New rearing method and larval diet for the mahogany shoot borer Hypsipyla grandella (Lepidoptera: Pyralidae)

Nancy Barradas-Juanz, Francisco Díaz-Fleischer, Pablo Montoya, Ana Dorantes, Diana Pérez-Staples

Abstract


A simplified and improved rearing system was developed for the mahogany shoot borer, Hypsipyla grandella (Zeller) (Lepidoptera: Pyralidae) in the laboratory. Improvements were made in neonate rearing, larval containers, adult mating cages and the diet, making the rearing protocols more suitable for eventual large-scale rearing. The larval diet was modified by replacing ingredients with cheaper equivalents that also would be more readily available throughout the year. Cedar seeds in the larval diet were replaced with dried cedar leaves, which are available for longer periods during the year. There were no significant differences in pupal weight, duration of pupal development, fertility (egg hatch) and fecundity (number of eggs oviposited) between organisms reared on the new diet or the original diet. However, larval development took 2 d longer using the new diet. A new method for rearing neonate larvae is proposed, which includes the use of well plates that contain the modified diet. This allowed the rearing of larvae from 1st to 3rd instars without the need for fresh material. Neonate larvae reared on this diet were heavier and survived longer compared to larvae reared on fresh cedar leaves. Jars used for the larval rearing phase were replaced with Petri dishes. Mating and oviposition were accomplished inside the insectaries with air flow directed through the rearing cages. This is the first report of rearing H. grandella successfully under artificial conditions for 7 generations. The new rearing protocols will allow the maintenance of larger-sized colonies for further development of bio-rational pest management strategies that could include a sterile insect technique (SIT) component.

 

Resumen

Se desarrolló un sistema de cría simplificado y mejorado para reproducir al pyralido barrenador de las meliáceas Hypsipyla grandella (Zeller) en laboratorio. Se realizaron modificaciones en la cría de neonatos, en los contenedores de cría larval, a la jaula de apareamiento y a los ingredientes de la dieta, sustituyéndolos por equivalentes de menor precio y mayor disponibilidad. El uso de semilla seca de cedro fue remplazado con hoja seca de cedro que se encuentra disponible más tiempo durante el año. No se encontraron diferencias significativas en cuanto al peso de las pupas, el periodo de desarrollo pupal, ni tampoco en la fertilidad y fecundidad. Sin embargo, el desarrollo larval tomó dos días más en individuos criados con la dieta modificada. El uso de placas de micropozos con la dieta modificada permite el desarrollo de larvas de primer a tercer instar con mayor peso y supervivencia comparadas con larvas criadas con hojas frescas. En la cría de larvas se sustituyó el uso de frascos por cajas Petri. Se logró que los adultos copularan y produjeran huevos fértiles colocando un flujo de aire a través de la jaula. Este es el primer reporte exitoso de cría de una colonia de H. grandella en laboratorio durante siete generaciones. Este método de cría facilitará el mantenimiento de colonias para el desarrollo de estrategias de control bioracional como la Técnica del Insecto Estéril.

 

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Keywords


mahogany (Meliaceae); sterile insect technique; adult rearing; larval rearing; oviposition; artificial diet

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