Biodiversity insect

Life in the oceans differs in most respects from life on land. The most remarkable observation is that the oceans are poorer in species but richer in phyla with respect to land (Chapter 1.2). This finds no easy answer, however. Perhaps the reason for the larger number of species on land lies in a wider diversification of habitat and climate than in the sea, which required a great deal of adaptation, accompanied by speciation. In these affairs, coevolution of plants with insects was a major trigger of biodiversity. 

If biodiversity decreases, natural product diversity also decreases, because of a link between the two (Part II). Modem times have seen the greatest natural product diversity. With the increase in plant species from 100,000 before the end-Cretaceous mass extinction to the 250,000 species of modem age, natural product diversity must also have increased. The estimate depends on how natural product diversity is evaluated, i.e. from the molecular skeletons or the actual metabolites. Metabolites of insects, fungi, and bacteria must be added to the list. The present man-made mass extinction may thus result in a larger numerical impact than any previous mass extinction, even if the loss of natiual product diversity occurs at the same percentage of previous catastrophes. 

Table 7.6 Hydrocarbons used in chemotaxonomy for potential insect biodiversity and bioindicator purposes.

Carpenter, J.M. (1997). Phylogenetic relationships among European Polistes and the evolution of social parasitism (Hymenoptera Vespidae Polistinae). In The Origin of Biodiversity in Insects Phylogenetic Tests of Evolutionary scenarios, ed. P. Grandcolas. Mem. Mus. Nam. Hist. Nat. 173, pp. 135-161. 

Organic systems seek to have a more measured pace of crop growth which encourages a more robust plant to resist pests and diseases. The greater balance of biodiversity achieves a more natural level of pest predators and a non-stressed crop is more likely to resist disease. Unless specifically targeted, some pesticides will kill beneficial as well as pest insects. 

Fungi are the second largest group of eukaryotic organisms and rank second only to the insects in estimated species biodiversity. There are approximately 72,000 recognised species of fungi of an estimated 1-1.5 million in total. This means that <5% of fungal species have been described to date. 

The more stringent the climate, the less the biodiversity. As one approaches the tundra, the number of species of trees, mammals, and insects diminishes. The same, of course, applies to the climatic zones created by successively higher elevations in mountainous terrains. 

They point out that biodiversity is necessary for the sustainability of agricultural, forest, and natural ecosystems on which humans depend. Roughly 99% of pests are controlled by natural enemies and by plant resistance. Loss of key pollinators may mean loss of a crop. Honeybees can pollinate some crops, but not all of them. There are already species for which no pollinators are left.12 Current extinction rates are 1000-10,000 times the natural rate. The concern is that keystone species (i.e., species without which the ecosystem cannot function) may be lost. These are more likely to be soil microbes or insects than pandas or tigers, despite the popular appeal of the latter. 

Researchers have found that, as far as insects and invertebrates are concerned, small yards are just as good for wildlife as larger ones. In a survey of biodiversity in 61 private yards ranging in size from 344-10,000 sq ft (32-940 sq m) in the city of Sheffield in the UK, the researchers caught and counted an astonishing 40,000 individual invertebrates, and found nationally rare beetles, bugs, snails, and flies, and a spider that had only previously been recorded on a mountain top. 

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