We investigated three-way interactions between plants, microbes and insects. A total of 71 isolates of fungi from the genera Metarhizium, Beauveria and Trichoderma were analysed for their ability to infect yellow mealworm larvae and stimulate maize growth. The isolates Metarhizium brunneum (1154) and Beauveria bassiana (2121) caused the highest mortality (100 %) in mealworms. Some isolates, such as Metarhizium robertsii (2693), showed potential for further research, as it not only caused 73 % mortality of mealworms, but also had a positive effect on all maize growth parameters. In further laboratory experiments, the effects of entomopathogenic fungi (EPF) on wireworms were investigated. It was found that M. brunneum (isolate 1868) significantly increased wireworm mortality and was most frequently reisolated from maize rhizoplane. Field trials have shown that soaking maize kernels in M. brunneum (1868) suspension resulted in a higher initial maize stand in three varieties, wherease in one variety also final maize stand was increased. Trials testing different EPF-based preparations of the genus Metarhizium for wireworm control showed that granular application of fungi (especially ATTRACAP and EPF formulated on rice) caused significant reduction of the proportion of damaged tubers. Plant diet influenced wireworm growth and development, but not necessarily susceptibility to EPF infection. Using a dual-choice olfactometer, we investigated the behavioural response of wireworms to EPF in the presence of maize plants. Although maize was a suitable attractant, we could not detect any repellent effect of EPFs. By analysing hyperspectral images in the spectral range of 400–2500 nm, we detected and discriminated between biotic (wireworms) and abiotic (drought) stress in maize with an overall accuracy of 86,7 %, confirming the potential of hyperspectral imaging for early detection of drought and/or wireworm infestation in maize.
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