Toxicity of allyl esters in insect cell lines and in Spodoptera littoralis larvae

We investigated the effects of five allyl esters, two aromatic (allyl cinnamate and allyl 2-furoate) and three aliphatic (allyl hexanoate, allyl heptanoate, and allyl octanoate) in established insect cell lines derived from different species and tissues. We studied embryonic cells of the fruit fly Drosophila melanogaster (S2) (Diptera) and the beet armyworm Spodoptera exigua (Se4) (Lepidoptera), fat body cells of the Colorado potato beetle Leptinotarsa decemlineata (CPB) (Coleoptera), ovarian cells of the silkmoth Bombyx mori (Bm5), and midgut cells of the spruce budworm Choristoneura fumiferana (CF203) (Lepidoptera). Cytotoxicity was determined with use of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and trypan blue. In addition, we tested the entomotoxic action of allyl cinnamate against the cotton leafworm Spodoptera littoralis .The median (50%) cytotoxic concentrations (EC50s) of the five allyl esters in the MTT bioassays ranged between 0.25 and 27 mM with significant differences among allyl esters (P = 0.0012), cell lines (P < 0.0001), and the allyl estercell line interaction (P < 0.0001). Allyl cinnamate was the most active product, and CF203 the most sensitive cell line. In the trypan blue bioassays, cytotoxicity was produced rapidly and followed the same trend observed in the MTT bioassay. In first instars of S. littoralis, allyl cinnamate killed all larvae at 0.25% in the diet after 1 day, while this happened in third instars after 5 days. The LC50 in first instars was 0.08%. In addition, larval weight gain was reduced (P < 0.05) after 1 day of feeding on diet with 0.05%. In conclusion, the data provide evidence of the significant but differential cytotoxicity among allyl esters in insect cells of different species and tissues. Midgut cells show high sensitivity, indicating the insect midgut as a primary target tissue. Allyl cinnamate caused rapid toxic effects in S. littoralis larvae at low concentrations, suggesting further potential for use in pest control.

La brúixola de les papallones

QUAN ARRIBA LA PRIMAVERA MOLTS INDRETS DE CATALUNYA s"omplen amb la xiscladissa de les orenetes que vénen de l"Àfrica, on han anat a passar l"hivern. Fa temps que es coneix amb cert detall el mecanisme que utilitzen els ocells migradors per orientar-se. Però hi ha altres animals que també migren dels quals encara es desconeixen els mecanismes d"orientació. Uns dels més famosos per les seves migracions són les papallones monarca (Danaus plexippus), tant per l"enorme quantitat d"aquests insectes lepidòpters que migren simultàniament, que fa que el cel s"enfosqueixi, com pel llarg recorregut que fan, de milers de quilòmetres. A la tardor (setembre i octubre) les papallones monarca d"Occident realitzen el seu viatge de migració des del Canadà fins a la costa de Califòrnia, als Estats Units, per passar l"hivern en petits boscos d"eucaliptus. Les papallones monarca d"orient viatgen al centre de Mèxic per passar l"hivern als boscos d"oyamel i pi per sobre dels 3.000 metres als estats de Mèxic i Michoacán.