Abstract

Biological control agents, specifically entomopathogenic nematodes (EPNs), appear as promising alternatives for insect control when considering the toxic damages caused by the excessive use of synthetic insecticides in agriculture. In many cases, EPNs are applied in combination with other agricultural inputs, which may include seaweed extracts. The question raised is whether these extracts are compatible or not with EPNs. The main objective of this research was to evaluate the compatibility between EPNs and different seaweed extracts. The study was run as a three single-factor experiment, using a completely randomized design. Three commercial seaweed extracts (Acadian®, SeamelPure® e SuperFifty®), manufactured using different hydrolysis processes, were evaluated using three nematode isolates. Each treatment was replicated five times. Each repetition consisted of a test tube with 2 mL of a suspension containing 1500 infective juveniles (IJs) and 15 mL of the diluted product or water (control). The parameters assessed included viability of EPNs, infectivity over Tenebrio molitor larvae and IJs reproductive potential after the contact with seaweed extracts. All seaweed extracts significantly affected the viability, infectivity and reproduction of all EPNs isolates tested. Nevertheless, Seamel PURE®, which is manufactured though an enzymatic instead of a highly aggressive alkaline hydrolysis process, was the only extract considered slightly harmful regarding the infectivity of all isolates tested. EPNs reproduction following the contact with each seaweed extract tested was reduced by 100% across all tested isolates. These findings indicate that under the tested conditions, seaweed extracts based on chemical hydrolysis are greatly incompatible with the evaluated nematode isolates.