Effect of fungal infection on reproductive potential and survival time of Tetranychus urticae (Acari: Tetranychidae)

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 (<or=2-day-old) on leaves were exposed to the sprays of Beauveria bassiana, Paecilomyces fumosoroseus and Metarhizium anisopliae at the concentrations of 1.13 x 10(3), 1.55 x 10(3) and 0.95 x 10(3) deposited conidia mm(-2) and then individually reared at 25 degrees 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 <or= N)] for the counts of infected and non-infected (control) females laying m eggs per capita (m <or= N) during 10 days fit very well the equation P(m <or= N) = 1/[1 + exp(a + bm)] (r(2) >or= 0.98), yielding a solution to the probability for the female mites to achieve a specific fecundity {P(m <or= N)-P[m <or= (N - 1)]}. Consequently, the infected mites had 71-78% chance to lay <or=5 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.

Laboratory evaluation of the effect of the entomopathogenic fungi, Hirsutella thompsonii and Paecilomyces fumosoroseus, against the citrus brown mite, Eutetranychus orientalis (Acari: Tetranychidae

“…Females in the control laid more eggs than those fungus-treated and infection of females affected the reproductive potential. Shi and Feng (2009) found that the infection of P. fumosoroseus not only killed T. urticae females, but greatly reduced their fecundity. The effect of fungal infection on the fecundity of pests is often revealed by fecundity differences between infected and non-infected mites (Wekesa et al 2006) and ticks (Samish et al 2001).…”

“…The effect of fungal infection on the fecundity of pests is often revealed by fecundity differences between infected and non-infected mites (Wekesa et al 2006) and ticks (Samish et al 2001). Thus, a modelling analysis of the fecundity probability might be an interesting method to evaluate the effect of the fungal infection on pest fecundity (Shi & Feng 2009). Generally, data in this study clearly indicate the potential of H. thompsonii and P. fumosoroseus to control E. orientalis, as mycoacaricides comparable to standard bioacaricides and synthetic acaricides (Iskander et al 1993), which indicates a potential use of these species for bio-control of this pest in Egypt.…”

Pathogenicity of Isaria fumosorosea to European red mite in the laboratory

“…Em ambos os experimentos, a mortalidade na testemunha variou de 10 a 20%. Essa mortalidade 'natural' é semelhante à encontrada em outros ácaros como T. cinnabarinus e T. urticae (SHI et al, 2008;FENG, 2009).…”

“…A mortalidade causada por fungos em outros experimentos parece se situar dentro dos limites dos resultados deste trabalho, ainda que a aqueles tenham alcançado cerca de 80% de mortalidade (SHI et al, 2008;FENG, 2009;AFIFI et al, 2010 …”

“…cinnabarinus com efetividade superior a 50% FENG, 2004;SHI et al, 2008) e T. urticae com 75% de mortalidade das fêmeas e redução de fertilidade FENG, 2009;ZHANG et al, 2014).…”