THE ELIMINATION OF INTRACELLULAR MICROORGANISMS FROM INSECTS - AN ANALYSIS OF ANTIBIOTIC-TREATMENT IN THE PEA APHID (ACYRTHOSIPHON-PISUM)

Antibiotics are routinely used to eliminate intracellular prokaryotic microorganisms from a wide range of insect species, but concerns about deleterious effects of antibiotic therapy on the insect host are seld om addressed. Here, the impact of antibiotic therapy in the symbiosis between the pea aphid Acyrthosiphon pisum and bacteria of the genus Bu chnera is reviewed. Antibiotic-treatment produces aposymbiotic (i.e, s ymbiont-free) aphids, but does not depress the mitochondrial complemen t, the assimilation of dietary amino acids or the incorporation of ami no acids into protein in these insects and does not impair osmoregulat ion, feeding rate and the capacity to penetrate plant tissues. It is c oncluded that the general malaise associated with aposymbiotic aphids is not attributable to a direct effect of the antibiotic. However, an important implication of this study is that aposymbiotic insects exhib it substantial metabolic adjustments to loss of the symbiosis; they ar e not simply aphids from which the symbiotic bacteria have been remove d. (C) 1998 Elsevier Science Inc. All rights reserved.