Microbial community ecology & insect nutrition

Abstract

As can be said fondly of many human relationships, associations between insects and microorganisms go back a long way. Basic nutritIonal deficiencies, biochemical needs, and even sexual compatibility requirements in insects are met through microbial "partnerships" (Bourtzis and O'Neill 1998, Moran and Telang 1998). These relationships, falling into the original broad definition of symbioses as coined by de Bary (1879), are widespread, varied, and, in many cases, reflect a pronounced history of co-evolution (Buchner 1965, Moran and Telang 1998). Although there is also an impressive record of what might be considered "unhealthy" insect-microbe relationships (i.e., microorganisms that are pathogenic or parasitic to insects and other hosts [see Steinhaus 1967, Lysenko 1985, Federici and Maddox 1996]), our focus will be on relationships benefiting insects in some fundamental way, particularly nutritional mutualisms and the exploitation of microorganisms as food items. The term 'microorganism' and its derivatives used here will refer mainly to bacteria, fungi, and protozoa, with the acknowledgment that many groups of viruses and algae also interact closely with a variety of insect species. Bacterial, fungal, and protozoal associations with insects have been included in previous reviews (e.g., Buchner 1965, Steinhaus 1967, Boush and Coppel 1974, Breznak 1984a, Jones 1984, Campbell 1989, Prins and Kreulen 1991, Kane 1997, Douglas 1998). It is our intent to highlight several examples from a slightly different perspective, stressing the complexity and dynamic nature of many insect-microbe relationships as revealed through current techniques used in microbial ecology.