Three major groups of insect pathogens - bacteria, viruses and Protozoa - have one feature in common: they normally infect or poison the insects perorally when they contaminate insect food. Thus to control an insect infestation they must usually be eaten, and need to be spread evenly over the food environment and be hardy enough to stay alive whilst waiting for the insect to eat them. Formulation is vital to ensure the efficiency of these processes. The first task is to make the pathogen-treated food palatable and able to cover the food evenly. On ingestion, the pathogens invade the haemolymph and target tissues, grow within and kill the insects; then in nature survival stages of the pathogen are protected inside the cadavers, which eventually disintegrate. In con-trast, survival stages of pathogens produced for insect control have to be applied as sprays or solids spread thinly over the surface of the insects’ food, and so are more exposed to the environment. Thus, formulation must replace the natural protection afforded by insect cadavers. The chosen pathogens need to be highly virulent to kill by the smallest possible dosages, a requirement also facilitated by formulation. The modes of action and the main features of the three peroral groups of pathogens are summarized in Table 3.1

Formulation of Bacteria, Viruses and Protozoa to Control Insects

Insect Management in Food Processing Facilities

Previous reviews on biological control of stored-product pests published during the last 30 years reported results of laboratory experiments, collected examples for practical application in grain stores and in processing companies, and summarized the literature on the relevant control agents dating back to the beginning of the last century.

Biological Control of Stored-Product Insects

https://mmbr.asm.org/content/mmbr/45/3/379.full.pdf

Applied and molecular aspects of insect granulosis viruses.

The Indianmeal moth, Plodia interpunctella (Lepidoptera: Pyralidae), is a common pest of stored goods with a worldwide distribution. The complete genome sequence for a larval pathogen of this moth, the baculovirus Plodia interpunctella granulovirus (PiGV), was determined by next-generation sequencing. The PiGV genome was found to be 112, 536 bp in length with a 44.2% G+C nucleotide distribution. A total of 123 open reading frames (ORFs) and seven homologous regions (hrs) were identified and annotated. Phylogenetic inference using concatenated alignments of 36 baculovirus core genes placed PiGV in the “b” clade of viruses from genus Betabaculovirus with a branch length suggesting that PiGV represents a distinct betabaculovirus species. In addition to the baculovirus core genes and orthologues of other genes found in other betabaculovirus genomes, the PiGV genome sequence contained orthologues of the bidensovirus NS3 gene, as well as ORFs that occur in alphabaculoviruses but not betabaculoviruses. While PiGV contained an orthologue of inhibitor of apoptosis-5 (iap-5), an orthologue of inhibitor of apoptosis-3 (iap-3) was not present. Instead, the PiGV sequence contained an ORF (PiGV ORF81) encoding an IAP homologue with sequence similarity to insect cellular IAPs, but not to viral IAPs. Phylogenetic analysis of baculovirus and insect IAP amino acid sequences suggested that the baculovirus IAP-3 genes and the PiGV ORF81 IAP homologue represent different lineages arising from more than one acquisition event. The presence of genes from other sources in the PiGV genome highlights the extent to which baculovirus gene content is shaped by horizontal gene transfer.

/pdf/the-complete-genome-sequence-of-plodia-interpunctella-4sjqebdk6h.pdf

The Complete Genome Sequence of Plodia Interpunctella Granulovirus: Evidence for Horizontal Gene Transfer and Discovery of an Unusual Inhibitor-of-Apoptosis Gene.

An aqueous suspension of a granulosis virus (GV) from Plodia interpunctella (Hubner) controlled P. interpunctella in stored inshell ‘Nonpareil’ almonds for 134 days. As a result, feeding damage to the treated nuts was substantially reduced, and the percentage of rejects was decreased by as much as 88%. Virus suspension stored at −80°C for 18 months lost no activity.

Granulosis Virus of the Indian Meal Moth as a Protectant for Stored Inshell Almonds

The effect of a granulosis virus on Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) infestations occurring in stored raisins

Field trials with Bacillus thuringiensis Berliner for control of paramyelois transitella (Walker) were conducted in commercial almond orchards in California. B. thuringiensis formulated as Dipel® (2% dust and WP), Thuricide® HPC (EC), and Biotrol® XK (WP) was applied starting at about the onset of hullcrack for 4–5 applications at 3–10 day intervals. A synthetic feeding stimulant, Mo-Bait,® also was tested. The highest level of control (44.8% damage reduction) was obtained with 4 applications of Thuricide HPC at a rate of 1 qt/25 trees. The addition of the feeding stimulant did not increase the effectiveness of the treatments. Navel orangeworms are difficult to control because they apparently move to the deeper areas of the hull-shell interspace that are not penetrated by the treatments.

D. K. Hunter

Papers

Granulosis Virus of the Indian Meal Moth as a Protectant for Stored Inshell Almonds

The effect of a granulosis virus on Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) infestations occurring in stored raisins

Field Evaluation of Bacillus thuringiensis for Control of Navel Orangeworms on Almonds