Title of the Project: ISOLATION, PURIFICATION AND CHARACTERISATION OF ADIPOKINETIC NEUROPEPTIDES FROM THE RUBBER BEETLE LUPROPS TRISTS (TENEBRIONIDAE: COLEOPTERA)
Name and Designation of the Principal Investigator: Dr. Mohammed Ismail. K., Associate Professor, Department of Zoology, MES Mampad College
SUMMARY
The rubber plantation beetle, Luprops tristis is common household pest of various parts of Kerala. This beetle belongs to the family Tenebrionidae of the Order Coleoptera. They invade the residential places near the rubber plantations in large masses especially after summer showers. They can discharge a phenolic secretion when disturbed. It can cause blisters in the skin, thus they badly affects the normal life of human beings. There have been quite a lot of reports on the incidence of infestation of this beetle. It was seen that all the conventional control measures are appeared to be ineffective. The present project is an attempt to isolate and characterize the heat stable metabolic neuropeptides from the brain-corpora cardiaca-corpora allata –suboesophageal ganglion complex of the L. tristis.
After the removal of brain-corpora cardiaca-corpora allata –suboesophageal tissue complex from the insect, the heat stable peptides were isolated by subjecting the tissues to high temperature by exposing to steam. Inorder to characterize the heat stable factors, from the brain-retrocerebral complex, they were tested for their cross reactivity in another insect, the plant bug, Iphitalimbata.
The present study revealed the presence of at least two important neuropeptides from the brain-retrocerebral-sub-oesophageal complex of L. tristis. These factors are found to affect the metabolism of both lipids and fats of the insect in which the cross reactivity was studied. They have both hyperlipaemic and hyperglycaemic effect in I. limbata. It was seen that the effect of such factors are dosage dependent. As the concentration increases, their activity is also found to be increased. When compared hyperglycemic activity, the hyperlipaemic activity is more pronounced. When the concentration of the tissue was set half, the lipid concentration was increased to only 117% of the control values. But the concentration was steadily increased to 134 and finally to 150 % as the concentration was raised to 1 and 1 ½ set of tissue complex. So among the different concentration tried, maximum activity was noticed when the insects were injected with 1 ½ set of tissue complex.
Even though the effect was little as far as the hyperglycaemic factors are concerned, it was dependent on the concentration of the extract. As the concentration of extract was increased (0.5, 1.0 and 1.5 brain-endocrine tissue complex) the carbohydrate titre was also increased in the haemolymph from 2.4 to 4.8 to 7.6% than the untreated sample. Thus the present study shows the hyperglycaemic effects of brain-CC-CA-subsoesophageal ganglion of L. tristis. Even though it was responsible only for slight increase in carbohydrate titre with ½ and 1 set of tissue extract, a 1 ½ set caused a considerable increase in carbohydrate titre. Corpora cardiaca extract induced hyperglycemia was reported earlier by different workers.