OBJECTIVES: To investigate how larval feeding regimens influence development and deltamethrin resistance of Aedes albopictus to provide evidence for standardizing larval feeding protocols in studies of insecticide resistance. METHODS: Aedes albopictus larvae of a laboratory resistant strain were divided into 3 groups (n=500) and reared with high, medium, and low food availability (100, 50, or 25 mg daily for the 1st and 2nd instars, and 500 mg 250, or 125 mg daily for 3rd and 4th instars). The developmental time, pupation rate, adult emergence rate, adult body weight, and wing length were recorded in each group, and deltamethrin resistance of the mosquitoes was assessed using larval bioassays and contact tube tests for adults. RESULTS: Significant developmental differences were observed across the 3 feeding groups. Larval development time decreased as the food availability increased, and both high- and low-food groups showed reduced pupation rates (χ²=16.282, 7.440) and emergence rates (χ²=4.093, 6.977) compared to the medium-food group. Adult body weight and wing length were positively correlated with the amount of larval food intake (P<0.05). In high, medium and low food intake groups, larval LC₅₀ values for deltamethrin were 0.110, 0.072 and 0.064 mg/L, adult KDT50 values were 97.404, 68.964 and 65.005 min, and adult mosquitoe mortality rates at 24 h after deltamethrin exposure were 12%, 16% and 19%, respectively. CONCLUSIONS The feeding amount during larval stage significantly impacts the development and deltamethrin resistance of Aedes albopictus, suggesting the importance of standardization of larval nutrition for ensuring comparability of resistance test data across laboratories.
Animals ; Aedes/physiology* ; Pyrethrins/pharmacology* ; Nitriles/pharmacology* ; Larva/physiology* ; Insecticide Resistance ; Insecticides/pharmacology* ; Feeding Behavior

OBJECTIVETo explore the effects of λ-cyhalothrin on hippocampus by interfering with estrogen.

METHODSThe healthy female ICR mice of postnatal 28 days were random divided into 12 groups, 4 of those were sham-operation include control, λ-cyhalothrin (LCT, 3.0 µg/g), Letrozole (Let, 1.0 µg/g), and LCT (3.0 µg/g)+Let (1.0 µg/g); and the last 8 were ovariectomized include OVX, Estradiol (E2, 10.0 µg/g), LCT, Let, E2+LCT, E2+Let, LCT+Let, E2+LCT+Let. 10 mice in every group received drugs by intraperitoneal injection for 2 days. Then half of every group initiate the ethological test (open field test and Morris water maze) 24 h later. The last half animals were sacrificed to made frozen section for immunofluorescent assay of postsynaptic density protein 95 (PSD95).

RESULTSIn ethological test, campared with Sham, OVX can lengthen incubation period in the first grid and to get on the platform (P < 0.05); campared with OVX, OVX+E2 can increase the total numbers of through grid and shorten the incubation period to get on the platform (P < 0.05); campared with OVX+E2, OVX+E2+LCT can reduce the number of grid and standing, lengthen incubation period to the platform (P < 0.05); campared with Sham, Sham+LCT can lengthen incubation period to the platform of Sham mice (P < 0.05), but campared with OVX, OVX+LCT can shoten incubation period in the first grid and to get on the platform in OVX mice (P < 0.05); campared with Sham+Let, Sham+LCT+Let can lengthen incubation period in the first grid, reduce the the number of grid and standing (P < 0.05). In the Immunohistochemical fluorescence experiment we find that, campared with Sham, OVX can reduce the expression of PSD95 in CA1,CA3 and DG (P < 0.05); however campared with OVX, E2 or LCT can both inhibit the effect of OVX (P < 0.05); campared with Sham, Sham+LCT can reduce the expression of PSD95, the same result when OVX+E2+LCT campared with OVX+E2 (P < 0.05); campared with OVX+E2+Let, OVX+E2+LCT+Let can reduce the expression of PSD95 in CA3 (P < 0.05); campared with OVX+Let, OVX+LCT+Let can increase the expression of PSD95 in DG (P < 0.05).

CONCLUSIONSWhen few estrogen exist in the body, LCT can show estrogen-like action to promote hippocampal synaptic development; but when circulating estrogen exist, LCT can inhibit synaptic development by interfering estrogen.

Animals ; Estradiol ; Estrogens ; pharmacology ; Female ; Hippocampus ; drug effects ; Humans ; Mice ; Mice, Inbred ICR ; Nitriles ; pharmacology ; Ovariectomy ; Pyrethrins ; pharmacology ; Random Allocation ; Synapses ; drug effects ; Triazoles

OBJECTIVETo investigate whether fenvalerate can induce mouse hippocampal nerve cell damage by interfering with estrogen (E2) effect.

METHODSHippocampus were dissected and cultured from Embryo 18 d ICR mice, the cells were cultured for 7 days. Fenvalerate (FEN, 0, 1, 10, 50 µg/ml), FEN (10, 50 µg/ml) and estrogen receptor antagonist ICI 182, 780 (1 µmol/L), FEN (0, 10, 50 µg/ml) and E2 (10 nmol/L) were applied to the cultured cells for 48h. Immunocytochemically stained with neurons and astrocytes to evaluate the levels respectively, and the growth of neurite. Result 1µg/ml FEN have no effect on neurons, neurites and protoplasmic astrocytes, 10 and 50 µg/ml FEN can significantly decrease the neuron viability and the length of neurite as well as increase the level of protoplasmic astrocytes (P < 0.05 vs. control group). ICI 182, 780 alone have no effect on neurons, neurites and protoplasmic astrocytes; ICI+10 µg/ml FEN significantly increase the cell viability and extend neurite length as well as decrease protoplasmic astrocytes (P < 0.05 vs. 10 µg/ml FEN alone group); ICI+50 µg/ml FEN significantly increase the cell viability and decrease protoplasmic astrocytes (P < 0.05 vs. 50 µg/ml FEN alone group). E2 alone have no effect on protoplasmic astrocytes, while can promote neuronal survival and neurite growth; E2+10 µg/ml FEN and E2+50 µg/ml FEN significantly decrease neuronal survival and neurite growth, as well as increase protoplasmic astrocytes (P < 0.05 vs. E2 alone group).

CONCLUSIONFenvalerate can induce the loss of hippocampal neurons through disrupting estrogen nuclear receptor signaling, and inhibit the length of neurite through disrupting estrogen nuclear receptor and membrane receptor signaling. The effect of estrogen disruption play an important role in developmental neurotoxicity by fenvalerate.

Animals ; Astrocytes ; drug effects ; Cells, Cultured ; Estrogens ; pharmacology ; Hippocampus ; drug effects ; pathology ; Mice ; Mice, Inbred ICR ; Neurons ; drug effects ; pathology ; Nitriles ; toxicity ; Pyrethrins ; toxicity

OBJECTIVETo investigate the estrogen interference property of fenvalerate in neurodevelopmental toxicity.

METHODSThirty 4-week-old healthy female ICR mice were randomly divided into 6 groups: sham operation group, ovariectomized control group, ovariectomized with estrogen (10 µg/g) group, ovariectomized with fenvalerate (5 µg/g) group, sham operation with fenvalerate group, and ovariectomized with estrogen and fenvalerate group, with 5 mice in each group. Fenvalerate was injected intraperitoneally once a day for 7 consecutive days. Mice were sacrificed at 24 h after the last exposure to separate the hippocampus. Immunofluorescence was used to detect neuron marker (NeuN) and astrocyte marker (GFAP) in hippocampal CA1, CA3, and DG regions.

RESULTSCompared with the sham operation group (numbers of NeuN-positive cells: CA1 (54.00±1.73), CA3 (59.00 ± 1.73), DG (100.00 ± 4.58)), the sham operation with fenvalerate group (CA1 (37.67 ± 2.08), CA3 (41.33 ± 1.15), DG (80.67±0.58)) and ovariectomized control group (CA1 (44.00 ± 3.00), CA3 (51.00 ± 3.00), DG (83.00 ± 1.72)) showed significant decreases in number of neurons (NeuN-positive cells) in the hippocampus (P < 0.05). Compared with the ovariectomized control group, the ovariectomized with fenvalerate group (CA1 (47.67 ± 3.21), CA3 (49.00 ± 1.73), DG (87.33 ± 4.04)) showed no significant change in number of hippocampal NeuN-positive cells. Compared with the ovariectomized with fenvalerate group (CA1 (47.67 ± 3.21), DG (87.33 ± 4.04)), the sham operation with fenvalerate group and ovariectomized with estrogen and fenvalerate group (CA1 (40.00 ± 1.00), DG (78.67 ± 2.31)) experienced significant decreases in NeuN-positive cells (P < 0.05). Compared with the sham operation group (CA3 (11.00 ± 1.12), DG (10.67 ± 1.15)), the sham operation with fenvalerate group (CA3 (18.67 ± 2.07), DG (16.33 ± 1.53)) showed significant increase in number of astrocytes (GFAP-positive) cells (P < 0.05). Compared with the sham operation with fenvalerate group, the ovariectomized with fenvalerate group (CA3 (12.00 ± 1.00), DG (11.68 ± 1.16)) showed significant decrease in GFAP-positive cells (P < 0.05). Compared with the ovariectomized with fenvalerate group, the sham operation with fenvalerate group and ovariectomized with estrogen and fenvalerate group (CA3 (16.67 ± 2.13), DG (15.38 ± 1.42)) showed significant increases in GFAP-positive cells (P < 0.05).

CONCLUSIONThe interference with circulating estrogen is an important mechanism underlying the neurodevelopmental toxicity of fenvalerate.

Animals ; Estrogens ; pharmacology ; Female ; Hippocampus ; drug effects ; pathology ; Mice ; Mice, Inbred ICR ; Neurons ; drug effects ; pathology ; Nitriles ; toxicity ; Ovariectomy ; Pyrethrins ; toxicity

OBJECTIVETo evaluate effects of cypermethrin on the testis histology and testosterone, LH and FSH in adult male Sprague-Dawley rats.

METHODSThe intact adult male rats were randomly divided into five groups and were treated with cypermethrin at doses of 0, 7.5, 15, 30, or 60 mg/kg per day by oral gavage for 15-days. After the treatments, serum was collected for hormone assays. The testes, epididymides, seminal vesicles, and prostates were excised and weighed. The right testis was frozen for daily sperm production and the left one was processed for histopathology.

RESULTSDaily sperm production decreased significantly in 30 and 60 mg/(kg•day) groups. Testicular structure abnormalities included atrophic and distorted seminiferous tubules, deformed and disordered arrangement of germ cells, reduced germ cells, Sertoli cells and Leydig cells, vacuolization and multinucleated formations of spermatids in the cypermethrin-treated rats. Vacuolization was found in Sertoli cells and the deformed nucleus was noted in Leydig cells. Serum testosterone reduced significantly in 30 and 60 mg/(kg•day) groups. Serum FSH increased significantly in 60 mg/(kg•day) group.

CONCLUSIONCypermethrin induces impairments of the seminiferous tubules structure and spermatogenesis in the rats. The damages of the male reproductive system may be attributed to the imbalance of circulating testosterone.

Animals ; Epididymis ; drug effects ; Male ; Prostate ; drug effects ; Pyrethrins ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Seminal Vesicles ; drug effects ; Spermatogenesis ; drug effects ; Testis ; drug effects ; Testosterone ; blood

BACKGROUNDFenvalerate (FEN) has been demonstrated to be a reproductive toxicant in humans and rodents. However, little is known about whether short-term exposure to low-dose FEN produces reproductive toxicity.

METHODSWe administered FEN (0.009 375, 0.1875, 3.750, or 45.00 mg×kg(-1)×d(-1) by gavage for 30 days) to male ICR mice and compared reproductive toxicity parameters between groups receiving different concentrations of FEN. Reproductive toxicity was evaluated by computer-assisted semen quality analysis (CASA), chlortetracycline (CTC) assay, and histopathology.

RESULTSThe sperm morphology and testis histology of FEN-exposed mice (all doses) were similar to that in controlling mice. Exposure to FEN at a concentration of 0.1875 mg×kg(-1)×d(-1) decreased sperm path straightness (STR) and linearity (LIN) (both P < 0.05), but had no significant impact on average path velocity (VAP), straight line velocity (VSL), curvilinear velocity (VCL), lateral amplitude (ALH), beat cross frequency (BCF), or progressive motility (MOT). FEN reduced the rate of mouse sperm capacitation in a dose-dependent manner.

CONCLUSIONThe present results demonstrate that exposure to low-dose FEN for 30 days reduces semen quality and sperm capacitation in adult mice.

Animals ; Body Weight ; drug effects ; Humans ; Male ; Mice ; Mice, Inbred ICR ; Nitriles ; pharmacology ; Organ Size ; drug effects ; Pyrethrins ; pharmacology ; Semen ; drug effects ; Semen Analysis ; Sperm Motility ; drug effects ; Testis ; drug effects

OBJECTIVETo study the protective effect of MG-132 on hippocampus cells apoptosis induced by deltamethrin (DM), one kind of pyrethroid pesticide.

METHODS40 Male wistar rats were randomly divided into four groups: olive oil control, DM treated alone (12.5 mg/kg), MG-132 (0.5 mg/kg) plus DM group, MG-132 treated 2h plus olive oil. After 24h treatment of DM, the hippocampus was taken out to detect the apoptotic cell rate, the level of bcl-2 and Caspase-3 activity.

RESULTSCompared with DM treated alone group (27.29% +/- 2.41%), the apoptotic cell rate in MG-132 + DM group (19.94% +/- 2.07%) was increased (P < 0.05), bcl-2 expression was enhanced [(0.43 +/- 0.06) vs. (2.01 +/- 0.23)] (P < 0.05) and the activity of Caspase-3 was decreased significantly (P < 0.05) in MG-132 treated 2h plus DM group [(4.55 +/- 0.46) vs.(3.73 +/- 0.35)].

CONCLUSIONMG-132 can protect hippocampus cells against apoptosis induced by deltamethrin.

Animals ; Apoptosis ; drug effects ; Hippocampus ; cytology ; drug effects ; Insecticides ; toxicity ; Leupeptins ; pharmacology ; Male ; Neurons ; drug effects ; Nitriles ; toxicity ; Pyrethrins ; toxicity ; Rats ; Rats, Wistar

Animals ; Cells, Cultured ; Interleukin-1beta ; pharmacology ; Male ; Neurons ; drug effects ; metabolism ; Nitric Oxide ; metabolism ; Nitriles ; toxicity ; Pyrethrins ; toxicity ; Rats ; Rats, Sprague-Dawley ; Sodium-Potassium-Exchanging ATPase ; metabolism

OBJECTIVETo study the damage of Agrotis ypsilon on Scrophularia ningpoensis and the control method, so as to provide scientific basis for its integrated pests management (IPM).

METHODThe field investigation and the field controlling trial were carried out for the research.

RESULTThere is obvious relationship between the pre-season crops and the damage degree of S. ningpoensis. The damage rate of the fields which had planted maize and tobacco in the last planting season was much higher than that of the other fields. The average damage rate could reach 12.43% and 15.68%. The result of five pesticides against A. ypsilon in field trial showed that the controlling effect of 10% beta-cypermethrin EC 2000 times and 40% chlorpyrifos EC 1500 times were 92.53% and 91.69%, respectively.

CONCLUSIONA. ypsilon could be well controlled while 10% beta-cypermethrin EC or 40% chlorpyrifos EC are sprayed during the period of seedling.

Animals ; Chlorpyrifos ; pharmacology ; Insect Control ; methods ; Insecticides ; pharmacology ; Moths ; drug effects ; physiology ; Plant Diseases ; parasitology ; Pyrethrins ; pharmacology ; Scrophularia ; parasitology

OBJECTIVETo investigate the diversity of acetylcholinesterase (AChE) activity in variety classes and strains of Culex pipiens pallens and provide a basis for the insecticide-resistance detection of mosquito by biochemical method.

METHODSAChE insensitivity of single mosquito was determined, using acetythiocholine iodide (ATch) as the substrate, 5,5'-dithio-bis (2-nitrobenzoic acid) (DTNB) as the developer, and propoxur as the inhibitor.

RESULTThere were significant differences in AChE activity among the four types of IV instar larvae and 3-day-old adult female of sensitive strain mosquito (P<0.01). The AChE activity of the 3-day-old adult female was higher than that of IV instar larvae of the four types of sensitive strain mosquito (P<0.01). The AChE activity of anti-DDVP (Rd) and anti-propoxur (Rp) strains of Culex pipiens pallens was significantly higher than that of sensitive (S) strain (P<0.01), while the AChE activity of anti-cypermethrin (Rc) strain of Culex pipiens pallens was similar to that of S strain (P>0.05). The individual frequency of insensitive AChE of Rd and Rp strains of Culex pipiens pallens was significantly higher than that of sensitive (S) strain (P<0.01), while the individual frequency of insensitive AChE of Rc strain of Culex pipiens pallens was similar to that of S strain(P>0.05).

CONCLUSIONThe AChE activity determination can be used to examine the insecticide-resistance of mosquito.

Acetylcholinesterase ; metabolism ; Animals ; Culex ; classification ; enzymology ; Dichlorvos ; pharmacology ; Female ; Insecticide Resistance ; Propoxur ; pharmacology ; Pyrethrins ; pharmacology ; Species Specificity