Albajes, R. | bioRxiv Science

bioRxiv2022

Effects of diversifying the planting period of maize on herbivorous and their natural enemies

Knowledge of the specific insect densities during crop development is necessary to perform appropriate measures for the control of insect pests and to minimize yield losses. In a previous study, both spatial and temporal approaches were adopted to analyse the influence of landscape structure and field variables on herbivore and predatory insects on maize. Both types of variables influenced insect abundance, but the highest effect was found with maize phenology. Given that the field planting date could modulate the influence produced by the structure of the landscape on herbivores and predatory insects, analyses of population dynamics must be performed at both the local and landscape levels. The anterior prompted us to study these aspects in the two common planting periods (early and late) in northern Spain. The present study tests the hypothesis that the period of maize planting could have a higher effect than phenology or interannual variation on the abundance of natural enemies and herbivores on maize. Our results showed that only the abundances of other herbivore thrips and Syrphidae were significantly different between the two planting periods. Moreover, we found significant effects of planting period when we performed yearly analysis in 2015 for Coccinellidae and Chrysopidae and in 2016 and 2017 for Aeolothrips sp. Most of the taxa had abundance peaks in earlier growth stages, which are related to pollination (before or during), while only Stethorus punctillum and Syrphidae increased later in the season. Furthermore, Frankliniella occidentalis, aphids, Syrphidae and Coccinellidae registered higher abundances in fields sown in the late planting period than in the rest of the insect species. The results of the present study highlight the effects of sowing dates on insect dynamics in maize. HighlightsO_LIHerbivorous and natural enemy abundance peaks in earlier growth stages. C_LIO_LIAbundance of thrip and Syrphidae were different between the two planting periods. C_LIO_LIAbundance of Coccinellidae, Chrysopidae and Aeolothrips sp. was different when performed yearly analysis. C_LI

ecology↗

bioRxiv2017

Genotype, nitrogen and herbivory shape plant defense: the case of a vitamin-enriched maize

The cultivation of crops with novel traits could interfere with ecosystem services delivered by arthropods through bottom-up effects. Here we tested the hypothesis that a vitamin enriched maize (CarolightR) is similar in terms of plant-arthropod interactions to its wild type when compared in controlled environment and under field conditions. In order to assess the robustness of their equivalence we tested two nitrogen availability regimes. We used arthropod field abundance, the behavior and fitness of a keystone maize herbivore - the leafhopper Zyginidia scutellaris - and above ground chemistry of maize plants (volatile, hormone and metabolite profiling) as indicators of potential changes in plant-insect interactions. Nitrogen availability was the key driver of herbivore abundance and behavior, and determined direct and indirect chemical defense in maize plants. Both genotypes presented similar constitutive and inducible phytohormone profiles independently of the nitrogen regime. However, feeding by the herbivore suppressed the levels of JA-Ile and JA, without impairing the release of induced plant volatiles. CarolightR and M37W differed to some degree in the concentrations of phenolics (hydroxycinnamic acids and lignans) and in the abundance of a volatile compound. Overall the effect of maize genotype on the herbivores was smaller than the effect of nitrogen fertilization.\n\nHIGHLIGHTWe show the separate and interactive effects of nitrogen availability and genotype on the performance and behavior of a herbivore, and related these changes to constitutive and inducible maize defenses.

plant biology↗