Determination of the number of larval instars ofSitona discoideusGyllenhal (Coleoptera: Curculionidae) using probit analysis

Abstract

Analysis of head-capsule widths of field-collected and laboratory-hatched Sitona disc?ideus Gyllenhal larvae confirmed that this species possesses five larval instars. Probit analysis allowed for more accurate statistical definition of the head-capsule size ranges of each particular instar, despite size overlap between successive instars.

Determinación de Estadios Larvarios deConotrachelus perseaeBarber (Coleoptera: Curculionidae)

“…= 3,322; P < 0.001), confirma los resultados observados por la relación lineal. Numerosos son los estudios que analizan el ancho de la cápsula cefálica de larvas de Curculionidae para determinar los estadios larvales (Frampton 1986, Jaya et al 2000, Aguilera y Rebolledo 2001, Goldson et al 2001, Pantoja et al 2006, Panzavolta, 2007, Wang et al 2009, Cazado et al 2014. Los resultados obtenidos coinciden con lo reportado por Racette et al (1992) y Bailez et al (2003), quienes determinaron para Conotrachelus nenuphar (Herbst) y C. psidii Marshall cuatro estadios larvarles; lo que difiere de Coria-Ávalos (1999), quien reportó la presencia de seis estadios larvarios en C. perseae, cuyos resultados no son respaldados por una metodología de medición y de un modelo matemático para la determinación de los estadios larvales.…”

“…Otros curculiónidos con diferente número de estadios larvarios incluye a las especies Sitona sp. (Leibee et al 1980, Frampton 1986), Metamasius sp. (Salas y Frank 2001, Cave et al 2006, Aegorhinus superciliosus (Aguilera y Rebolledo 2001), Listronotus bonarensis (Goldson et al 2001), Homalinotus coriaceus (Sarro et al 2004), Anthonomus grandis (Reardon et al 2002), Rhynchophorus ferrugineus (Jaya et al 2000), y Cosmopolites sordidus (Germar) (Pantoja et al 2006).…”

Biological traits and life history of Pagiophloeus tsushimanus (Coleoptera: Curculionidae), a weevil pest on camphor trees in China

“…Commonly, the morphological measurement data of different instars overlap to some extent and make it difficult to determine the accurate instar of a sample larva (Yazdani et al 2015). Various techniques have been applied to estimate the overlap between adjacent instars in order to provide classification rules for field-collected larvae (Fox et al 1972;Frampton 1986;Mcclellan and Logan 1994;Goldson et al 2001;Hammack et al 2003). Head capsule width is the most frequent measure used to determine larval instar and has been widely applied to other weevils, such as Eurhinus magnificus Gyllenhal (Coleoptera: Curculionidae), Cosmopolites sordidus Germar (Coleoptera: Curculionidae), and Sitophilus zeamais Motchulsky (Coleoptera: Curculionidae) (Logan et al 1998;Merville et al 2014).…”

Adult and larval hoverfly communities and their parasitoid fauna in wheat in New South Wales, Australia

“…Morphometric classification of larval instars has been used successfully in the navel orangeworm Amyelois transitella (Walker) (Beaver & Sanderson 1989) and on larvae of the sitona weevil, Sitona discoideus Gyllenhal (Frampton 1986). In the latter, probit analysis was used to confirm the presence of five larval instars based on head-capsule size.…”