EXPRESSION OF INSECT RESISTANCE IN IN-VITRO-DERIVED CALLUS-TISSUE INFESTED WITH LEPIDOPTERAN LARVAE

Plant-insect relations were studied by rearing larvae of herbivorous l epidopteran insects on tissue culture-derived callus. The callus was g enerated from cotton (Gossypium hirsutum) and tomato (Lycopersion escu lentum, L chmielewskii and L hirsutum) genotypes previously identified as differing in their insect field resistance. Calli were infested wi th newly hatched neonate larvae of Helicoverpa armigera, Spodoptera li ttoralis, Earias insulana and Phthorimaea operculella. Growth retardat ion of larvae and larval mortality were observed among insects fed wit h calli of resistant hosts. The response of the insects was very much dependent on exposure of the callus to light during its formation, and on the plant growth regulator composition of the callus growth medium . Our results indicate that factors imparting resistance in tissues of intact plants were also likely to be present in callus.