LACEWINGS (NEUROPTERA, HEMEROBIIDAE AND CHRYSOPIDAE) AND INTEGRATED PEST-MANAGEMENT - ENZYME-ACTIVITY AS BIOMARKER OF SUBLETHAL INSECTICIDEEXPOSURE

Specific activities of head acetylcholinesterase (AChE) and whole body glutathione-S-transferase (GST) were assayed as biomarkers of subleth al exposure to insecticides in larvae of 2 lacewing species, the Chrys opid Chrysoperla carnea Stephens and the Hemerobiid Micromus tasmaniae Walker. When M. tasmaniae was exposed to the organophosphates methyl- parathion or azinphos-methyl, the rate of AChE-inhibition was toxin-sp ecific, exponentially dose-dependent, and increased within 21 h of exp osure. Activity of AChE was less inhibited in C. carnea larvae, which reflected its higher tolerance to organophosphates in mortality tests. No inhibition of AChE activity (e.g., resulting from nonspecific bind ing to the enzyme) was observed following treatment with the pyrethroi d cypermethrin and the insect-growth regulators fenoxycarb, diflubenzu ron, and tebufenozide. The activity of GST increased significantly in M. tasmaniae larvae treated with sublethal doses of cypermethrin and d ecreased significantly in larvae treated with fenoxycarb. In contrast, no changes in GST activity were observed in C. carnea larvae for any of the compounds tested. Inhibition of AChE in lacewings proved a usef ul tool to study the impact of different organophosphates used in inte grated pest management. However, further investigations are necessary to evaluate the potential applicability of GST activity as a biomarker in lacewings as different results are likely for different lacewing s pecies, varying exposure times, repeated dose levels, different-aged l arvae, and different substrates for the enzyme reaction.