Impact of Agroecological Infrastructures on the Dynamics of Dysaphis plantaginea (Hemiptera: Aphididae) and Its Natural Enemies in Apple Orchards in Northwestern France

Phenolic compound profiles in Finnish apple (Malus × domestica Borkh.) juices and ciders fermented with Saccharomyces cerevisiae and Schizosaccharomyces pombe strains

The phenolic compounds in juices and ciders made with Saccharomyces cerevisiae or Schizosaccharomyces pombe from eleven Finnish apple cultivars were analyzed using liquid chromatographic and mass spectrometric methods combined with multivariate data analysis. In general, the ciders contained less phenolic compounds than corresponding apple juices. In the studied apple juices and ciders, hydroxycinnamic acids were the most predominant, accounting for around 80% of total phenolic compounds. Apple juices contained more flavonol glycosides and dihydrochalcones whereas cider processing resulted in increased amount of free hydroxycinnamic acids. The contents of individual phenolic compounds were more dependent on the apple cultivars than the yeast species. Certain cultivars contained remarkably higher contents of dihydrochalcones and hydroxycinnamic acids when comparing with other cultivars. Ciders made using S. pombe remained higher contents of procyanidins and (+)-catechin while S. cerevisiae ciders contained higher individual hydroxycinnamic acids, such as 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 3-O-p-coumaroylquinic acid, and 4-O-p-coumaroylquinic acid.

Impacts of Wildflower Interventions on Beneficial Insects in Fruit Crops: A Review

Integrated pest management (IPM) has been practiced by the fruit industry for at least 30 years. Naturally occurring beneficial insects have been encouraged to thrive alongside introduced predatory insects. However, Conservation Biological Control (CBC) and augmented biocontrol through the release of large numbers of natural enemies is normally only widely adopted when a pest has become resistant to available conventional pesticides and control has begun to break down. In addition, the incorporation of wild pollinator management, essential to fruit production, has, in the past, not been a priority but is now increasingly recognized through integrated pest and pollinator management (IPPM). This review focuses on the impacts on pest regulation and pollination services in fruit crops through the delivery of natural enemies and pollinating insects by provisioning areas of fruiting crops with floral resources. Most of the studies in this review highlighted beneficial or benign impacts of floral resource prevision to fruit crops. However, placement in the landscape and spill-over of beneficial arthropods into the crop can be influential and limiting. This review also highlights the need for longer-term ecological studies to understand the impacts of changing arthropod communities over time and the opportunity to tailor wildflower mixes to specific crops for increased pest control and pollination benefits, ultimately impacting fruit growers bottom-line with less reliance on pesticides.

A Comparison of Flower and Grass Strips for Augmentation of Beneficial Arthropods in Apple Orchards

Sowing plants that provide food resources in orchards is a potential habitat management practice for enhancing biological control. Flowering plants (providing pollen and nectar) and grasses (providing alternative prey) can benefit natural enemies in orchards; however, little is known about their relative importance. We studied the effect of management practices (flower strips, grass strips, and spontaneous grass) on arthropod predators under organic apple management regimes in apple orchards in Beijing, China. Orchards located at two different sites were assessed for 3 years (2017–2019). The cover crops had a significant impact on the abundance and diversity of arthropod predators. The grass treatment consistently supported significantly greater densities of alternative prey resources for predators, and predators were more abundant in the grass than in the other treatments. The Shannon–Wiener diversity was significantly higher for the cover crop treatment than for the control. Community structure was somewhat similar between the grass and control, but it differed between the flower treatment and grass/control. Weak evidence for an increase in mobile predators (ladybirds and lacewings) in the orchard canopy was found. Ladybirds and lacewings were more abundant in the grass treatment than in the other treatments in 2019 only, while the aphid abundance in the grass treatment was lowest. The fact that grass strips promoted higher predator abundance and stronger aphid suppression in comparison to the flower strips suggests that providing alternative prey for predators has great biocontrol service potential. The selection of cover crops and necessary management for conserving natural enemies in orchards are discussed in this paper.

Stable Isotopes Reveal the Dominant Species to Have the Widest Trophic Niche of Three Syntopic Microtus Voles

Simple Summary

Diets and the trophic positions of animals are fundamental issues in their ecology. We analysed the isotopic niches (as a proxy for trophic niches) of common (Microtus arvalis), field (M. agrestis), and root (M. oeconomus) voles co-occurring in orchards, berry plantations, and nearby meadows using isotopic (δ¹⁵N and δ¹³C) compositions from hair samples. We tested if the niche of the dominant common vole was widest, whether its width was related to the presence of other Microtus species, and whether there were intraspecific differences in average δ¹³C and δ¹⁵N stable isotope values. The obtained results showed relative stability in the trophic niche across the vegetative period. The isotopic niche of the common vole was the widest, exceeding the other two Microtus species by 1.6–3 times. Co-occurring vole species were separated according to δ¹³C (i.e., used different plants as main food), but they maintained similarity according to δ¹⁵N distribution. The effect of animal age and gender on the width of the trophic niche was strongest in root vole, which is a species that has spread across the country in the last 70 years. These results give new insights into the trophic ecology small herbivores, showing the impact of species co-occurrence.

Abstract

Diets and trophic positions of co-occurring animals are fundamental issues in their ecology, and these issues in syntopic rodents have been studied insufficiently. Using carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope ratios from hair samples, we analysed the trophic niches of common (Microtus arvalis), field (M. agrestis), and root (M. oeconomus) voles co-occurring in orchards, berry plantations, and nearby meadows (as control habitat to orchards and plantations). We tested if the niche of the dominant common vole was the widest, whether its width depended on the presence of other vole species, and whether there were intraspecific differences. Results suggest stability in the trophic niches of all three Microtus species, as season explained only 2% of the variance. The widest trophic niche was a characteristic of the dominant common vole, the range of δ¹³C values exceeding the other two species by 1.6, the range of δ¹⁵N values exceeding the other two species by 1.9, and the total area of niche exceeding that of the other voles by 2.3–3 times. In the meadows and apple orchards, co-occurring vole species were separated according to δ¹³C (highest values in the dominant common vole), but they maintained similar δ¹⁵N values. Results give new insights into the trophic ecology small herbivores, showing the impact of species co-occurrence.

Biological Control of Aphis spiraecola (Hemiptera: Aphididae) Using Three Different Flowering Plants in Apple Orchards

Increasing the biodiversity of agroecosystems can increase populations of natural enemies that are useful for pest control. Orchards often have a low diversity of plant species, which is not conducive to maintaining ecosystem functions and services. However, additional flowering plants could provide natural enemies with beneficial resources. To assess the ability of flowering plants to attract predators and increase the biological control of Aphis spiraecola Patch, we established individual plots of three different flowering plant species with sequential bloom periods between the rows of apple orchard. These plants attracted predators such as Coccinellidae, Syrphidae, and Chrysopidae when flowering. The density of predators on trees in the three flowering plant plots was significantly higher than that in the control, whereas the density of aphids on trees in Orychophragmus violaceus (L.) O. E. Schulz (Rhoeadales: Brassicaceae) and Cnidium monnieri (Linn.) Cuss. (Apiales: Apiaceae) plots were significantly lower than that in control. The density of aphids on trees in Calendula officinalis L. (Asterales: Asteraceae) plots was significantly lower than in other plots at second peak period. There was a significant negative correlation between the population of aphids and predators on trees at peak of aphids. Cage exclusion tests showed that the biocontrol services index (BSI) of O. violaceus was highest (32.7%) on 24 May, and the BSI of C. monnieri was highest (47.6%) on 7 June. Our results suggest that the temporal combination of different flowering plants could provide useful effective biocontrol to management pest in orchard.

Managing Floral Resources in Apple Orchards for Pest Control: Ideas, Experiences and Future Directions

Functional biodiversity is of fundamental importance for pest control. Many natural enemies rely on floral resources to complete their life cycle. Farmers need to ensure the availability of suitable and sufficient floral biodiversity. This review summarizes 66 studies on the management of floral biodiversity in apple orchards, published since 1986. Approaches followed different degrees of intervention: short-term practices (mowing regime and weed maintenance, cover crops), establishment of durable ecological infrastructures (perennial flower strips, hedgerows) and re-design of the crop system (intercropping, agroforestry). Although short-term practices did not always target the nutrition of natural enemies by flowering plants, living conditions for them (alternative prey, provision of habitat) were often improved. Perennial flower strips reliably enhanced natural enemies and techniques for their introduction continuously developed. Resident natural enemies and their impact in pest control reacted positively to the introduction of a more diversified vegetation, whereas the response of very mobile organisms was often not directly linked to the measures taken. A careful selection and management of plants with particular traits exploitable by most natural enemies emerged as a key-point for success. Now the elaborated design of such measures needs to be adopted by stakeholders and policy makers to encourage farmers to implement these measures in their orchards.

Local pesticide use intensity conditions landscape effects on biological pest control

Complex landscapes including semi-natural habitats are expected to favour natural enemies thereby enhancing natural pest biocontrol in crops. However, when considering a large number of situations, the response of natural biocontrol to landscape properties is globally inconsistent, a possible explanation being that local agricultural practices counteract landscape effects. In this study, along a crossed gradient of pesticide use intensity and landscape simplification, we analysed the interactive effects of landscape characteristics and local pesticide use intensity on natural biocontrol. During 3 years, using a set of sentinel prey (weed seeds, aphids and Lepidoptera eggs), biocontrol was estimated in 80 commercial fields located in four contrasted regions in France. For all types of prey excepted weed seeds, the predation rate was influenced by interactions between landscape characteristics and local pesticide use intensity. Proportion of meadow and length of interface between woods and crops had a positive effect on biocontrol of aphids where local pesticide use intensity was low but had a negative effect elsewhere. Moreover, the landscape proportion of suitable habitats for crop pests decreased the predation of sentinel prey, irrespectively of the local pesticide use intensity for weed seeds, but only in fields with low pesticide use for Lepidoptera eggs. These results show that high local pesticide use can counteract the positive expected effects of semi-natural habitats, but also that the necessary pesticide use reduction should be associated with semi-natural habitat enhancement to guarantee an effective natural biocontrol.

The Contribution of Surrounding Margins in the Promotion of Natural Enemies in Mediterranean Apple Orchards

(1) Habitat management can enhance beneficial arthropod populations and provide ecosystem services such as biological control. However, the implementation of ecological infrastructures inside orchards has a number of practical limitations. Therefore, planting/growing insectary plants in the margins of orchards should be considered as an alternative approach. (2) Here, we assessed the efficacy of a flower margin composed by four insectary plant species (Achillea millefolium, Lobularia maritima, Moricandia arvensis and Sinapis alba), which was placed on an edge of four Mediterranean apple orchards to attract natural enemies of two apple tree aphids (Dysaphis plantaginea and Eriosoma lanigerum). We also characterized the natural enemies present in the aphid colonies. (3) Our results show that the implementation of a flower margin at the edge of apple orchards attracts predators (Syrphidae, Thysanoptera, Araneae, Heteroptera, Coleoptera) and parasitoids. Parasitoids are the main natural enemies present in aphid colonies in our area. (4) The implementation of the flower margins successfully recruited natural enemy populations, and the presence of parasitoids in the surroundings of the orchards increased the parasitism of D. plantaginea colonies.