Synomones induced by herbivore also have key involvement in the location of habitat by aphid parasitoids. A great upwind flight had been recorded by Guerrieri et al. (1993) as A. ervi responded to a system of plant- host than to either the plant along or aphid in the tests of wind tunnel. The parasitoid also can be seen responding to a number of plants damaged by host from which there had been a removal of aphids. There had been a demonstration of similar response to the complec plant- host by A. ervi by Powell et al. (1998) and Du et al. (1997). The response of female to broad plants of beans damaged due to Acyrthosiphon pisum had been greater in comparison with mechanically damaged or undamaged plants.
Two-Chamber Olfactometer Experiments
Bioassays were designed to observe the preference of A. ervi about the induced plant’s volatiles by aphids with or without symbiont H.defensa. 2-chamber olfactometer was used to test. As you can see in figure1, this 2-chamber olfactometer is a plastic cylinder with a wall in the center that separates the chamber into two halves that each contain an odor source, which will be induced plants by aphid clone with or without endosymbiont. A thin mesh on the top separates the parasitoid wasp from the plants.
The lid on top of the mesh prevents the wasp from escaping. In the test of olfactometer, no response of D. rapae had been found by Reed et al. (1995) to the leaves of cabbage. However, there was attraction of females to B. brassicae infesting the leaves with the wheat aphid of Russia, namely, Diuraphis noxia. In another study of wind tunnel, it had been found by Sheehan and Shelton (1989) that there had been a rearing of D. rapae over collards showing increased responses of flight to the plants in comparison with that of potato.
The underlying suggestion is that D. rapae is known for having an innate preference for the crucifer that feeds the system of aphid. Even though these types of experiments consider permitting a number of conclusions, there is an existence of few data from the experiments of the field. Also, it is not necessary that significant response will be implied in an olfactometer for the attraction of longer range within the field.
There are 6 groups presented in Table1. Tests will perform the preference of wasps about different odor sources—plant induced by the same clone aphids but with or without symbiont. The time A.ervi spent in each side of the chambers with two odor sources shows the wasp’s preference. Every experiment will be performed independently by using 2-chamber olfactometer. For all the experiments, two different odor source were offered to the wasps and their preference was recorded. Induced plant with H.defensa will be put in one chamber and the induced plants without H.defensa will be put in the other chamber.
The wasps were released at the middle point on the walking area of the olfactometer. 60 seconds were given to set them free of the tube. Then recorded 5 minutes (300 seconds), counted the time wasps spent in each side. Each pair 5 wasps and in total 10 pairs were tested each treatment. Total 50 wasps were tested each compare group. Change the side of treatment and control plants after three wasps, to avoid other possible preference. All the experiments will be done in the ecological laboratory under a fiber optic lights source placed above the 2-chamber olfactometer at room temperature. By long time co-existing, the plant defense evolved, in the mean while, the insects as one of the most diverse groups evolved by changing foraging behavior. Symbiotic association is one of the co-evolution results. Associations between different organisms can be concluded as symbiosis, parasitism and predator-prey system. During natural selections, symbiosis sparked for it is a kind of associations that both of the participating organisms get benefits.