Entomopathogens and multitrophic interactions
Entomopathogens are microorganisms that infect insects, including viruses, fungi, and bacteria. These pathogens can cause overt infections, leading to noticeable symptoms and potential population collapses, or covert infections, where individuals carry the pathogen without evident symptoms. Traditionally, entomopathogens have been studied for their potential use as bioinsecticides. In recent years, there has been a growing interest in understanding their role in preserving industry-reared insect populations from microbial disease outbreaks, particularly in insects reared for food, feed, or as biocontrol agents.
However, the influence of entomopathogens goes beyond direct mortality. Their actions often trigger cascading ecological effects involving plants, herbivores, and natural enemies. Both overt and covert infections can alter insect behaviour, impact plant response to herbivory (directly or indirectly), and reshape community structures and predator-prey dynamics. As such, entomopathogens are dynamic players in ecological networks, influencing biodiversity and ecosystem resilience. In return, multitrophic interactions can modulate the relationship between insects and their pathogens. The infection status is the result of a continuous evolutionary arms race between the host, which is constantly optimizing strategies to reduce the burden of infection, and the pathogen’s counteradaptations to overcome insect defenses. In nature, these interactions are never binary but are affected by external biotic and abiotic factors including the trophic networks in which both insect and pathogen are embedded.
Our research aims to determine and characterize the outcomes of, and mechanisms underlying, multitrophic interactions involving insects and their pathogens. By understanding these interactions, we ultimately aim to improve or develop novel strategies to increase the efficacy of natural pathogens in controlling significant agronomical pests, as well as to comprehend the dynamics of pathogenic infections in mass-reared insects.
Subtopics:
- Microbe regulation of plant-insect interactions
Plant–insect interactions involve complex physiological and adaptive processes that enable insects to feed and thrive on plants. To begin with, insects rely heavily on their chemosensory systems to locate suitable host plants. This involves detecting long-distance cues, such as plant volatiles through olfaction, as well as short-range cues through taste. Once an insect locates a host plant, it must overcome plant defenses. Being sessile, plants have evolved sophisticated strategies to counteract herbivory, including the activation of chemical and physical defenses. In response, many insects have evolved mechanisms to feed while minimizing the impact of these defenses—either by avoiding detection or by detoxifying plant-produced defensive compounds (xenobiotics). Moreover, insects must cope with the nutritional challenges of a plant-based diet, which is often low in nitrogen. At every step of this interaction—from host detection to feeding and nutrient assimilation—the presence of a pathogenic infection in the insect can alter its performance. Pathogens may reduce insect fitness and survival, acting as unintended plant allies by limiting herbivory. However, in some cases—particularly with covert infections—pathogens may actually enhance insect performance and survival.
Our research focuses on disentangling the ecological effects of insect pathogens, particularly viruses, on plant–insect relationships. We aim to uncover both the ecological consequences and the molecular mechanisms involved, using experimental approaches such as CRISPR/Cas9-based genetic manipulation.
- Biotechnological Potential of Biocidal Secondary Metabolites from Photorhabdus and Xenorhabdus
Beyond their role in insect pathogenesis, the secondary metabolites produced by Photorhabdus and Xenorhabdus exhibit a wide range of biological activities. Many of these compounds possess antimicrobial, antifungal, cytotoxic, and immunosuppressive properties, making them promising candidates for applications in agriculture, medicine, and industry.
Our work explores the diversity, structure, and function of these metabolites, with a particular interest in those capable of overcoming resistance mechanisms in pests and pathogens. Some metabolites have shown strong activity against bacteria that are resistant to conventional antibiotics, highlighting their potential in addressing one of the most pressing challenges in global health.
By combining analytical chemistry, omics technologies, and functional assays, we aim to catalog and evaluate these compounds for their potential as novel biopesticides or antimicrobial agents.
This line of research not only contributes to sustainable agriculture but also positions Photorhabdus and Xenorhabdus as valuable biofactories for the discovery of new natural products with cross-sector impact. In close collaboration with Hospital La Fe, we explore the clinical applications of these compounds, strengthening the bridge between agricultural biotechnology and human health.
Research projects
Selected publications
Proteomic variation in the rral secretion of Spodoptera exigua and Spodoptera littoralis larvae in response to different food sources
García-Marín E., J. Gamir, and C. M. Crava, 2025. Journal of chemical ecology 51:10.
Constitutive and inducible tomato defenses contribute to Bacillus thuringiensis lethality against Spodoptera exigua. Biological control
Frattini, A., R. M. González-Martínez, J. M. García, Z. Minchev, M. J. Pozo, V. Flors, C. M. Crava, and S. Herrero., 2024. 198: 105624.
Compatibility of mycorrhiza-induced resistance with viral and bacterial entomopathogens in the control of Spodoptera exigua in tomato
Frattini, A., M. Martínez -Solís, A. Llopis-Giménez, M. J. Pozo, J. Rivero, C. M. Crava, and S. Herrero. 2022. Pest management science 78: 4388-4396.
Baculovirus infection affects caterpillar chemoperception
Llopis-Giménez, A., G. Caballero-Vidal, E. Jacquin-Joly, C. M. Crava, and S. Herrero. 2021. Insect Biochem Mol Biol 138: 103648.
