Life histories and host specificities of theEchium flea beetlesLongitarsus echii andL. Aeneus [Col. Chrysomelidae]
Two halticine flea beetles,Longitarsus echiiKoch andLongitarsus aeneusKutsch, occurring on the boraginaceous plantEchium plantagineum L. in the western Mediterranean region are potential biological control agents in Australia where the plant has become a weed (Paterson's curse). The adults of both species feed by making “shot holes” in the leaves. The larvae of both species attack the roots ofEchium, those ofL. echii feeding more centrally in the root than those ofL. aeneus which attack the outer cortex and rootlets. Both species are univoltine. The host restrictions of both flea beetles as adults and as larvae were tested using the criteria already established for theEchium leaf minerDialectica scalariellaZeller (Wapshere & Kirk, 1977). This testing established that it would be safe to introduce the 2 insects into Australia for the biological control ofE. plantagineum and they are now under quarantine.RésuméDeux altises,Longitarsus echiiKoch etLongitarsus aeneusKutsch, vivant surEchium plantagineum L. dans l'ouest de la région méditerranéenne, sont des agents de contrôles biologiques potentiels de cette adventice en Australie. Les adultes des 2 espèces creusent des trous dans les feuilles et leurs larves attaquent les racines de la plante. Les larves deL. echii se nourrissent plus de la partie centrale de la racine, alors que celles deL. aeneus préfèrent le cortex extérieur et les radicelles. Les 2 espèces ont une génération par an. La spécificité d'hôte des 2 espèces, tant adultes que larves, a été étudiée selon les critères déjà établis pourDialectica scalariellaZeller (Wapshere & Kirk, 1977). Ces essais ont confirmé que l'introduction des 2 insectes en Australie pour la lutte biologique contreEchium plantagineum serait sans danger, et cette introduction a eu lieu récemment.
Rapid preliminary characterisation of host specificity of leaf-beetles (Coleoptera: Chrysomelidae)
Rapid characterisation of host specificity is important both in biological control of weeds and studies in ecology and evolution. A means for doing this was developed and tested on four species of leaf beetles of interest for biological control of the weed Mimosa pigra (Mimosaceae). We identified the most promising for the more detailed tests necessary to obtain release approval. The impact of time-dependent effects and effects of experience were also investigated as part of this study but were not detected. Short-term host specificity tests on adult feeding accurately predicted the results of longer term trials. The long-term trial showed that survival on a plant species depended on feeding on it. Hence short-term feeding trials can predict the longer term survival of adults on other plant species. Different feeding results were obtained in cut foliage versus entire plants but no consistent pattern was shown: of the two insect species tested, one species ate more of the cut material while the opposite was demonstrated for the second species. Species in order of priority for further consideration as biocontrol agents were Syphrea bibiana, Genaphthona sp., Syphrea sp. and Paria sp. The latter three species were probably not sufficiently specific for release. The tests done here allow the identification of the most likely species upon which to conduct the more laborious and difficult larval developmental tests, saving considerable resources.
Speci fi cation Test for Panel Data Models with Interactive Fixed E ff ects ∗
In this paper, we propose a consistent nonparametric test for linearity in a large dimensional panel data model with interactive fixed effects. Both lagged dependent variables and conditional heteroskedasticity of unknown form are allowed in the model. We estimate the model under the null hypothesis of linearity to obtain the restricted residuals which are then used to construct the test statistic. We show that after being appropriately centered and standardized, the test statistic is asymptotically normally distributed under both the null hypothesis and a sequence of Pitman local alternatives by using the concept of conditional strong mixing that was recently introduced by Prakasa Rao (2009). To improve the finite sample performance, we propose a bootstrap procedure to obtain the bootstrap -value. A small set of Monte Carlo simulations illustrates that our test performs well in finite samples. An application to an economic growth panel dataset indicates significant nonlinear relationships between economic growth, initial income level and capital accumulation.