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Biological control agents including a wide range of organisms such as predators, parasitoids, and entomopathogens (bacteria, fungi, nematodes, and viruses) are frequently used to control insect pests. Despite commercial availability of these biocontrol agents their widespread use is limited due to biological and economic difficulties. Efficient mass-production relies heavily on the environment in which the agent is grown. Nutrition can play a significant role in important biocontrol traits such as colonization and survival, tolerance to environmental stress, reproduction, and longevity. Therefore, to increase biocontrol potential nutritional aspects should be considered prior to commercial production. This review aims to explore the role nutrition plays in the production and efficacy of biocontrol agents by summarizing the effect nutrition has on important biocontrol traits, specifically traits in organisms that target insect pests including predators, parasitoids, and microbial agents.

Biological control agents have become increasingly important in integrated pest management programs. However, certain traits of these agents that are needed for efficient biocontrol often decrease or are lost during in vitro rearing. Entomopathogenic nematodes (EPNs) often exhibit trait deterioration when reared under laboratory conditions. EPN trait deterioration has been attributed (at least in part) to genetic causes; however, the underlying causes of trait deterioration in its bacterial endosymbiont have not been explored. In this study the EPN symbiont Photorhabdus luminescens was monitored for the deterioration of three traits; inclusion body production, reproductive potential, and virulence, in three different nutritional environments; lipid liquid medium (LLM), nutrient broth (NB), and tryptic soy broth + yeast extract (TSY). Significant trait deterioration did not occur for any of the traits in any environment. There was an increase in inclusion body production in TSY. Additionally, there was variation in growth within NB and TSY sub-cultured population lines and one TSY sub-population line was less virulent than the other two. However, returning bacteria to LLM restored all traits to wild-type levels. We infer the observed trait deterioration in Photorhabdus was minimal and appeared to be driven by environmental conditions as opposed to stable genetic changes. Our data suggest that variation among traits of in vitro cultures of Photorhabdus is more likely due to environmental variation than inadvertent laboratory selection or other genetic processes.

Nematodes are one of the most abundant animals on earth, and bacteria comprise the most biologically and phylogenetically diverse domains of organisms. On at least two separate occasions a soil dwelling nematode and a bacterium have entered into a mutualistic, insecticidal association. From such origins arose two distinct lineages of nematode–bacterium entomopathogens, Steinernema–Xenorhabdus and Heterorhabditis–Photorhabdus. Herein, we present a summary and discussion of the known evolutionary diversity and systematics of these two groups relative to other nematodes and bacteria, and their shared evolutionary history.

Nematodes are one of the most abundant animals on earth, and bacteria comprise the most biologically and phylogenetically diverse domains of organisms. On at least two separate occasions a soil dwelling nematode and a bacterium have entered into a mutualistic, insecticidal association. From such origins arose two distinct lineages of nematode–bacterium entomopathogens, Steinernema–Xenorhabdus and Heterorhabditis–Photorhabdus. Herein, we present a summary and discussion of the known evolutionary diversity and systematics of these two groups relative to other nematodes and bacteria, and their shared evolutionary history.