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1 November 2008 Biology of Thrypticus truncatus and Thrypticus sagittatus (Diptera: Dolichopodidae), Petiole Miners of Water Hyacinth, in Argentina, with Morphological Descriptions of Larvae and Pupae
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Abstract

The mining flies Thrypticus truncatus Bickel & Hernández and Thrypticus sagittatus Bickel & Hernández (Diptera: Dolichopodidae) are being evaluated as biological control agents for the water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae). The behavior of adults and larvae of these species was studied in the laboratory and in several water courses of the Paraná River basin, Argentina. The larvae feed on sap from feeding points scraped in the vascular bundles in the petioles of E. crassipes. Pupation occurs in a chamber dug near one of the mine’s openings. External morphology of larvae and pupae, larval cephalic skeleton, and tracheal system are described. The pupae of both species have the ventrally flattened profile of the Medeterinae, with a transverse serrate ridge divided by a notch at the apex of the head. The mines, described herein in detail, constitute the microhabitat where the larvae live throughout their development, and obtain food and protection. Both species are active and reproduce on water hyacinth from spring to the end of fall, and overwinter as larvae inside the mines in the petioles. No morphological or behavioral differences were evident between the immature stages of these species, except in the apical ridges of the pupae. Both species seem to occupy the same niche on the plants.

RESUMEN Las moscas minadoras Thrypticus truncatus Bickel & Hernández y Thrypticus sagittatus Bickel & Hernández (Diptera: Dolichopodidae) están siendo evaluadas como agentes para el control biológico de la maleza acuática Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae). Se realizaron observaciones de comportamiento de adultos y larvas de estas especies, en laboratorio y en diversos cuerpos de agua de la cuenca del Río Paraná, en Argentina. Las larvas se alimentan de savia a partir de orificios de alimentación roídos en los haces vasculares de los pecíolos de E. crassipes. Ellas desarrollan toda su vida dentro de la mina hasta empupar en una cámara construida en un extremo de la misma. Se describen la morfología externa de larvas y pupas, el esqueleto cefálico y el sistema traqueal de las larvas. Las pupas poseen el perfil plano de las Medeterinae, con una estructura serrada dividida por una hendidura transversal en el ápex de la cabeza. Se describe la estructura de la mina, la que constituye el micro hábitat donde las larvas obtienen alimento y protección. Ambas especies están activas y se reproducen sobre E. crassipes desde primavera hasta fin del otoño y sobreviven durante invierno como larvas dentro de los pecíolos de E. crassipes. No se encontraron diferencias morfológicas ni de comportamiento entre las larvas de ambas especies, excepto en el serrado apical de las pupas. Ambas especies parecen ocupar el mismo nicho sobre la planta.

M. Cristina Hernández "Biology of Thrypticus truncatus and Thrypticus sagittatus (Diptera: Dolichopodidae), Petiole Miners of Water Hyacinth, in Argentina, with Morphological Descriptions of Larvae and Pupae," Annals of the Entomological Society of America 101(6), 1041-1049, (1 November 2008). https://doi.org/10.1603/0013-8746-101.6.1041
Received: 28 April 2008; Accepted: 1 August 2008; Published: 1 November 2008
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