New cost-effective bioconversion process of palm kernel cake into bioinsecticides based on Beauveria bassiana and Isaria javanica

• Published in: Applied microbiology and biotechnology Vol. 102; no. 6; pp. 2595 - 2606
• Main Authors: do Nascimento Silva, Jaqueline, Mascarin, Gabriel Moura, dos Santos Gomes, Isabel Cristina, Tinôco, Ricardo Salles, Quintela, Eliane Dias, dos Reis Castilho, Leda, Freire, Denise Maria Guimarães
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-03-2018; Springer; Springer Nature B.V
• Subjects: Agricultural management; Analysis; Atmospheric moisture; Beauveria bassiana; Bioconversion; Biological control; Biological insect control; Biomedical and Life Sciences; Biotechnological Products and Process Engineering; Biotechnology; Byproducts; Conidia; Diseases and pests; Drying; Edible vegetable oils; Fermentation; Fungi; Growth conditions; Insecticides; Insects; Isaria javanica; Life Sciences; Mass production; Methods; Microbial Genetics and Genomics; Microbiology; Moisture; Mortality; Optimization; Palm oil; Pests; Production management; Solid state fermentation; Substrates; Whiteflies; Brazil; Agro-industrial by-products; Solid-state fermentation; Entomopathogenic fungi; Biological control; Cordycipitaceae; Bemisia tabaci
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-018-8805-z

The present study aimed to add value to palm oil by-products as substrates to efficiently produce conidia of
Beauveria bassiana
and
Isaria javanica
(
Hypocreales
:
Cordycipitaceae
) for biological control of the whitefly
Bemisia tabaci
(
Hemiptera
:
Aleyrodidae
), through a solid-state fermentation process using palm kernel cake and palm fiber as nutrient source and solid matrix, respectively. The optimum culture conditions yielded high concentrations of viable conidia after air-drying, when the fungi were grown on palm kernel cake (
B
.
bassiana
7.65 × 10
9
and
I
.
javanica
2.91 × 10
9
 conidia g
−1
dry substrate) after 6 days under optimal growth conditions set to 60% substrate moisture and 32 °C. Both fungal strains exhibited high efficacy against third-instar whitefly nymphs, inducing mortality up to 62.9 and 56.6% by
B. bassiana
and
I. javanica
, respectively, assessed after 9 days post-application in a screenhouse. Furthermore, we noted that insect mortality was strongly correlated with high atmospheric moisture, while
B. bassiana
appeared to require shorter accumulative hours under high moisture to kill whitefly nymphs compared to
I. javanica
. Our results underpin a feasible and cost-effective mass production method for aerial conidia, using palm kernel as the main substrate in order to produce efficacious fungal bioinsecticides against an invasive whitefly species in Brazil. Finally, our fermentation process may offer a sustainable and cost-effective means to produce eco-friendly mycoinsecticides, using an abundant agro-industrial by-product from Brazil that will ultimately assist in the integrated management of agricultural insect pests.