Tuesday, 13 February 2018

The Big Wasp Survey

Having listened to Adam Hart’s piece on Radio 4 (I was vaguely aware of the project last year) I found myself asking ‘why do we need this project when we already have BWARS, the most comprehensive dataset on aculeate Hymenoptera in the UK?' In the course of the programme, I expected to hear a little bit about BWARS but, no there was nothing! Why not? Maybe the academics knew nothing about BWARS? (I have come across other academic proposals to conduct studies that would miror the work of existing Recording Schemes).

The Radio 4 programme was interesting and addressed a much wider issue about killing insects, but it seemed to me that it missed most of the critical points about killing insects. Yes, the Krefeld project was mentioned, so too was work on dung beetles, but I felt there was a serious omission. Most of our understanding of insect distribution and abundance is dependent upon specimens that have been killed and stored as ‘voucher specimens’. Almost all Red Lists of invertebrates are entirely dependent upon people who are prepared to take specimens and supply data to conservation organisations. They are not in the academic world and therefore get ignored!  No insect collecting equates to no capacity to develop species status reviews or to take the necessary measures to conserve critical habitats.

In many ways, this piece mirrored the problems I had with the hype surrounding the Krefeld project: It is a very narrow academic presentation of what is going on. There are vast numbers of records streaming in from what the academics like to call ‘Citizen Scientists’ many of whom are the ‘real’ 'experts' (I prefer the term 'specialist'). Yes it is possible for an academic study of a dozen or so social wasps, but what about the other 500+ aculeates? Did we need a study that used the public to generate a questionable dataset? How many of the less common Vespids were recorded and did the data match those already held by BWARS?

I ask these questions rhetorically. Of course the study was needed because it raised profile for social wasps - they are critical ecosystem regulators. Likewise the Radio 4 programme was valuable because it highlighted an important scientific and social issue surrounding the retention of insect specimens. BUT, to my mind, both failed to highlight the most important points: that most of our knowledge of species’ abundance and distribution is actually generated by organisations such as BWARS (and the HRS), and that for almost all of the time the data that are critical are dependent wholly upon volunteers who compile data without support from the academic world.

I suspect that we can probably say as much about social wasps from BWARS data as was gathered by the ‘Big Wasp Survey’. But, have we actually got any further in justifying the use of mass-killing projects? I doubt it, but believe that there are compelling reasons for supporting the continued use of lethal techniques to ensure that sufficient data exist to understand what is happening to our invertebrate fauna.

Sunday, 4 February 2018

Validating records that are not supported by a voucher

I am currently working my way through iRecord data for 2017. Some of it is relatively straightforward, especially where I know the recorder and his/her abilities and techniques. But, what do you do with records from somebody you don't know who has submitted a record that might be plausible but you know could easily be wrong?

Several records gave me this conundrum today. I had the usual problem with Syrphus ribesii being used for all yellow and black striped Syrphus. For these, unless there is a photo that I can work from, I mark all with a query because I've seen so many unidentifiable photographs posted as this species. I do accept records by people I know and whose techniques I am familiar with.

The bigger problems come in the case of relatively easily identified species at the wrong time of year. Two examples emerged today: three records of Volucella bomylans in August and one of Merodon equestris in late July. The problem is that they were the majority of records seen for these species in today's session and they don't tally with the normal phenology plots for either species. Fortunately, we have a way of telling whether they are well within or on the limits of believability.

This is where extracting records direct from Facebook helps. I have access to a detailed dataset for both species in 2017 all of which I have checked from photographs. In the case of V. bombylans there are 202 records and for M. equestris there are 353 records. In neither case is there much evidence of large numbers at the times of year of the questionable records, as can be seen from the accompanying graphs.

So, do I mark as plausible, or should I reject the records? What would you do?

Figure 1. Phenology of Volucella bombylans in 2017.

Figure 2. Phenology of Merodon equestris in 2017

Thursday, 1 February 2018

Why the decline in insect biomass (and diversity)?

The work of the Krefeld Entomological Society surfaced again this week in post on the UK Hoverflies Facebook page, raising the big question ‘why such a decline’? In the absence of fully correlated data it is very difficult to draw any firm conclusions but I suspect we are looking at some form of ‘death by a thousand cuts’.

A lot of blame must lie with post-war agricultural intensification: increased use of pesticides, deep ploughing, amalgamation of fields and the loss of a huge acreage of hedgerows and associated habitat. But, the decline has been ongoing, whilst many of the (seemingly) most damaging actions took place before the Krefeld sampling programme first started. So, although DDT took a terrible toll on insect life, it is not the only culprit. There have been subsequent generations of insecticides, all of which must have some impact, if not quite so serious. Maybe Neonectinoids are to blame for post 1980s crashes? They will have had some impact and it is possible that they will still be found to have had a bigger impact than is currently believed?

I suspect that we are actually looking at a series of hammer blows. Post-war intensification must already have had a massive impact by the time I started to take an interest in insects; yet in my childhood I could still find, with relative ease, the larvae of puss moth, poplar and lime hawkmoth, and a plethora of other lovely animals. Now I cannot, even though I still visit the same place and look on many of the same trees! My garden moth trap is no longer invaded by clouds of garden tiger moths and I cannot recall when I last found its caterpillar in south London!

My local ‘patch’ comprises several square kilometres of open habitat enclosed by urban sprawl. I guess it has become somewhat more isolated over time but, even so, it has not been affected by herbicides and pesticides. It has, however, been affected by increased nitrification and the vegetation seems to me to have lost some of its low-nutrient characteristics, even though most of the characteristic plants still survive. At the same time, we are told that air quality has improved, and so it has if the range of lichens now growing on our roof are a reasonable indicator. We no longer have vast quantities of atmospheric lead from car exhausts, but do we have higher volumes of pm10s.

More recent events

In my lifetime I have witnessed several ‘events’ in which insect numbers have crashed. Each has corresponded to a major drought and period of extreme temperatures. So, in the course of 40 years we have seen a sequence of catastrophic events that will not have helped insect/invertebrate populations. The biggest ones I think were 1976/77, 1990/91 and several years in the early 2000s. Bearing in mind that nine out of the ten hottest years since 1910 have occurred in the past 17 years, climate change is something we have definitely got to look to as a major factor behind insect declines.

It is not, however, individual actions or events that really set the scene. Insect populations are remarkably robust, swinging back and forth as environmental forcing impacts upon them. An obvious example is the rise and fall of the holly blue butterfly whose numbers fall precipitously as parasite levels climb, but once the parasite peaks, its numbers crash and those of the holly blue climb again. Similar patterns can be seen in many species and can also be detected in response to droughts. For example, in 1947 it was remarked that the summer generation of the hoverfly Rhingia campestris failed to materialise. We have seen similar events from time-to-time in response to prevailing arid conditions.

My examples so far are individual species, but what happens when whole assemblages are hit by a particular environmental anomaly? Alan Stubbs always cites the impact of drainage at Wisley Common on its cranefly fauna as an example of how a major land-management change can impact an entire ecosystem. In that case, ditching caused changes in the water table and the cranefly fauna crashed; it never recovered because the change was profound and substantially irreversible. Anecdotally, Dipterists noticed a huge decline in wetland species in the 1990s, especially Sciomyzidae (snail-killing flies). This decline seems to have partially reversed during wetter periods. But, if conditions do not quickly recover towards the ‘norm’ the impact of the change will be longer-lasting and less reversible. Similarly, each autumn, our field meetings are punctuated with a general feeling that cranefly diversity is substantially down; anecdotally perhaps by as much as 30% since the 1970s.

So, why don’t we have the insects that used to occur? It seems to me that we can blame a combination of definable human impacts such as pesticides and intensification/loss of habitat. But, we must also put some blame at the insidious effects of climate change, which is also substantially an anthropogenic effect.

The catastrophic decline in insects highlighted by the Krefeld Entomological Society is simply an expression of the way the earth’s ecosystem is responding to anthropogenic perturbation. If we want to focus blame, we must do so on our entire community. It has become accepted that we will have access to ever-cheaper food, transport and consumer goods. There has to be a cost, and that may well be the demise of current ecosystems that are in fact our own life-support system!

Saturday, 27 January 2018

The perils of licensing invertebrate collecting

A contributor to the BWARS Facebook group recently expressed surprise that there was limited control over who collects insects or other invertebrate specimens. The comment drew attention to an important issue that I think is poorly understood.

In the UK, we don't have a single law banning insect collection except by a few privileged individuals who can fight their way through masses of officialdom (i.e. a few academics). Yes, we do have a system whereby there is a need for a permit to collect from certain land designations. There is also provision to protect certain species that are vulnerable to the effects of collecting. Fortunately, the latter is fairly light touch but there are restrictions that could cause problems where species are very similar. In addition, some landowners, such as the National Trust and Forestry Commission, do have general permitting systems.

There is also a growing question of whether collected specimens are accompanied by permits in order that they be accepted by museums? So, in fact we have quite a range of officialdom ourselves - it just that it is not unified and there are grey areas.

The drawbacks of permitting

For the serious entomologist permits can be a problem.

Until recently, I ran Dipterists Forum's summer field meeting. It is a Mammoth undertaking. At one time, these meetings tried to visit as many SSSI in the area visited. They relied on the then organiser (who was a Grade 7 in the Nature Conservancy Council) to organise all the access permissions. When the NCC was disbanded there was nobody to do this and it became increasingly difficult to run such meetings. There is a good two months’ work involved in securing access to sufficient sites to keep a team of 20+ Dipterists occupied for a week. It is not really a job that can be undertaken by a volunteer and' in my experience, it became very difficult to get help from Statutory Agency staff. I well remember spending several trips simply visiting the local offices each day to sort out permissions - so if you are paying £300 to £400 for a week away, you don't really want to spend your time cooped up in an office, ringing landowners!

The solution was to stop attempting to visit SSSI and to concentrate on land where one could secure blanket access permission: The Wildlife Trusts, Forestry Commission, National Trust and local National Nature Reserves. Hopefully that job can be done in a day - but it is still a demanding job for a volunteer. Needless to say, I lost enthusiasm for the job of running field meetings and eventually bowed out of running such big events. Finding a replacement for such an onerous job is not easy and I doubt that such meetings will carry on for that much longer.

This situation highlights a critical issue: most of the UK's biodiversity data comes from volunteers and the highest quality data come from those few specialists who do collect specimens. If we don't have a practical way of managing permits then we will probably lose access to a lot of new data and will see a decline in the numbers of specialists who are prepared to provide information to UK data users. If one looks for an analogous situation, it is worth thinking about the difficulty of obtaining collecting permits for some European countries. Do they have a wealth of data on difficult taxa? Simple answer: No! Conversely, the UK is one of the richest countries for biodiversity data, including for many difficult groups.

It seems to me that the comparison tells an important story. If you impose a strict permitting system you will lose access to data. So, the moral of the story seems to me to be that if you want information it is essential to make the system simple as possible.