Response to walnut olfactory and visual cues by the parasitic wasp Diachasmimorpha juglandis

Diachasmimorpha juglandis is a specialist parasitoid attacking fly larvae in the genus Rhagoletis that feed exclusively on walnut fruit husks. In a free-foraging assay comparing response to uninfested, infested, and mechanically damaged fruits, we first determined that D. juglandis use host feeding damage on the fruit as a cue for host presence. In another free-foraging assay that used artificial walnut models and wind tunnel experiments, D. juglandis distinguished infested from uninfested fruits by using either olfactory or visual cues separately. However, the response rate of wasps in the wind tunnel was raised considerably when visual cues were also available. We analyzed the volatile compounds emitted by cohorts of uninfested, mechanically damaged, and infested fruits 1, 3, 5, 8, and 10 days after oviposition by flies into the infested fruits. Total volatile emissions did not differ significantly among treatments, but quantitative changes in volatiles distinguished infested fruits from uninfested and damaged fruits. The fact that parasitoids did not distinguish between infested and damaged fruits in assays where damage was visible indicates that they rely on visual cues when those are available.     

Monolithiation of 5,5′‐Dibromo‐2,2′‐bithiophene Using Flow Microreactors: Mechanistic Implications and Synthetic Applications

The lithiation of 5,5′‐dibromo‐2,2′‐bithiophene with one equivalent of an alkyllithium such as n‐BuLi or s‐BuLi was studied by varying the residence time in flow microreactors. With a short residence time, the product 2,2′‐bithiophene (3) derived from dilithiation was obtained preferentially and a significant amount of the starting material 5,5′‐dibromo‐2,2′‐bithiophene remained unchanged. An increase in the residence time caused a higher yield of the product 5‐bromo‐2,2′‐bithiophene derived from monolithiation with expense in the yields of 2,2′‐bithiophene and 5,5′‐dibromo‐2,2′‐bithiophene. The lithiation using MeLi gave the product 5‐bromo‐2,2′‐bithiophene preferentially even with a very short residence time.     

Predator Avoidance by Phytophagous Mites is Affected by the Presence of Herbivores in a Neighboring Patch

When predators invade a leaf patch inhabited by herbivores, the herbivores disperse to a neighboring predator-free leaf patch, thus escaping from the predators. However, the neighboring patch might already be used by con- or heterospecific herbivores. We used laboratory bioassays to examine whether perception of odor from con- or heterospecific competitors on a neighbored lima bean leaf patch influences dispersal behavior of the herbivorous mite Tetranychus urticae when attacked by predatory mites Phytoseiulus persimilis. The dispersal rates of T. urticae that perceived odors from leaf patches infested by conspecifics or cowpea aphids (Aphis craccivora) did not differ from the control (the dispersal rate of T. urticae that perceived odor from uninfested leaf patches). By contrast, the dispersal rate of T. urticae was reduced when they perceived odors from leaf patches that were currently or had previously been infested by larvae of the common cutworm (Spodoptera litura). Previous herbivory by S. litura larvae induced resistance in leaf patches to T. urticae as indicated by the reduced number of eggs laid by T. urticae. Our results are discussed with respect to the feeding behavior of the tested competitors of T. urticae and the impact of the plant and arthropod community on the dispersal behavior of these mites.     

Exploiting Temporal Relations in Mining Hepatitis Data

Various data mining methods have been developed last few years for hepatitis study using a large temporal and relational database given to the research community. In this work we introduce a novel temporal abstraction method to this study by detecting and exploiting temporal patterns and relations between events in viral hepatitis such as “event A slightly happened before event B and B simultaneously ended with event C”. We developed algorithms to first detect significant temporal patterns in temporal sequences and then to identify temporal relations between these temporal patterns. Many findings by data mining methods applied to transactions/graphs of temporal relations shown to be significant by physician evaluation and matching with published in Medline.     

Specialist Leaf Beetle Larvae Use Volatiles from Willow Leaves Infested by Conspecifics for Reaggregation in a Tree

Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to exhibit characteristic aggregation-dispersion-reaggregation behavior and local fidelity to a host tree. In this study, we investigated whether plant volatiles induced by feeding P. versicolora larvae were involved in the reaggregation behavior. Under laboratory conditions, we conducted dual-choice bioassays and found that the first and second instars discriminated between volatiles from leaves infested by larvae and volatiles from uninfested leaves. The discriminative behavior was dependent on both the time leaves were infested and the age of discriminating larvae. First and second instars preferred odor from 1-d-infested leaves to odor from uninfested leaves, whereas third instars (solitary stage) did not discriminate between these volatile blends. Odor from 2-d-infested leaves was preferred to odor from 1-d-infested leaves by first instars, whereas odor from leaves infested for 3 d was not attractive to these very young larvae. Neither was odor of leaves infested for 1 d and then left uninfested for 1 or 2 d attractive to young larvae. The data suggest that the first and second instars use volatiles from a leaf newly infested by conspecific larvae as one of the reaggregation cues. We detected several herbivore-induced compounds in the headspace of the attractive leaves. Among those, a mixture of synthetic (E)-β-ocimene, (Z)-β-ocimene, allo-ocimene, and linalool was found to attract the larvae.     

Present or Past Herbivory: A Screening of Volatiles Released from <Emphasis Type="Italic">Brassica rapa</Emphasis> Under Caterpillar Attacks as Attractants for the Solitary Parasitoid, <Emphasis Type="Italic">Cotesia vestalis</Emphasis>

Females of the solitary endoparasitoid Cotesia vestalis respond to a blend of volatile organic compounds (VOCs) released from plants infested with larvae of their host, the diamondback moth (Plutella xylostella), which is an important pest insect of cruciferous plants. We investigated the flight response of female parasitoids to the cruciferous plant Brassica rapa, using two-choice tests under laboratory conditions. The parasitoids were more attracted to plants that had been infested for at least 6 hr by the host larvae compared to intact plants, but they did not distinguish between plants infested for only 3 hr and intact plants. Although parasitoids preferred plants 1 and 2 days after herbivory (formerly infested plants) over intact plants they also preferred plants that had been infested for 24 hr over formerly infested plants. This suggests that parasitoids can distinguish between the VOC profiles of currently and formerly infested plants. We screened for differences in VOC emissions among the treatments and found that levels of benzyl cyanide and dimethyl trisulfide significantly decreased after removal of the host larvae, whereas terpenoids and their related compounds continued to be released at high levels. Benzyl cyanide and dimethyl trisulfide attracted parasitoids in a dose-dependent manner, whereas the other compounds were not attractive. These results suggest that nitrile and sulfide compounds temporarily released from plants under attack by host larvae are potentially more effective attractants for this parasitoid than other VOCs that are continuously released by host-damaged plants.     

Investigation of tritrophic interactions in an ecosystem using abstract chemistry

We investigated the population dynamics of a tritrophic interaction mediated by herbivore-induced plant volatiles that attracted carnivorous natural enemies of herbivores. We modeled the system by abstract chemistry, and an abstract rewriting system of multisets (ARMS), and compared the case where plants produced herbivore-induced volatiles with the case where they did not. We found that there was a case where herbivore-induced volatiles that attract carcivores resulted in a population increase of herbivores. This work was presented, in the Sixth International Symposium on Artificial Life and Robotics, Tokyo, Japan, January 15–17, 2001     

Estimation method of frequency bias using normal operating data

A technique of calculating the frequency bias of an electric power system from frequency fluctuation data and total output power is described. An evaluation method for testing the calculations by the new method is developed. The results are in good agreement with estimates based on generator speed regulation but the method gives an excessively high figure for the load frequency bias.