RELATIVE IMPORTANCE OF NEUTRAL LIPIDS AND GLYCOGEN AS ENERGY STORES IN DAUER LARVAE OF 2 ENTOMOPATHOGENIC NEMATODES, STEINERNEMA-CARPOCAPSAE AND STEINERNEMA-FELTIAE

The infectivity of Steinernema carpocapsae dauer larvae (infective juv eniles) remained nearly constant up to 60 days of storage in water at 25 degrees C and then declined rapidly over the next 30 days. Few indi viduals remained infective after 120 days. Concurrent measurements sho wed that the mean neutral lipid content of individual S. carpocapsae d eclined to about 10% of initial levels after 60 days, and staining of individual nematodes with Oil Red O indicated that the population was almost homogeneous for low levels of neutral lipids. In contrast, the mean glycogen content of S. carpocapsae only declined significantly be tween 60 and 90 days of storage. These results show that the decline i n infectivity In S. carpocapsae is correlated primarily with the decli ne in glycogen reserves and suggests that glycogen is the key late ene rgy store in aged infective juveniles. In contrast, Steinernema feltia e dauer larva showed a much more gradual decline in infectivity over a 150- to 180-day storage period with a concurrent decline in neutral l ipids, whereas glycogen levels declined up to 90 days of storage and t hen remained nearly constant. Thus, unlike S. carpocapsae, neutral lip ids remain an important energy store in S. feltiae during storage, alt hough glycogen also appears to be important, at least initially. (C) 1 997 Elsevier Science Inc.