Evaluation of Serangium parcesetosum (Coleoptera: Coccinellidae) as a biological control agent of the silverleaf whitefly (Homoptera: Aleyrodidae)

The coccinellid predator from India, Serangium parcesetosum Sicard, was studied as a potential biological control agent of the silverleaf whitefly Bemisia argentifolii Bellows & Perring [also known as the sweetpotato whitefly B. tabaci (Gennadius) Biotype B]. Studies were performed on prey preference, and effects of host plant on predation. and temperature on life-history and predation rates. In one test, the predator was offered simultaneously 5 prey choices: corn earworm, Helicoverpa zea (Boddie) eggs; tobacco hornworm, Manduca sexta (L.) eggs: and approximately 200 eggs and early instars of B. argentifolii reared on poinsettias, cantaloupes, or cucumbers. S. parcesetosum did not consume any lepidopteran eggs; however, they devoured nearly all whitefly prey offered averaging approximately 600 prey per 24-h feeding period. Mean adult longevities were 27.6 d on cantaloupe. 24.5 d on cucumber, 44.2 d on hibiscus, and 27.8 d on tomato. Each S. parcesetosum adult consumed approximately 170-200 whitefly eggs and immatures per 12-h feeding period. The predation rate was highest on cucumbers, followed by tomato and cantaloupe, and lowest on hibiscus. Under constant temperature conditions of 20, 30, and 40 degrees C, adults survived best at 20 degrees C with a mean longevity of approximately 75 d. Adults lived approximately 25 d at 30 degrees C, whereas, 40 degrees C resulted in death within 3 d. Predation rate was found to increase with temperature. The mean number of total immature B. argentifolii consumed by S. parcesetosum adults was 138.9, 180.8, and 187.4 per 12-h feeding period at 20, 30, and 40 degrees C, respectively. The maximum cumulative lifetime predation was measured at >10,000 whiteflies consumed in the most long-lived individuals, despite feeding only 12 h/d at 1- to 3-d intervals. Mean cumulative lifetime predation was measured at 4,909.5, 2,586.1, and 224.9 whiteflies at 20, 30, and 40 degrees C, respectively. Because of its voracity in both immature and adult stages, and its apparent preference for whiteflies, including B. argentifolii (compared with lepidopteran eggs), S. parcesetosum is a promising biological control agent against the silverleaf whitefly.