A native with a taste for the exotic: weeds and pasture provide year‐round habitat for Nysius vinitor (Hemiptera: Orsillidae) across Australia, with implications for area‐wide management

Abstract

While pest management tends to focus on pests that are already present in crops, non-crop hosts may play a crucial role in supporting pest populations outside the crop growing season. Non-crop hosts may allow pest populations to persist throughout the year, build-up and colonise crops after emergence. Here, we assess the hosts of the Rutherglen bug, Nysius vinitor Bergroth, which is a polyphagous native insect pest of growing economic importance in Australia. We conducted a literature review on the occurrence of N. vinitor on crop and non-crop hosts and analysed field survey data on N. vinitor abundance from two independent field studies in three agricultural regions of Australia. We differentiated between juvenile (nymph) and adult stages to consider the function of plants as reproduction sites. The literature review resulted in reports of N. vinitor on 44 crop species from 18 plant families. Pigweed Portulaca oleracea and capeweed Arctotheca calendula were the most cited weed hosts. In the field study, N. vinitor was primarily found on exotic weeds and grasses within pastures, Lucerne and degraded native vegetation remnants. While N. vinitor was found on a total of 16 weed plant families, juvenile stages of N. vinitor were most often observed on fleabane (Conyza spp.), goosefoot Chenopodium pumilio (Amaranthaceae) and plants of the Asteraceae family, indicating that these are important host plants for N. vinitor reproduction. Grasses appear to be an important but understudied host plant group; citations in the literature do not reflect the extent to which N. vinitor was found on grasses in the field. In contrast, the field survey indicated that very few native plant species supported N. vinitor, which was consistent across regions and confirms findings from the literature review. Our findings suggest that exotic weeds and grasses (but not native plants) play a key role in supporting N. vinitor populations in Australian agricultural landscapes. Reducing exotic weeds in pastures and non-crop habitats may limit breeding opportunities of N. vinitor and may be an important component in the area-wide management of this polyphagous pest.

Economic benefits of conservation biocontrol: A spatially explicit bioeconomic model for insect pest management in agricultural landscapes

“…Here, we focus on the management of the pest in canola. It can be highly mobile and is known to be supported by multiple hosts in the Australian landscape, so habitat management is important (see Parry et al, 2019). Many other pests may also be impacted by similar noncrop management practices in Australia (see Parry et al, 2015;Downes et al, 2017), so although the focus here is on a single species the findings have broader relevance.…”

Temporal Resource (Dis)continuity for Conservation Biological Control: From Field to Landscape Scales

“…Non-crop vegetation could also be managed to disrupt resource continuity for pests, such as by removing alternative host plants in the landscape. For example, Parry et al (2019) demonstrate that exotic weeds in found in alfalfa fields and pasture in Australia act as early season hosts for a native hemipteran pest, the Rutherglen bug, and suggest that reducing weeds in these habitats could disrupt temporal resource continuity and facilitate better landscape-scale management. Similarly, soybean aphids and their overwinter host European buckthorn constitute two key pillars of an "invasional meltdown" North America; removing buckthorn in the landscape could promote the suppression of soybean aphid as well as other co-invaders (Heimpel et al, 2010).…”

Genome-wide analysis of diamondback moth, Plutella xylostella L., from Brassica crops and wild host plants reveals no genetic structure in Australia

“…Protecting crops from attack by these pests is difficult for pest managers due to the unpredictable nature of seasonal outbreaks, particularly when insecticide resistant genotypes are present 4 , 5 . For mobile insect pests, dispersal among crop and non-crop host plant resources influences both the seasonal dynamics and genetic background of pest populations, with direct consequences for pest management 6 – 9 . Molecular studies of population structure and gene flow can potentially provide insight into patterns of insect movement in agricultural landscapes 10 , 11 .…”