How do caterpillars cope with xenobiotics? The case of Mythimna unipuncta, a species with low susceptibility to Bt

Mythimna unipuncta is a species with low susceptibility to the Bacillus thuringiensis (Bt) toxin, and this insect occasionally causes devastating damage to maize. In the study region, M. unipuncta-developed larvae were observed moving from a non-Bt crop to a nearby Bt crop. Although the first response of many caterpillars to xenobiotics, such as the Bt toxin, is to reduce food intake and prolong development, few studies have focused on the causes and consequences of this response in terms of resistance evolution. To clarify the causes of this response, this work compared changes in the feeding behaviour, cytochrome P450 expression and juvenile hormone titre during the last larval instar of M. unipuncta after Bt ingestion. Four P450 enzymes related to the xenobiotic metabolism of the CYP9 and CYP6 families were identified. Developed larvae fed the Bt diet reduced their food intake and CYP9 expression, experienced prolonged development and presented an altered juvenile hormone balance. The CYP9s were not increased in the larvae that consumed Bt, as previously expected, although their highest expression was observed when larval feeding increased. The high recovery capacity of the larvae contributed to their development when they were fed a non-Bt diet. The efficiency of responses that act jointly as a defence mechanism against Bt might favour the development of field resistance to the toxin. Therefore, these responses should be further investigated for resistance management programmes

Zoophytophagous predator-induced defences restrict accumulation of the tomato spotted wilt virus

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. \ua9 2019 Society of Chemical Industry

Classical biological control of the African citrus psyllid Trioza erytreae, a major threat to the European citrus industry

Citrus greening or huanglongbing (HLB) is the main threat to the European citrus industry since one of its vectors, the African citrus psyllid, Trioza erytreae, has recently become established in mainland Europe. In this context, classical biological control programmes should be implemented to reduce the spread of the psyllid. The aims of this study were to: i) disentangle the parasitoid complex of T. erytreae combining morphological and molecular characterization; and ii) to study the biology of its main parasitoids in its area of origin in South Africa for their future importation into Europe. The main citrus producing areas of South Africa were surveyed during 2017. In contrast to previous studies, the parasitoid complex of T. erytreae included three species of primary parasitoids: Tamarixia dryi, Psyllaephagus pulvinatus and another parasitoid of the genus Tamarixia. Molecular analysis showed that it is a new species closely related to T. dryi. Tamarixia dryi was the most abundant parasitoid but its relative abundance varied among sampling sites. The sex ratio (males/females) of T. dryi and Tamarixia sp. decreased with T. erytreae size and became female biased when psyllid nymphs were larger than 0.6 and 1.2 mm2, respectively. These parasitoids were attacked by three species of hyperparasitoids, Aphidencyrtus cassatus, Marietta javensis and a species of the genus Aphanogmus. Aphidencyrtus cassatus, the most abundant hyperparasitoid, tended to emerge from large nymphs, and adult females lived as long as those of T. dryi. The implications of these results are discussed within the framework of the introduction of T. dryi into Europe.The European Union’s Horizon 2020 research and innovation programme, the Spanish Ministry of Economy and Competitiveness, the Conselleria d’Agricultura, Pesca i Alimentació de la Generalitat Valenciana, a pre-doctoral grant from Generalitat Valenciana (Spain), and a research fellowship from the INIA Spain (Subprogramme DOC-INIA-CCAA).http://www.nature.com/sreppm2020Zoology and Entomolog

Resilience and robustness of IPM in protected horticulture in the face of potential invasive pests

Recently, various approaches for the biological control of major pests in protected crops have successfully been adopted. These successes have primarily occurred via the selection, release and/or conservation of generalist native predators that naturally colonize Mediterranean crops that are highly adapted to local environmental conditions. These generalist predators have resulted very effective in controlling key pests; as a result, pesticide use has been reduced considerably. In addition, because these predators are typically highly polyphagous, horticultural crops have become more resilient to newly emerging pests, which are preyed upon by these predators. Possibilities to further strengthen pest management in horticultural crops have recently arisen, such as the use of bene fi cial microbes (BM) to induce plant resilience. In this review, we used a tomato crop as an example to present two new, highly interrelated plant defense induction strategies: the use of Miridae zoophytophagous predators and the use of Tri- choderma spp. microbial biological control agents. Both the mirid predators and Trichoderma symbiotic fungi can activate direct and indirect plant defense responses, which may increase the robustness of pest management against invading organisms. The practical use of these new approaches is discussed.The research leading to these results received funding from the European Union Seventh Framework Program (FP7/2007/2013) under grant agreement no 265865. The authors thank Jan van der Blom (Coexphal, Almería-Spain) and Javier Calvo (KOPPERT BS) who provided useful information for this manuscript. MP-H was the recipient of a postdoctoral fellowship from the MCINN (Juan de la Cierva program)

Resilience and robustness of IPM in protected horticulture in the face of potential invasive pests

Recently, various approaches for the biological control of major pests in protected crops have successfully been adopted. These successes have primarily occurred via the selection, release and/or conservation of generalist native predators that naturally colonize Mediterranean crops that are highly adapted to local environmental conditions. These generalist predators have resulted very effective in controlling key pests; as a result, pesticide use has been reduced considerably. In addition, because these predators are typically highly polyphagous, horticultural crops have become more resilient to newly emerging pests, which are preyed upon by these predators. Possibilities to further strengthen pest management in horticultural crops have recently arisen, such as the use of beneficial microbes (BM) to induce plant resilience. In this review, we used a tomato crop as an example to present two new, highly interrelated plant defense induction strategies: the use of Miridae zoophytophagous predators and the use of Trichoderma spp. microbial biological control agents. Both the mirid predators and Trichoderma symbiotic fungi can activate direct and indirect plant defense responses, which may increase the robustness of pest management against invading organisms. The practical use of these new approaches is discussed

Electroweak parameters of the z0 resonance and the standard model

Contains fulltext : 124399.pdf (publisher's version ) (Open Access