The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin and predatory mite Neoseiulus barkeri Hughes
are effective biological control agents of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), one of the most
important pests of ornamentals and vegetables world-wide. Combined application of both may enhance control efficiency.
The functional response for N. barkeri on the first instar larvae of western flower thrips which were infected by B. bassiana
for 12 and 24 h in the laboratory ((25±1)°C, (70±5)% RH, L:D=16 h:8 h) was determined. The virulence of B. bassiana
against the second instar and pupae of the thrips attacked by N. barkeri were also tested. The results showed that
N. barkeri exhibited a Holling type II functional response on treated thrips. After having been treated with the fungus for
12 h and then offered to the predator, thrips were more vulnerable to be killed by N. barkeri. The second instar larvae and
pupae of the thrips which had been attacked by predatory mites were markedly more susceptible to B. bassiana infection
than normal thrips; the cumulative corrected mortality of B. bassiana of the second instar and pupae which were attacked
by N. barkeri were 57 and 94%, respectively, compared to 35 and 80% in controls on the day 8. These findings highlight
the potential use of B. bassiana in combination with N. barkeri to control F. occidentalis.