The reproductive seasonality and flight capability of Sitona discoideus Gyllenhal (Coleoptera: Curculionidae) and its pattern of larval establishment in Canterbury lucerne
type: CreativeWork
description: In order to improve the level of understanding of the reproductive seasonality and flight potential of Silona discoideus Gyllenhal, samples were taken at regular intervals from lucerne (Medicago saliva L.) stands throughout the 1982-83 and 1983-84 seasons. Changes in the weevil's reproductive condition and flight muscle morphology were monitored by dissection. This work confirmed that the univoltine adult weevils entered aestivatory diapause some three to four weeks after the eclosion of the new generation in December-January each year. Flight to aestivation sites remote from the host crop, was preceded by a vigorous feeding phase during which time the indirect flight muscles developed. The existence of aestivatory diapause was further supported by an observed suppression of reproductive development, absence of mating, increase in fat content of the weevils and changes in the proportional representation of several fatty acid constituents of the total fatty acid complement. During aestivation there were also changes in the indirect flight musculature of S. discoideus. Following flight to aestivation sites, the indirect flight muscles atrophied. Subsequently, the muscles regenerated, enabling reinfestation flight to the lucerne to commence. Aestivatory diapause was found to last some seven to eight weeks. However, in late eclosing weevils, the predetermined time period for diapause development was not always completed before cool winter conditions limited flight muscle regeneration. Hence, throughout this study, some S. discoideus were able to be located at aestivation sites. Laboratory experiments revealed that depleted metabolic reserves in these weevils ultimately made muscle regeneration impossible irrespective of temperature, thus precluding a spring invasion of lucerne by these laggard aestivators. Generally reproductive activity in adult S. discoideus was found to commence with the successful termination of aestivatory diapause. Oviductal eggs were located in t…
abstract: In order to improve the level of understanding of the reproductive seasonality and flight potential of Silona discoideus Gyllenhal, samples were taken at regular intervals from lucerne (Medicago saliva L.) stands throughout the 1982-83 and 1983-84 seasons. Changes in the weevil's reproductive condition and flight muscle morphology were monitored by dissection. This work confirmed that the univoltine adult weevils entered aestivatory diapause some three to four weeks after the eclosion of the new generation in December-January each year. Flight to aestivation sites remote from the host crop, was preceded by a vigorous feeding phase during which time the indirect flight muscles developed. The existence of aestivatory diapause was further supported by an observed suppression of reproductive development, absence of mating, increase in fat content of the weevils and changes in the proportional representation of several fatty acid constituents of the total fatty acid complement. During aestivation there were also changes in the indirect flight musculature of S. discoideus. Following flight to aestivation sites, the indirect flight muscles atrophied. Subsequently, the muscles regenerated, enabling reinfestation flight to the lucerne to commence. Aestivatory diapause was found to last some seven to eight weeks. However, in late eclosing weevils, the predetermined time period for diapause development was not always completed before cool winter conditions limited flight muscle regeneration. Hence, throughout this study, some S. discoideus were able to be located at aestivation sites. Laboratory experiments revealed that depleted metabolic reserves in these weevils ultimately made muscle regeneration impossible irrespective of temperature, thus precluding a spring invasion of lucerne by these laggard aestivators. Generally reproductive activity in adult S. discoideus was found to commence with the successful termination of aestivatory diapause. Oviductal eggs were located in t…
author: Frampton, E. R.
language: en
keywords: Sitona discoideus, weevils, lucerne, Medicago sativa L., larval establishment, reproduction, Marsden::300204 Plant protection (pests, diseases and weeds), Marsden::270501 Animal systematics, taxonomy and phylogeny
license: https://researcharchive.lincoln.ac.nz/pages/rights
date published: 1987
date modified: 2026-07-24T02:50:42Z
provider: Lincoln University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Lincoln College, University of Canterbury

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10182/1673