Evaluation of Serangium parcesetosum (Coleoptera: Coccinellidae) as a Biological Control Agent of the Silverleaf Whitefly (Homoptera: Aleyrodidae)

Abstract

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 ≈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 ≈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 ≈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°C, adults survived best at 20°C with a mean longevity of ≈75 d. Adults lived ≈25 d at 30°C, whereas, 40°C resulted in death within 3 d. Predation rate was found to increase with temperature. The mean number of total immature B argentifolu consumed by S parcesetosum adults was 138.9, 180,8, and 187 4 per 12-h feeding period at 20, 30, and 40°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°C, respectively. Because of its voracity in both immature and adult stages, and its apparent preference for whiteflies, including B. argentifolu (compared with lepidopteran eggs), S. parcesetosum is a promising biological control agent against the silverleaf whitefly.