MadSci Network: Environment/Ecology

Re: How many bugs are there in the world and how many of them are being killed

Date: Thu Apr 16 23:26:09 1998
Posted By: Neala MacDonald, Grad Student, MSc in Zoology, University of Western Ontario
Area of science: Environment/Ecology
ID: 891410441.En


It has been estimated that there are between 2 and 6 million species of 
Insects on earth. This is a greatly debated number, and indeed one person 
by the name of Terry Erwin used a technique of 'smoking' insects out of the 
jungle canopy and based on the number of different insect species that were 
identified, he extrapolated (an expanded, educated guess) this to mean that 
up to 30 million different species could be in existence! 
It is even more difficult to get a good estimate of the rate of death among 
insect species - but given that the greatest invertebrate populations exist 
in the rain forests of the world, it is likely that one of the major causes 
is deforestation. This is particularly damaging to insects because they 
generally cannot move out of these deforested areas - and the huge 
reduction in diversity of plant food species available will reduce insect 
populations. For example, many species of weevil (a type of beetle) have 
special mouth parts for feeding on particular parts of particular plants. 
If these food sources are removed the weevils will starve, and that 
population could become extinct, regardless of how good they are at 
reproducing (which insects generally do in large volume). So this reminds 
us how important biodiversity, from the plants to the insects and up the 
food chain, is to the survival of all species.
Compiled in consultation with Rod Hallum, Entomology Technician at the 
University of Western Ontario, Canada.
-Neala MacDonald

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