N. Cañas-Hoyos, T. Lobo-Echeverri, C. I. Saldamando-Benjumea
Southwestern Entomologist 42 (2), 375-394, (1 June 2017) https://doi.org/10.3958/059.042.0207
Fall armyworm, Spodoptera frugiperda (J.E. Smith), is a Neotropical polyphagous moth that is an important pest of maize, Zea mays L., in the Western Hemisphere. In the Americas, including Colombia, the insect also is a pest of rice, Oryza sativa L.; sorghum, Sorghum bicolor (L.) Moench; cotton, Gossypium hirsutum L.; and sugarcane, Saccharum officinarum L. The species in Colombia has diverged into strains in maize and rice as their most frequent hosts. Studies of reproductive isolation in Colombia showed that females of the corn strain rarely mated with males of the rice strain while females of the rice strain mated with both strains. Because behavioral isolation can be influenced by chemical composition of female sexual glands, we examined the volatile compounds for both strains, considering the time of extraction and male stimulation in production of metabolites. Altogether, 27 compounds were detected by gas chromatography coupled to mass spectrometry in the female sexual glands of both strains under laboratory conditions. The most relevant were the pheromones (Z)-9-tetradecenyl acetate and (Z)-7-dodecenyl acetate, among other volatiles reported for Lepidoptera. While 11 constituents were exclusive for the rice strain and eight for the corn strain, nine were common to both strains. A detrended correspondence analysis associated a group of compounds with each strain, while no significant differences were found in the abundance of compounds in common (T-test/Mann Whitney). In addition, the production of compounds was optimal after 3 hours of the scotophase for the corn strain and after 6 hours for the rice strain, while the presence of males was a positive influence in the production of compounds for females of both strains.