A unique seasonal cycle in a leaf gall‐inducing insect: the formation of stem galls for dormancy

Abstract

The mechanisms by which gall‐inducing insects cope with variation in their host plant phenology are poorly known. Pseudotectococcus rolliniae Hodgson and Gonçalves (Hemiptera: Eriococcidae) induces leaf galls in Rollinia laurifolia Schltdl. (Annonaceae), which loses its leaves during the dry season. The fate of the gall‐inducing stage during that season was determined by sampling a natural population of P. rolliniae during 3 years. Morphometric comparison among different larval instars and morphological descriptions of plant and gall features were performed. Crawlers leave the galls before leaf fall and move to the stems, where they induce a second gall morphotype and undergo dormancy throughout the dry season. They moult when the vernal rains begin, move to sprouting leaves and induce leaf galls, as second‐instar nymphs, not as crawlers as is usual for Eriococcidae. This is the first report of an insect gall induced for dormancy, which is likely to be a true diapause phenomenon.

Keywords:

• Annonaceae
• Eriococcidae
• Pseudotectococcus rolliniae
• Rollinia laurifolia
• seasonal adaptation

Acknowledgements

The authors thank Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG – CRA – 2387/98) for financial support. Thanks are also due to Denis C. Oliveira and Diogo Lima (UFMG) for helping with the statistical analysis. We are especially grateful to Maurice and Catherine Tauber (Cornell University) and to two anonymous reviewers, for the significant improvements in the final version of the manuscript made possible by their comments. All experiments comply with the current Brazilian laws.