External morphology of Cotesia flavipes (Hymenoptera: Braconidae) during larval development

Abstract

Cotesia flavipes (Cameron, 1891) (Hymenoptera) is a gregarious endoparasitoid used in applied biological control against Diatraea saccharalis (Fabricius, 1794) (Lepidoptera). In this study, we characterize the larval external morphology and the number of instars of C. flavipes. Parasitized larvae of D. saccharalis were sampled from the 1st to the 10th day after parasitism and dissected in an anticoagulant buffer for collection of C. flavipes immatures. Immatures were processed for scanning electron microscopy. Larvae of C. flavipes were prepared in NaOH solution and slide mounted to allow for mandible size measurements. Analysis of measurements of the parasitoid larval mandible size indicated that C. flavipes has three instars. Newly hatched larvae are caudate-mandibulate, assuming a hymenopteriform shape later in their development. The anal vesicle began to expand in the first instar and, once expanded, remained unchanged up to the beginning of the third instar. At the third instar, the anal vesicle decreased in volume. Herein we report the development and possible functions of the larval external structures modified during the development of C. flavipes, as for example their role in aiding newly-eclosed larvae to avoid the host immune response and to move within the host. To summarize the morphological changes during parasitoid growth, we should mention that the modifications in the anal vesicle were correlated with the feeding activity, and the maintenance of the anal vesicle indicates that this structure remained functional, probably playing a role in nutrient absorption and host regulation. On the other hand, the mandibles of early stage larvae are probably used to assist the parasitoid larvae during eclosion

THE PARASITOID, Cotesia flavipes (CAMERON) (HYMENOPTERA: BRACONIDAE), INFLUENCES FOOD CONSUMPTION AND UTILIZATION BY LARVAL Diatraea saccharalis (F.) (LEPIDOPTERA: CRAMBIDAE)

“…The increased activities of α‐amylase and trehalase at 1 DAP suggest that parasitoids require a source of energy easier to process when compared to other substrates at the early phase of parasitization. As C. flavipes was still in the egg stage at 1 DAP (Pinheiro et al., ), changes in the host enzyme activity of α‐amylase and trehalase could have been induced by maternal‐derived factors (Asgari and Rivers, ), such as those in the calyx fluids of C. flavipes , which are injected along with eggs during oviposition.…”

Biología de Cotesia flavipes Cameron sobre el Taladrador del Tallo, Diatraea saccharalis Fabricius, en Varios Medios de Cría

“…Las larvas mudaron al segundo estadío, 3,5 días después de la eclosión de los huevos. Además de esta especie, la presencia de la vesícula anal ha sido observada en otros himenópteros parasíticos (Clausen 1940;Xu et al, 2007;Fischer et al, 2008) y se sugiere que favorece el desarrollo del parasitoide como una adaptación al ambiente interno del hospedero (Pinheiro et al, 2010). Las dimensiones observadas son superiores a las referidas por Fajardo y Mendoza (1993) en un estudio de biología realizado en similares condiciones de temperatura y humedad relativa en Ecuador hace casi tres décadas e inferior a la longitud obtenida por Hernández (2010).…”

“…La larva de tercer estadío midió 4,367 x 1,014 mm; observándose una coloración blanco cremosa, y presentó una vesícula anal bien desarrollada (Figura 1D) a inicio de la muda, pero cuando avanzó en desarrollo a prepupa fue disminuyendo de tamaño. Pinheiro et al (2010) señalaron que la vesícula anal aumenta de tamaño en los primeros días y luego decrece hacia el final del período larval, cambios de tamaño han sido correlacionados con la actividad de alimentación de la larva del parasitoide. Este estadío se completó en 2,6 días.…”

Morphological characterization of immature stages of Habrobracon hebetor (Hymenoptera, Braconidae) ectoparasitoid of Ephestia kuehniella (Lepidoptera, Pyralidae)

“…Even though there are descriptions of the immature external morphology of some braconid species (Yu et al 2008, Carabajal-Paladino et al 2010, Pinheiro et al 2010, Qureshi et al 2016. The study by Sudheendrakumar et al (1982) describes the biology and morphology of the immature stages of Bracon brevicornis (Wesmael) (Hymenoptera: Braconidae), species denominated junior synonym of H. hebetor (Yu et al 2012).…”