Comparative studies of acetylcholinesterase purified from three field populations of Liposcelis entomophila (enderlein) (psocoptera: liposcelididae)

Abstract

Acetylcholinesterace (AChE) is known to be the major target for organophophate and carbamate insecticides and biomolecular changes to AChE have been demonstrated to be an important mechanism for insecticide resistance in many insect species. In this study, AChE from three field populations of Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae) was purified by affinity chromatography and subsequently characterized by its Michaelis-Menten kinetics to determine if detectable changes to AChE have occurred. Bioassays revealed that the potential resistance threat of psocids in Sichuan Province (GH) was greater than either Hubei Province (WH) or Chongqing Municipality (BB). Compared to the other two populations, the WH population possessed the highest specific activity of purified AChE. Kinetic analyses indicated that the purified AChE from GH population expressed a significantly lower affinity to the substrate and a higher catalytic activity toward acetylthiocholine iodide (ATChI) (i.e., higher K(m) and V(max) values) than BB and WH populations. In vitro studies of AChE suggest that five inhibitors (aldicarb, eserine, BW284C51, omethoate, and propoxur) all possess strong inhibitory effects with eserine having the strongest inhibitory effect against purified AChE. According to bimolecular rate constants (k(i)), the purified AChE from GH population was least sensitive to all inhibitors except for omethoate. The differences in AChE among the three populations may be partially attributed to the differences in pesticide application and control practices for psocids among the three locations.

De Novo Assembly, Gene Annotation, and Marker Discovery in Stored-Product Pest Liposcelis entomophila (Enderlein) Using Transcriptome Sequences

“…Thus, the greater heat tolerance and higher heterogeneity of response to heat shock in L. entomophila might facilitate its development of thermal tolerance or resistance to heat treatments in the grain storage facilities [14] . At present, a few studies have been conducted mainly focus on the ecology, molecular identification, and physiology and biochemistry of L. entomophila [4] , [15] – [17] . However, discovery of the underlying biochemical and physiological mechanisms of L. entomophila to insecticides resistance and adaptability to adverse environments remains challenging.…”

Acetylcholinesterases from Leaf-Cutting antAtta sexdens: Purification, Characterization, and Capillary Reactors for On-Flow Assays

“…With this substrate, AChEs usually have optimum pH around 7.0–8.0. For example, it has been reported that AChEs in Liposcelis entomophila has pH around 7.0 [43] while in H. bacteriophora the pH values were around 8.5 [41]. Meanwhile, for As AChEs, the pH values were above the usual.…”

“…The optimum temperature for As AChE-B was 20°C (Figure 2(b)), as expected for AChEs from insects, but for As AChE-A two temperatures (30 and 50°C) gave the maxima of activity (Figure 2(b)). Optimum temperature for AChEs is found in a broad range, varying from 35 to 45°C [41, 43, 44].…”

Biochemical and molecular characterisation of acetylcholinesterase in four field populations of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

“…16,21,26 Although an increase in AChE activity has been found in particular insects such as Locusta migratoria manilensis, 27 Schizaphis graminum 28 and Bemisia tabaci, 15 these changes usually lead to a decrease in hydrolysis ability of AChE. 29,30 In a resistance study of Bactrocera oleae, 31 it was shown that two point mutations (I214V and G488S) are associated with a 35-40% reduction in AChE catalytic efficiency, which produced up to a 16-fold decrease in insecticide sensitivity. In contrast, previous studies have also discovered that there are other mutations producing higher AChE activity and increasing insecticide resistance.…”