Fig 1.
Schematic of a four chambered olfactometer.
The main choice arena of the olfactometer measured 30.48 x 30.48 x 2.54 cm, and was covered with a removable lid. It consisted of four outlet ports laterally connected to four odour source chambers, and a ventral insect inlet port to introduce the test insect. Each lateral outlet port was connected to the internal odour source (IOS) with a glass insect isolation trap (IIT). The odour source was connected to an air delivery system that pumped moist air through the odour sources to the choice arena, and a vacuum to the insect inlet chamber to centralize the airflow throughout the choice arena. The rate of air delivery was 1 L/min. The air from all the odour sources was directed to the insect inlet chamber using a vacuum suction mechanism, and this exposed the test insect to odours emanating from different chambers, allowing it to make a choice. Image source: ARS, Gainesville, Florida.
Fig 2.
Response of the adults (%) of P. melanarius, A. littoralis and H. affinis responding to odour emanating from a) unimbibed seeds and b) imbibed seeds of B.napus, S.arvensis, T. arvense and control chambers of a four chambered olfactometer.
Fig 3.
Mean residence time i.e. time spent by the carabid species P. melanarius, A. littoralis and H. affinis in the odour chamber from a) unimbibed seeds and b) imbibed seeds of B.napus, S.arvensis, T. arvense and control chambers of a four chambered olfactometer.
For a given carabid species, treatment means with different letters indicate significant differences in percent response to odours from different seed treatments using Tukey’s test.
Fig 4.
Response of the adults (%) of P. melanarius, A. littoralis and H. affinis responding to odour emanating from unimbibed and imbibed seeds of B.napus in a two choice bioassay.