Interactions between the omnivorous bug Nesidiocoris tenuis (Heteroptera: Miridae) and the tomato pests Helicoverpa armigera (Lepidoptera: Noctuidae) and Phthorimaea absoluta (Lepidoptera: Gelechiidae): predation, phytophagy, and prey preference

Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is a zoophytophagous bug that can derive nutrients from 3 trophic levels: plants, herbivorous arthropods, and other predators. On tomato, besides damaging the plants as they feed, might the mirid also forage on pest species and repel pests. In greenhouse and laboratory experiments, we investigated the functional response of the bug, its prey preference, and its influence on the oviposition potentials of 2 major pest species Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and Phthorimaea absoluta Meyrick (Lepidoptera: Gelechiidae) on tomato Solanum lycopersicum L. (Solanaceae). Nesidiocoris tenuis showed a Type II functional response to both prey species. The estimated handling time was higher for H. armigera eggs than for P. absoluta yet N. tenuis attack rates did not differ between the 2 prey species. Nesidiocoris tenuis did not show a preference for 1 species when prey eggs were provided in equal proportions. The feeding on tomato plants by N. tenuis did not affect oviposition by the 2 moth species, as neither species showed a preference for clean or N. tenuis-adult-damaged plants and clean or N. tenuis-nymph-damaged plants. This study shows that N. tenuis can prey upon eggs of both moth species as the 3 species co-occur in tomato fields. However, because of the shorter handling time of P. absoluta eggs by the predator and the higher number of eggs laid by H. armigera, the co-occurrence might be less detrimental to the H. armigera populations compared to P. absoluta.

Half Friend, Half Enemy? Comparative Phytophagy between Two Dicyphini Species (Hemiptera: Miridae)

Despite their importance as biological control agents, zoophytophagous dicyphine mirids can produce economically important damage. We evaluated the phytophagy and potential impact on tomato plants of Dicyphus cerastii and Nesidiocoris tenuis. We developed a study in three parts: (i) a semi-field trial to characterize the type of plant damage produced by these species on caged tomato plants; (ii) a laboratory experiment to assess the effect of fruit ripeness, mirid age, and prey availability on feeding injuries on fruit; and (iii) a laboratory assay to compare the position of both species on either fruit or plants, over time. Both species produced plant damage, however, although both species produced scar punctures on leaves and necrotic patches on petioles, only N. tenuis produced necrotic rings. Both species caused flower abortion at a similar level. Overall, N. tenuis females produced more damage to tomato fruit than D. cerastii. There was an increased frequency of D. cerastii females found on the plants over time, which did not happen with N. tenuis. Our results suggested that, although D. cerastii caused less damage to fruit than N. tenuis, it still fed on them and could cause floral abortion, which requires field evaluation and caution in its use in biological control strategies.

Global change calls for novel plant protection: reviewing the potential of omnivorous plant-inhabiting arthropods as predators and plant defence inducers

Global change poses new challenges for pest management. Omnivorous predatory arthropods play an important role in pest management, yet their potential has not been fully explored. Not only do they consume prey, but their plant-feeding induces plant defences that decrease herbivores' performance, and increases production of volatiles that attract natural enemies. Growing evidence from different plant-arthropod systems indicates the generality of plant defence induction following omnivore plant-feeding. Furthermore, these responses appear to affect other organisms (e.g. plant viruses), altering multi-trophic interactions. Here, we review the dual role of omnivores (as predators and plant inducers), identify knowledge gaps and provide future perspectives to increase our understanding of omnivores' multiple functions, and how this can be applied to advance plant protection strategies.

Jekyll or Hyde? The genome (and more) of Nesidiocoris tenuis, a zoophytophagous predatory bug that is both a biological control agent and a pest

Nesidiocoris tenuis (Reuter) is an efficient predatory biological control agent used throughout the Mediterranean Basin in tomato crops but regarded as a pest in northern European countries. From the family Miridae, it is an economically important insect yet very little is known in terms of genetic information and no genomic or transcriptomic studies have been published. Here, we use a linked-read sequencing strategy on a single female N. tenuis. From this, we assembled the 355 Mbp genome and delivered an ab initio, homology-based and evidence-based annotation. Along the way, the bacterial "contamination" was removed from the assembly. In addition, bacterial lateral gene transfer (LGT) candidates were detected in the N. tenuis genome. The complete gene set is composed of 24 688 genes; the associated proteins were compared to other hemipterans (Cimex lectularis, Halyomorpha halys and Acyrthosiphon pisum). We visualized the genome using various cytogenetic techniques, such as karyotyping, CGH and GISH, indicating a karyotype of 2n = 32. Additional analyses include the localization of 18S rDNA and unique satellite probes as well as pooled sequencing to assess nucleotide diversity and neutrality of the commercial population. This is one of the first mirid genomes to be released and the first of a mirid biological control agent.