Abstract

LOGARZO, Guillermo  and  GANDOLFO, Daniel E.. Voltinism and Diapause in Populations of Apagomerella versicolor (Coleoptera: Cerambycidae) in the Distribution of its Latitudinal Gradient. Rev. Soc. Entomol. Argent. [online]. 2005, vol.64, n.3, pp.68-71. ISSN 0373-5680.

ABSTRACT. Apagomerella versicolor (Boheman), a long horn stem-borer beetle of the host genera Pluchea., Xanthium, and Ambrosia (Asteraceae). In Argentina, it occurs between 25 and 39 o S. Studies conducted in Buenos Aires (35 o S) indicated that A. versicolor is univoltine and has a winter diapause, and also indicate that diapuse larvae exposed to low temperatures broke the diapuse. However, some observations suggested that populations from northern Argentina could be bi or multivoltine and did not diapause. The voltinism and the diapause of A. versicolor were studied along its latitudinal distribution, between 25 and 32 o S. We conducted an experiment to identify diapause presence; larvae collected at different latitudes were separate in two groups, one of them were exposed to low temperatures to break the diapause, the other one was control. Those diapausing larvae that received cold treatment should pupate in a shorter time than those that did not receive it. In addition, ten collecting trips were made in January, March, July, August, October and December in different years in the study area to observe the immature stages present in its main hosts, Pluchea sagittalis Cabr. and Xanthium cavanillesii Schouw, at different latitudes. It was found evidence that A. versicolor is at least bivoltine between 25 º and 27 o S, and it does diapause at latitudes over 31 o S. The influence of the biology of the host plants on voltinism and diapause is discussed here.

Keywords : Cerambicid; Geographic races; Stemborer.Asteraceae; Xanthium cavanillesii; Pluchea sagittalis.

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