A Scouting Method for Estimating Insect Populations in an Encarsia formosa (Hymenoptera: Aphelinidae) Mass Rearing System.

Encarsia formosa (Gahan) (Hymenoptera: Aphelinidae) has been used to control for the biological control of Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) in greenhouse tomato crops. One aspect that influences the success of this method is the continuous availability of large numbers of E. formosa that enable the grower to release them at the proper time and in the quantity required. Rearing facilities of this parasitoid require reliable and low time-consuming methods for scouting populations of insects to forecast production. In this work, we develop a time-effective method for estimating insect populations in a mass rearing system with T. vaporariorum, using common bean plants as hosts. The population density of T. vaporariorum in highly infested leaves was determined to be 27.5 nymphs/cm using a linear regression model. Using an effort curve and binomial distribution, we determined that 14 and 54 leaves are the minimum number of sampling units required to estimate the T. vaporariorum nymphs and E. formosa pupae populations, respectively. A wasp ratio was determined by dividing the number of E. formosa produced by the total number used in the process. This index was higher when less than 7000 E. formosa were released per production batch in 1 week. When high populations of E. formosa are released in a batch, the production efficiency decreases, producing fewer new adults per adult used in the batch.