Search

Start Over Creator Oku, Keiko

1. Effects of starvation and mating status on the activity of the flea beetle, Phyllotreta nemorum (Coleoptera: Chrysomelidae)

Creator:
Oku, Keiko, M.C.A. Vermeer, Kim, Verbaarschot, Patrick, and Jong, Peter W. de
Type:
article, model:article, and TEXT
Subject:
Chrysomelidae, Phyllotreta nemorum, female movement, flight activity, mating status, and starvation
Language:
English
Description:
Flea beetles are characterized by their tendency to jump. They can also fly. First, the effects of starvation on flight activity in the flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae) were determined. After starving P. nemorum for five days a greater number of individuals of both sexes flew than when fed continuously for the same period. In addition, the effect of the mating status of females of P. nemorum on their movement was determined. Mated females were more active than virgin females. It is concluded that starvation stimulates the flight activity of both sexes and mating activates the movement of females of P. nemorum.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Role of excreta in predator avoidance by the Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae)

Creator:
Oku, Keiko
Type:
article, model:article, and TEXT
Subject:
Tetranychidae, Tetranychus kanzawai, Phytoseiidae, Neoseiulus womersleyi, predator avoidance, refuge, webs, and excreta
Language:
English
Description:
The Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae) constructs webs over leaf surfaces and usually lives under these webs. T. kanzawai produces two types of excreta, black and yellow pellets, and uses its webs as a place for excretion. T. kanzawai also uses its webs as a refuge when the predatory mite, Neoseiulus womersleyi (Acari: Phytoseiidae) is present. To clarify what factors deter N. womersleyi from foraging on T. kanzawai webs, I experimentally examined the effects of T. kanzawai excreta on its own fitness (fecundity) and the foraging behaviour of N. womersleyi. When the excreta of T. kanzawai was put on leaf surfaces, the fecundity of T. kanzawai adult females was reduced by the black but not the yellow faecal pellets. On the other hand, predation by N. womersleyi was reduced by the yellow but not the black pellets. Although this effect of the yellow pellets on N. womersleyi did not last on leaf surfaces, it deterred N. womersleyi from staying on the web regardless of its freshness. These results suggest that T. kanzawai deposits black pellets on webs to avoid its negative effect on their own fitness, and yellow pellets are deposited on webs to reduce the risk of predation.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public