FAT METABOLISM IN INSECTS

Abstract

The study of fat metabolism in insects has received considerable attention over the years. Although by no means complete, there is a growing body of information about dietary lipid requirements, and the absolute requirement for sterol is of particular note. In this review we (a) summarize the state of understanding of the dietary requirements for the major lipids and (b) describe in detail the insect lipid transport system. Insects digest and absorb lipids similarly to vertebrates, but with some important differences. The hallmark of fat metabolism in insects centers on the lipid transport system. The major lipid transported is diacylglycerol, and it is carried by a high-density lipoprotein called lipophorin. Lipophorin is a reusable shuttle that picks up lipid from the gut and delivers it to tissues for storage or utilization without using the endocytic processes common to vertebrate cells. The mechanisms by which this occurs are not completely understood and offer fruitful areas for future research.

Effect of Irradiation on Mating Ability in the Male Sweetpotato Weevil (Coleoptera: Curculionidae)

“…It was possible that the disturbance in fatty and amino acids was a result of TCA cycle disruption. Fatty acids, also as an energy source, are an integral part of cell membranes (Canavoso et al 2001). Cell membrane fluidity, which is dependent on the lipid and fatty acid composition, is vital for normal cell functions (Werner and Simmons 2008).…”

Population dependent effects of photoperiod on diapause related physiological traits in an invasive beetle (Leptinotarsa decemlineata)

“…Previous studies have shown that the main portion of fat body total lipids is triacylglycerides (Canavoso et al 2001), which are part of the neutral or simple lipids. To confirm that this is the case in L. decemlineata the abdominal total lipids were fractioned.…”

“…In the fat body, most hemolymph lipids garnered from the breakdown of food are converted into neutral lipids (triglycerides or triacylglycerides) (Arrese & Soulages 2010). Neutral lipids are the main form of storage lipids in the insect fat body, usually constituting more than 90 % of the fat body total lipid mass (Canavoso et al 2001). It is of importance to note that also reproductively active individuals gather lipids, which are used for oogenesis and to fuel mating behavior, and that these lipids also can be in the form of neutral lipids stored in the fat body (de Loof & Lagasse 1970).…”

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

“…H. subflexa larvae feed exclusively on the fruits of Physalis spp., which are physically encased within an inflated calyx of the flower and defended by the presence of secondary compounds (e.g., withanolides and flavonol glycosides) (12,13). We have discovered an additional feature of these fruits that might be expected to deter insect herbivory: P. angulata fruits lack an important fatty acid, linolenic acid (LA), which is required for the normal development and metamorphosis of most insect larvae (14)(15)(16).…”