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Despite the liberal use of broad-spectrum insecticides to keep many insect pests of agricultural and veterinary importance at bay, food losses, both pre- and post-harvest, due to these insect pests contribute significantly to the high prevalence of undernourishment in the world. New, innovative pest control tactics and strategies are therefore needed that are both effective and not detrimental to the environment. As part of the arsenal of environmentally-friendly control tactics, the sterile insect technique (SIT) has proven to be a very effective tool against selected insect pests when used as part of an area-wide integrated pest management (AW-IPM) approach. Likewise, the use of natural enemies for augmentative or inundative biological control is now a major component of pest control in many parts of the world. Both control tactics are complementary and even synergistic under certain circumstances, but their combined use has so far not been applied on an operational scale. Ionising radiation can be readily employed to effectively and safely induce sexual sterility in insects. Although the sterile insect technique has often been associated with an eradication strategy, major advances in rearing efficiency, and improved handling and release methods, have made the use of sterile insects economically feasible for insect pest suppression, prevention or containment. Recently, more emphasis has been placed on the quality of the sterile insect once released in the field rather than mainly assessing quality in the rearing facility. This combined with other innovations such as the development of genetic sexing strains, better understanding the impact of radiation on radio-resistant species such as Lepidoptera and the development of the F1 sterility concept, advances in monitoring the induced sterility, etc. have significantly increased the efficiency of the sterile insect technique for several insect species. The action of sterile insects is inversely dependent on the density of the target population, and sterile insects have the intrinsic capacity to actively search for and mate with the last individuals of a pest population. These two characteristics make them ideal to deal with outbreaks of invasive insect pests. The use of sterile insects presents no threat to the environment, but aspects such as diet and waste disposal in large rearing facilities or bio-security in cases where the rearing facility is located in an area that is already free of the pest require the necessary attention. Ionising radiation can also be applied to greatly improve the efficiency of mass-rearing, handling and shipment of insect parasitoids and predators. Area-wide integrated pest management programmes that use sterile insects or natural enemies are complex and management-intensive, and require a management structure that is exclusively dedicated to the programme. Past and current examples have shown the enormous benefit-cost ratios that these programmes can generate and their importance for enhanced agriculture is increasing in significance.

Several species of tsetse flies can be infected by the Glossina pallidipes salivary gland hypertrophy virus (GpSGHV). Infection causes salivary gland hypertrophy and also significantly reduces the fecundity of the infected flies. To better understand the molecular basis underlying the pathogenesis of this unusual virus, we sequenced and analyzed its genome. The GpSGHV genome is a double-stranded circular DNA molecule of 190,032 bp containing 160 nonoverlapping open reading frames (ORFs), which are distributed equally on both strands with a gene density of one per 1.2 kb. It has a high A+T content of 72%. About 3% of the GpSGHV genome is composed of 15 sequence repeats, distributed throughout the genome. Although sharing the same morphological features (enveloped rod-shaped nucleocapsid) as baculoviruses, nudiviruses, and nimaviruses, analysis of its genome revealed that GpSGHV differs significantly from these viruses at the level of its genes. Sequence comparisons indicated that only 23% of GpSGHV genes displayed moderate homologies to genes from other invertebrate viruses, principally baculoviruses and entomopoxviruses. Most strikingly, the GpSGHV genome encodes homologues to the four baculoviral per os infectivity factors (p74 [pif-0], pif-1, pif-2, and pif-3). The DNA polymerase encoded by GpSGHV is of type B and appears to be phylogenetically distant from all DNA polymerases encoded by large double-stranded DNA viruses. The majority of the remaining ORFs could not be assigned by sequence comparison. Furthermore, no homologues to DNA-dependent RNA polymerase subunits were detected. Taken together, these data indicate that GpSGHV is the prototype member of a novel group of insect viruses.

Correspondance: a.m.m.abd-alla@iaea.org; A PCR based diagnostic method to detect salivary gland hypertrophy virus (SGHV) in tsetse flies is described. Two sets of primers GpSGHV1F/GpSGHV1R and GpSGHV2F/GpSGHV2R were selected from a virus-specific sequence. Both primer sets can detect specifically the virus in individual tsetse flies by generating an amplicon of 401 bp. Attempts were made to develop a simple and reliable non-destructive virus detection method in live flies. PCR reactions were performed on either crude or purified tsetse DNA from saliva and legs. While saliva can be an indicator for the presence of the virus in flies, the method is laborious. Crude extract from an excised middle leg resulted in a positive PCR reaction equivalent to crude extract from whole fly. However, sensitivity could be significantly increased when purified DNA was used as the template. In conclusion, PCR using a purified DNA template from a single tsetse leg represents an efficient, non-destructive method for virus diagnosis in live tsetse flies