Beauveria bassiana submerged spores for control of two-spotted spider mite (Tetranychus urticae Koch (Acari: Tetranychidae)): production, stability, and virulence.

In this study, IBCB 66, IBCB 868, and CBMAI 1306 isolates of Beauveria bassiana were grown in liquid culture for 4 days, leading to elevated submerged spores (SS) levels. The influence of the addition of different glycerol concentrations (0, 3, and 6%) (v/v) in the liquid culture was investigated regarding the stability (at 4 and 27 °C) of dried formulations. The virulence of SS was compared with aerial spores (AS) against Tetranychus urticae (Koch) (Acari: Tetranychidae). The results demonstrate the potential of using SS to control T. urticae. CBMAI 1306 and IBCB 868 isolates caused T. urticae mortality rates of 91.11% and 88.89% 5 days after treatment, respectively, when applied at concentrations of 1 × 108 SS mL-1. The median Lethal Time (LT50) values for these strains were 2.64 and 2.61 days, respectively. The dried formulations showed potential acaricidal activity. Higher glycerol concentrations in the liquid culture medium reduced formulation stability at 27 °C.

Biological Features of Neoseiulus californicus (Acari: Phytoseiidae) Feeding on Schizotetranychus oryzae (Acari: Tetranychidae) Kept on Rice Leaves.

Schizotetranychus oryzae Rossi de Simons attains pest level in rice crops. This study aimed to evaluate the biological features of Neoseiulus californicus (McGregor) feeding on S. oryzae on leaves of flooded rice. We also evaluated N. californicus behavior in response to S. oryzae and conspecific cues. Thirty-two eggs were individually placed in arenas on rice leaves and fed on S. oryzae for the biological test. Three cultivars were used to test the behavior of N. californicus in response to S. oryzae and conspecific cues. The intrinsic rate of increase (rm) of the predator feeding on S. oryzae was 0.21 female/female/day. Schizotetranychus oryzae was considered a suitable prey for N. californicus under laboratory conditions. The results obtained in behavioral tests showed that N. californicus preferred laying eggs on leaves uninfested by S. oryzae and it did not show oviposition preference in arenas with conspecific predator cues. This predator was found in all rice cultivation areas in the state of Rio Grande do Sul, Brazil. Neoseiulus californicus proved to be a control agent for S. oryzae.

The effect of temperature on the biology of Phytoseiulus macropilis (Banks) (Phytoseiidae) in applied biological control program / Efeito da temperatura sobre a biologia de Phytoseiulus macropilis (Banks) (Phytoseiidae) em programa de controle biológico aplicado

Phytoseiulus macropilis (Banks) (Phytoseiidae) is a natural enemy of Tetranychus urticae Koch (TSSM), a common pest in several cultures, especially in greenhouses. This research aimed to know the biological parameters of a strain of P. macropilis from Vale do Taquari, State of Rio Grande do Sul, feeding on TSSM at different temperatures. The study was initiated with 30 eggs individualized in arenas under the temperature of 20, 25 and 30 ± 1°C and relative humidity of 80 ± 10%. The average length (T) of each generation decreased with the increase of temperature, ranging from 25.71 days at 20°C to 11.14 days at 30°C. The net reproductive rate (Ro) ranged from 45.47 at 20°C to 18.25 at 30°C; the innate capacity for increase (rm) was 0.15 at 20°C, reaching 0.26 at 30°C and the finite increase rate (λ) ranged from 1.41 to 1.82 females day-1 at 20 and 30°C, respectively. In the present study, it was observed that the strain of the evaluated predatory mite from mild climate of South Brazil, might present a good performance to control TSSM when exposed to a temperature range between 20 and 30°C.

Phytoseiulus macropilis (Banks) (Phytoseiidae) é um inimigo natural de Tetranychus urticae Koch (ácaro rajado), uma praga comum em diversas culturas mantidas em estufas. Esta pesquisa teve o objetivo de conhecer características biológicas de uma linhagem de P. macropilis do Vale do Taquari, Rio Grande do Sul, que se alimenta do ácaro rajado em diferentes temperaturas. O estudo foi iniciado com 30 ovos individualizados em arenas nas temperaturas de 20, 25 e 30 ± 1°C e umidade relativa de 80 ± 10%. A duração média (T) de cada geração diminuiu com o aumento da temperatura, variando de 25,71 dias, a 20°C, e 11,14 dias, a 30°C. A taxa líquida de reprodução (Ro) variou de 45,47, a 20°C, para 18,25, a 30°C; a capacidade inata de crescimento (rm) foi de 0,15, a 20°C, atingindo 0,26, a 30°C, e a taxa de aumento finito (λ) variou 1,41 até 1,82 fêmeas/dia, a 20 e 30°C, respectivamente. No presente estudo, observou-se que a estirpe de predador avaliada, de clima ameno do Sul do Brasil, pode apresentar um bom desempenho para controlar TSSM quando exposta a temperatura entre 20 e 30°C.