Aphid-infested beans divert ant attendance from the rosy apple aphid in apple-bean intercropping

Abstract

Ecological intensification of cropping systems aims at restoring multi-functionality while supporting current productivity levels. Intercropping is a form of ecological intensification involving ecological processes beneficial to farmers that do not take place in monocultures. Thus, it represents a practical approach to decrease the use of synthetic inputs such as insecticides in cultivated systems. Whereas insecticide reduction via intercropping-facilitated suppression of aphids is reported in literature, the majority of published studies focussed on herbaceous crops. Thus, the effect of intercropping on aphid populations of cultivated trees remains largely unaddressed. In this study we hypothesized that intercropping a specific companion plant within perennial crops would divert ant attendance from an aphid attacking the crop to another aphid feeding on the newly introduced plant, reducing aphid damage on the crop. We tested our hypothesis in the system of apple (Malus domestica Borkhausen), the rosy apple aphid (Dysaphis plantaginea Passerini) and the black garden ant (Lasius niger L.). Bean plants (Vicia faba) with the black bean aphid (Aphis fabae Scopoli) were intercropped within apple trees inoculated with D. plantaginea. We measured ant attendance, aphid development and survival as well as honeydew composition on both plant species through semi-field and field experiments. The majority of ants chose to attend A. fabae over D. plantaginea in the semi-field experiment with potted plants. In the orchard, a larger majority of scouts were scored on A. fabae over D. plantaginea. A higher number of D. plantaginea colonies remained active in the apple control, whilst they were almost eradicated by intercropping. Although chemical analyses of honeydew disclosed differences in the carbohydrate and amino acid profiles between aphid species, the difference in honeydew composition did not explain the preference for A. fabae. Ants did not discriminate between the two honeydew mimics both in laboratory and field bioassays. Our results showed the potential of intercropping apple trees with beans as a method to reduce ant attendance and thus colony survival. We propose that intercropping represents a bottom-up approach towards ecological intensification of perennial crops. Together with other ecosystem-based measures such as habitat management, intercropping should be considered when planning ecosystem redesign to increase biological control of pests. Ecological intensification of agro-ecosystems is recognized as a fundamental change to restore multi-functionality while supporting high productivity levels 1. It is predicted that the integration of ecosystem-based strategies with agro-ecological processes will allow for the development of productive and resilient farming systems 2. Among various on-farm possibilities, such an objective can be achieved via improvement of the existing cropping systems, through both intraspecific and interspecific botanical diversification 3,4. Benefits such as increased crop productivity, im...

Implementing wood ants in biocontrol: Suppression of apple scab and reduced aphid tending

“…It should be mentioned that an alternative to artificial sugar feeders are trap crops infested with alternative and more preferred trophobionts for the ants to attend. Intercropping apples with aphid infested beans, for example, distracted ants from apple trees and led to reduced numbers of aphids on those trees 48 …”

“…Intercropping apples with aphid infested beans, for example, distracted ants from apple trees and led to reduced numbers of aphids on those trees. 48 When offering artificial carbohydrates, placing sugar dispensers in canopies may be preferred rather than placing them on the ground, as canopy dispensers will increase ant activity on the foliage where pest control is needed. 38 Even in cases where ants show no effects on pest arthropods, increased canopy activity may lead to higher deposition rates of antibiotics and facilitate pathogen control.…”

Differential transport of a guild of mutualistic root aphids by the ant Lasius flavus

“…Workers of an ant colony show marked preferences for seeds of myrmecochorous plants (Leal et al 2014; Miller et al 2020) or for tending lycaenid caterpillars (Stadler et al 2003). Ant visitation of aboveground aphids is also not random, with some aphids being much more tended than others (Fischer et al 2001; Woodring et al 2004; Akyildirim et al 2014; Pålsson et al 2020). Interestingly, the quality of honeydew secreted by aboveground aphids may correspond with the attendance preference of ants (Völkl et al 1999; Woodring et al 2004; Xu and Chen 2021).…”

Establishing repellent effects of aromatic companion plants on Dysaphis plantaginea, using a new dynamic tubular olfactometer

“…in Europe and North America (Blommers et al, 2004). Previous studies have investigated the impact of agroecological infrastructures on the biological control of this aphid (Brown & Mathews, 2007; Dib et al, 2010; Albert et al, 2017; Pålsson et al, 2020). However, the direct effect of CPs on the behavior and growth dynamics of D. plantaginea colonies is unknown, unlike for another major pest, green peach aphid, Myzus persicae (Sulzer) (Dardouri et al, 2019a,b).…”