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Psyche
Volume 2009, Article ID 159478, 9 pages
http://dx.doi.org/10.1155/2009/159478
Research Article

Extremely Long-Closed Galls of a Social Aphid

1Faculty of Economics, Chuo University, 742-1 Higashinakano, Hachioji, Tokyo 192-0393, Japan
2Faculty of Economics, Rissho University, Osaki 4-2-16, Tokyo 141-8602, Japan

Received 10 December 2008; Accepted 18 June 2009

Academic Editor: James Traniello

Copyright © 2009 Utako Kurosu and Shigeyuki Aoki. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The aphid Nipponaphis monzeni (Hormaphidinae, Nipponaphidini) forms large, hard, completely closed galls on the evergreen Distylium racemosum, its primary host, in south-western Japan. By marking 100 galls on a tree and monitoring them over five years, and by sampling many immature galls from another tree in various seasons and dissecting them, we found that galls of N. monzeni are initiated in June, that they remain small for at least 21–22 months and that tiny fundatrices survive for over one year. Some galls rapidly expand during April/May in the third year. Others remain small and swell up in the fourth year and still others in the fifth year. Full-grown galls open in November/December, and alates fly to evergreen oaks, the secondary host. Thus galls of N. monzeni take 2.5 years to mature at earliest (3-year life cycle) and some galls 3.5 or 4.5 years (4- or 5-year life cycle).