The e-bean


Midori TUDA's research activities, collaborators, awards, and more

Video (my goals of research, education and university governance: as a trainee of the diversity program, SENTAN-Q supported by MEXT)NEW

Diversity and conservation of seed-feeding insects (JSPS Grant-in-Aid for Scientific Research (C), 2007-2009 to MT)

Large seed size is beneficial for germination. On the other hand, the benefit of large seed size in terms of escape from predators is not straightforward: Seed predators attack larger/smaller seeds, depending on plant-herbivore combinations: Larger seed attackers are often free from interspecies competition, whereas smaller seed attackers tend to have competitors. This is probably because mothers pay more costs to find and deposit their eggs on larger seeds in specialist bruchines and the cost may be paid off in the next generation. Additionally, seed predator larvae in small seeds are more prone to parasitoid attack. This is probably equivalent to what happens to gall makers. Interestingly, seed germination is promoted by predation in few plant species.

In East European plant (seeds of Vicia, Lathyrus and Pisum) and herbivore (Bruchus seed predators) interactions...

For plant (legume)-herbivore (seed predator) relationship to be mutually symbiotic, the number of herbivore species per plant species had to be one (independent of the herbivore being specialist/generalist), whereas other factors like the plant being annual/perennial, the size, hardness and number of seeds, the body size of herbivores, and ancestral states were not important. In the most symbiotic combination of species, the germination of uninfested seeds was impossible, the number of eggs laid per seed was the highest, and the probability of sympatry with other related legumes was the lowest. Thus, since this legume species requires a symbiotic herbivore for its germination and forest rim with few competitors, it is relevant to conserve such habitat for its existence.

A braconid wasp, Heterospilus prosopidis

From top: a female and a male H. prosopidis (Braconidae), and a female and a male Callosobruchus chinensis (Bruchinae)

The female wasp is in attempt to oviposit on the surface of larvae or pupae of the azuki bean beetle C. chinensis inside beans (see below). Several genera of the bean beetles (Chrysomelidae: Bruchinae) are known as stored product pests (e.g., Callosobruchus, Acanthoscelides, Caryedon and Bruchidius) (Tuda, 2007).
Evolution of stored bean pests has been driven primarily by a climatic factor (long dry season) (Tuda et al., 2006).

Conversely, some bean beetles are beneficial and used as control agents of weedy plants (Tuda, 2007).

Ecological studies using bruchine beetles in the lab have been contributed to the development of population and evolutionary dynamics theories.

Bruchine larvae and pupae inhabiting inside beans (soft-X-ray images of infested beans)

Cavities made by bruchine larvae. You can see the larvae and pupae inside the cavities.

Scramble-type larvae avoid competition
and share the resource

Contest-type larvae kill each other
and only one of them can dominate the resource

Evolutionary population dynamics of the cowpea bean beetle (the host) and Heterospilus prosopidis (the parasitoid)

The larval competition type of the cowpea bean weevil has shifted from the scramble type to the contest type after about 400 days, that is, 20 host generations.

The ecological characteristics of the parasitoid have not changed. We found that the evolutionary change in the host competition type alone can generate the stabilization and the switch in population levels between host and parasitoid (Tuda and Iwasa, 1998; Tuda, 1998; Tuda and Shimada, 2005).

Our evolutionary model shows that it was the bean size that increased the frequency of the contest type.

This is one of the few studies that demonstrate an evolutionary change influences population dynamics of both host and parasitoid.

Introduction of an alien parasitoid and its ecological consequences

The introduction of an alien parasitoid (on day 440) modified an ecological trait of a native parasitoid, which consequently altered the dynamical behavior of the whole ecological assemblage from stability to unstable complex dynamics (Tuda and Shimada, 2005).

From top; the host (Callosobruchus chinensis), the native parasitoid (Anisopteromalus calandrae) and the alien parasitoid (Heterospilus prosopidis)


Before the introduction of the alien parasitoid (blank bars, right pied chart). After the introduction (gray bars, left pied chart). Top: dominant Lyapunov exponents of bootstrapped population dynamics. Some time series were chaotic (indicated by positive Lyapunov exponents). Bottom: population behavior of the bootstrapped time series.


Midori TUDA's list of papers, research activities, collaborators, awards, and more

Link to the e-bean

Out of town:

4-12 July, 2012     First Joint Congress on Evolutionary Biology (Canada)
17-27 Nov, 2011    Field work (Thailand)
19-22 Aug., 2011    International workshop on global legume diversity assessments (Fukuoka)
12-28 July, 2011    Field work and experiment (Hungary)

17-27 June, 2011 Second Entomophagous Insects Conference (France)
8-12 March, 2011 Annual meeting of Ecological Society of Japan (Sapporo)
18-21 Feb, 2011    Seminar (Shizuoka)
12-16 Feb, 2011    Field work (Hawaii)
11-21 Nov, 2010    Field work (Thailand)
15-20 Mar, 2010    Annual meeting of Ecological Society of Japan (Tokyo)
2-6 Aug, 2009       Journal of Experimental Biology Symposium: Survival in a Changing World (Awaji)
18-19 Oct, 2008     Annual Meeting of the Society of Population Ecology (Tokyo)
17-23 May, 2008   Field work (Hungary)
14-17 March, 2008 Annual meeting of Ecological Society of Japan (Fukuoka)
11-20 Feb., 2008   Experiment and field work (Thailand)
19-22 Oct, 2007     Symposium of Society of Population Ecology (Sapporo)
18-19 Sep., 2007   Invited talk at International Workshop on Ecological Informatics of Chaos and Complex Systems- Spectral Imaging for Ecosystem Modelling (Tokyo)
26 June-27 July, 2007 Research visit (Hungary)
26 May-2 June, 2007 Field work (Hungary)

2002 - March 2007

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