Search

Background The use of zoophytophagous predators in protected crops has been widely adopted to manage pests in southern Europe. We hypothesized that plant defence responses would be induced by zoophytophagous predators and this induction could affect plant virus occurrence; the phytophagy of these predators induces plant defences similarly to that of viral infection. Therefore, we evaluated whether or not mirid predator-activated plant defences limited the accumulation of Tomato Spotted Wilt Virus (TSWV) in mechanically infected sweet pepper. Results Our results revealed TSWV accumulation in mirid-punctured plants to be significantly lower than in intact plants. This is most likely associated with the upregulation of the jasmonate acid pathway triggered by mirid phytophagy. Conclusion Activation of induced defences by mirid predators has been demonstrated for the first time to limit the accumulation of TSWV in sweet pepper. This novel approach can offer new control strategies for the management of plant diseases. © 2019 Society of Chemical Industry.

Pest management in protected sweet pepper crops mainly rely on biological control (BC) strategies. Recently, the zoophytophagous predatory mirids, Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus maroccanus, proved to be effective in the control of aphids on sweet pepper, for which the current biological control strategies have been meagre. The next step to integrate the possible use of these mirids in sweet pepper BC practices would be to ascertain their potential control on other sweet pepper pests. In this research, a comparative study to assess the establishment and the efficacy of N. tenuis, M. pygmaeus, and D. maroccanus on the two sweet pepper key pests; the thrips, Frankliniella occidentalis, and the whitefly, Bemisia tabaci was conducted. This study was carried out with two different temperature regimes, 20 °C and 27 °C, which simulated the mean temperatures registered in the two main crop cycles in Spain (the winter and summer planting period). Both, N. tenuis and M. pygmaeus were able to establish on sweet pepper and significantly reduced the number of F. occidentalis and B. tabaci adults, larvae and nymphs. Macrolophus pygmaeus had the highest density at 20 °C, whereas N. tenuis was more abundant at 27 °C. In contrast, D. maroccanus was less abundant under both temperatures studied; and did not reduce neither F. occidentalis nor B. tabaci infestations in this crop. None of the three mirids were observed to cause any damage to the pepper plant. The implications of these results applied to the use of mirids in sweet pepper crops are discussed.

[EN] Orius laevigatus is a generalist predator that is widely used in augmentative strategies against the key pest of sweet pepper, Frankliniella occidentalis. Despite being a zoophytophagous predator, the phytophagous behavior of O. laevigatus has not been previously explored in depth nor has the impact of phytophagy on plant physiology. Here, the hierarchical significance of O. laevigatus feeding on sweet pepper is compared with other behaviors. O. laevigatus spends the majority of its time (38%) feeding on apical meristems and apical fresh leaves, which were also preferred residence locations. Here, the phytophagous feeding behavior of O. laevigatus on sweet pepper is shown to trigger defensive responses in the plant. These O. laevigatus plant-induced defenses are then shown to contribute to the repellence or attraction of pests or natural enemies, respectively. Specifically, O. laevigatus-punctured sweet pepper plants induce repellency for the whitefly Bemisia tabaci and the thrips species F. occidentalis. In contrast, the whitefly parasitoid Encarsia formosa was significantly attracted to O. laevigatus-punctured plants. The plant responses to O. laevigatus punctures include the release of an altered blend of volatiles and activation of the jasmonic acid and salicylic acid signalling pathways. These results highlight an interesting facet to the biology of O. laevigatus, in which the ability of the predator to induce defensive responses in sweet pepper plants may serve to improve the biological control of both thrips and whiteflies., The research leading to these results was partially funded by the Spanish Ministry of Economy and Competitiveness (AGL2014-55616-C3) and the Conselleria d'Agricultura, Pesca i Alimentacio de la Generalitat Valenciana. The authors thank Dr. Javier Calvo (KOPPERT BS, Spain) for supplying the insects, Dr. Pablo Bielza (Universidad Politecnica de Cartagena, Spain) for thrips colonies, Dimitrios Afentoulis, Zoi Thanou and Konstantinos Birmpilis (Erasmus + from Agricultural University of Athens) for providing support in the behavior experiments and Alice Mockford (University of Worcester) and two anonymous reviewers for their constructive review of this manuscript. MP-H was the recipient of a postdoctoral fellowship from the MEC (Juan de la Cierva program-FPDI-2013-17968) and SB was the recipient of a grant from Russell IPM Ltd.

The combined release of Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) with Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) provides effective control of sweet pepper key pests, such as thrips and whiteflies. However, the management of the aphids can still be improved. Recently, the predatory mirids Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) and Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) have been found to be effective in the control of aphids, thrips and whiteflies when tested alone. Hence, integrating one of these two mirids with A. swirskii might enhance sweet pepper pest management. In this work, we began by investigating the co-occurrence of both mirid species when released together with A. swirskii. This was compared to the standard release of O. laevigatus with A. swirskii. N. tenuis and A. swirskii were involved in a bidirectional intraguild predation (IGP). On the contrary, this interaction (IGP) was apparently unidirectional in the case of M. pygmaeus with A. swirskii and O. laevigatus with A. swirskii. Both, M. pygmaeus and O. laevigatus significantly reduced the abundance of A. swirskii. Secondly, in a greenhouse experiment, where the same release combinations were tested (either N. tenuis, M. pygmaeus or O. laevigatus combined with A. swirskii), IGP seemed to be neutralized. Mirids with A. swirskii significantly suppressed thrips, whitefly, and aphid infestations. Contrarily, the combined use of O. laevigatus with A. swirskii did not reached a satisfactory control for aphids, despite the reduction in thrips and whitefly densities. Therefore, our results suggest that the use of mirids combined with A. swirskii could result in more efficient and robust biological control programs in sweet pepper crops.