in ...

A micro capillary agar-gel diffusion system for the detection of botulinal toxin in foods and cultures was developed and evaluated. Toxins types A, B, and E, produced in culture broth with and without added trypsin, and type E toxin, produced in inoculated canned clams, were tested with this system and with the mouse bioassay procedure. With nontrypsinized toxin, the capillary diffusion system ...