Abstract
Acidic methanolic extracts of haemolymph, cuticle and eyes of larvae and adults of the migratory locust, Locusta migratoria migratorioides (R. et L.), were subjected to thin layer chromatography. The Rf-values as well as the fluorescent colour of the spots under ultraviolet illumination at 350 nm, were compared to those of 12 pteridine standards. Most of the standards showed a major spot, as well as up to 3 additional minor spots, probably due to the presence of isomers and degradation products. The extract of the haemolymph of untreated larvae and adults yielded 6 different spots. Cuticle and eyes had their own specific pattern. Application of methoprene (analogue of juvenile hormone) induced solitary phase-like pigmentation of the cuticle and green-coloured haemolyph. The content of pterin, biopterin, leucopterin, isoxanthopterin, and probably also of lumazin, increased. The melanization of the cuticle nearly completely disappeared. Similar, but weak effects were observed in neem-oil treated locusts. Application of precocene caused a number of changes in the pigment pattern of all extracts. It also induced some melanization of the cuticle in particular in larvae. Many pigment spots were observed which did not correspond to any of the 12 standard pteridines. The classical concept about the pigment composition of locust haemolymph, namely that it is restricted to melanin, carotenes and biliverdin, needs modification.
Highlights
IntroductionPteridines or pterins (Ferre et al, 1991) represent one of the families of pigmentary colours of insect cuticle, but some of them are important eye pigments (Chapman, 1969)
Pteridines or pterins (Ferre et al, 1991) represent one of the families of pigmentary colours of insect cuticle, but some of them are important eye pigments (Chapman, 1969). They produce a variety of colours, ranging from white, or red over yellow to fluorescent blue under ultraviolet light
We report on the pteridine pattern of Locusta as well as on how it is affected by some biologically active substances like juvenoids, precocene, azadirachtine and metyrapone
Summary
Pteridines or pterins (Ferre et al, 1991) represent one of the families of pigmentary colours of insect cuticle, but some of them are important eye pigments (Chapman, 1969). Pteridines have been identi fied in some Holometabola (Fuzeau-Braesch, 1972), as well as in Hemimetabola In the latter, in particular Oncopeltus fasciatus (Forrest et al, 1966), Pyrrhocoris apterus (Socha & Němec, 1992), Rhodnius prolixus (Viscontini & Schmid, 1963), and Dysdercus cardinalis, D. intermedius and D. nigrifasciatus (Melber & Schmidt, 1992, 1994, 1997) were intensively studied
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