Learning and orientation to odor in the bug Rhodnius prolixus Stal 1859 under laboratory conditions

Abstract

Two experiments are described investigating learning and orientation in the triatomine Rhodnius prolixus. In experiment 1, Pavlovian conditioning was investigated. The experiment differed from our previous work in that the intensity of the conditioned and unconditioned stimuli were reduced and the number of training trials increased. Once again, no evidence for Pavlovian conditioning was found. In experiment 2, an "orientation arena" was developed in which the orientation of R. prolixus to a human forearm was investigated when an area of the forearm was impregnated with the odor of ruda or almizcle compared to a forearm with no odor. The various paths of the animal from the bottom of the arena until ascending and piercing the forearm, located at the top of the arena, was scored using a grid system and videotaped. The results indicated that under the no odor condition R. prolixus predominately travels in a straight line from the bottom of the arena to the top where the forearm is located. In contrast, the most variable number of paths occurred with exposure to ruda. Exposure to almizcle elicited straight line paths but other paths were evident, although not as variable as that observed with ruda.

Learning the way to blood: first evidence of dual olfactory conditioning in a blood-sucking insect, Rhodnius prolixus. I. Appetitive learning

“…Concerning R. prolixus, only negative results have been reported (Abramson et al, 2005;Aldana et al, 2008). In the present study, the accumulated knowledge on R. prolixus biology was exploited in order to adapt a conditioning procedure to its haematophagous way of life and to assess whether their behavioural response to a neutral odour could be modified by individual experience.…”

“…Comparing our experimental approach to previous ones may shed some light on the reasons behind these contradictory results, and provide some insights for future work. In their foray, Abramson et al (Abramson et al, 2005) and Aldana et al (Aldana et al, 2008) also paired an olfactory CS with a thermal US using an artificial feeder. The major differences with our work lie in the way they developed their experimental design.…”

“…Nevertheless, since most studies have been conducted in natural or not completely controlled conditions, few provide unquestionable evidence of learning in this group of insects (Alonso et al, 2003;Alonso and Schuck-Paim, 2006). In haematophagous bugs, vectors of Chagas disease, some experimental studies have been conducted in order to investigate olfactory learning in these insects, but no evidence could be obtained (Abramson et al, 2005;Aldana et al, 2008).…”

Learning and Memory in Disease Vector Insects

“…Subsequent studies, however, were unsuccessful in demonstrating the ability of the bugs to perform associative learning [23-24]. These negative results could have been due to the fact that the stimuli and reward did not adequately match the biology of bugs.…”

Aedes aegypti Mosquitoes Exhibit Decreased Repellency by DEET following Previous Exposure

“…Conditioning has been shown in R. prolixus [10], [11], D. melanogaster [12], and the parasitic wasp Microplitis croceipes [13]. For mosquitoes, some studies have found no evidence for behavioral adaptation [14], [15], while more recent work has demonstrated conditioning to odours [16]–[18].…”