A desk review of the ecology of heather beetle.

Abstract

The heather beetle Lochmaea suturalis is a naturally occurring species in the heather dominated landscapes of the United Kingdom. When the heather beetle population density increases dramatically it can cause significant damage to heather plants. It has been suggested that burning heather outside the permitted heather-burning season will promote the regeneration of heather following heather beetle damage. There is also some discussion as to whether burning outside the permitted season might also help control heather beetle. For these reasons Natural England regularly receives applications for licences to burn outside the permitted season. However, burning at this time of year may have effects on a wide range of biodiversity. Therefore, Natural England commissioned this report, and (NEER009 - Desk review of burning and other management options for the control for heather beetle) to ensure the best available evidence is being used. This report is based on an extensive literature review to determine the current state of knowledge of the ecology of the heather beetle. Some of the older references, which appear to form the basis for much current thinking on the subject, are now out of print and were not accessible for this review. A flurry of work was published in the 1980s and early 1990s, but much of this was either: • based at the same experimental plots; • involved relatively low levels of replication; or • did not report heather beetle damage as a central focus of the work. More recently, there have been some PhDs quantifying the ecology of heather beetles in more detail, but these have rarely been published in the peer-reviewed literature. Therefore, current thinking may be influenced by out-of-date information and experimental work that does not truly back up the conclusions of authors. This makes it difficult both to confidently discern patterns over time in frequency and severity of attacks (such as might be caused by climate change or changing nutrient deposition loads) and to be certain which factors control population levels in most year’s at most heather-dominated sites. Much more, and higher quality, monitoring and experimental work needs to be carried out to be able to predict the likely population dynamics of this species under different scenarios. The potential for parasites and parasitoids to control population numbers is particularly worthwhile. More detailed spatial analyses based on citizen science records, combined with carefully designed laboratory studies, might also be used to more clearly elucidate the relationship between beetle numbers and climatic conditions, enabling prediction of the relative likelihood of outbreaks occurring in the future.