Surveys on the spread of non-native garden insects

RHS project team
Dr Andrew Salisbury, RHS
UK gardeners and the National Biodiversity Network (NBN)
Start date
02/01/2008 00:00:00

Lily beetle, red lily beetle, scarlet lily beetle, Lilioceris lilii, hemerocallis gall midge, day lily gall midge, Contarinia quinquenotata, Berberis sawfly, Arge berberidis, rosemary beetle, Chrysolina americana, box tree caterpillar, box tree moth, Cydalima perspectalis, invasive non-native pests, web survey, citizen science.

The problem

Non-native animals and pathogens can pose a threat to plant health and biodiversity worldwide, this includes horticulture, agriculture and native wildlife. In addition to the problems they cause in gardens some non-natives can cause problems in the wider environment, for example lily beetle has the potential to threaten snakes-head fritillary populations (Fritillaria meleagris) and the berberis sawfly can defoliate native Berberis vulgaris, threatening the rare barberry carpet moth (Pareulype berberata). Box tree caterpillar could threaten box (Buxus) stands in areas such as Box Hill, Surrey. In order to assess these threats and provide accurate advice to gardeners the establishment, distribution and spread of non-native animals is monitored.

Historically the RHS has collected data on the distribution of invasive garden invertebrates through enquiries sent to RHS Gardening Advice. For example, detailed information has been gained in this way on the establishment, rate of spread and host range of lily beetle (Lilioceris lilii) and rosemary beetle (Chrysolina americana).

A more proactive approach for five insects has been developed using internet-based surveys that enable gardeners to submit their own records. Information submitted via the RHS website is analysed and maps, web pages and advice updated accordingly on an annual basis. This information is shared with the National Biodiversity Network (NBN).

Across the five surveys, more than 37,000 reports had been received by the end of 2016.

The RHS is keen for the data to be used in further research projects and collaborations. Email [email protected] if you would like to use RHS data for research.
Benefits to gardeners

The project is providing information on the distribution and host range of four non-native invasive garden pests, improving knowledge of these insects and the advice provided by the RHS. These pests are lily beetle (Lilioceris lilii), rosemary beetle (Chrysolina americana), Hemerocallis (day lily) gall midge (Contarinia quinquenotata), box tree caterpillar (Cydalima perspectalis) and berberis sawfly (Arge berberidis).

The information gathered means that a more accurate assessment can be made of the threat that these non-natives pose to gardens and the wider environment.

There are the additional benefits of engaging with current and future RHS members and the general public ('citizen science'), informing policy and contributing to the scientific community worldwide.

Further information

Outcomes of the surveys blog

Animated maps of the changing distributions

Rosemary beetle
Lily beetle
Berberis sawfly
Hemerocallis gall midge
Box tree caterpillar

Sumbit records and find out more

Lily beetle

Berberis sawfly
Hemerocallis gall midge
Rosemary beetle
Box tree caterpillar

Lead scientist profile

Andrew Salisbury, RHS

Get involved

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