Comparison of artificially vs. Naturally reared natural enemies and their potential for use in biological control.

Abstract

Quality assessment of entomophagous arthropods used in augmentative biological control is one of the main concerns after their mass production. The quality-testing procedures for natural enemies reared on artificial diets largely remain to be defined. As a first approach, comparisons of some relevant parameters between in vivo- and in vitro-reared entomophages are presented in this chapter. Results from experiments with different kinds of diets with or without insect components, developed for parasitoids and predators, are examined. Morphological traits as well as development and reproduction parameters used for comparisons between in vivo- and in vitro-grown arthropods are discussed. Morphological characters include body size and weight and the occurrence of abnormalities. Immature development is assessed by measuring duration and survival rates of the different stages. Sex ratio and symbiont association, fecundity-fertility and longevity are compared as reproduction parameters. It is important to consider biochemical parameters, such as protein, lipid and carbohydrate content, for quality control. These parameters may also indicate the deficiency or excess in a particular nutritional component. Behavioural and genetic parameters are considered as well. The establishment of relationships between certain parameters, e.g. between body size and fecundity or longevity, may help in simplifying quality control procedures. The ultimate quality criterion for an artificially reared natural enemy is its capacity to reduce pest populations, which can be evaluated by measuring the predation efficiency or the parasitization rate under laboratory or field conditions.

Prey range of the predatory ladybird Cryptolaemus montrouzieri

“…First, long-term rearing of natural enemies could induce selective adaptation to the food source offered in the laboratory and could result in natural enemies that have lost their ability to feed on some of their natural prey (Grenier and De Clercq 2003), which might lead to an underestimation of the prey range. Also, the potential of C. montrouzieri to reproduce in the absence of mealybugs might have been overestimated due to the experimental methods used.…”

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

“…Moreover, the existence of catabolism and inter-conversion metabolism impede from knowing the exact form (mono or polymers) of each component to incorporate into the food. One advantage of these carcass analyses is also to give an evaluation of the quality of an insect grown on artificial food by comparison with insect grown on control food, and to allow improving the composition of this food (Grenier and De Clercq 2003, Zapata et al 2005, Dindo et al 2006, Sighinolfi et al 2008). …”

“…Morphological characters, immature development parameters, sex ratio, symbiont association, fecundity, longevity as well as biochemical parameters are important cues to be considered for quality control and in addition, these latter could indicate the deficiency or excess in a particular nutritional component. In fine the predation efficiency or the parasitization rate have to be evaluated (Grenier and De Clercq 2003).…”

Cold tolerance of the predatory ladybird Cryptolaemus montrouzieri

“…Besides, diets used in commercial insectaries may have a strong impact on the physiological responses of the natural enemies produced. Unnatural (factitious) foods may change the fitness of a natural enemy (Grenier and De Clercq 2003) and may thus also influence its responses to climatic challenges. Therefore, we tested the cold tolerance of C. montrouzieri ladybirds fed on a natural prey (the citrus mealybug P. citri) or on a factitious food (frozen eggs of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)).…”