Temperature-Driven Selection of Predatory Mirid Bugs for Improving Aphid Control in Sweet Pepper Crops

Recent studies have suggested that predatory mirid bugs may be an effective alternative for controlling aphids in sweet pepper greenhouses. This study examined the effect of three constant temperatures (18, 24, and 30 °C) on the life history traits of predatory mirid species Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus bolivari, preying on the aphid Myzus persicae nicotianae in sweet pepper plants. As the temperature increased, the survival rate decreased for M. pygmaeus and D. bolivari, while for N. tenuis, it was the opposite, and their survival increased. When considering all the biological traits studied together, the estimated intrinsic rate of increase (rm) decreased as the temperature increased for M. pygmaeus and D. bolivari. In contrast, the rate increased as the temperature increased for N. tenuis. These results suggest that M. pygmaeus and D. bolivari are better adapted to lower temperatures than N. tenuis, which is more adapted to warm temperatures. The implications of these results for improving the biological control of aphids in sweet pepper greenhouses through the use of mirid bugs are discussed in relation to different temperature regimes

Functional response and predation rate of Dicyphus cerastii Wagner (Hemiptera: Miridae)

Dicyphine mirids are important biological control agents (BCAs) in horticultural crops. Dicyphus cerastii Wagner can be found in protected tomato crops in Portugal, and has been observed feeding on several tomato pests. However, the predation capacity of this species is poorly studied. In order to investigate the predation capacity of D. cerastii, and how it is affected by prey size and mobility, we evaluated the functional response (FR) and predation rate of female predators on different densities of four prey species: Myzus persicae 1st instar nymphs (large mobile prey), Bemisia tabaci 4th instar nymphs, Ephestia kuehniella eggs (large immobile prey) and Tuta absoluta eggs (small immobile prey). Experiments were performed on tomato leaflets in Petri dish arenas for 24 h. Dicyphus cerastii exhibited type II FR for all prey tested. The predator effectively preyed upon all prey, consuming an average of 88.8 B. tabaci nymphs, 134.4 E. kuehniella eggs, 37.3 M. persicae nymphs and 172.3 T. absoluta eggs. Differences in the FR parameters, attack rate and handling time, suggested that prey size and mobility affected predation capacity. Considering the very high predation rates found for all prey species, D. cerastii proved to be an interesting candidate BCA for tomato cropsinfo:eu-repo/semantics/publishedVersio

Induced Tomato Plant Resistance Against Tetranychus urticae Triggered by the Phytophagy of Nesidiocoris tenuis

The zoophytophagous predator Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is capable of inducing plant defenses in tomato due to its phytophagous behavior. These induced defenses, which include the release of herbivore-induced plant volatiles (HIPVs), have been proven to affect the oviposition behavior and reduce the subsequent performance of some tomato pests. However, the effect of induction of plant defenses by N. tenuis on the preference, development, and reproduction of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) remains unknown. In this research, T. urticae did not show preference for the odor source emitted by intact tomato plants when compared with N. tenuis-punctured plants and jasmonic acid (JA) deficient mutant tomato plants. Furthermore, the number of eggs laid by T. urticae on intact tomato plants or on N. tenuis-punctured plants was similar. However, in a greenhouse experiment conducted to evaluate whether the defense induction mediated by N. tenuis had an effect on T. urticae the infestation of T. urticae was significantly reduced by 35% on those plants previously activated by N. tenuis when compared to the control. The expression of a JA-responsive gene that was upregulated and the transcription of the plant protein inhibitor II was higher on activated plants relative to the control. These results can serve as a basis for the development of new management strategies for T. urticae based on plant defense mechanisms induced from the phytophagous behavior of N. tenuis

Silenciamiento de genes diana de Delottococcus aberiae DeLotto (Hemiptera: Pseudococcidae) mediante tecnología RNAi

El RNA de interferencia (RNAi) es una de las herramientas biotecnológicas con mayor potencial en la protección de cultivos frente a insectos plagas. Con esta técnica de silenciamiento postranscripcional se puede bloquear la expresión de genes diana de interés al destruir eficazmente su correspondiente RNA mensajero (mRNA). En los últimos años se han logrado avances significativos en varios aspectos del mecanismo de silenciamiento génico postranscripcional mediado por moléculas de RNA de doble cadena (dsRNA). En la actualidad el mundo científico se encuentra en disposición de poder transferir y aplicar de manera práctica esta potente herramienta al control biológico de plagas

The olfactive responses of Tetranychus urticae natural enemies in citrus depend on plant genotype, prey presence, and their diet specialization

[EN] Sour orange, Citrus aurantium, displays higher constitutive and earlier inducible direct defenses against the two-spotted spider mite, Tetranychus urticae, than Cleopatra mandarin, Citrus reshni. Moreover, herbivore-induced plant volatiles (HIPVs) produced by sour orange upon infestation can induce resistance in Cleopatra mandarin but not vice versa. Because the role of these HIPVs in indirect resistance remains ignored, we have carried out a series of behavioral assays with three predatory mites with different levels of specialization on this herbivore, from strict entomophagy to omnivory. We have further characterized the volatile blend associated with T. urticae, which interestingly includes the HIPV methyl salicylate, as well as that produced by induced Cleopatra mandarin plants. Although a preference for less defended plants with presumably higher prey densities (i.e., C. reshni) was expected, this was not always the case. Because predators' responses changed with diet width, with omnivore predators responding to both HIPVs and prey-related odors and specialized ones mostly to prey, our results reveal that these responses depend on plant genotype, prey presence and predator diet specialization. As the different volatile blends produced by infested sour orange, induced Cleopatra mandarin and T. urticae itself are attractive to T. urticae natural enemies but not to the herbivore, they may provide clues to develop new more sustainable tools to manipulate these agriculturally relevant species.The research leading to these results was partially funded by the Spanish Ministry of Economy and Competitiveness (AGL2014-55616-C3; AGL2015-64990-2R). The authors thank M. Piquer (UJI) for technical assistance. MC received a pre-doctoral fellowship from the Spanish Ministry of Economy and Competitiveness (BES-2015-074570), and MP was the recipient of a research fellowship from INIA, Spain (subprogram DOC INIA-CCAA).Cabedo López, M.; Cruz-Miralles, J.; Vacas, S.; Navarro-Llopis, V.; Pérez-Hedo, M.; Flors, V.; Jaques, JA. (2019). The olfactive responses of Tetranychus urticae natural enemies in citrus depend on plant genotype, prey presence, and their diet specialization. Journal of Pest Science. 92(3):1165-1177. https://doi.org/10.1007/s10340-019-01107-7S1165117792

Orius laevigatus Induces Plant Defenses in Sweet Pepper

Pest management in protected sweet pepper crops primarily relies on biological control strategies. The release of the phytoseiid Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) and the anthocorid Orius laevigatus Fieber (Hemiptera: Anthocoridae) provides effective control of the two key pests of this crop, the thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) and the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) (Sanchez et al., 2000; Calvo et al., 2009; van der Blom et al., 2009). A part of their direct effect on pest predation, zoophytophagous predators may induce defensive plant responses due to their plant feeding behaviour which involves the release of diverse volatiles through different pathways that are triggered by phytohormones (De Puysseleyr et al., 2011; Naselli et al., 2016; Pappas et al., 2015, 2016; Pérez-Hedo et al., 2015a,b). These responses may result in the repellence or attraction of pests and natural enemies. It is hence hypothesized that O. laevigatus would be able to induce plant responses in sweet pepper as has been demonstrated in other plantzoophytophage systems. As a first step to better understand the interaction between O. laevigatus and sweet pepper, the behavior of O. laevigatus on the plants was studied and plant feeding behaviour quantified to compare general behaviors. Orius laevigatus spends the majority of its time (38%) feeding on apical meristems and apical fresh leaves, which were also preferred residence locations (Bouagga et al., 2017)