Primer registro documentado de Neodiprion abietis (Harris, 1841) (Hymenoptera: Diprionidae) para México

Neodiprion abietis es un dipriónido que tiene una distribución transcontinental en Norteamérica, y se alimenta del follaje de árboles de los géneros Abies, Pseudotsuga y Pinus. Una referencia de 1995 menciona la presencia de esta especie de insecto en México; sin embargo, carece de datos de ubicación. El objetivo del presente estudio fue determinar el taxón de un dipriónido que en 2016 se observó defoliando a Abies concolor, dentro del Área de Protección de Flora y Fauna Campo Verde, en Madera, Chihuahua, México. A través de exploraciones de campo realizadas en 2019, se recolectaron larvas directamente del follaje de sus hospedantes; además, de un adulto en el follaje y varios capullos en el suelo. Las larvas fueron confinadas en jaulas entomológicas y se alimentaron con follaje de sus hospedantes, hasta que tejieron sus capullos. La cría de los insectos se completó introduciendo los capullos a una cámara de crecimiento que se mantuvo a una temperatura de 26 ±2 ºC, con un fotoperiodo de 14:10 luz: oscuridad, hasta la obtención de adultos. La determinación de la especie se realizó mediante la observación de las características morfológicas externas y del ovipositor, basados en claves taxonómicas especializadas e ilustraciones de referencia de fuentes científicas. Los especímenes examinados correspondieron a N. abietis, lo cual confirma su presencia en el norte de México.

Host–tree oviposition preference of balsam fir sawfly, Neodiprion abietis (Hymenoptera: Diprionidae), in New Brunswick, Canada

Laboratory experiments using field-collected females were carried out to determine the oviposition preference of the balsam fir sawfly, Neodiprion abietis (Harris) (Hymenoptera: Diprionidae) in New Brunswick, Canada. Unmated adult females given no choice among host–plant foliage laid ∼98% of available eggs on balsam fir (Abies balsamea (Linnaeus) Miller; Pinaceae), but only 8% and 10%, respectively, on white spruce (Picea glauca (Moench) Voss; Pinaceae) and black spruce (Picea mariana (Miller) Britton, Sterns, and Poggenburg). Given a choice among shoots from all three hosts in the same chamber, unmated females laid all but one egg in balsam fir. Host plant had no effect on female longevity, although there were nearly four- to eightfold more empty egg slits on balsam fir needles, owing presumably to the greater activity of females on this preferred host foliage.

Pathology of aGammabaculovirusin Its Natural Balsam Fir Sawfly (Neodiprion abietis) Host

TheNeodiprion abietis Gammabaculovirus(Baculoviridae: NeabNPV) is virulent, highly contagious, and infects only midgut epithelial cells of balsam fir sawfly larvae, but infections can carry through to adult sawflies in the midgut. Larval infections are characterized by hypertrophy of midgut epithelial cell nuclei, where virogenic stromata develop to produce nucleocapsids that are singly enveloped before occlusion into occlusion bodies. Infected, occlusion body-laden cells slough from the midgut epithelium as a result of a dissolution of the basal lamina. Infected cells undergo lysis, and viral occlusion bodies exit affected larvae in a watery diarrhea to infect other balsam fir sawfly larvae. A budded virus stage was not observed, but nucleocapsid and occlusion body formation resembled the development of occlusion-derived virions and occlusion bodies in lepidopteran alphabaculoviruses.

Histology of the LarvalNeodiprion abietis(Hymenoptera: Diprionidae) Digestive Tract

The alimentary canal ofNeodiprion abietislarvae is a straight tube divided into foregut, midgut, and hindgut. Posterior to the mouth, the foregut is further divided into the pharynx, esophagus (crop), and proventriculus, all of which are lined with cuticle. A pair of muscular, chitin-lined pouches branch off the anterior foregut and lie lateral to the alimentary canal. Gastric caeca are located at the anterior end of the midgut, where the peritrophic membrane is formed and was observed throughout the midgut. A single layer of midgut columnar epithelial cells abuts on the basal lamina at one end with microvilli extending into the gut lumen at the other. Nidi of regenerative cells were observed between columnar epithelial cells at the basal lamina. Malpighian tubules are attached to the posterior end of the midgut. The hindgut consists of the pylorus, a muscular ileum connecting to a bulbous rectum, which then opens to the anus.

In vivo replication kinetics and transcription patterns of the nucleopolyhedrovirus (NeabNPV) of the balsam fir sawfly, Neodiprion abietis

DNA replication and transcription of NeabNPV, the nucleopolyhedrovirus (NPV) of the balsam fir sawfly, Neodiprion abietis (Hymenoptera: Diprionidae), in host larvae were investigated. NPV DNA replication kinetics and gene-expression patterns have been resolved only in lepidopteran cell-culture systems and in limited in vivo experiments with lepidopteran larvae. Furthermore, there are significant differences in pathologies caused by lepidopteran NPVs, which replicate in many tissues, and hymenopteran NPVs, known to replicate in midgut epithelium only. Despite the differences in host specificity and pathology, NeabNPV DNA replication kinetics were similar to those reported for lepidopteran NPVs. Maximal NeabNPV DNA synthesis was observed between 4 and 24 h post-inoculation (p.i.) but, in contrast to lepidopteran NPVs, synthesis continued at a lower rate up to 72 h p.i. Selected NeabNPV genes exhibited a cascade pattern of transcription similar to that of lepidopteran NPVs. RT-PCR products of the NeabNPV lef-1, lef-2 and dnapol transcripts were observed as early as 2 h p.i., whilst lef-8 and lef-9, encoding putative viral RNA polymerase subunits, were detected at 1 and 6 h p.i., respectively. Two structural late transcripts (gp41 and p74) were observed from 6 h p.i. The very late factor 1 (vlf-1) transcript, a transactivator of very late genes, was observed from 12 h p.i., but the very late transcript polh, encoding the major occlusion protein, polyhedrin, was observed from 24 h p.i. This study provides the first insight into DNA replication and gene expression of a non-lepidopteran baculovirus.