EFFECT OF STARVATION ON LIPOPHORIN DENSITY IN FIFTH INSTAR LARVAL Manduca sexta

Lipophorin ( L p) is a major insect lipoprotein and is responsible for lipid transport between organs. In this study, the effect of starvation on L p properties was analyzed in larval Manduca sexta during the fifth instar. L p hemolymph concentrations in larvae at days 1 and 2 were around 2–3 mg/ml and at day 3 it increased to 8 mg/ml. When larvae were starved for 24 h, they did not grow, but their body mass and hemolymph volume did not decrease significantly. Differences in L p densities were observed. In fed larvae, from days 1 to 4, two major L p populations were found with densities of 1.124 ± 0.002 (high density L p‐larval 1 , HDL p‐ L 1 ) and 1.141 ± 0.002 g/ml ( HDL p‐ L 2 ). When larvae were starved for 24 h, only one L p population was present, with density 1.114 ± 0.001 g/ml ( HDL p‐ L s ). When larvae were abdominally ligated at day 1 or 2 of fifth instar, only HDL p‐ L s was found after 24 h, indicating that the formation of this HDL p population was not dependent on any factor released by head. On the other hand, larvae that were ligated at day 3 showed the same L p populations as the fed ones. In 24‐h starved larvae, lipid load in L p was higher as compared to the fed controls. In 24‐h ligated larvae L p lipid content increased when ligation was performed on day 1 or 2, but not on day 3. So, different responses to starvation can be observed depending on the developmental phase of the same larval instar.