Artificial Rearing of Entomophagous Insects, with Emphasis on Nutrition and Parasitoids - General Outlines from Personal Experience

Abstract

The disposability of high numbers of entomophagous insects for their use in biological control strategies is an old objective carried on, between others, by the rearing in different kinds of artificial diets. The definition and the perfecting of these diets are at first based on nutritional studies. Food or carcass analyses, nutritional balance studies, and deletion/supplementation methods allow to evaluate the different nutritional needs. Nitrogen sources are the most critical needs especially with fast growing entomophagous insects. Lipids and carbohydrates mainly constitute energy sources with storage possibility. Other nutrients such as salts and vitamins are also needed, and sometimes some specific polyunsaturated fatty acids. There are other important physiological requirements, concerning the digestion process, the respiration, or the hormonal balances. Physico-chemical factors such as Osmotic Pressure and pH often show critical values for the normal development, mostly of endoparasitoid insects. For egg parasitoids and predators, the presentation of the food is of prime importance for a normal food intake, and finally for the success of the rearing. Sterilization of the diet or incorporation of preservative agents is often necessary for preventing bacterial or fungal contaminations. Many successes were obtained for artificial rearing of entomophagous insects, but ultimate efforts are still needed for crucial improvements and supports that may lead to the extension of the use of this biological control strategy.

Orthogonal array design for optimization of an artificial medium for in vitro rearing of Trichogramma dendrolimi

“…Water is essential to regulate osmotic pressure, consistency, and pH of the artificial medium. Indeed, the physicochemical properties of a medium for endoparasitoids may be as important as its nutrient composition (Cônsoli & Grenier, ), given that the medium is not only their food source, but also the environment in which they are bathed throughout their larval life (Grenier, ).…”

Production of Dipteran Parasitoids

“…Casein, lactalbumine, ovalbumine, serumalbumine, soybean extract, and yeast are commonly used as crude proteins or hydrolysates. Supplying aromatic amino acids is complicated because some free amino acids may be toxic at high concentrations, like phenylalanine, or have low solubility, like tyrosine (Grenier et al, 1994;Grenier, 2012). The best way to deliver aromatic amino acids is within peptides or proteins rich in tyrosine and/or phenylalanine.…”

“…The pH has to be stabilized between 6.5 and 7.5, even if some species seem highly tolerant to extreme levels, such as E. bryani (Nettles, 1986). In different tachinid species, the optimum dietary osmolarity varies between 350 and 450 mOsm (Grenier, 2012).…”

In Vitro Cultivation of the Hymenoptera Genetic Model, Nasonia

“…1a) and a liquid medium containing processed fly pupae (hereafter referred to as Nasonia rearing medium). Previous investigations have cultivated parasitoids outside their hosts under a variety of nutrient conditions and as liquid, gel, or encapsulated media environments (as reviewed in [7]). Although there are similar methodologies for rearing parasitoids, with the nutritional composition of the media being the major limiting factor for parasitoid rearing, our rearing method is unique for its use of a transwell rearing chamber, and it is the first in vitro cultivation method of the Nasonia model.…”

“…The difference in developmental time observed in other in vitro cultivated parasitoid species has been associated with restricted nutritional components of the artificial diet [7]. When developing this protocol, we first provided fresh media every third day.…”