Development of the braconid wasp Cotesia flavipes in two Crambids, Diatraea saccharalis and Eoreuma loftini: Evidence of host developmental disruption A.M.A. Mahmoud a, b, ⁎, E.J. De Luna-Santillana a , X. Guo a , F. Reyes-Villanueva a , Mario A. Rodríguez-Pérez a a Centro de Biotecnología Genómica (CBG), Instituto Politécnico Nacional (IPN), México b Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada (CICATA), Instituto Politécnico Nacional (IPN), México abstract article info Article history: Received 19 January 2011 Revised 22 July 2011 Accepted 23 July 2011 Available online 05 August 2011 Keywords: Diatraea saccharalis Mexican rice borer Encapsulation Parasitism Polydnavirus Permissive and non-permissive hosts Cotesia flavipes is an important gregarious larval endoparasitoid of several crambid stem borers, including Diatraea saccharalis. The suitability of two crambid species, Eoreuma loftini and D. saccharalis, pests of sugarcane and rice in Texas, for C. flavipes development was tested. The effect of parasitization by C. flavipes on encapsulation response was assessed in vivo in both D. saccharalis and E. loftini. The results indicated that the parasitoid developed and emerged successfully in D. saccharalis larvae. Although E. loftini larvae were readily parasitized by C. flavipes parasitoids, no wasp larvae hatched from the eggs in this host because eggs were encapsulated by the host's hemocytes. The developmental fate of the E. loftini larvae with encapsulated parasitoids was variable. Most died as abnormal fifth instars or as post-wandering prepupae, while a few developed normally to the pupal stage. In vivo experiments, there was a significant reduction in the percent of beads encapsulated in parasitized larvae in both hosts. However, the percent of beads showing melanization decreased significantly in parasitized D. saccharalis larvae but did not differ significantly in parasitized or unparasitized E. loftini larvae. Our results showed that D. saccharalis is a suitable host for C. flavipes whereas E. loftini is an unsuitable host. This study indicated that lepidopteran stem borers that are taxonomically, behaviorally, and ecologically very similar can differ in their ability to encapsulate a parasitoid species. © Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2011. Published by Elsevier B.V. All rights reserved. Introduction The ability of an endoparasitoid to develop in a host depends on the physiological suitability of the host and on the immune response of the invading species (Godfray, 1994). Many endoparasitoids inject factors into the host at oviposition such as venoms, ovarian proteins, teratocytes (that are liberated from the serosa of the egg membrane at hatching), virus like particles, and polydnaviruses (PDVs) to make the physiological condition of the hosts suitable for the parasitoid development (Pennacchio and Strand, 2006; Pruissjers et al., 2009). These factors disrupt the cellular immune responses of the host and prevent the host from growing so large that the parasitoid progeny cannot successfully consume it (Pennacchio and Strand, 2006; Suzuki and Tanaka, 2006). The fates of parasitized hosts can be classified into three categories: (1) permissive hosts in which the immune response is suppressed by parasitoid immunosuppressive factors and the hosts succumb as larvae, however, the parasitoid larvae develop and emerge successfully; (2) non-permissive hosts in which the parasit- oids are encapsulated by host hemocytes and neither the host nor the parasitoid survives; and (3) semi-permissive host species in which the parasitoids remain unencapsulated but fail to emerge due to nutritional or other physiological factors (Harwood et al., 1998; Beckage and Tan, 2002; Lovallo et al., 2002; Beckage et al., 2003; Rodríguez-Pérez et al., 2005). Lepidopteran stem borers in the families Pyralidae, Crambidae, and Noctuidae are pests of many crops worldwide (Smith et al., 1993). The New World Crambids Diatraea saccharalis (F.) and Eoreuma loftini (Dyar) (sugarcane borer and Mexican rice borer, respectively) are common pests of grass crops. In North America, the sugarcane borer and Mexican rice borer are economically important pests of sugarcane, rice, sorghum, and corn in the United States of America and Mexico (Reay-Jones et al., 2003, 2005, 2007a, b, 2008; Showler and Castro, 2010). These two species are taxonomically and ecologically related and share many of the same hosts and larval feeding behaviors (Smith et al., 1993; Reay-Jones et al., 2007a,b). Cotesia flavipes Cameron is a gregarious larval endoparasitoid of stem borers. C. flavipes was introduced from Africa to Texas, USA to control the stem borers (Mahmoud et al., 2011). Stem borers attack a variety of crops in the New World, such as Diatraea saccharalis, D. grandiosella, Ostrinia nubilalis, and Chilo spp. (Overholt et al., 1994a,b; Ngi-Song, 1995; Ngi-Song et al., 1995; Alleyne and Wiedenmann, 2001a,b). The parasitoid induces cellular immunosuppression (encapsulation and nodulation) in D. saccharalis larvae (Mahmoud Journal of Asia-Pacific Entomology 15 (2012) 63–68 ⁎ Corresponding author. Tel.: + 20168052549; fax: + 52 2088337114. E-mail address: alialimh@yahoo.com (A.M.A. Mahmoud). 1226-8615/$ – see front matter © Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society, 2011. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Asia-Pacific Entomology journal homepage: www.elsevier.com/locate/jape