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The Chinese citrus fruit fly, Bactrocera minax is one of the most economically important and aggressive pests threatening the Chinese citrus industry. In order to provide some recommendations for the improvement of integrated pest management of this species, the authors evaluated the toxicity of 6 insecticides on the second stage larvae, fourth stage larvae, and adult flies from multiple geographical B. minax populations. In addition, the influences of each pesticide on pupation and emergence were examined for one population, from Hanzhong. The 6 reagents displayed a wide range of toxicity on various stages of B. minax. Abamectin and Dichlorphos displayed the highest and lowest toxicities, respectively. All of the insecticides had negative effects on pupation and emergence of B. minax from Hanzhong, while Chlorpvrifos had the strongest impact on pupation, and Phoxim had the strongest influence on emergence. Though Phoxim and Chlorpvrifos were both effective, these insecticides belong to the class of organophosphorus pesticides, and their use should be reduced in orchards because of their high toxicity and long residual period.

The inhibition kinetics on carboxylesterase (CarE) and acetylcholinesterase (AChE) of Liposcelis bostrychophila and Liposcelis entomophila of paraoxon and carbosulfan were compared. The results showed that L. entomophila exhibited significantly greater specific activity of CarE than L. bostrychophila [0.045 vs. 0.012 μmol of α-naphthyl acetate (a-NA) hydrolysed/mg protein/min]. Moreover, L. entomophila showed higher affinity (i.e. lower K m value) to the substrate α-NA than L. bostrychophila (0.29 vs. 0.67 mM). For AChE-specific activity and affinity, no significant differences between the two species were observed. Based on the I 50 values, AChE of L. bostrychophila was more sensitive to paraoxon and carbosulfan than that of L. entomophila. According to inhibition kinetics, the results revealed that AChE of L. bostrychophila was 3.8-fold more sensitive to inhibition by paraoxon than that of L. entomophila, but L. entomophila was 1.5-fold more susceptible to carbosulfan.

The differences of bionomics and ecologies of the two populations of Callosobruchus chinensis on mung bean (Vigna radiatus) at six constant temperatures (20, 25, 28, 30, 32, 35°C) and 75% r. h. were researched. ANOVA showed that temperature affected the developmental period and fertility significantly (P < 0.05). T-test indicated there was significant difference of the combined immature stages between the two geographical populations at 25 and 32°C (P < 0.05). The average oviposition between the two geographical populations differed significantly at the same temperature (P < 0.05). At 30°C and 75% r. h., effects of 5 commercially grown legume seeds on development and reproduction of the two geographical populations of Callosobruchus chinensis (L.) were researched. The results showed that broad bean and soybean were more suitable for increase for Xichang population in terms of rm values. The adult weight and diameter of emergency hole of the two populations were also compared. According to the differences in the characteristics of development, reproduction, and damage to host seeds between the two geographical populations, conclusion can be drawn that both are different geographical populations.

The effects of controlled atmosphere (CA) and DDVP on population growth and resistance development by the psocid, Liposcelis bostrychophila Badonnel, were studied in the laboratory. Results indicated that the population of L. bostrychophila increased rapidly under natural conditions; after 11 weeks, this population had increased 48.1-fold at 28°C, 80% relative humidity (r.h.). Exposure to CA (35% CO 2 , 1% O 2 ) or DDVP (Dichlorvos, 0.3 mg/ml) alone failed to control the population growth. After 11 weeks, populations increased 4.3- and 9.1-fold, respectively. However, alternating exposure to CA and DDVP provided a significant increase in mortality as compared to those exposed to CA or DDVP alone. The results of bioassay showed that both populations exposed to CA and DDVP developed a low but significant resistance to CA and DDVP, respectively. After six exposures, the level of resistance to CA and DDVP increased 1.8- and 2.0-fold, respectively. Probit analysis did not show an appreciable increase in slope value of either population in spite of continuous exposures, indicating considerable heterogeneity of these psocids in response to CA or DDVP and suggesting a greater potential for the development of higher levels of resistance. It is suggested that alternating CA with insecticides could be an important management measure for psocids in storage.

Six plant essential oils alone as repellent and fumigant, and in combination with the controlled atmosphere against Liposcelis bostrychophila Badonnel were assessed in the laboratory. These essential oils were extracted from the leaves of six source plants: Citrus tangerina Tanaka, Citrus aurantium L., Citrus bergamia Risso et Poiteau, Pinus sylvestris L., Cupressus funebris Endl., and Eucalyptus citriodora Hook. The repellency test indicated that L. bostrychophila adults were repelled by filter paper strips treated with six essential oils. Of these essential oils, the C. funebris oil was most effective followed by that of P. sylvestris, C. tangerina, C. bergamia, and E. citriodora. The average repellency of the C. aurantium oil against L. bostrychophila adults was significantly lower than other five test oils by day 14. These essential oils had a high level of toxicity in the fumigation assay against L. bostrychophila adults at both 10 and 20 ppm. When combined with two controlled atmosphere tre...

The interactive effects on the development, survivorship and reproduction of Liposcelis bostrychophila Badonnel, of two biologically relevant controlled atmosphere (CA) environments 10% CO2 + 5% O2, and 12%CO2 + 9% O2, were determined at eight constant temperatures (17.5, 20, 22.5, 25, 27.5, 30, 32.5 and 35°C) in the laboratory. The life cycle parameters measured under nonmodified atmosphere conditions served as a control. A population reared at 17.5°C failed either to develop or to reproduce regardless of atmospheric conditions, whereas populations reared under combined conditions successfully completed their life cycles. However, development, survivorship, and reproduction were all inhibited by hypoxia and hypercarbia compared with the control atmosphere. Egg development was more sensitive to 12% CO2 than to 10% CO2 exposure. Nymphal development, survivorship, and reproduction were more sensitive to 5% O2 (10% CO2) than 9% O2 (12% CO2). Sensitivity was evident at higher temperatures. The first and secon...

Liposcelis tricolor Badonnel (Psocoptera: Liposcelididae) is worldwide and commonly found in various processed and unprocessed dry foods in households, granaries, and warehouses. The development, survival, and reproduction of L. tricolor were evaluated at eight constant temperatures (20, 22.5, 25, 27.5, 30, 32.5, 35, and 37.5°C). The population reared at 37.5°C failed to develop or reproduce. Between 20 and 35°C, developmental period from egg to adult varied from 56.37 d at 20°C to 30.74 d at 32.5°C. Based on a nonlinear model, the lower temperature developmental thresholds from egg, first through fourth stadia, and combined immature stages were estimated at 9.57, 9.02, 10.04, 13.69, 14.38, and 11.30°C; the upper temperature thresholds were 39.28, 37.55, 37.85, 38.26, 37.37, and 38.98°C, respectively. The survival rate from egg to adult was 67.26% at 27.5°C, 43.62 and 24.22% at 20 and 35°C, respectively. After emergence, the adult had a preoviposition period that ranged from 65.74 d at 20°C to 3.52 d at 30°C. L. tricolor produced the most eggs (53.91) at 27.5°C and the fewest (17.58) at 35°C. The population reared at 30°C had the highest intrinsic rate of increase (0.0367), net reproductive rate (13.55), the shortest populations doubling time (18.89 d), and shorter mean generation time (71.05 d) compared with the populations reared at six other constant temperatures. The populations reared at 30°C had type I survivorship pattern, whereas populations reared at other temperatures had type III survivorship curve as determined by a Weibull frequency distribution. The optimal range of temperature for L. tricolor population growth was 25–30°C.

Adults of the psocid Liposcelis bostrychophila Badonnel were exposed to atmospheres containing 35% and 55% CO2 for 30 generations to select strains resistant to high CO2 content (HCC). Selection pressure was maintained at around 70% of mortality. At the 30th generation, comparison of sensitivities between the selected strains (HCC1 and HCC2) and the original susceptible strain (MA-S) revealed a resistance factor (RF) at the 50% mortality level (LT50) of 4. 6-and 5. 3-folds, respectively. Throughout the selection process, log-time against probit-mortality lines remained roughly parallel and the slopes remained lower than that of MA-S strain until the last generation. It is inplied that the genetic potential of L. bostrychophila to develop resistance to CO2 was not exhausted until the 30th generation. Removal of selection pressure for 5 generations from 2 sub-populations of two selected strains from the 25th generation caused significant reduction in resistance. In the absence of MAs exposure, the two selected strains (HCC1 and HCC2) possessed the fitness defect. HCC1 and HCC2 were calculated by R0 to have a fitness value of 0. 52 and 0. 45 relative to MA-S.

This paper deals with the biological characteristics of the psocid Liposcelis entomophila (Enderlein) on a diet composed of whole wheat flour and yeast (10: 1) under different temperatures (17.5–35C) and relative humidities (50%-90% RH). The results showed that at 75% RH development time from egg to adult varied from 71. 9 d at 20% to 21.7 d at 35C. At 28C it varied from 23.0 d at 90% RH to 34.4 d at 60% RH. The development threshold and the effective accumulated temperature for entire immature stages were estimated at 15. 7C and 460. 7 day-degree, respectively. The survival rate from egg to adult was 64. 5% at 27. 5C while at 20C and 35C it was only 32.1% and 37. 0%, respectively. At 28C the survival rate ranged from 31. 2% at 60% RH to 67.8% at 80% RH. L. entomophila could not survive at any humidity at 17. 5C and below 50% RH. The average longevity of adult ranged from 32.4 d at 35C and 64.4 d at 20C. At 75% RH the mean egg production varied from 27.1 at 27. 5 C and 13. 9 at 20C and the greatest fecundity occurred at 90% RH with 28C. The optimal ranges of temperature and humidity for L. entomophila population growth were 27. 5–30C and 80%—90% RH. The distribution and the reason for its serious infestation in China are discussed.

With bare land, farmland, and masson pine forestland in the Eupatorium adenophorum- invaded area of Dechang County, Sichuan Province as test habitats, this paper studied the seed population dynamics of E. adenophorum at the levels of seed rain and seed bank, and its seed germination characteristics under effects of light and soil medium. The results showed that in the three habitats, the seed population of E. adenophorum only existed from March to June, and reached its peak by the end of April. The annual seed rainfall in bare land habitat amounted to 2.4 x 10(5) individuals per square meter, and all the seeds were distributed in the soil layer above 2 cm. The thousand seed weight and seed activity of E. adenophorum in bare land habitat were significantly higher than those in another two habitats. No active seed was found in the three habitats by the first ten days of July. Under artificial light condition, full light had some inhibitory effects on seed germination, while 28% of full light gave the highest germination rate. Sandy loam soil was more favorable for the seed germination, while in un-reclaimed red soil, both the germination velocity and germination rate were the lowest.

The simulation study under laboratory condition showed that the functional responses of Typhlodromus bambuse to Schizotetranychus bambuse at different development stages could be expressed by the curve of Holling Type II. The number of prey consumed by predator quickly increased with initial prey density, but soon leveled off. At 25 +/- 0.5 degrees C, the handling time (Th) of T. bambuse to S. bambusae at the stages of egg, larva, protonymph, deurtonymph and female was in order of egglarvaprotonymphdeurtonymphfemale, and the selection coefficient (Q) of T. bambusae to S. banzbusae egg, larva, protonymph, deurtonymph and female adult was 1.47, 1.34, 1.16, 0.90 and 0.15, respectively. The numerical response of T. bambusae to S. bambusae revealed that the fecundity of the Phytoseiidae mite was significantly affected by the prey density. When the ratio of predator to prey was 1: 1-9, the daily oviposition of the predator varied from 0.5 to 2.0 eggs per female, which was increased with increasing prey density, while if the ratio was 1:15 or more, the daily oviposition decreased to about 1.8 eggs per female, which was probably due to the interference of high prey density to predation.

In a series of laboratory trials, this paper studied the responses of eggplant (Solanum melongena), the host plant of carmine spider mite Tetranychus cinnabarinus, to different pH values simulated acid rain. The results showed that with the increasing acidity of simulated acid rain, the CAT activity and the contents of P and soluble protein in egg plant leaves increased significantly first, reaching the highest at pH 4.0 or 3.0, and then decreased; while the POD activity and soluble sugar content were in adverse. The reduced sugar content and SOD activity of eggplant leaves increased, but the pH value decreased with increasing acidity of acid rain. Acid rain had no effect on leaf water content. Among the test indices, leaf POD was most insensitive to the acid rain, followed by leaf pH, SOD and CAT, while the others were very sensitive. Weak acid rain (pH4.0) promoted the protective ability of eggplant leaf and its growth, and the growth of T. cinnabarinus was also promoted because of the changed contents of soluble sugar, P and soluble protein in eggplant leaves being more favorable to its eating; while strong acid rain (pH3.0) inhibited the growth of both host plant and mite.

Development, survivorship, reproduction and procreation isolation of Schizotetranychus bambusae from the bamboo species Phyllostachys pubescens and Neosinocalamus affinis reared on different host plants were evaluated in laboratory. The results showed that the population of S. bambusae from Phyllostachys pubescens (PhS) failed to complete its life cycle when reared on the leaf of N. affinis. When the population of S. bambusae from N. affinis (NeS) was reared on the leaf of P. pubescens, the survivorship and fecundity decreased. The rm, lambda and Ro were 0.0391, 1.0399 and 2.5542, respectively. At 27 degrees C, when the PhS was reared on P. pubescens, rm, lambda and Ro were 0.1415, 1.1520, and 15.6298, respectively, whereas NeS was reared on N. affinis, rm, lambda, and Ro were 0.0993, 1.1044, and 10.0622, respectively. Reciprocal cross test between PhS and NeS showed tht the two populations could mate, but laid unfertilized eggs that produced male only, indicating the existence of reproductive isolation.

Systematic analysis of aphid populations and niches patterns on spring sowing maize was carried out during 1998-1999 in the suburbs of Chongqing. The results indicated that there were three aphid populations Rhopalosiphum maidis Fitch., Rhopalosiphum padi Linn. and Sitobion avenae Fabricius distributed on the spring sowing maize. The mixed aphid populations traded off during the growth period of spring sowing maize, and two peaks of quantitative counts were shown at the mid and last ten days of May and the last ten days of June. In addition, the niches of aphid population were also discussed from one dimension (i.e., temporal or spatial) to two dimensions (i.e., temporal and spatial). Through the quantitative analysis of niche breadth and niche overlap, the highly temporal differentiation of M. avenae and the highly gathering character of R. maidis were all indicated. R. padi showed an indistinct differentiation, while R. maidi was a dominated population on the spring sowing maize.

Book louse Liposcelis bostrychophila is a minor pest in stored products, and may seriously infest the stored products when its population outbreaks. This study was conducted to evaluate the toxic effect of DDVP on various development stages of L. bostrychophila. The results showed that at 28 +/- 0.5 degrees C and 24 h exposure under 75%-80% RH, the LC50 of the eggs, larvae of 1st to 4th stadium, and adults was 16.83, 0.22, 0.22, 0.23, 0.26 and 0.25 micrograms.L-1, respectively. The lethal effect of DDVP on the adults at different exposure periods showed that their mortality was linearly related to the treated time, implying that the test colony of L. bostrychophila was susceptible to DDVP. In the practical fumigation, DDVP as a fumigant had a good effect on the pest control if the development stage, time and periods of treatment were appropriate.

The inhibition kinetics of dichlorvos on carboxylesterase and acetylcholinesterase (AChE) activity extracted from Liposcelis bostrychophila and L. entomophila (Psocoptera: Liposcelididae) were compared. The results showed that L. entomophila had significantly greater specific activity of carboxylesterase than L. bostrychophila (0.045 versus 0.012 µmoles /mg /min). Moreover, the carboxylexterase of L. entomophila showed higher affinity (i.e. lower Km value) to the substrate 1-naphthyl acetate than L. bostrychophila (0.29 versus 0.67 mM). The specific activity and affinity of AChE of the two species were not significantly different. The carboxylesterase of L. bostrychophila was more sensitive to the insecticide dichlorvos than that of L. entomophila. The I50s values of dichlorvos to carboxylesterase for L. bostrychophila and L. entomophila were 1.43 and 3.28 µM, respectively, and to AChE were 324 and 612 nM, respectively. Inhibition kinetics revealed that AChE from L. bostrychophila was 5.8-fold more sensitive to inhibition than AChE from L. entomophila. Abbreviation: 1-NA 1-naphthyl acetate AChE Acetylcholinesterase ATChI Acetylthiocholine iodide E3 carboxylesterse isozyme (E.C.3.1.1)

The insecticidal activity of 2% Celangulin E.C against some populations of Tetranychus cinnabarinus, including a susceptible strain (SS), a fenpropathrin-resistant strain (FeR) and an abamectin-resistant strain (AbR), was studied. Laboratory bioassays indicated that the toxicity of celangulin against the SS strain was highest, its LC50 being 1.3883mg/L, compared with pyridaben (53.8446mg/L) and omethoate (116.0337mg/L), and the toxicity of celangulin against FeR (LC50=1.3825mg/L) was almost the same as that of the SS strain, i.e. there was no cross resistance between celangulin and fenpropathrin. But the toxicity of celangulin against AbR (LC50=6.9203mg/L) was inferior to that against SS, and its LC50 value increased 4.98-fold, which showed that some cross resistance existed between celangulin and abamectin. The effect of celangulin E.C against T. cinnabarinus was higher than pyridaben and omethoate in a potted plant experiment. The dose of the celangulin's active ingredient that was needed to ob...

The survival and fecundity of the spider mite, Schizotetranychus bambusae Reck, on the detached leaves of the moso bamboo, Phyllostachys pubescens Mazel, from 1–4yr-old bamboo plants, were evaluated in the laboratory. The age-specific and time-specific life tables of the experimental populations of S. bambusae were constructed. The relationship between the population dynamics of this mite and 1–4yr-old bamboo plants was analyzed. The results showed that the survival of immature stages was 92.00%, 88.46%, 70.81%, and 94.34% when fed on the leaves from 1, 2, 3, and 4yr-old bamboo leaves, respectively. The mean number of eggs laid per female which were reared on leaves from four kinds of bamboo leaves, were 41.4, 37.3, 14.7, and 42.8, respectively. The trend index of population (I), net reproductive rate (R0), intrinsic rate of increase (rm) and finite rate of increase (λ) were 5.2073, 5.7719, 0.1117, 1.1182 on the 3yr-old bamboo leaves, respectively, and the population doubling time (DT) was the lo...

Development, survivorship, and reproduction of the mite Schizotetranychus bambusae Reck reared on fresh bamboo leaf were evaluated at 5 constant temperatures (21, 24, 27, 30, and 33°C). The development time from egg to adult varied from 16.7 d at 21°C to 7.6 d at 33°C. The developmental thresholds for egg, larva, protonymph, deurtonymph, pre-oviposition and combined immature stages were estimated at 12.4, 15.3, 14.0, 15.2, 10.7 and12.5°C, respectively. High temperature (33°C) engendered a decline in larval and protonymphal development. A modified nonlinear Logan model describing the relationship between developmental rate and temperature for all immature stages was constructed. Survivorship was highest (88.3%) at 27°C; whereas at 21 and 33°C, it came to 61.7 and 55.7%, respectively. After emergence the adult had a pre-oviposition period that ranged from 1.9 d at 21°C to 1.0 d at 33°C. The highest number of eggs (23.4) was produced at 27°C, the lowest at 33°C. The longest reproductive duration (15...

The feeding behaviour of omethoate-resistant and susceptible strains of the spider mites (Tetranychus cinnabarinus) on cowpea leaves was studied by electrical penetration graph (EPG). EPG waves of the mite feeding were divided to two forms, the high frequency (7.7–8.7 Hz) and low frequency waves (2.4–3.0 Hz), representing feeding and non-feeding behaviour respectively. The average duration of feeding periods was not significantly different between resistant and susceptible mites. However, the amplitudes of feeding waves were significantly greater in pesticide-resistant mites than susceptible mites.

The effects of simulated acid rain sprayed directly on carmine spider mite, Tetranychus cinnabarinus,were investigated in a series of laboratory trials. The indirect effects, by the induced changes of development, physiological and biochemical aspects of host plant were eliminated from this experiment. The results indicated that there was no acute lethality of sprayed simulated acid rain of pH 4.0–3.0 on the tested developmental stages of carmine spider mite. However, the developmental duration of larvae, nymph and pre-oviposition was prolonged; and the longevity of adult mite and the duration of generation were shortened. The results of the life table study showed that the mite, which was sprayed directly by the simulated acid rain of pH 4.0, 3.5 and 3.0, had lower values of the net reproduction rate (R0), innate rate of increase (rm), finite rate of increase (λ) and mean generation duration (T), and greater population doubling time (t) than controls. The results implied that the population deve...

This paper reviews the development of pesticide resistance in Tetranychus cinnabarinus (Boisduval) and studies on the genetics and management of pesticide resistance in China. This mite has developed resistance to at least 25 pesticides in China. It first developed resistance to parathion and demeton. As early as 1962, the level of resistance to demeton in T. cinnabarinus reached 62 times, which resulted in control failure of this mite on cotton in most cotton growing areas in China. The genetics of omethoate-resistance and monocrotophos-resistance in T. cinnabarinus is each controlled by an incompletely dominant gene and the development of resistance is therefore rapid. The developmental time and other life table parameters of T. cinnabarinus are altered when the mite becomes pesticide-resistant: life cycle becomes shorter and reproductive rate becomes greater. This is another reason for the rapid development of pesticide resistance in T. cinnabarinus. Pesticide resistance may be managed by rotational use of pesticides, biological control and other methods.