Insecticidal Effect of the Entomopathogenic Fungus HK-1 in (Hemiptera: Aphididae).

(Hemiptera: Aphididae) is an important pest affecting various crops worldwide. However, only few studies have been conducted on the infection of by and related insecticidal mechanisms. We investigated the infection process of by HK-1 using fluorescence microscopy and scanning electron microscopy (SEM), and our results indicated that the conidia of strain HK-1 easily attached to the feet and dorsum of . The activities of chitinase and extracellular protease were induced in the aphid after treatment with HK-1. A bioassay on showed that the median lethal concentration (LC) of the fungus crude extract was 24.00 mg mL for 24 h of treatment. Additionally, the results showed that the crude extract disrupted the enzyme system of , inducing the inhibition of carboxylesterase (CarE) and the induction of glutathione S-transferase (GST) and acetylcholinesterase (AChE). Combining these results with those of a gas chromatography-mass spectrometry (GC-MS) analysis, it is suggested that -cymene, hymecromone, 9,12-octadecadienoic acid (Z, Z) methyl ester, and 9,12-octadecadienoic acid (Z, Z) may be connected to the insecticidal effects we observed. This study provides a theoretical basis for the use of HK-1 as a potential biological control agent.