Abstract: By using cis-3-hexenyl acetate as standard chemical, the electroante
nnogram (EAG) responses of Maruca testulalis (Lepidoptera, Pyralididae) to p
lant volatiles and sex pheromone were investigated. Both the males and the femal
es of M. testulalis showed strong EAG responses to the volatiles, but no sig
nificant difference was observed under most test concentrations. Among the test
nine plant volatiles, the males and females had greater difference in the shape
of EAG response to trans-2-hexenal, and their maximum  EAG relative response to
 high concentration trans-2-hexenal was 250% and 260%, respectively. No obviou
s EAG responses were observed to the cedrene and cedrol from cowpea Vigna unguic
ulata floral. Both the male and the female moths showed clear EAG responses to s
ex pheromone, and significant difference was detected between males and females.
 The maximum  EAG relative response of the males to (E10, E12)-16 CHO, a main co
mponent of sex pheromone, was 250%, while that of the females was only 53%. The
difference in the EAG responses between the males and females reflected the diff
erence in the structure, function and behavior of the males and females olfacto
ry system.

Key words: Maruca testulalis, electroantennogram (EAG), plant volatiles, sex pheromone, muskmelon, increasing application of CO₂ to rhizosphere, photosynthetic characteristics, yield, quality.