Biological and biochemical effects of organo-synthetic analogues of Trypsin Modulating Oostatic Factor (TMOF) on Aedes aegypti, Heliothis virescens and Plutella xylostella

The three-dimensional conformation of Aea-TMOF (Aedes aegypti Trypsin Modulating Oostatic Factor), a decapeptide (YDPAPPPPPP) isolated from mosquito ovaries that inhibits the translation of many trypsin-like serine proteases, e.g. in mosquitoes, flies and lepidopterans, was used as a model for the synthesis of 10 aromatic and aliphatic organic acid and ester analogues. The organic TMOF analogues were tested against herbivorous pest lepidopterans and larval Ae. aegypti. The compounds administered to microtiter plates or to leaf disks caused mortality to mosquito larvae and the diamondback moth, Plutella xylostella, larvae 3-6 days after treatment. The surviving diamondback moth larvae were sluggish, immobile and stopped feeding. A biochemical analysis showed that in larval P. xylostella the trypsin activity was low and correlated with the observed mortality. No activity was found against Heliothis virescens when four of the synthetic compounds that affected P. xylostella and Ae. aegypti were tested, although the decapeptide, TMOF, does affect trypsin biosynthesis in H. virescens.