This paper describes the current status of resistance in insects to spinosad, and summarizes spinosad resistance mechanism from the aspects of physiological and biochemical mechanism, as well as molecular implication. The resistance mechanism of insects to spinosad, however, remains unclear. It is very important to study the mechanism and delay the insects'development of resistance to spinosad.

Objective To study the activity of Glutathione S-transferase (GSTs) of German cockroaches (Blattella germanica) at different developmental stages (from nymph to adult) and different field strains in Beijing. Methods The specific activity of GSTs and resistance levels of B. germanica were determined by spectrophotometry and contact biossay. Results The specific activity of GSTs increased gradually during the nymph period and reached the highest by week 4, which then decreased to the lowest value during eclosion. The specific activity of GSTs in susceptible strains of B. germanica was 2.70 nmol/(min·mg) with K_m of 2.26 mmol/L and V_max of 0.33 nmol/(min·mg); the specific activity of GSTs in nine field strains ranged from 2.76-8.69 nmol/(min·mg) with K_m of 0.65-2.37 mmol/L and V_max of 0.33-0.54 nmol/(min·mg) V_max. Compared with susceptible strains, field strains had higher specific activity and V_max yet lower K_m values. Field strains also demonstrated different degrees of resistance to two commonly used pesticides (cypermethrin 1.50-8.37 fold; propoxur 1.04-3.34 fold). Conclusion GST activity varied in the developmental stages from nymph to adult, which may be involved in the development of insecticide resistance in the field strains of B. germanica.

Objective To analyze the overall situation and development trends of professionals in pest control organization (PCO) in China. Methods The staff composition (including practice time, age and education background), training, remuneration and health insurance in this domestic industry were compared with the foreign counterparts. Results Professionals in China’s PCO had short practice time, wide-span age distribution, deficient experience, low educational level, unstable performance, poor remuneration and shortage of corresponding occupational health insurance, indicating significant difference with the same industry in foreign countries. Conclusion PCO professionals are the key to the development of an enterprise, or even the whole industry. Their quality is determinant of the industry’s overall service quality. With the overall improvement of the quality of PCO professionals in China, this industry will achieve rapid development and present a new image.

Objective Propoxur-susceptible Musca domestica strains were established through reverse selective breeding in the laboratory setting. The discriminating concentration of insensitive acetylcholinesterase (AChE) was established according to the AChE sensitivity of the strains. The insensitive gene AChE phenotypes of outdoor M. domestica populations were investigated to provide the basis for delaying pesticide resistance development in M. domestica. Methods The susceptible strains were bred through elimination selection. The insensitive AChE phenotypes in the natural population were investigated by biochemical approaches. Results After 6 cycles of elimination, the sensitivity of the original susceptible strain of M. domestica to propoxur had a 13.87 fold increase. The investigation result showed that more than 40% of the natural population in Beijing had insensitive AChE. Conclusion Carrying insensitive AChE, the susceptible strain of M. domestica should be subject to further reverse selective breeding. The natural population was resistant to propoxur. Hence, the application of this pesticide should be stopped and replaced with an alternative to avoid or delay the development of pesticide resistance.

Objective To identify the body and subcellular distribution of acetylcholinesterase (AChE) activities in the Blattella germanica. Methods The AChE activities in different body parts and subcells were determined. Results The AChE activities in the head, chest and abdomin of male adults were 56.9%, 19.5% and 23.6% of the total activity, respectively. The difference in activity between the three body parts was statistically significant (F＝127.96，P＜0.05), where the AChE activity in the head was significantly higher than those in the chest and abdomen (P＜0.001). The subcellular organelles in descending order of the total and specific AChE activity were: mitochondria＞microsomes＞cytoplasmic solution＞nuclei and cell debris. Conclusion AChE activities were distributed in the head, chest and abdomen of B. germanica, with the highest in the head accounting for more than 50% of the overall activity. Subcellular distribution showed the highest AChE activity distribution in the mitochondria, accounting for almost 50% of the total activity.

【Abstract】 Objective To screen resistance?related gene from the susceptible strains and field resistant strains of Blattella germanica by comparing their gene expression products. Methods Based on the known B.germanica sequence information released by NCBI database, the oligonucleotide probes were designed and synthesized. The oligonucleotide microarray was employed to analyze the expression profile of susceptible and resistant strains and differential expression genes associated with resistance were screened out. The results were confirmed by real time RT?PCR. Results Five differential expression genes were screened out, including three of up?regulated genes (fold change≥2) such as CYP6K1,  alpha?amylase mRNA and aspartic protease precursor and two of  down?regulated  genes (fold change≤0.5) like allergen Bla g 6.0101 mRNA and allergen Bla g 8 mRNA. Conclusion It is possible to screen out differential expression gene by self?made gene chip, and CYP6K1 is perhaps closely related to resistance.

Objective To study the role of carboxylesterase in the development of organophosphate resistance and the activity variance of carboxylesterase in different strains of German cockroach( Blattella germanica).Methods Relationship between carboxylesterase and organophosphate resistance in German cockroach was studied with bioassay,biochemical analysis and synergistic test.The cockroaches from the susceptible strain(SS) of laboratory and field strains of different areas in Beijing [Xuanwu(XW) district,Changping(CP) district,Shunyi(SY) district and Shijingshan(SJS) district] were used as test insects. Results The synergistic test showed that synergistic ratio of TPP to malathion and dichlorvos were 1.86 and 1.51 fold in susceptible strain,respectively.And in field strains(XW,CP,SY and SJS),they were 5.79,20.08,15.26 and 4.74 fold for malathion,respectively and 2.00,1.67,2.16 and 4.81 fold for dichlorvos,respectively.There was significant difference between the Michaelis-Menten constants( K _m) and the maximum velocity( V _max) of carboxylesterase from two strains of German cockroach.The K _m and V _max of caboxylesterase in susceptible strain were 0.1580 mmol/L and 58.4225 μmol/(mg pro·min),respectively.And in field strains(XW,CP,SY and SJS),the K _m and V _max of carboxylesterase were 0.1279,0.1071,0.1080,0.1095 mmol/L and 307.2550,338.5755,340.3300,212.4570 μmol/(mg pro·min),respectively.The inhibition medium concentration(I ₅₀) of malathion and dichlorvos to caroxylesterase from SS strain were 17.64 mmol/L and 0.91 μmol/L,respectively.For field strains,the I ₅₀ of malathion were 80.48,35.49,83.24 and 82.29 mmol/L,respectively,and that of dichlorvos were 15.35,7.89,11.52 and 8.60 μmol/L respectively.The inhibition of malathion and dichlorvos to caroxylesterase from SS strain(I ₅₀ were) was much lower than from field strains strain(XW,CP,SY and SJS).Conclusion The enhancement of detoxification activity was one of resistance mechanism to organophosphate in German cockroach.

Objective Discrimination dosages of 5 insecticides to adult mosquito of Culex pipiens pallens were calculated from full long-dosage probit line which was established by known "susceptible" strains.Methods Mosquitoes were tested by WHO test kits with mortality assessed after 24 hours.Results Discrimination dosages of dichlorvos,deltamethrin,lambda-cypethrin,permethrin and allethrin to adult mosquito of Cx.pipiens pallens were 3300,7700,7900,250 and 200 mg/L,respectively.Conclusion Discrimination dosages of 5 insecticides to adult mosquito could be used for the resistance detection of Cx.pipiens pallens in China.

Objective To confirm the resistance status of Blattella germanica through studying its carboxylesterases(CarE) characteristics systemically and establish a quick, accurate and simple detection method. Methods The optimal concentrations of CarE and substrate, pH, temperature and reaction time of the reaction system, were determined by orthogonal matrix methods. And the optimal group was selected in the experiment. The data was analyzed with range analysis and analysis of variance. Results The results revealed that there were significant difference among various levels of the selected five factors which affected specific activity of CarE from Blattella germanica. The optimal levels of A (CarE concentration), B (substrate concentration), C (reation time), D (reation temperature) and E (pH of reation system) were A ₄ (0.35 head/ml), B ₃ (0.6 mmol/L), C ₁ (5 minutes), D ₄ (40 ℃) and E ₂ (pH 6.5), respectively. The results of range analysis and variance analysis indicated that the optimal combination was A ₄B ₃C ₁D ₄E ₂, and the maximum specific activity of CarE was 37.286 μmol/(mg pro·min) determined under the optimal conditions. The effect of factors on CarE specific activity were in the order of temperature>time>substrate>enzyme concentration>pH. Conclusion The optimal condition were: 0.35 head/ml, 0.6 mmol/L substrate, 5 mintues, 40 ℃, respectively.

Objective To preliminary identify biochemical mechanism of insecticide resistance by studying CO difference spectra and content of cytochrome P450 in susceptible and resistant populations of German cockroach, Blattella germanica.Methods Activity and CO difference spectra of cytochrome P450 were made by method of Omura and Sato.Results The CO difference spectrum of Cyt P450 in susceptible strain showed maximal absorbance at 450 nm,but the absorption maximum was not observed at 450 nm in resistance population and the absorption in 420 nm was in evidence.Conclusion The results indicated that cytochrome P450 was correlated with resistance to insecticide in resistant strains of German cockroach.

Objective To preliminarily identify biochemical mechanism of insecticide resistance by comparing the activities of CarE in susceptible and 9 field resistant populations of German cockroach, Blattellagermanica in Beijing.Methods Activity of CarE was tested by methods of Asperen and GAO Xi-wu.Results The activity of carboxylesterase in resistance strains was higher than that in the susceptible strain.The affinity of CarE was much higher toward α-naphthyl acetate( α-NA) than toward β-naphthyl acetate(β-NA) in both susceptible and resistant strains,but the affinity of CarE was much higher toward α-NA in susceptible strain than that in resistance strains.Activity of CarE was increased in 8 of 9 field populations collected from Beijing,relative resistance ratio ranged from 1.23 to 2.83 fold.Conclusion The results suggested that insecticide resistance in German cockroach field populations may be correlated with elevated activity of CarE.

Objective:To preliminaty identify biochemical mechanism of insecticide resistance by comparing activities of Acetylcholinesterase(AChE) and Glutathione S-transferase(GSTs) amorg different field strains of German cockroach, Blattella germanica in Beijing.Methods:Activity of AChE and GSTs were made by methods of Gorun and Habig respectively.Results:Biochemical analysis showed that there was significant difference in AChE and GSTs activities of different stains.Activity of s AChE and GSTs was elevated in 4 strains,of which the activity of AChE and GSTs in KFQ strain and BYS strain was 1.57 fold and 2.33 fold respectively compared with susceptible strain.Activity of AChE and GSTs was decreased in one strain,activity of AChE was elevated but activity of GSTs was decreased in other 3 strains.Conclusion:Insecticide resistance in German Cockroach field strains may be correlated with elevated activity of AChE and GSTs,and involved multiple resistant mechanism.