Effect of fungal infection on reproductive potential and survival time of Tetranychus urticae (Acari: Tetranychidae) Wei-Bing Shi Æ Ming-Guang Feng Received: 25 October 2008 / Accepted: 6 January 2009 / Published online: 20 January 2009 Ó Springer Science+Business Media B.V. 2009 Abstract The effect of fungal infection on the reproductive potential of two-spotted spider mite, Tetranychus urticae, was evaluated as part of the full biocontrol potential of three entomopathogenic fungi by modeling of fecundity probability. Female mites (B2-day-old) on leaves were exposed to the sprays of Beauveria bassiana, Paecilomyces fumosoroseus and Metarhizium anisopliae at the concentrations of 1.13 9 10 3 , 1.55 9 10 3 and 0.95 9 10 3 deposited conidia mm -2 and then individually reared at 25°C and 12:12 L:D for oviposition. Mite mortalities 10 days after spraying were 73.1, 75.4 and 67.9% in the fungal treatments versus 15.5% in control. On average, females infected by the three fungal species survived 5.8, 6.2 and 6.3 days, and laid 3.1, 4.0 and 4.0 eggs per capita, respectively. These were 3–4 fold lower than the control fecundity at 12.3. The cumulative probabilities [P(m B N)] for the counts of infected and non-infected (control) females laying m eggs per capita (m B N) during 10 days fit very well the equation P(m B N) = 1/[1 ? exp(a ? bm)] (r 2 C 0.98), yielding a solution to the probability for the female mites to achieve a specific fecundity {P(m B N)-P[m B (N - 1)]}. Consequently, the infected mites had 71–78% chance to lay B5 eggs per capita but only 5–8% to deposit [ 10 eggs despite some variation among the tested fungi. In contrast, the chances for the non- infected mites to achieve the low and high fecundities were 23 and 55%. The fitted probabilities provide a full coverage of the fecundity potential of infected versus non- infected mites and are more informative than the mean fecundities. Keywords Spider mites  Beauveria bassiana  Paecilomyces fumosoroseus  Metarhizium anisopliae  Tetranychus urticae  Mortality  Fecundity  Longevity W.-B. Shi  M.-G. Feng (&) Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People’s Republic of China e-mail: mgfeng@zju.edu.cn 123 Exp Appl Acarol (2009) 48:229–237 DOI 10.1007/s10493-009-9238-2