Entomopathogenic nematodes and fungi in Mediterranean Ecosystems and Evaluation of their Potential as Biological Control Agents of Insect Pest Populations in Fruticulture.

The term “microbial control” has been used to describe the use of microbial pathogens (bacteria, viruses, or fungi) or entomopathogenic nematodes (EPNs) to control various insect pest populations. EPNs and EPF are widely recognized as valuable assets in soil ecosystems due to their role as effective biological control agents (BCAs). They are among the best biocontrol agents, and major developments in their use have occurred in recent decades, with many surveys having been conducted all over the world to identify EPNs and EPF that may have potential in the management of insect pests. Entomopathogenic nematodes (EPNs) are obligate parasites to wide range of insect pests mostly for soil-dwelling insects. Pathogenicity of EPNs is due to the nematode and their symbiotic bacteria (Photorhabdus spp. in Heterorabditids and Xenorhabdus spp. in Steinernematids). Non-toxic bio-insecticides for vertebrates and harmless to humans and the environment with Commercialised species in the families Steinernematidae and Heterorhabditidae families. Conidia is the infectious unit for EPF (Beauveria spp. and Metarhizium spp.). It germinates (germination tube) and grow as hyphae. In the host, development occurs with the formation of blastospores that multiply by budding process. A conidium must adhere to the insect host to induce germination and production of a germ tube. Mechanical pressure and secretion of enzymes are employed to breach the cuticle. The fungus switches to blastospore growth to colonize the host hemocoel, where it secretes toxins and feeds on sugars in the hemolymph. The blastospores evade the host immune responses and secrete toxins that facilitate killing of the host. After the host has died, the fungus breaches the cuticle again from the inside and sporulates on the cadaver Good results in IPM with EPNs and good results with EPF. Why do not use EPN & EPF together: possible synergistic effects, EPF conidia do not move but EPNs can move, and where they could have the maximum effect acting together is within cryptic habitats against xylophagous pests. This is the idea: EPF as preventive control method and EPNs as curative control method. Experiences on EPN and EPF use in agroforestry ecosystems (in IPM control strategies of xylophagous Lepidoptera Parahypopta caestrum, Zeuzera pyrina and Cossus Cossus, Coleoptera curculionid Rhynchophorus ferrugineus, buprestid Capnodis tenebrionis, and cerambycid Arhopalus syriacus), is presented to testify and demonstrate that biological control with EPNs and EPF is possible and offers many advantages over chemicals, such as end-user safety, minimal damage to natural enemies, and lack of environmental pollution, which are essential conditions for an advanced IPM strategy.