Enhancement and quantification of repellent activity in Chenopodium cells

Abstract

Arthropod–plant interactions are vital in agriculture and pharmacology. However, enhancement and quantification of plant cell behavioural activity is still a challenge. Therefore, the finding of chitosan-induced anti-fungal activity in plants suggested a promising potential. Consequently, we treated autotroph and heterotroph Chenopodium rubrum L. cell cultures with chitosan to test behavioural activity with Tenebrio molitor L. larvae. We found chitosans to enhance repelling, depending on low molecular weight, partial degree of deacetylation, plant cell type and age. These effects of chitosans were compared with abiotic stresses induced by salt, osmotic changes and heat shock, collecting data of six plant cell samples, 18 plant cell treatments, 6,912 larvae and 8,424 analyses of regression and variance. Behavioural activity was quantified by linear, multivariate and nonlinear approaches, testing an exponential model in 78 segments of 5 h time kinetics. Thereby, we introduced a sensitive, low-cost bio-assay and a preference index constant as a measure of transient behaviour. Multivariate analyses revealed the five principal factors to enhance the behavioural activity in plant cells: (1) salt-osmo-sensor, (2) high molecular weight chitosan sensor, (3) acetic acid-antagonized low molecular weight chitosan sensor, (4) heat shock sensor and (5) mannitol-sensitive chitosan sensor. Thus, we suggest the independent factors (1)–(5) for the management of insect pests by autotroph and heterotroph plant materials.