Effect of phenotype and cassava planting density on phytophagous mites on the Atlantic coast

Abstract

Phenotypic factors such as plant morphology, and physical factors such as planting density, effects in the creation of a microclimate that influences the population growth of phytophagous mites and of their natural enemies in cas­saya. Three planting densities (5,000, 10,000, and 15,000 plants per hectare) and three cas­saya clones: CM 681-2 (low vigor and small leaves), M Col 1505 (vigorous and with inter­mediate leaves size) and M MAL-2 (very vig­orous and with large leaves) were evaluated. M MAL-2 is considered to be mite susceptible, while CM 681-2 and M Col 1505 are moder­ately resistant. Periodic mite population evalu­ations were made and the leaf area was mea­sured at three plant levels to calculate the num­ber of mites per unit area for each genotype. At the lowest planting density (5,000 plants/ ha) the highest increase in phytophagous mites and the lowest increase in predator mites of the Phytoseiidae family were observed. The most favorable density for an increase in phy­tophagous mite populations was 15,000 plants/ ha. The highest number of phytoseiid mite predators was observed on the done CM 681­2, where the highest density of the phytophagous mite population was also recorded.