Coleoptera, representative insects

There are more species of Coleoptera than of any other order of insects. It has been estimated that over 350,000 species of beetles have been described, and this order represents about half of the total number of species (l). Thus it is somewhat surprising to discover from recent surveys of the literature (2,3) that pheromones have been identified for only about 50 to 75 species of Coleoptera. In contrast, sex pheromones or sex attractants (most of the latter discovered by screening procedures) are available for over 500 species of Lepidoptera. Furthermore, over half of the known coleopterous pheromones have been isolated and identified from species in the family scolytidae. 

Over the past four decades, extensive research on insect pheromones has resulted in the chemical and/or behavioural elucidation of pheromone components from over 1500 of the estimated 875,000 described species of insects [3-5]. Research on representative species within four orders Blattodea 4000 species Coleoptera > 300,000 species Diptera -150,000 species and Lepidoptera 150,000 species [5], shows the abundance and diversity of insects. 

Studies carried out on the protease content of the gut of different Coleoptera have shown the presence of cysteine proteases, which, in many cases, represent the major class of digestive proteases [33]. The cDNA of OC-I, a rice cysteine PI, has been constitutively expressed in different plant species. When expressed to a level of 1 percent of the soluble proteins in poplar, it causes an increase in insect mortality however, this lethal effect is observed mainly at the end of the larval stages [34]. A significant growth reduction in Colorado potato beetle larvae was observed when OC-I was expressed in potatoes [35]. However, OC-I expression in oilseed rape failed... 

---