A uni- and multivariate analysis approach to reveal sexual size dimorphism in Iranian populations of Hypera postica (Coleoptera: Curculionidae)

Abstract

Body size dimorphism between genders is a commonly observed phenomenon in insects, usually manifested in larger female body size. Sexual Size Dimorphism (SSD) varies from species to species, the degree and direction influenced by certain evolutionary pressures. Intraspecific variation in SSD may also occur between populations. The Hypera postica (Gyllenhal, 1813) is a well-known alfalfa plant pest that shows a degree of morphological divergence in its populations. The female alfalfa weevils are very fecund and have a larger body size compared to males. To improve our knowledge on magnitude and direction of SSD in alfalfa weevil, we studied 200 specimens of H. postica from four Iranian populations (Karaj1, Karaj2, Tuyserkan and Jovein). 10 morphological variables from three external anatomic parts (pronotum, elytra and rostrum) and 45 ratio characters were statistically analyzed in order to determine the amount of SSD in Iranian populations. In addition we investigated for morphological divergence pattern in mentioned populations. The results of this study show that a low degree of morphological divergence occurs in Iranian populations. Measured variables indicate that the SSD pattern of H. postica is compatible with the Rensch’s rule, and is related to high fecundity of females and a lack of strong sexual selection. Also it is mentioned that the larger rostrum in females may correspond to its unique role in egg laying.

Global genetic diversity, lineage distribution, and Wolbachia infection of the alfalfa weevil Hypera postica (Coleoptera: Curculionidae)

“…Each strain was introduced to America via an independent route and time (Radcliffe & Flanders, ). While there is a lack of distinct morphological characters (Bland, ; Pienkowski, Hsieh, & Lecato, ; Sanaei, Seiedy, & Momtazi, ), several fluctuating ecological traits were diagnosed to be strain specific including response to parasitoids and location of pupation (Coles & Day, ; Dewitt & Armbrust, ; Litsinger & Apple, ). However, the usefulness of these characters is questionable as strains with certain ecological characters were determined only based on their location and most of the mentioned characters were not applicable or showed huge variation and overlap among strains (Bundy et al, ; Sanaei et al, ).…”

Deep divergence and evidence for translocations between Iranian and European populations of the alfalfa weevil (Coleoptera: Curculionidae) based on mitochondrial DNA

“…The alfalfa weevil ( Hypera postica (Gyllenhal); Coleoptera: Curculionidae) is a common pest of alfalfa ( Medicago sativa Linnaeus; Fabaceae) (Summers 1998; Sanaei et al 2015a). This weevil is a species autochthonous in the Palaearctic region (Skuhrovec 2013), but was accidently introduced to other continents and geographic regions.…”

“…Despite the economic importance of the alfalfa weevil in the western Palaearctic (Kuwata et al 2005; Yardim et al 2006; Skuhrovec 2009; Coskuncu and Gencer 2010; Khanjani 2012; Sanaei et al 2015a), little is known about the genetic identity and relationships of European populations of the species. The central Palaearctic and the Middle East have been suggested as the origin of alfalfa (Moradi-Vajargah et al 2011) and accordingly it is likely that the origin of H. postica traces back to this region as well.…”

“…The central Palaearctic and the Middle East have been suggested as the origin of alfalfa (Moradi-Vajargah et al 2011) and accordingly it is likely that the origin of H. postica traces back to this region as well. The species is the most important pest in Iranian alfalfa fields and has a wide distribution in this country (Khanjani and Pourmirza 2004; Sanaei et al 2015a). A recent morphological and geometric morphometric study indicated a weak divergence between Iranian populations (Sanaei et al 2015a).…”

“…The species is the most important pest in Iranian alfalfa fields and has a wide distribution in this country (Khanjani and Pourmirza 2004; Sanaei et al 2015a). A recent morphological and geometric morphometric study indicated a weak divergence between Iranian populations (Sanaei et al 2015a). Hence, we were interested to test if the Iranian populations are genetically diverged and how they are related to European populations.…”