Original paper

Life-cycles and Competition-avoiding Strategies of Seed-eating Weevil Species on Broom Species (Coleoptera: Curculionidae / Leguminosae: Genisteae)

[Ciclos biologicos y estrategias para evitar la competencia en gorgojos seminivoros de Genisteas (Coleoptera: Curculionidae / Leguminosae: Genisteae)]

Sanz, M José; Gurrea, Pilar

Entomologia Generalis Volume 24 Number 4 (2000), p. 237 - 254

48 references

published: Jul 1, 2000

DOI: 10.1127/entom.gen/24/2000/237

BibTeX file

ArtNo. ESP146002404002, Price: 19.80 €

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Abstract

In the centre of the Iberian Peninsula, 5 species of seed-eating weevils show different degrees of host specificity inhabiting species of the broom genera Cytisus Linnaeus and Genista (Tournfourt). Almost all of them are confined to one or 2 closely related host species. There are (a) monophagous species: Exapion laufferi (Schilsky 1906), restricted to Genista cinerascens Lange; (b) oligophagous species restricted to one genus: E fuscirostre (Fabricius 1775) to the genus Cytisus, and E putoni (Ch Brisout 1866) to the genus Genista; (c) oligophagous species in a broad sense: E compactum (Desbrochers 1888) and Pachytychius sparsutus (Olivier 1807) exploiting several species of both genera. Species of the broom genera Adenocarpus De Candolle and Retama Rafinesque were not found to be inhabited by seed-eating weevils, perhaps because of the chemical and morphological characteristics of their pods. In accordance with their degree of specialization, there is a close synchrony between the life cycles of the various weevil species and the phenology of their host plants: The weevils reached peak numbers when the respective main food source for their larvae was available, i. e, when the specific host plants began pod formation. The specialization of these weevil species, such as differences in their oviposition sites, ways of entering the seeds as well as the larval feeding positions inside the seed, are strategies to avoid competitors, to foster coexistence, and to enable the optimal explotation of the resource.

Abstract

En el centro de la Peninsula Iberica, 5 especies de gorgojos seminivoros de los generos Cytisus Linnaeus y Genista (Tournfourt) muestran distintos grados de especificidad. La mayoria se restringe a una o 2 especies de Genisteas relacionadas. Existen especies: (a) monófagas: Exapion laufferi (Schilsky 1906) restringida a Genista cinerascens Lange; (b) especies oligófagas restringidas sólo a un genero: E fuscirostre (Fabricius 1775) que utiliza el genero Cytisus, y E putoni (Ch Brisout 1866) que utiliza el genero Genista: (c) especies oligófagas en sentido amplio: E compactum (Desbrochers 1888) y Pachytychius sparsutus (Oliver 1807) que utilizan varias especies de ambos generos de Genisteas. Sin embargo las especies de los generos Adenocarpus De Candolle y Retama Rafinesque no son utilizadas por ningun gorgojo seminivoro, quizas debido a las caracteristicas quimicas y morfológicas que poseen sus legumbres. En funcion del grado de especializacion, existe una fuerte sincronia entre los ciclos biologicos de estas especies de gorgojos y la fenologia de las plantas huesped: Las especies seminivoras alcanzan el maximo poblacional cuando el recurso alimenticio de las larvas se encuentra disponible, es decir, cuando sus plantas nutricias inician la fructificacion. Ciertos patrones de comportamiento de estos gorgojos seminivoros, como utilizar distinto lugar de puesta, formas de entrada en la semilla, y ocupar diferente posición en el interior de la semilla, constituyen estrategias que evitan la competencia, permiten la coexistencia y facilitan una óptima explotacion del recurso.

Keywords

Exapion laufferi (Schilsky 1906)E Juscirostre (Fabricius 1775)E putoni (Ch Brisout 1866)E compactum (Desbrochers 1888)Pachytychius sparsutus (Olivier 1807)Cytisus LinnaeusGenista (Tournfourt)Adenocarpus De CandolleRetarna Rafinesque Genista cinerascens Langebehaviour patternmonophagous speciesoligophagous speciespod exploitationpatrones de comportamientoespecies monófagasespeci