Z-Ligustilide Exerted Hormetic Effect on Growth and Detoxification Enzymes of Spodoptera litura Larvae

Abstract EN

Plants have evolved a variety of phytochemicals to defense insect feeding, whereas insects have also evolved diverse detoxification enzymes, which are adaptively induced as a prosurvival mechanism.

Herein, Z-ligustilide in Ligusticum chuanxiong Hort.

was found to exhibit a similar trend in the accumulation from December to May as the occurrence of Spodoptera litura (Fabricius) larvae.

Importantly, S.

litura larvae feeding enhanced Z-ligustilide level in the stem and leaf (p < 0.01).

Moreover, Z-ligustilide ranging from 1 to 5 mg·g−1 exhibited remarkable larvicidal activity, antifeedant activity, and growth inhibition against S.

litura larvae.

The LC50 values of larvicidal activity for phthalides in L.

chuanxiong were compared as follows: Z-ligustilide > levistilide A > senkyunolide A > 3-butylidenephthalide > senkyunolide I, implicating the critical role of conjugated structure.

Notably, there was a biphasic dose response for glutathione S-transferase (GST), cytochrome P450 (CYP) 450, Acetylcholinesterase (AChE), and Carboxylesterase (CarE) activities and GSTs1, cytochrome P450 (CYP) 4S9, and CYP4M14 mRNA expression.

Particularly, low dose (0.1 mg·g−1) of Z-ligustilide conferred the resistance of S.

litura larvae against chlorpyrifos (p < 0.05).

Together, our data suggest that Z-ligustilide may function in a hormetic way in the chemical defense of L.

chuanxiong against S.

litura larvae.