Influence of host plant condition on population increase of Tetranychus telarius (Linnaeus) (Acarina: Tetranychidae)

Host-plant nutrition influenced population increase by affecting both longevity and fecundity. Adult female longevity was adversely affected when the mites were confined to plants grown in nutrient solutions deficient in phosphorus, nitrogen or potassium, rather than in full-nutrient solutions. In the host-plant nutrition studies, nitrogen deficiency was most detrimental for survival and phosphorus deficiency least detrimental. Age-specific fecundities were severely reduced when females were confined to plants grown in the deficient solutions. The phosphorus-deficient treatment gave the greatest reduction in total fecundity as well as maximum fecundity attained. This was true for both old and young leaves. The old leaves of the potassium-deficient treatment induced the second greatest reduction in both total and maximum fecundities. The nitrogen-deficient treatment was superior to either mentioned above but significantly inferior to the full-nutrient treatment. The young foliage in the potassium-deficient treatment was somewhat superior to the old foliage in the full-nutrient treatment in both total and maximum fecundities.