Abstract
ObjectiveTetranychus cinnabarinus (Boisduval) is an agricultural mite pest threatens crops throughout the world, causing serious economic loses. Exploring the effects of acaricides on predatory mites is crucial for the combination of biological and chemical control of T. cinnabarinus. Neoseiulus californicus (McGregor) is one of the principal natural enemies of T. cinnabarinus, which can be applied in protected agriculture. In this study, the effects of sublethal concentrations of a new acaricide, SYP-9625 on two mite species, and the effects of the application concentration on predatory mite, N. californicus were assessed. The aim of the present study was to evaluate the effect of SYP-9625 on life parameters and predation capacity of N. californicus based on the concentration-response bioassay of T. cinnabarinus to explor the application of the new acaricide with natural enemy N. californicus.MethodAll of the experiments were conducted under laboratory conditions [25 ± 1°C, 16: 8 h (L: D) and 75 ± 5% RH]. The sublethal concentrations LC10 (0.375μg/mL) and the LC30 (0.841μg/mL) against T. cinnabarinus and the application concentration (100μg/mL) against N. californicus were used to evaluate the effects of SYP-9625 on population parameters of N. californicus based on an age-stage, two-sex life table and its predation capacity by functional response.Resultcinnabarinus females treated with LC30 exhibited significantly reduced net reproductive rates (R0 = 11.02) in their offspring compared with females treated with LC10 (R0 = 14.96) and untreated females (R0 = 32.74). However, the intrinsic rate of increase (rm) and the finite rate of increase (λ) of N. californicus indicated that the application concentration of SYP-9625 had no significant negative effect on N. californicus eggs (rm = 0.277, λ = 1.319) compared to the control (rm = 0.292, λ = 1.338). Additionally, most population parameters of N. californicus showed a dose-dependent manner with the increase of the concentration of SYP-9625 against T. cinnabarinus. SYP-9625 also stimulated the control efficiency of N. californicus against immobile stages including eggs and larvae.ConclusionThis study demonstrated that sublethal concentrations of SYP-9625 can inhibit the population growth of T. cinnabarinus. In addition, the sublethal concentrations and the application concentration showed no effect on the population growth of N. californicus. These two advantages described above showed great commercial potential of this new acaricide based on population parameters of the two mite species and predation capacity of the predatory mite under laboratory conditions.
Highlights
Nowadays, agricultural spider mite pests are becoming one of the major threats to some important crops such as vegetables, fruits and ornamentals throughout the world
Mollaloo investigated the effect of three lethal concentrations pyridaben on the developmental and reproductive parameters of Neoseiulus californicus (McGregor), which confirmed that the maneuverability about the combination of natural enemies such as phytoseiid predators with compatible acaricides is the key to decrease chemical applications and the environmental hazards [10]
Pesticide exposure can significantly influence the functional response of predators, so many studies have assessed the effects of pesticides on the functional response of predatory mite species [13]
Summary
Agricultural spider mite pests are becoming one of the major threats to some important crops such as vegetables, fruits and ornamentals throughout the world. In integrated pest management (IPM) systems, natural enemies and compatible acaricides can be applied in a conjunct group, and a proportion of studies tend to paying more attention to the toxicity of acaricides on predatory mites [3,4,5,6,7]. Based on the inter-population differences in the sensitivities of these natural enemies, Lima evaluated different acaricide toxicities against Neoseiulus barkeri (Hughes) and suggested that fenpyroximate and chlorfenapyr can be used together with the predatory mite application [4, 8]. Mollaloo investigated the effect of three lethal concentrations pyridaben on the developmental and reproductive parameters of Neoseiulus californicus (McGregor), which confirmed that the maneuverability about the combination of natural enemies such as phytoseiid predators with compatible acaricides is the key to decrease chemical applications and the environmental hazards [10]. Poletti reported that acetamiprid did not affect the functional responses of N. californicus, it weakened the predation capacity of Phytoseiulus macropilis (Banks) [4]
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