Life history of Eretmocerus melanoscutus (Hymenoptera: Aphelinidae) parasitizing nymphs of Bemisia tabaci Biotype B (Homoptera: Aleyrodidae)

Eretmocerus melanoscutus Zolnerowich and Rose was originally imported from Thailand, and has been released in southern Texas, Arizona and California for biological control of Bemisia tabaci (Gennadius) biotype 'B.' Studies were conducted to determine biological parameters of E. melanoscutus, and evaluate its potential as a biological control agent of B. tabaci under laboratory conditions [26.7 ± 2 °C, 50-75% RH and a photoperiod of 14:10 (L:D) h]. E. melanoscutus successfully oviposited under all nymphal instars of B. tabaci on cabbage with the exception of late fourth instars. The females oviposited least under first instars (25.6 ± 3.2 eggs) and most under third instars (122.7 ± 9.6 eggs), followed by similar numbers of eggs under the second (95.6 ± 8.5 eggs) and early fourth instars (85.6 ± 6.9 eggs). Regardless of host stage parasitized, 93.4% adults emerged. Parasitoid development averaged 16.8 d from oviposition to adult emergence. Each female laid an average of 122.4 (±13.1) eggs during her lifespan or 11.2 ± 0.6 eggs per day. Mean longevity of adult females and males on plants with whitefly nymphs was 9.8 ± 0.9 and 13.2 ± 1.4 d, respectively. Of the offspring, 53.9% were females. The intrinsic rate of natural population increase (rm), net reproductive rate (Ro), generation time (T), doubling time (DT), and the finite rate of increase (λ) of E. melanoscutus were estimated by life table analysis at 0.2175/d, 61.42 offspring, 19.0 d, 3.2 d, and 1.2429/d, respectively. These values are higher than those reported for B. tabaci on any host plant, indicating that E. melanoscutus has a great potential as a biological control agent of B. tabaci.