Duration and location of attraction to herbivore-damaged plants in the tachinid parasitoid Exorista japonica

Abstract

Odors from corn plants infested with the larvae of the noctuid herbivore Mythimna separata attract tachinid fly, Exorista japonica, females. We investigated the effects of elapsed time on the attraction of E. japonica to plants after host larvae were removed. The behavior of the flies within 5 min from introduction was observed in a wind tunnel. The percentage of flies attracted to the plants remained high (70%) for 5 h and decreased gradually after 24 h. The percentage of flies attracted to continuously damaged plants remained high for 5 days. In contrast, the percentage of flies reaching artificially damaged corn plants was high (85%) when tested soon after damage but decreased to 40% 1 h after damage. We also examined whether undamaged leaves from a damaged plant attracted tachinid flies. Undamaged leaves were not attractive when all other leaves on the same plant were damaged, even if damaged for several hours. In addition, the undamaged part of damaged leaves was not attractive. These results indicate that volatiles that attract E. japonica are only released from the damaged parts of leaves and these volatiles gradually decrease as the damaged plant ages.

Feeding behaviour of young larvae of Pieris rapae crucivora (Lepidoptera: Pieridae) and its effect on parasitism by Cotesia glomerata (Hymenoptera: Braconidae)

“…In contrast, the area close to young marks (< 24 h) are highly vulnerable sites for host larvae. For another host-parasitoid relationship, Hanyu et al (2009) report that the feeding mark made by the northern armyworm, Mythimna separata, is attractive for the parasitoid fl y, Exorista japonica. The attractiveness of this mark decreases over a similar period of time, as observed in the present study.…”

Wind Tunnel: a Tool to Test the Flight Response of Insects to Semiochemicals

“…For diurnal insects, we established wind tunnel experiments for Aphidius colemani in our laboratory and used a light intensity of 150 lx, because female A. colemani did not show good orientation toward the odor source (herbivore damaged plant) under lighter conditions and flew upward to the ceiling of the tunnel at 2,000 lx (Fujinuma et al, unpublished). However, the tachinid fly Exorista japonica readily flew to the target plant under full light conditions (>2,000 lx) (Kainoh et al, 1999;Ichiki et al, 2008Ichiki et al, , 2011Hanyu et al, 2009). As a light source, we use Vitalite ® (40W, 6 tubes) to maintain light conditions similar to sunlight, and the light intensity can be changed with a voltage converter from 0 to 6,000 lx.…”

“…5)' (Noldus Information Technology, Wageningen, The Netherlands) (Fig. 7) is used to record the behavior of insects in a wind tunnel (Hanyu et al, 2009). We can record each behavioral event (walking, flying, stationary or grooming) and location (release site, floor, wall, ceiling, target), and then calculate the duration, average time on the release site (latency), total time flying in the wind tunnel, total time walking on the floor, wall or ceiling and other parameters from these recordings (Fig.…”

Effects of larval densities and the duration since larval infestation on the host-searching behavior of Diadegma semiclausum, a parasitoid of diamondback moth larvae on plants

“…Thus, prey density on a plant (e.g., Maeda and Takabayashi 2001b;Gols et al 2003;Shiojiri et al 2010) and duration since the last infestation (Hanyu et al 2009;Kugimiya et al 2010;Mandour et al 2011) would be important factors for foraging carnivores. We recently reported host-density dependent/independent response of parasitic wasps to hostinfested plant volatiles (Shiojiri et al 2010).…”