Antifungal phytochemicals from the methanol and aqueous extract of Acacia concinna and Lantana camara and synergistic biological control of the Hibiscus mealybug (Maconellicoccus hirsutus)

Abstract

The antifungal and biological control effects of phytochemicals from the leaves and seeds of Acacia concinna and Lantana camara were analyzed against plant phytofungi and the mealy bug Maconellicoccus hirsutus. The methanol and aqueous extract derived from A. concinna and L. camara inhibited the growth of phytofungi. The methanol extracts showed the broad spectrum antimicrobial properties as they inhibited the mycelial growth of Alternaria alternate K3, Fusarium oxysporum S10, Fusarium solani L16, Aspergillus flavus J12, and Colletotrichum falcatum Went C9. The methanolic extract of A. concinna seed inhibited the growth of A. flavus J12 and the mycelia growth was 10 ± 2 mm after three days, whereas the leaf extract effectively inhibited mycelia growth (23 ± 1 mm) after seven days of culture. Minimum inhibitory concentration values of methanolic extract of A. concinna seed was 125 ± 25 μg/mL against A. alternate K3, and 100 ± 0 μg/mL against F. solani L16. The phenolic content was 479 ± 13.8 GAE/g dw in A. concinna in seeds while in L. camara seeds it was 548 ± 20.1 GAE/g dw. The flavonoid content was high in L. camara seed extract (282 ± 10.1 mg QE/g) than A. concinna seeds (214 ± 2.49 mg QE/g). The methanolic extract of leaves and seeds showed pesticide activity against mealy bug. The mortality of the adult mealy bugs was maximum after 72 h of treatment. The concentration of L. camara seed extract (0.2%–1.0%) exhibited increased mortality than control. Additionally, L. camara and A. concinna extracts improved activity against mealy bug. Considering these facts, medicinal plants-derived secondary metabolites represent a novel source of various bioactive potentials with synergism against phytopathogenic fungi and insect pests.