Ovarian Development Of Chrysomya Megacephala And Its Oviposition Lure Identification

The blowfly, Chrysomya megacephala, known as forensic insect or insect vector, show special tropism to fresh dejection or rotten meat for oviposition. But the compounds that attract C. megacephala to oviposition sit are not clear. To finish this work, we observed adult body parts sensillum of C. megacephala, evaluated diets effect on ovary development by measuring ovarian morphological changes, identified the ingredients of volatile that attracted C. megacephala and demonstrated their biological activity. It turns out that acetic acid show inhibiting effect on C. megacephala oviposition. On the contrary, valeric acid and indole show acceleration effect on C. megacephala oviposition. The main research results are as follows:1 Sensilla morphology on antenna, mouthparts, wing, haltere, leg and ovipositor were described with scanning electron microscope. There are 5 types of sensilla on antenna,3 on the proboscis and ovipositor,2 on the haltere and leg and only 1 on the wing. Mechanoreceptors are present in all body parts of adults.2 The ovary development of adult C. megacephala is signally effected by diets. It would be quicker when meats were added, be slower when eggs were added, be uncompleted when milk powder or dung were added. Moreover, the females would lay eggs at the 5th day after emergence if feed them with meats and get into the first spawning peak at the 7th day after emergence. The last spawning peak will end at the 25th day and stagnation of 1-3 days would appear after each spawning peak.3 The oviposition lure experiment show that C. megacephala will spawn on gill and rotten meat, and they prefer gill than meat. Hexane extracts from gill and rotten meat are detected response peaks by gas chromatography-electroantennographic detection (GC-EAD). Nine volatiles were selected after GC-EAD and GC-MS analysis. Bioactivity detection show that acetic acid, valeric acid,4-methylphenol,4-ethylphenol, indole,3-methylindole (skatole) can make evident electroantennogram (EAG) response to female C. megacephala. Besides female C. megacephala show phobotaxis was detected to acetic acid in 10-2,10-3,10-4 density. On contrary, they show obvious tropism was detected to butyric acid, pentanoic acid, indole, 3-methyl indole in 10-3,10-4 density and propionic acid in 10-4. Moreover, in 10-4 density, acetic acid inhibited C. megacephala to spawn while pentanoic acid and indole promoted.