Within-plant distribution and sampling of mealybugs in plantain var. FHIA 21. (150)
Keywords:Dysmicoccus sp., Mealybug, Plantain, Sampling, Distribution, Honduras
AbstractThe within-plant distribution of mealybugs (Homoptera: Pseudococcidae) was determined on plantain (Musa paradisiaca) var. FHIA 21 grown on a commercial plantation in Chotepe, Honduras, in 1996 and in Calan, Honduras, in 1997. Dysmicoccus sp. was the most common (>97% at Chotepe) mealybug species encountered in visual inspections of plants. In the Chotepe study, mean numbers of mealybugs per sample unit on the pseudostem were 2.07 ± 0.35, 3.30 ± 1.50, and 1.79 ± 0.40 for the lower (ground to 1.5 m), middle (1.5-2.5 m), and upper (>2.5 m) portions. This was equivalent to 94.5% of the total mealybugs sampled. Few mealybugs were detected in debris under plants, on roots and adjacent soil, leaf petioles or blades, or on fruit. In the Calan field in 1997, 78.3% of the total sampled mealybugs were observed on the pseudostem. The pseudostems were often encased in old decaying leaf petioles which appeared to provide an acceptable habitat for mealybug development. Apparent benefits of this habitat were optimum humidity, shelter from rain, an environment favourable to symbiosis with ants, and some protection from natural enemies. A significant correlation between the number of mealybugs on the lower and middle pseudostem with the total mealybugs in the sample was obtained and is described by the equation Y = 1.805 + 1.060X where Y = total mealybugs per plant quadrant and X = the number of mealybugs per sample unit. The sampling procedure did not require excessive labour or time, was non-destructive to the plant, and provided a reliable estimate of the total mealybugs per plant.