|Lee, Richard - MIAMI UNIV, OXFORD, OH|
Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2004
Publication Date: July 1, 2004
Citation: Nelson, D.R., Lee, R.E. 2004. Cuticular lipids and desiccation resistance in overwintering larvae of the goldenrod gall fly, Eurosta solidaginis (diptera: tephritidae). Comparative Biochemistry and Physiology B 138(3):313-320. Interpretive Summary: Within their gall, larvae of the goldenrod gall fly, Eurosta solidaginis, experience severe dessication as well as highly variable thermal conditions and extreme cold during winter. Through the autumn and early winter, field-collected larvae acquired markedly enhanced resistance to desiccation and freezing. At the same time they increased their cuticular surface hydrocarbons. Hydrocarbons were the major lipid class extracted by hexane or chloroform from the cuticular surface of overwintering gall fly larvae. The major hydrocarbon class were the 2-methylalkanes which consisted mainly of 2-methyltriacontane. 2-Methyltriacontane comprised 48 to 68% of the total hydrocarbons during the larval stages. Total hydrocarbons increased from 122 ng/larva in early third instar larvae collected in September to 4,900 ng/larva in those collected in January. Although washing of the cuticular surface with chloroform or chloroform:methanol (2:1, v:v) caused marked increases in rates of water loss, treatment with hexane and methanol had little effect on water loss rates.
Technical Abstract: The goldenrod gall fly is noted for its ability to survive extreme desiccating conditions and temperatures as low as -55 degrees centigrade; as well as fluctuating temperatures up to 35 decrees centigrade during the winter. Lipids and waxes on the surface of the insect have been proposed as being responsible for the resistance to desiccation. In this study we found that the cuticular surface lipids increase during the larval stage 40-fold irrespective of larval size. This increase corresponds with an increased ability of the larvae to survive freezing temperatures. Removal of these lipids resulted in a marked increase in loss of body water from the larvae.