Feeding habits species differences

The nutritional requirements of insect species exhibiting different feeding habits like scavengers, parasites, predators and phytophagous insects, are similar in a qualitative sense (O. Each insect species needs, however, a particular quantitative composition of nutrients in its diet to complete development ( ). The presence of toxic substances in plants, secondary plant substances as they were formerly called by phytochemists, forms a barrier which phytophagous insects have overcome by specialization. Thus, an insect can tolerate or detoxify the secondary plant substances present in its host plants, while the majority of these substances being present in other plants still acts as toxins (J ). In this way phytophagous insects are adapted to the metabolic qualities of their host plants, i.e. a particular chemical composition of nutrients and secondary plant substances. 

All animals probably harbor bacteria and sometimes protozoans and other primitive organisms in their alimentary tracts this state may be considered normal. The balance maintained by the host and these microorganisms is undoubtedly influenced by the character of the alimentary tract and the food eaten by the host. Therefore, in considering the role of microorganisms in a particular host, reference must repeatedly be made to the physical and chemical state of the food. This being so, it is understandable that different species of animal with different feeding habits should possess fauna and flora that may be characteristic of the species. The feeding habits, however, may not be the only factor concerned, for the environ-... 

The effects of prior experience on taste preference behavior of the fowl was demonstrated ( ) by the fact that ascending versus descending series of preference test concentrations yield vastly different data. The importance of prior experience was confirmed by Davidson (8 ) who reported on preference behavior of various bird species toward berries and seeds in natural settings. He has suggested that low consumption of a new food item by many bird species for 1-10 days is of no particular significance. Thus, certain avian species may be extremely slow to change their normal feeding habits. 

Most avian studies emphasize ingestion as the primary route of exposure to toxic metals, because other routes of exposure are extremely uncommon. Because risk of exposure is greatly influenced by bird feeding and nesting habits, the characteristics of birds need to be taken into account for any study and its subsequent results. Age and sex differences in uptake and distribution of metals also influence metal exposure. Ultimately, even the same species of bird may behave differently in different environments, creating variations in risk of exposure (20). 

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