Associative learning and memory duration of Trichogramma brassicae

Document Type: Original Research Papers


1 Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran

2 Department of Psychology, California State University, Fresno, California, USA


Learning ability and memory duration are two inseparable factors which can increase the
efficiency of a living organism during its lifetime. Trichgramma brassice Bezdenko (Hym.:
Trichogrammatidae) is a biological control agent widely used against different pest species.
This research was conducted to study the olfactory associative learning ability and memory
duration of T. brassicae under laboratory conditions. According to our results, T. brassicae
showed olfactory learning ability in response to conditioned odors, and this learned olfactory
stimuli lasted for 20 hours. In a second experiment, the effects of frequent experiences on the
memory duration of females were studied. A direct relationship between frequent experiences
and memory duration was observed. When exposed to a conditioned odor, wasps’ memory
duration increased in response to the number of experiences. Memory was observed at 28 h
after one extra conditioning. The duration of the associative memory lasted 42 hours when 2
extra experiences were given, 50 hours after 3 experiences, and 58 hours after 4 extra
conditioning experiences. Our results showed that T. brassicae can associate new odors to host
existence, and they will show increased memory duration after multiple experiences.


Main Subjects