RESISTANCE TO THE PINK POTATO APHID, MACROSIPHUM-EUPHORBIA, IN 2 ACCESSIONS OF LYCOPERSICON-HIRSUTUM F GLABRATUM

Accessions PI 126449 and PI 134417 of wild tomato, Lycopersicon hirsut um f. glabratum C.H. Mull, were assessed for resistance to the pink po tato aphid, Macrosiphum euphorbiae (Thomas). Aphid populations under f ield and greenhouse conditions were significantly lower on the L. hirs utum f. glabratum plants compared to L. esculentum. Removal of trichom e glands and exudates by wiping the leaf surface resulted in a dramati c decrease in aphid mortality. Compared to L. esculentum, aphid behavi or on the L. hirsutum f. glabratum plants was characterized by 40 to 5 2% abandonment, delay in time for first probe, reduction of number and duration of probes and decrease in the total proportion of time probi ng. Removal of the trichomes reduced the percentage of abandonment and increased the total proportion of time probing. Density and type of g landular trichomes varied among plant lines and on adaxial and abaxial leaf surfaces within a line, particularly for the L. hirsutum f. glab ratum plants. PI 134417 was, in general, more resistant to the aphids than PI 126449.