Please cite this article as: Lacey, L.A., Grzywacz, D., Shapiro-Ilan, D.I., Frutos, R., Brownbridge, M., Goettel, M.S., Insect pathogens as biological control agents: back to the future, Journal of Invertebrate Pathology (2015), doi: http://dx.doi.org/10.1016/j. jip.2015.07.009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The development and use of entomopathogens as classical, conservation and augmentative 26 biological control agents have included a number of successes and some setbacks in the past 15 27 years. In this forum paper we present current information on development, use and future 28 directions of insect-specific viruses, bacteria, fungi and nematodes as components of integrated 29 pest management strategies for control of arthropod pests of crops, forests, urban habitats, and 30 insects of medical and veterinary importance. 31Insect pathogenic viruses are a fruitful source of MCAs, particularly for the control of 32 lepidopteran pests. Most research is focused on the baculoviruses, important pathogens of some 33 globally important pests for which control has become difficult due to either pesticide resistance 34 or pressure to reduce pesticide residues. Baculoviruses are accepted as safe, readily mass 35 produced, highly pathogenic and easily formulated and applied control agents. New baculovirus 36 products are appearing in many countries and gaining an increased market share. However, the 37 absence of a practical in vitro mass production system, generally higher production costs, limited 38 post application persistence, slow rate of kill and high host specificity currently contribute to 39 of Bt toxins, has been conducted over the past two decades. The Bt genes used in insect-resistant 54 transgenic crops belong to the Cry and vegetative insecticidal protein families of toxins. Bt has 55 been highly efficacious in pest management of corn and cotton, drastically reducing the amount 56 of broad spectrum chemical insecticides used while being safe for consumers and non-target 57 organisms. Despite successes, the adoption of Bt crops has not been without controversy. 58

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Xenorhabdus and Photorhabdus species dedicate a large amount of resources to the production of specialized metabolites derived from non-ribosomal peptide synthetase (NRPS) or polyketide synthase (PKS). Both bacteria undergo symbiosis with nematodes, which is followed by an insect pathogenic phase. So far, the molecular basis of this tripartite relationship and the exact roles that individual metabolites and metabolic pathways play have not been well understood. To close this gap, we have significantly expanded the database for comparative genomics studies in these bacteria. Clustering the genes encoded in the individual genomes into hierarchical orthologous groups reveals a high-resolution picture of functional evolution in this clade. It identifies groups of genes-many of which are involved in secondary metabolite production-that may account for the niche specificity of these bacteria. Photorhabdus and Xenorhabdus appear very similar at the DNA sequence level, which indicates their close evolutionary relationship. Yet, high-resolution mass spectrometry analyses reveal a huge chemical diversity in the two taxa. Molecular network reconstruction identified a large number of previously unidentified metabolite classes, including the xefoampeptides and tilivalline. Here, we apply genomic and metabolomic methods in a complementary manner to identify and elucidate additional classes of natural products. We also highlight the ability to rapidly and simultaneously identify potentially interesting bioactive products from NRPSs and PKSs, thereby augmenting the contribution of molecular biology techniques to the acceleration of natural product discovery.

The factors which influence the success or failure of biological control programmes with entomopathogenic nematodes are discussed. Case studies of insect control in 3 different cropping systems are also discussed. The systems were chosen to illustrate an example in which nematodes failed (cotton), have been slightly successful (turf) and have succeeded (citrus).

Harmonia axyridis (Coleoptera: Coccinellidae) has been introduced widely for biological control of agricultural pests. Harmonia axyridis has established in four continents outside of its native range in Asia and it is considered an invasive alien species (IAS). Despite a large body of work on invasion ecology, establishment mechanisms of IAS and their interactions with natural enemies remain open questions. Parasites, defined as multicellular organisms that do not directly kill the host, could potentially play an important role in regulating host populations. This study presents a review of the parasites of H. axyridis, discussing their distributions and effects on host populations across the host's native and invasive range. These parasites are: Hesperomyces virescens Thaxt. fungi, Coccipolipus hippodamiae (McDaniel and Morrill) mites, and Parasitylenchus bifurcatus Poinar and Steenberg nematodes.

Because of their selectivity and safety, microbial control agents (MCAs) appear to be ready-made components of integrated pest management (IPM) systems that do not pose a threat to applicators or the environment and allow other natural enemies to function. Control of several orchard pest insects using MCAs, including viruses, Bacillus thuringiensis, fungi, and entomopathogenic nematodes (EPNs), have been demonstrated in apple, pear, stone fruits, citrus, and several nut crops. B. thuringiensis is the most used MCA for control of lepidopteran orchard pests. Significant use of EPNs in citrus for control of root weevils is also reported. The granulovirus of codling moth is used increasingly in apple and pear by organic growers, with interest also shown by conventional growers. Although some success has been achieved, in most orchard systems MCAs account for a relatively small proportion of the pest control tactics employed, and in some systems they are not used at all. Research toward improving MCA efficacy and economic competitiveness is required to enhance the role of MCAs in IPM.

This paper presents an overview of the biology of woodwasp Sirex noctilio and of the classical entomopathogenic nematode (EPN) Beddingia siricidicola and discusses application procedures (including plantation and tree inoculations) of EPNs, effect of choice of species and strain, the deterioration of strains and their replacement, nematode reisolation from the area of original release, storage in liquid nitrogen, culturing nematodes (establishment of cultures, mass culture and dispatch), monitoring and efficacy.