Natural Enemies of Dactylopius confusus (Homoptera: Dactylopiidae): Exclusion and Subsequent Impact on Opuntia (Cactaceae)

Collections of Opuntia spp. (Cactaceae) cladophylls infested with Dactylopius confusus (Cockerell) from two sites in west central Texas during 1982–84 yielded seven natural enemies, all predators. Major predators were Laetilia coccidivora (Comstock), Leucopis bellula Williston, and Hyperaspis trifurcata Schaeffer. Several parasites and hyperparasites were reared from these predators. No parasites or pathogens of D. confusus were detected. Continuous exclusion of natural enemies from cladophylls artificially infested with D. confusus resulted in high densities of D. confusus. When natural enemies were continuously admitted for comparison, D. confusus populations remained below the original infestation levels, and natural enemies admitted after D. confusus population densities had increased through at leastone generation resulted in an immediate decrease in the D. confuses density. When natural enemies were continuously excluded from D. confusus-infested cladophylls, up to 81% of the cladophylls became necrotic, and only 4% produced new growth the following spring. However, where natural enemies were admitted, only 8%of the cladophylls manifested necrosis, and 75% produced new growth.