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Title: BIOCHEMICAL AND CYTOIMMUNOLOGICAL EVIDENCE FOR CONTROL OF AEDES AEGYPTI LARVAL TYPSIN WITH AEA-TMOF

Author
item BAROVSKY, DOV - UNIV OF FLORIDA
item Meola, Shirlee

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2003
Publication Date: 3/1/2004
Citation: Barovsky, D., Meola, S.M. 2004. Biochemical and cytoimmunological evidence for control of Aedes aegypti larval typsin with Aea-TMOF. Archives of Insect Biochemistry and Physiology. 55(3):124-139.

Interpretive Summary: New chemicals are needed to control the development of mosquito populations in an environmentally-benign manner. A chemical (trypsin-modulating oostatic factor or TMOF) produced by a layer of cells surrounding the developing eggs of mosquitoes was found to prevent the production of a chemical needed to digest the blood meal in mosquitoes. When injected into mosquito larvae, TMOF also prevented digestion of food. Analysis of the cells in both adult and larval mosquitoes using a compound that is specifically attracted to TMOF revealed that the central nervous system of both male and female adult and larval mosquitoes produce TMOF, while cells in a glandular organ of adults and larvae entering the adult stage also produce this chemical. The importance of TMOF is that this compound retains its activity after being eaten by mosquitoes, preventing digestion of food and starving the insects.

Technical Abstract: The amount of trypsin and chymotrypsin-like enzymes synthesized in the larval gut of Aedes aegypti was followed during the four larval instar stages and the pupal stage. Both enzymes are synthesized in the gut during all larval development stages. The amount of trypsin synthesized in the larval gut was 2-fold higher than chymotrypsin. However, both enzymes are important in food digestion. Feeding Aea-TMOF to Ae. Aegypti and Culex quinquefasciatus larvae inhibited trypsin biosynthesis in the larval gut (88% and 91.7% respectively), stunted larval growth and development, and caused mortality. The lethal concentration of 50% mortality (LC50) was determined for Ae. Aegypti, Cx. Quinquefasciatus, Culex nigripalpus, Anopheles quadrimaculatus and Aedes taeniorhynchus indicating that all mosquito species have a TMOF-like hormone. The differences in potency of TMOF on different mosquito species indicate that these hormones are similar but probably do not have the exact amino acid sequence of Aea-TMOF. Feeding of 29 different Aea-TMOF analogues to mosquito larvae indicate that full biological activity of the hormone can be achieved with the tetrapeptide YDPA. Using cytoimmunochemical analysis TMOF immunoreactive (IR) material was localized in all the ganglia of the central nervous system in both larvae, male and female Ae. Aegypti adults. The subesophageal, thoracic, and abdominal ganglia contain TMOF-IR cells located in the same regions in both larval and adult stages of development. No TMOF-IR was visible in the corpus cardiacum (CC) of newly molted 4th instar larvae; however, some accumulation of TMOF-IR was found in the CC of the late 4th instar larvae. In both males and females the intrinsic neurosecretory cells of the CC are filled with densely stained TMOF-IR material. These results indicate that TMOF-IR is synthesized in sugar fed male and female adults and larvae by the CNS cells.