The relationship between fecundity and oocyte resorption in field populations of Lucilia cuprina

Abstract

In the Australian sheep blowfly, Lucilia cuprina, the number of ovarioles, and hence the maximum number of eggs developed in each ovarian cycle, is a linear function of adult size (headwidth). Field females have a mean headwidth of 3.0 mm (range=2.30–3.50 mm) and a mean potential fecundity/cycle of 232 eggs (range=111–318 eggs). Realised fecundity is influenced by the quality and amount of protein in the adult diet. All field females appear to have the same minimum protein requirement for egg maturation, i.e., whatever their size (potential fecundity) females must obtain sufficient protein to mature at least 110 eggs in order to become gravid. Females whose protein intake exceeds this minimum but falls short of the amount needed for maturation of their full egg complements resorb some of their oocytes and mature the remainder. Since potential fecundity increases with fly size, large females resorb more oocytes than small females under suboptimal protein regimes, i.e., the proportion of oocytes resorbed increases with fly size. Under field conditions, females rarely matured full complements of eggs, which indicates a general shortage of protein‐rich material. The mean reduction in fecundity of field females during these studies was 53.4 eggs/cycle (23.2%). RÉSUMÉ Relations entre la fécondité et la resorption des ovocytes dans des populations de la nature de Lucilia cuprina Wiedemann (Diptera: Calliphoridae) Chez Lucilia cuprina Wied., le nombre d'ovarioles, et ainsi le nombre maximum d'oeufs développés au cours de chaque cycle ovarien, est une fonction linéaire de la taille de l'adulte (largeur de la tête). La largeur moyenne de la tête des femelles de la nature est 3 mm (2,3 à 3,5) et la fécondité potentielle moyenne par cycle de 232 oeufs (111 à 318). La fécondité réelle est influencée par la qualité et la quantité de protéines dans le régime alimentaire. Toutes les femelles de la nature semblent avoir les mêmes exigences minimales en protéines pour la maturation des ovocytes, c'est à dire que quelle que soit leur taille (fécondité potentielle) les femelles doivent obtenir les protéines suffisantes à la formation d'au moins 110 ovocytes pour devenir gravides. Les femelles dont l'absorption de protéines dépasse ce minimum, mais est insuffisant pour permettre la maturation de la totalité de leurs ovocytes, en résorbent quelques uns et conduisent à maturité le reste. Puisque la fécondité potentielle augmente avec la taille des mouches, les grosses femelles résorbent plus d'ovocytes que les petites avec un régime suboptimal en protéines, c'est à dire que la proportion d'ovocytes résorbés augmente avec la taille des mouches. Dans les conditions de la nature, la totalité des ovocytes parvient rarement à maturité, ce qui indique une limitation générale en aliments riches en protéines. La réduction moyenne de la fécondité chez les femelles de la nature a été au cours de cette étude de 53,4 oeufs par cycle (23,2%).

Extracts of four plant species used traditionally to treat myiasis influence pupation rate, pupal mass and adult blowfly emergence of Lucilia cuprina and Chrysomya marginalis (Diptera: Calliphoridae)

“…Similar results of small-sized flies resulting from underfed larvae being able to lay eggs were reported in L. cuprina by Webber (1955). The latter study also demonstrated that their fecundity was reduced as the numbers of functional ovarioles, and hence the maximum number of eggs developed in each ovarian cycle, is a linear function of adult size (Mackerras, 1933;Webber, 1955;Foster, et al, 1975, Vogt et al, 1985.…”

Larviposition in the ovoviviparous blowfly Calliphora dubia

“…These larvae are either dying or are being resorbed, more than probably as a result of a lack of sufficient protein sources and/or suitable larviposition sites. There is evidence in the field of delays in the location of suitable oviposition sites in female Lucilia cuprina (Diptera: Calliphoridae) (Vogt et al , 1985a). How long after larval development is complete this process commences is unknown.…”

Annual and spatial activity of dung flies and carrion in a Mediterranean holm‐oak pasture ecosystem

“…The presence of livestock, mainly cattle, plays a very important role in the management of the dehesa ecosystem. Although carrion represents the natural source of high quality protein in the field, faeces of grazing animals are also believed to be an important source of protein for egg maturation ( Vogt et al . 1985b ; Stoffolano et al .…”