BACKGROUND
Wireworms (Coleoptera: Elateridae) are major insect pests of worldwide relevance. Owing to the progressive phasing‐out of chemical insecticides, there is great demand for innovative control options. This study reports on the development of an attract‐and‐kill co‐formulation based on Ca‐alginate beads, which release CO2 and contain neem extract as a bioinsecticidal compound. The objectives of this study were to discover: (1) whether neem extract can be immobilized efficiently, (2) whether CO2‐releasing Saccharomyces cerevisiae and neem extract are suitable for co‐encapsulation, and (3) whether co‐encapsulated neem extract affects the attractiveness of CO2‐releasing beads towards wireworms.
RESULTS
Neem extract was co‐encapsulated together with S. cerevisiae, starch and amyloglucosidase with a high encapsulation efficiency of 98.6% (based on measurement of azadirachtin A as the main active ingredient). Even at enhanced concentrations, neem extract allowed growth of S. cerevisiae, and beads containing neem extract exhibited CO2‐emission comparable with beads without neem extract. When applied to the soil, the beads established a CO2 gradient of >15 cm. The co‐formulation containing neem extract showed no repellent effects and was attractive for wireworms within the first 24 h after exposure.
CONCLUSION
Co‐encapsulation of S. cerevisiae and neem extract is a promising approach for the development of attract‐and‐kill formulations for the control of wireworms. This study offers new options for the application of neem extracts in soil. © 2017 Society of Chemical Industry