Insect nutritional requirements

Although many insects nutritionally require ascorbic acid, numerous species have apparently been reared on artificial or synthetic diets without ascorbic acid or related nutrients. These include Diptera and assorted roaches, crickets, beetles, and moths, whose normal food comprises detritus, seeds, carrion, and dry stored products that are deficient in ascorbate for certain vertebrate animals. The general presumption has been that the diets lack vitamin C and that certain insects can biosyn-... 

For a species of insect to survive (to pass through the sieve of Figure 1), its food must contain the nutrients essential for that species. Nutrition used in this narrow sense (as opposed to the broader term insect dietetics) delineates the minimal nutritional requirements for successful growth, development, and reproduction (13). Serving as a nutrient is not an inherent quality of a... 

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. 

As alluded to above, even a crop that sustains losses from an insect pest may actually be capable of inhibiting insect growth. A number of aspects of the insect dietetics may be interacting to produce such a situation. The feeding insect must ingest food "that not only meets its nutritional requirements, but is also capable of being assimilated and converted into the energy and structural substances required for normal activity and development" (2,. ... 

Mitsuhashi J (1989), Nutritional requirements of insect cells in vitro, In Mitsuhashi J (Ed.), Invertebrate Cell System Applications, CRC Press, Boca Raton, pp. 3-20. 

An important aspect of biopesticide production using insect cell lines is the maximization of cell growth. Culture media must satisfy the environmental and nutritional requirements of the cell line. Hence, many studies have been carried out to characterize the nutrient requirements and metabolic pathways of these cells (see Chapters 4 and 5). 

We are concerned here with the enzymatic liberation of products that convert chemicals to less utilizable forms. The idea is to employ plant enzymes to strike directly at the insect s most critical needs, essential nutrients. In general, plant tissues are low in total nitrogen and pose a "nutritional hurdle" for insect herbivores (94). Plant proteins normally have low sulfhydryl and lysine content (95), which are nutritional requirements for insects (90,91). The nucleophilic properties of these limiting amino acids make them particularly susceptible to covalent binding by strongly electrophilic molecules such as o-quinones, hydroperoxides, ben-zoxazinones, and isothiocyanates formed in damaged plant tissues. 

Reported isolations of either yeast outside of fermentation facilities are rare. Van der Walt (1970) reports isolation of Brettanomyces from honey and tree exudates. It appears likely that subsequent transmission to fermenting juice and wine is the result of insect vectors. Aside from this report, the generally accepted habitat of both Brettanomyces and Dekkera is from fermenting products and their associated environs. It is likely that this ecological restriction is the result of their rather fastidious nutritional requirements. 

A recently discovered specific receptor for the nucleoside adenosine and adenine by Ma (1977a) and Ma and Kubo (1977) was not unexpected, as Hsiao (1969) identified both compounds as feeding stimulants for the alfalfa weevil, Hypera postica. This receptor cell, identified in the lateral sensilliun stylo-conicum of Spodoptera exempta larvae, perceives adenosine that occurs in host plants and its activity is correlated with feeding. Adenosine is known to occur in all living tissues and presumably Spodoptera larvae, as other insects, have no specific nutritional requirement for this compound. The question arises if this sensitivity is unique to Spodoptera larvae and why such a chemoreceptor has... 

Another chemoreceptor cell with a sensitivity which cannot be easily explained is the inositol receptor found in many lepidopteran larvae (Schoonhoven, 1972a). Most insects appear to synthesize myo-inositol from glucose, thus having no nutritional requirement for this compound. One known exception is the larva of the moth, Heliothis zea, which is dependent upon dietary inositol (Chippendale, 1978). For some larvae inositol in pure form is a feeding stimulant (Blom, 1978, Stadler and Hanson, 1978) but others such as S. exempta show no behavioral response, despite the fact that inositol occurs in its food plants and that it has a receptor cell for the compound (Ma, 1976a). 

Insecta, could have arisen from annelids, which never acquired the ability to biosynthesize sterols. To date, no insect has been found to be capable of biosynthesizing the steroid nucleus (3). Thus, insects require a dietary source of sterol to support development and reproduction, and this dietary requirement for sterol is the only known difference in nutritional requirements between insects and... 

Our results have been recapitulated with other proteins of varying nutritional value to S. exigua and H. zea they include soy protein, tomato foliar protein, corn gluten and zein. In all cases, more than 2.5% dietary protein was required to alleviate antinutritional effects, because these proteins are less nutritious than casein (Table III). The ability of a protein to alleviate the toxicity of o-quinones is proportional to its nutritional value to the insect (Table III). The proteins ability to function as an alkylatable sink (alleviation of antinutritive effects) is correlated with the relative amounts of alkylatable amino acids (e.g., lysine, cysteine, histidine, methionine Felton and Duffey, unpublished data). 

Blum (38) observed that many Insects have the capability to feed on "so-called" toxic plants, having developed the required detoxification systems. Nutritional factors may become critical as a consequence of stresses to the Insect involved with the energy requirements devoted to detoxification, deactivation, or sequestration. 

HISTORY. Carnitine was first isolated from meat extract in 1905, but its structure was not established until 1927. Then, another 20 years elapsed before Fraenkel, in 1947, while investigating the role of folic acid in the nutrition of insects, found that the meal worm (Tenebrio moli-tor) required a growth factor present in yeast. Frankel called this factor Vitamin BT vitamin B because of its water-soluble property, and the T standing for Tenebrio. Because of not being recognized as a vitamin, the name was subsequently changed to carnitine. 

Data for calculation of nutritional analyses are much the same for all methods of statistical analysis described above. Basic precautionary steps recommended for selection of individuals, pretest conditions, and standardization of both test animals and test diets have been discussed elsewhere (Berenbaum 1986). Nutritional indices are extremely sensitive to small errors in computation (Schmidt Reese 1986 Stamp 1991), thus, efforts to reduce such sources of variation are of utmost importance in such studies. All consumption experiments must provide food ad libitum unless effects of starvation are being tested, and careful planning and some preliminary experiments may be required to determine how much food must be prepared or obtained in advance to complete the entire experiment. This is especially important when insects are to be tested on plant food to avoid introducing variation in food quality due to difference in plant or leaf age into the experimental design. 

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