The replication of Nodamura virus, type species of the family Nodaviridae, takes place principally into the interfibrillar spaces of the sarcoplasm in close association with mitochondria in the infected muscles of both G. mellonella and suckling mice. The most striking event in infection of G. mellonella muscle cells was the aggregation and shape modification of numerous mitochondria (elongation, interdigitation, and vesiculation) at an early stage of infection. These clusters of mitochondria were cemented by a thick electron-dense material at the periphery of which viral particles undergo maturation process. In a later stage, degenerated and dilated mitochondria showed a clear assembling of virus particles on their outer membrane and occasionally on some inner membranes. These facts and the localization of RNA by RNase-gold technique in the assembling sites of viruses around and inside the mitochondria allowed us to postulate a role for the mitochondria as supports and/or energy suppliers for viral RNA synthesis and translation.

The pathogenesis and morphogenesis of the Nodamura virus, an insect picorna- virus which can also infect vertebrates such as newborn mice, are described in the larvae of G. mellonella. Examination of thin sections of muscle, salivary and moulting glands, hemocytes adipose tissue and hypodermis of the infected larvae of G. mellonella shows in the cytoplasm the accumulation of viral particles either dispersed or in a stringlike or paracrystalline array. These arrays of virions can be within membrane- bound vesicles. Helical filaments of 110 A of diameter can be observed inside the basal membranes and later in the cytoplasm, in relation to the infection of muscular or adipose tissues. The morphogenesis of Nodamura virus in G. mellonella or in suckling mice is very similar to that of the Coxsackie A virus observed in the mouse.

A typical lake outlet of the Canadian Shield was treated for 15 min with a high dose (5.28 g/L s−1 of discharge) of Teknar®, a commercial formulation of Bacillus thuringiensis serovar. israelensis. Efficacy on Simuliidae larvae and impact on non-target aquatic insects of this stream were monitored using drift nets, counting plates, and artificial turf substrates along a 1000-m section downstream of the site of application. Compared with a 4-day pre-treatment average for 12-h sampling periods, drift of Simuliidae increased from 64 to 92 ×, with shorter peaks of 133–184 ×, 2–6 h after treatment. There was no evident drift increase in larvae of Ephemeroptera, Plecoptera, Trichoptera, Chironomidae, or dipterous pupae, but larvae of Blephariceridae (Diptera) were severely affected as their drift was increased by up to 50 × and remained high for 3 days. After 30 h the mortality of Simuliidae on counting plates ranged from 95 to 82% in the first 300 m, with detachment rates of 78.5–46.5%. Densities of non-target insect larvae were not reduced on the artificial substrates, except for 2 genera of Chironomidae (Eukiefferella and Polypedilum) which were reduced 26 to 39% of their original density. Drifting larvae of 1 chironomid genus (Phaenopsectra) also showed symptoms of toxemia by B.t.i. The main impact of the treatment was thus seen in 2 Nematocera families (Chironomidae and Blephariceridae) which were mainly exposed to B.t.i. sedimented on the bottom of the stream or attached to periphyton growing on rocks.

No abstract

Three cell lines (A.t. GRIP-1, 2, and 3) were established from Aedes triseriatus (Say) embryonated eggs or neonate larvae and their morphology, growth, karyotype, and isozyme pattern were studied. The isozyme alleles observed in the 3 cell lines also were found in adults of the original mosquito colony. Each cell line differed in enzymatic, morphological, and karyotypical patterns. La Crosse encephalitis (LAC) and snowshoe hare (SSH) viruses, members of the California encephalitis virus group, were able to replicate in these 3 cell lines. Furthermore, these cell lines, especially A.t. GRIP-1, were more sensitive than the Aedes aegypti (L.) (ATC 10) cell line for detection of small amounts of delta-endotoxin of Bacillus thuringiensis serovar. israelensis (de Barjac).