Low and high input agricultural fields have different effects on pest aphid abundance via different invasive alien weed species

Attila-Károly Szabó,János Bálint,Szidónia Kőszeghi,Hugh D Loxdale,József Kiss,Adalbert Balog

doi:10.3897/neobiota.43.31553

Abstract

We conducted field surveys to detect the population density of the most important invasive weed species and their associated virus vectoring aphids in crops grown under high input field (HIF) vs low-input field (LIF) conditions, with and without fertilizers and pesticides. The most frequent invasive weed species were Stenactisannua, Erigeroncanadensis and Solidagocanadensis. These species were hosts predominantly for the aphids Brachycaudushelichrysi and Aulacorthumsolani in both management systems. The 13% higher coverage of S.annua under LIF conditions resulted in a 30% higher B.helichrysi abundance and ~85% higher A.solani abundance compared with HIF conditions. Host plant quality was assessed by measuring peroxidase enzyme activity. There was a significantly increased POD activity at 10 μmol min−1 mg protein−1 unit in S.annua under LIF conditions, suggesting a higher stress by aphids under this management regime. The high colonization intensity of B.helichrysi on maize, potato and alfalfa crops were detected from both S.annua and E.canadensis. We conclude that new and faster methods need to be used to prevent colonization of such virus vectoring aphids and their host plants, even under low input regimes.

Highlights

Invasive pests represent serious threats to crop production as global trade expands and climatic conditions shift (Copping 1998; Agrow 2015; USDA Forest Service 2015)
S. canadensis was only present in low-input field (LIF), with an average coverage of 2.5%
No other invasive weeds were detected under this management system during the assessment E. canadensis was only present under high input field (HIF) with an average coverage of 15%

Summary

Introduction

Invasive pests represent serious threats to crop production as global trade expands and climatic conditions shift (Copping 1998; Agrow 2015; USDA Forest Service 2015). Weed management strategies involve different methods, including physical (mulching, tilling, burning), chemical and cultural control (high quality seeds, rotate crop, species, herbicide) (Chitsaz and Nelson 1983; Rand and Louda 2004; Uchino et al 2012; Mabuza et al 2013), the areas covered by invasive weed species are still increasing (Tunaitienė et al 2015; Pacanoski 2017) Another important factor that is rarely considered is the effect of these invasive weeds on local sap-feeding pest insect populations such as aphids (Hemiptera, Aphididae) and the influence of the invasive weeds on neighbouring crop plants via aphids (through damage and virus transmission). The effect of the virus vectoring aphids, whose host range naturally includes both local and invasive plant species from the same family (e.g. Asteraceae), needs to be considered in testing associational relations in plantplant interactions (Bell 1983; Popkin et al 2017)

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