Parasitic Suitability of Two Strains of Encarsia formosa on Bemisia tabaci

The parasitic suitability of two strains of Encarsia formosa on Bemisia tabaci was assessed in the laboratory. Results showed that both strains, introduced from UK and USA respectively, could parasitize all the instars of B. tabaci. Parasitic rates on the 3rd instar were 55.3% by the British strain and 576% by the American strain, and on the 1st instar were 412% and 438% respectively. The emergence rate of adult was also the highest (913% and 928%) in host parasitized in the 3rd instar and only 795% and 83.6% in that parasitized in the 1st instar. The developmemtal period of Encarsia that parasitized the 1st instar Bemisia nymph was the longest (British strain 240d and American strain 234d) and that parasitized the 4th instar was the shortest (British strain 189d and American strain 158d).Females emerged from the host parasitized in the 4th instar could starve the longest period (British strain 48d and Amrican strain 49d) and those parasitized in the 1st instar host starved the shortest (25d for both strains).