# The Current State and Future Potential of Microbial Control of Scarab Pests
## 10 Future Advancements
### Paenibacillus  
Genetic engineering of pathogens provides an opportunity to increase lethality, by creating strains that are hyper-pathogenic [290]. This can be accomplished by inserting genes for toxins, hormones, or enzymes, often sourced from other taxa, that increase pathogen kill time. Genes encoding toxins found in mites, scorptions, spiders, and sea anemones have all been engineered into baculoviruses and tested on a range of insect pests [291; 292]. Toxins from scorptions, spiders, and sea slugs have also been introduced into recombinant fungi, yielding up to a 22-fold decrease in lethal dose [293; 294; 295]. The homologous toxin complex found in _Serratia_ and _Plotorhabbus_, which consists of a plasmidcarrying the _sep_ABC genes responsible for the symptoms of amber disease, have also been engineered into other bacteria and shown to increase insect mortality [76].  
Cell signaling molecules and hormone genes, including diuretic, orthoracicotropic, and eclosion hormones [296; 297; 298], have been inserted into baculoviruses to increase insect killing speed. Many of these genes have also been engineered into fungi, such as _B. bassiana_, to improve insecticidal activity [299; 300; 301]. RNA interference was used to increase the pathogenicity of a strain of _I. fumosorosea_ by inserting the sequence for a dsRNA that successful knocked down an immunity gene in infected whitefly nymphs [302]. Genes encoding enzymes, such as juvenile hormone esterases, chitinases, and proteases, have also been engineered into entomopathogens. chitinase gene insertions into _Trichoderma konigii_ from _M. anisopliae_ increased the mortality of Asian corn borer and silkworm [303]. The insertion of chitinase and protease genes from the silkworm (_Bombyx mori_) into _B. bassiana_ has been reported to improve cuticle penetration [304; 305; 306].  
Additionally, genes providing tolerance to environmental factors have also been introduced into fungi [307] and to a lesser extent, entomopathogenic nematodes, to increase their stability in the environment. Photolyase and thioredoxin genes from bacteria have been engineered into _B. bassiana_ and _M. robertsi_ to improve UV tolerance and reduce the damage caused by UV radiation, making the recombinant fungi more stable in sunny environments [308; 309]. Similarly, a recombinant strain of _S. feltiae_ was engineered to be more osmo- and desiccation-tolerant by introducing a heat shock gene from _Caenorhabditis elegans_[310].  
The expression of existing and introduced genes can also be modulated through the insertion of different promoters to increase or decrease gene expression [291; 292]. This has been carried out to increase chitinase, trehalose, and protease expression in _B. bassiana_ and _Metrahizium_ species [311; 312; 313; 314]. Expression of superoxide dismutase has also been overexpressed in _B. bassiana_ to improve UV tolerance [315]. Alternatively, genes involved in delaying host mortality in viruses can also be deleted. [PERSON] and [PERSON] [316] successfully deleted the _egt_ gene in a recombinant baculovirus (AcMNPV), which reduced feeding behavior in the infected host and decreased the time to mortality.