Attribution of oral cancer in the Sudan to Toombak dipping

Abstract

The objective of this study was to determine whether differences in tomato hairiness affect the devlopmental time, survival and fecundity of Tetranychus urticae Koch and Neoseiulus californicus (McGregor). Laboratory experiments were performed on 2 tomato hybrids (Fortaleza and Parador) with different density of glandular hairs. There were no significant differences in developmental time of immature stages and total preadult time of T. urticae and N. californicus, between hybrids. Survival of both immatures and adults T. urticae was not affected by tomato hairiness, but fecundity, although low in both hybrids, was significantly lower in the most pubescent hybrid. Neoseiulus californicus did not show any difference among hybrids in none of the life history traits studied. However, there was a trend towards reduced cohort survival when hairiness increased. Tomato plant seems to be a very poor resource for the performance of T. urticae and N. californicus compared to other horticultural crops. An antibiosis process due to glandular hairs could be, at least in part, the cause of this detrimental effect. Implications of these observations in the control of T. urticae on tomato are discussed.