An improved core-shell microcapsule diet for rearing larvae of Mallada basalis (Neuroptera: Chrysopidae)

Green lacewings (Neuroptera: Chrysopidae) are important beneficial insects that can be raised on artificial diets for culturing experimental lines. An encapsulation method for embedding a core material within a sealed shell to prevent evaporation and biological contamination is crucial for providing food to these predatory insects.

This study presents a new encapsulation process to mass produce a core-shell microcapsule diet for rearing Mallada basalis (Walker) (Neuroptera: Chrysopidae). This new process provided consistent quality control and effectiveness of the microcapsule diet (742.1 ± 11.3 μm in diameter and 44.2 ± 1.9 μm in shell thickness). Furthermore, significant differences were measured in larval development (24.0 ± 0.3 vs. 20.1 ± 0.6 days) and fecundity (465 ± 65.05 vs. 678 ± 54.91 eggs) on comparing the development of M. basalis larvae fed the old and new diets. Survival rates increased in both single- and group-rearing tests for adults fed the new diet during the larval stages. Neither diet affected predation rates for M. basalis larvae preying on nymphs of Aphis gossypii Glover (Hemiptera: Aphididae) and Bemisia argentifolli Bellows and Perring (Hemiptera: Aleyrodidae).

Compared with the old process, the new encapsulation process requires reduced effort during preparation, and reduces the weight, cost and space occupied by the equipment. The results of this study suggest that this new spherical microcapsule artificial diet is suitable for group-rearing of M. basalis and may be appropriate for mass-rearing of other types of carnivorous insects. © 2019 Society of Chemical Industry.