The Rothamsted Insect Survey Datasets
The Rothamsted Insect Survey
holds the world's most extensive terrestrial invertebrate time series for academic study and policy development. In that role it is tasked with ensuring our high quality aphid and moth data, which extend back to 1964, are provided to organisations that wish to independently or collaboratively analyse these datasets to progress science. Some of the most recent exciting discoveries have arisen as a result of such provision. Examples include new ways to calculate spatial synchrony
, the detection of the evolution of plant defences that confer resistance to herbivores like aphids
and the changing seasonal timing of aphids, moths and many other taxa over several decades under climate change
. It may be surprising to some that we provide data to many organisations at a rate of one request every 14 days or so.
The State of Nature consortium have previously been provided with a large moth dataset and have issued reports in 2013 and now in 2016. Ignoring the findings for one moment, it's a testament to our commitment to recording that the UK can issue such reports, charting the changes in various taxa over time like no other country in the world can. Along with the State of Britain's Larger Moths Report in 2013 led by Butterfly Conservation, these reports have shown that declines are evident, which is in agreement with independent networks such as the Garden Moth Scheme. Perhaps it's worth noting that the moth report in 2013 also showed that 53 species actually increased in number.
I think the State of Nature authors will readily admit, as I will, that working at very large scales is a challenge and it's often difficult to find parallel datasets that are as long and as detailed as the RIS data and that would show unequivocally the mechanism(s) for species declines. However, it is compelling that the Clean Air Act of 1993 has helped some lichen feeding moths, such as the Dingy Footman, that have increased spectacularly over recent decades thanks to a reduction in sulphur dioxide allowing the host to proliferate. Can we say that this is the main cause for the increase in the Footman? That's a difficult one to state absolutely and it's simply not possible to provide a mechanistic understanding from a correlation of lichens and adult moths caught in light traps, however suggestive. We could do a simple laboratory experiment but this would ignore some of the collinear effects such as a change in winter temperature, population regulators, light pollution and the unknown unknowns.
Whilst not understanding the mechanisms, the declines are the best insight into biodiversity changes that are attainable, but we need more studies on how we can help reverse those trends. Rothamsted is committed to playing its part in that and over the next four years as part of a PhD project we'll examine new seed mixes and field margin management regimes to help pollinating moths. We will quantify the effects of different types of host plants and floral resources on caterpillar and adult behaviour using a set of field trials. Like so many initiatives such as the Entry Level Stewardship
), farmers have been quick to adopt schemes that seek to improve our environment. Our hope is that we can tap into future policy with our seed mix findings and continue to make a positive contribution to both agriculture and conservation.