Post‐dispersal seed predation of non‐target weeds in arable crops

Abstract

Summary Field experiments were conducted to quantify the natural levels of post‐dispersal seed predation of arable weed species in spring barley and to identify the main groups of seed predators. Four arable weed species were investigated that were of high biodiversity value, yet of low to moderate competitive ability with the crop. These were Chenopodium album, Sinapis arvensis, Stellaria media and Polygonum aviculare. Exclusion treatments were used to allow selective access to dishes of seeds by different predator groups. Seed predation was highest early in the season, followed by a gradual decline in predation over the summer for all species. All species were taken by invertebrates. The activity of two phytophagous carabid genera showed significant correlations with seed predation levels. However, in general carabid activity was not related to seed predation and this is discussed in terms of the mainly polyphagous nature of many Carabid species that utilized the seed resource early in the season, but then switched to carnivory as prey populations increased. The potential relevance of post‐dispersal seed predation to the development of weed management systems that maximize biological control through conservation and optimize herbicide use, is discussed.

The use of insects in integrated weed management

“…Conservation biological control is often not targeted directly at the pest, as the abundance may lead to enhanced weed suppression in many agricultural systems is widely accepted ( Gallandt et al, 2005 ;Westerman et al, 2005 ). While in some instances seedeating carabid abundance has been positively related to seed predation level ( Menalled et al, 2007 ) or change in the weed seedbank , other studies have failed to demonstrate such links ( Davis and Raghu, 2010 ;Gaines and Claudio Gratton, 2010 ;Mauchline et al, 2005 ;Saska et al, 2008 ). The lack of a clear numerical response of weed predation to seed-eating carabid abundance possibly refl ects differences in the species present in the experiment, and insuffi cient consideration may have been given to the diversity of trophic and functional roles within this group.…”

“…Carabids might alter their behaviour, in response to the risk of intra-guild predation, by lowering their level of activity or by leaving prime foraging locations, in order to reduce their individual risk ( Prasad and Snyder, 2004 ;Guy et al, 2008 ). Finally, several studies suggest the existence of shifts in diet, in seed-eating carabids, which depend upon the prevailing conditions ( Marino et al, 2005 ;Mauchline et al, 2005 ;Brooks et al, 2012 ); indeed fi eld surveys indicate that specifi c spatial associations vary in time ( Trichard et al, 2014 ). Such prey switching has been found for carabids that can, for example, feed on weed seeds and animal pests such as slugs ( Fig.…”

Nonconventional Weed Management Strategies for Modern Agriculture

“…Experimental and modeling studies have clearly shown that predation significantly affects weed seed demographics (Mauchline et al 2005 . Meiss et al (2010) reported that the vegetative cover influences weed-seed predators by altering the habitat quality.…”

A synthesis of feeding habits and reproduction rhythm in Italian seed-feeding ground beetles (Coleoptera: Carabidae)

“…In the temperate zone, these are the most important seed predators (Honek et al, , 2005 in intensively managed agricultural landscapes (Saska et al, 2014). Granivorous carabids are important pre-and postdispersal weed seed predators, and in terms of agricultural ecosystem services are biological control agents of weeds (Mauchline et al, 2005;Jacob et al, 2006;Gaines & Gratton, 2010;Kulkarni et al, 2015).…”