SCIENCE AND INSECT POPULATION DECLINE

There are a lot of journalistic articles around now about the massive insect decline almost every major newspaper it seems has run such a story. All talk about one study or another that has been conducted by scientists but few if any ever actually reference the study in question.
So I went and checked. Here is the consolidated rundown.

1. Several studies have been done recently and realized that there are a lot more insects than their used to be. The latest one that has fired off a lot of the recent articles has examined 73 studies from around the world. They concluded that insects were indeed vanishing at alarming rates and over 40% of the species may be extinct in the next decade. The most at risk were the butterflies (which everybody love), the bees, and dung beetles which may sound yucky but they get rid of all the poop in the world.
Also at risk are a lot of fresh water insects which mean the fish will have much less to eat and may starve. There goes your fishing!

2. The major problem from a science perspective is that up until now most scientists did not study insect populations. We just took them for granted. Science may have studied some individuals but not whole populations. Possibly because no one ever considered they would vanish and most likely no one was willing to fund any such study. Until now. This means we don't have any base line to compare the populations we have now to the ones in the past to see how much they have actually declined.

3. One study that was done in Puerto Rico's Luquillo rainforest has data that spans 36 years beginning in 1976. They found that the insect populations have declined up to 60 times the amounts first recorded along with parallel decreases in the animals that feed on them, mostly birds, lizards and frogs.

4. Another study from Germany also covers 27 years and 96 locations in Germany. They simply measured the weight on insects that they caught in traps from year to year and found there was between a 76% and 82% decline in flying insect weights between 1990 and 2011.

5. Innumerable new studies are now being undertaken for individual insect species or small populations and most seem to have the same conclusion that a lot of the insects are declining and quite a few are probably already extinct.

6. One nay sayer has been sited by some journalistic stories. Manu Saunders a University of New England ecologist decries the study listed in point 1 claiming that the reviewers only looked at studies that related to insect decreases not to increases which he claims are happening in many places. Unfortunately the only study he sites is not accessible for anyone to read, not even an abstract is available just a few pretty photos of butterflies. This makes it impossible to tell if there are indeed increases or not.

Considering that there is so much evidence and so many studies showing the massive decrease in insects its hard to deny that this is really happening. For anyone who has spent much time outside in the last thirty years its hard not to see this is happening. Once there were masses of fireflies when night fell, now there are few. There are less and less butterflies and very few bugs splatting against the car windscreen than there were even five years ago.

7. A study conducted by Cornell University in 2006 details exactly what the economic value of wild insects is to the United States. It estimates the value of their 'work' at $57 billion and they consider this estimate to be very conservative! This figure does not include honey bees or their use in pollination services only the wild insects and native pollinators. They broke this down into four major categories

a. pollination $3.07 billion. This is native pollinators only which are far more effective than honey bees.

b. Dung burial $0.38 billion. This would be dung from both wild animals and domestic ones that wander in pasturelands. Dug burial helps keep the country clean and recycles nutrients to the soil for plants to access and grow. It also ensure that the grass is clean for the cattle and other animals to eat. Thus reducing the spread of diseases and pest flies.

c. Pest control for native plant eating insects. $4.49 billion. Beneficial insects eat a lot of pest insects, pest are much more likely to survive as they have been sprayed for years and become resistant to many chemicals while beneficials have not. If these insects vanish more chemicals will be needed to suppress the pests which will become more prolific.

d. Human recreation $49.96 billion. Fishing is a major sport in the United States and most of those fish eat insects either aquatic ones or those that come to drink. If these vanish then so do the fish, so no more fishing. Commercial fishing is also impacted as many marine fish spend their early years in rivers and depend on insects when they are young. Many game birds and migrating wildfowl also eat insects so hunting will also be severely impacted.

8. While it would be nice to think that the study sited by Manu Saunders in point 6 above does show an increase in a few individual insect populations without access to the data it is difficult to tell. A search of the scientific literature turned up no papers reporting increases in insect populations since 1953. While my search was certainly not exhaustive it is concerning that no other papers seem to appear and searches are overwhelmed by dozens of other papers all claiming insect population declines.

All References

SCIENCE AND INSECT POPULATION DECLINE

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