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Loss of invertebrates

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Old Thursday 25th January 2018, 15:43   #1
citrinella
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Loss of invertebrates

In the UK, and also reported by a recent paper from Germany, invertebrates have declined sharply in recent decades. I have been making great efforts to try to stop this over the last 15 years or so, establishing wildflower strips and meadows. I thought things were going quite well, with these areas thronged with moths, bumblebees, hoverflies and all sorts I am less than familiar with then ...

In 2015 there was virtually nothing, almost no beasties at all until high summer and even then very few. Apparently moth recorders up and down the UK found it a miserable year. After all my efforts truly dispiriting. Since then things have not been quite so bad. However bird numbers on this farm have declined sharply over the last 10 years or so and I suspect problems during the breeding season - we make great efforts to keep food available all winter so residents should be OK, but birds like yellowhammer have declined massively.

While other factors are also likely to be important - spells of foul weather at nesting have had obvious serious impacts on nests I monitor - I wonder if the reduced availability of invertebrates for chick food could be a major issue.

The other day a neighbour made an observation which woke me up, I don't know if he originated it, but I had not heard it before. With climate change we now get short mild spells frequently in the winter. Sometimes this results in noticeable emergence of masses of invertebrates. However these spells do not offer suitable conditions - duration or resources - for the invertebrates to complete their life cycles, so possibly significant decreases in the potential breeding population could be occurring before the breeding season has even started.

It is easy to see that if these affects are indeed happening on an increasingly common basis populations could be badly affected over a period of decades.

Obviously such effects would not be uniform across species, some species would not react to these mild spells, and hopefully would not be directly affected, though some of those (non-reactors) might be dependent on those that do react, such as by preying on them. Never-the-less, it could be a significant part of the problems that seem to be affecting our invertebrates and causing such frightening declines in their abundance.

Mike.
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Old Saturday 27th January 2018, 17:51   #2
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I saw this German article. It is interesting.

It is possible that decades of pesticides blowing from fields slowly destroyed insects in the whole landscape. It is also possible that small patches of habitat in farmland - hedgerows and such - lost their invertebrates, in an island extinction theory. Also, there are subtle changes of habitat, which may be important for insects but not visible in statistics: meadows now are more improved and flower-poor than meadows decades ago, loss of uncultivated patches with weeds, drying of wet spots in meadows etc.

However, I think it is also possible that it is an artifact, or actually sign of positive changes in the environment. Number of big animals like bigger birds or deer have increased in recent decades. Plant productivity is fixed, so more big fauna presumably means less insects. In Germany, woodlands have increased and matured. Presumably, meadows and young scrub appear to have numerically more insects than mature forest, because insect life there is at treetop level.

I don't know what to think about it, quite curious.

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Old Sunday 28th January 2018, 08:25   #3
Purple Heron
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The insect decline worldwide is very serious, and Buglife, UK has a lot of information about this on their website--the rates of decline and loss of biodiversity is truly shocking. One reason for the decline is electromagnetic radiation from cell towers. Buglife started a topic with the EU EKLIPSE Mechanism, which just held a web conference about the effects of electromagnetic radiation (EMR) on all life forms (vertebrates, invertebrates, and plants). A committee of scientists examined peer-reviewed studies on this subject and determined that EMR does indeed affect all life forms. I have a report about that on my thread, also in the Conservation forum, "Cell tower radiation harms birds" which has been running for several months (we have also been discussing insects). What you say is very interesting, Mike--would you join us on that thread? Unquestionably there is more than one cause behind insect declines, and in the UK you have immense habitat loss. Where I live, in Greece, habitat loss is not the issue, and in many cases such as the island where I live pesticides are not the main problem either. Nor is climate change, because the insect loss is sudden and dramatic and I haven't seen climate variation that would account for it. I have observed that, especially since cell tower went to 4G/4G+, and also with the addition of many new cell towers, insects are declining drastically--all kinds of things from wasps to beetles, crickets to walking sticks to dragonflies to butterflies and moths. What about cell towers in your area? I know UK cell coverage is spotty, with some places at 4G and some still at 2G. Again, do have look at my thread as there are many studies and articles you might find interesting.
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Old Monday 29th January 2018, 19:16   #4
citrinella
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Thanks Purple Heron,

This farm is undulating and to describe mobile phone coverage as spotty is being very kind. At one side of the farm there is excellent reception beside the masts on my neighbour's. At the other side, over the hill, there is no reception. Beasties here have been declining for a long time, no matter whether there is phone reception or not. There have been further declines since one out of two masts was removed.

It's not just EMR we have to worry about, I'd be surprised, given the timescales over which invertebrate declines have been recorded, if climate change wasn't far more important than EMR.

Mike.
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Old Wednesday 7th February 2018, 03:20   #5
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Mike

I recommend the Butterfly Conservation publications and analyses on declines:-

https://butterfly-conservation.org/1...indecline.html

For me, the main reasons for invertebrate decline are:-
1. Loss of habitat including of marginal habitat such as waste ground and hedgerows due to tidying, increased development and intensification of farming;
2. Long term pesticide/insecticide use and the build up of this effect; &
3. Changing weather patterns effecting the life cycles of species - particularly vulnerable are species that overwinter as adults or larvae when emergence early can ruin their life cycle but there can be myriad mismatches even for species where life cycle is triggered by day length rather than temperature if temperature is causing a mismatch with foodplants.

As you say, the periods and nature of declines show no suggestion of a link to mobile phones and I cannot see any evidence to suggest that it is somehow linked to maturing habitat or the success of larger species. Indeed the opposite is the case and we are seeing larger species crashing in response to invertebrate decline eg farmland birds & cuckoos.

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Old Thursday 8th February 2018, 18:37   #6
citrinella
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Thanks Paul, interesting read.

I agree with what you say but think that #2 is incomplete, it is not just what we use as insecticides/pesticides that affect invertebrates (and other wildlife) but also many other pollutants we are inadvertently (or not inadvertently) losing into the environment. All the time we are hearing that commonly used materials can be detected in areas hitherto considered remote and "safe" such as Antarctica let alone on our doorstep where all sorts of pollution are visible and accepted as normal. So it is not just pesticide/insecticide users that need to improve practice, but every single one of us.

Mike.
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Old Saturday 17th February 2018, 17:18   #7
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Quote:
Originally Posted by Paul Chapman View Post
Butterfly
Butterflies are not a good proxy of all insects. They are almost all herbivores as larvae and nectar-feeders as adults, are more often tied to open habitats and almost never aquatic.

I thought about another problem of long-term ecological studies. Study plots or transects are not set randomly. They are usually put in a good habitat and with good access point. This is essentially a fringe of habitat, which is likely to be much more destroyed than 'an average'. Also, succession will likely take place but no account will be taken of posssibly other habitat plots created.
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Old Sunday 25th February 2018, 18:23   #8
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Quote:
Originally Posted by jurek View Post
Butterflies are not a good proxy of all insects. They are almost all herbivores as larvae and nectar-feeders as adults, are more often tied to open habitats and almost never aquatic.

I thought about another problem of long-term ecological studies. Study plots or transects are not set randomly. They are usually put in a good habitat and with good access point. This is essentially a fringe of habitat, which is likely to be much more destroyed than 'an average'. Also, succession will likely take place but no account will be taken of posssibly other habitat plots created.
The links are not about butterflies and the studies are not based on plots or transects. The actual studies match hours of discussions that I have had with experts with decades of experience as well as my own personal observations.
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Old Sunday 25th February 2018, 22:55   #9
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Around here in west Leicestershire I would suggest that the loss of set aside in the farm payment scheme has been a significant factor in the loss of invertebrates along with the increased use of sewage sludge as a fertilizer. the latter almost certainly contains residues of neonics used on urban pets. The river seems to have lost almost all its sizable fish, and the adjacent meadowland has far fewer craneflies than in the past.There are also plenty of worm casts about and more mole activity than there has been for a few years. Flocks of wintering birds are not so noticeable as a few years ago. No artificial fertilizers have been applied for about 20 years, and very little spray has been used in the same period. Feeding flocks of birds have been on the ground where the river has flooded and receded, and on neighbouring ground where stock are being outwintered or manure spread. I suspect that the significant changes were about 5-7 years ago and it has taken time for them to be noticed

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