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Man-qun Wang - One of the best experts on this subject based on the ideXlab platform.

  • transgenic cry1c gene rough rice line t1c 19 does not change the host preferences of the non target stored product pest rhyzopertha dominica fabricius coleoptera bostrichidae and its parasitoid wasp Anisopteromalus calandrae howard hymenoptera pterom
    Ecotoxicology and Environmental Safety, 2015
    Co-Authors: Xiao Sun, Miao-jun Yan, Aijun Zhang, Man-qun Wang
    Abstract:

    Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C(⁎) gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC-MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.

  • Transgenic cry1C(⁎) gene rough rice line T1C-19 does not change the host preferences of the non-target stored product pest, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae), and its parasitoid wasp, Anisopteromalus calandrae (Howard) (Hyme
    Ecotoxicology and environmental safety, 2015
    Co-Authors: Xiao Sun, Miao-jun Yan, Aijun Zhang, Man-qun Wang
    Abstract:

    Abstract Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C⁎ gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC–MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.

Xiao Sun - One of the best experts on this subject based on the ideXlab platform.

  • transgenic cry1c gene rough rice line t1c 19 does not change the host preferences of the non target stored product pest rhyzopertha dominica fabricius coleoptera bostrichidae and its parasitoid wasp Anisopteromalus calandrae howard hymenoptera pterom
    Ecotoxicology and Environmental Safety, 2015
    Co-Authors: Xiao Sun, Miao-jun Yan, Aijun Zhang, Man-qun Wang
    Abstract:

    Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C(⁎) gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC-MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.

  • Transgenic cry1C(⁎) gene rough rice line T1C-19 does not change the host preferences of the non-target stored product pest, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae), and its parasitoid wasp, Anisopteromalus calandrae (Howard) (Hyme
    Ecotoxicology and environmental safety, 2015
    Co-Authors: Xiao Sun, Miao-jun Yan, Aijun Zhang, Man-qun Wang
    Abstract:

    Abstract Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C⁎ gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC–MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae.

Jun Abe - One of the best experts on this subject based on the ideXlab platform.

  • Sperm-limited males continue to mate, but females cannot detect the male state in a parasitoid wasp
    Behavioral Ecology and Sociobiology, 2019
    Co-Authors: Jun Abe
    Abstract:

    Female mating frequency and male ejaculate allocation are likely to interact. Females may adjust their propensity for remating based on the amount of provided sperm to ensure a sufficient sperm supply, and males may determine sperm allocation based on female availability and female mating frequency. In this study, I investigated male and female mating behaviors in the parasitoid wasp Anisopteromalus calandrae. The wasp exhibits the haplo-diploid sex determination, in which sperm-depleted females are constrained to produce only sons by laying unfertilized eggs. The first experiment showed that a rapid succession of male mating decreased the production of daughters (fertilized eggs) by the inseminated females, suggesting that sperm-limited males provided an insufficient amount of sperm to the females. Although the males appeared to replenish their sperm store after 6 h, they mated upon encountering females despite their sperm shortage. The second experiment showed that copulation reduced the subsequent mating receptivity of the inseminated females irrespective of whether the females received a sufficient amount of sperm. Moreover, although approximately 26% of females accepted a second mating and recovered a certain degree of daughter production, remating was independent of the mating status of their first mating partner or the social environment. These results suggest that sperm-limited males may benefit from continuing to mate because their copulation prevents competing males from reproducing with their mates. Females incur a cost from not remating depending on the amount of sperm provided, which may result from weak environmental selection pressure or manipulation by the initial mate. Male and female mating strategies are likely to evolve interdependently. Specifically, in species that produce limited numbers of sperm, the mating behavior of males and females is likely to be influenced by sperm transfer. The results of the present study suggest that males of the parasitoid wasp Anisopteromalus calandrae can replenish their sperm stores over time. However, sperm-limited males that encounter a potential mating partner mate rather than wait for sperm recovery. Females do not discriminate the male state before copulation, and those that mate with sperm-limited males suffer from sperm shortage. Although females can augment their sperm supply by remating, only a portion of females do so, regardless of sperm supply. The lack of a female facultative response suggests weak environmental selection on the species or the existence of sexual conflict over sperm transfer.

  • Sperm-limited males continue to mate, but females cannot detect the male state in a parasitoid wasp
    Behavioral Ecology and Sociobiology, 2019
    Co-Authors: Jun Abe
    Abstract:

    Female mating frequency and male ejaculate allocation are likely to interact. Females may adjust their propensity for remating based on the amount of provided sperm to ensure a sufficient sperm supply, and males may determine sperm allocation based on female availability and female mating frequency. In this study, I investigated male and female mating behaviors in the parasitoid wasp Anisopteromalus calandrae . The wasp exhibits the haplo-diploid sex determination, in which sperm-depleted females are constrained to produce only sons by laying unfertilized eggs. The first experiment showed that a rapid succession of male mating decreased the production of daughters (fertilized eggs) by the inseminated females, suggesting that sperm-limited males provided an insufficient amount of sperm to the females. Although the males appeared to replenish their sperm store after 6 h, they mated upon encountering females despite their sperm shortage. The second experiment showed that copulation reduced the subsequent mating receptivity of the inseminated females irrespective of whether the females received a sufficient amount of sperm. Moreover, although approximately 26% of females accepted a second mating and recovered a certain degree of daughter production, remating was independent of the mating status of their first mating partner or the social environment. These results suggest that sperm-limited males may benefit from continuing to mate because their copulation prevents competing males from reproducing with their mates. Females incur a cost from not remating depending on the amount of sperm provided, which may result from weak environmental selection pressure or manipulation by the initial mate. Significance statement Male and female mating strategies are likely to evolve interdependently. Specifically, in species that produce limited numbers of sperm, the mating behavior of males and females is likely to be influenced by sperm transfer. The results of the present study suggest that males of the parasitoid wasp Anisopteromalus calandrae can replenish their sperm stores over time. However, sperm-limited males that encounter a potential mating partner mate rather than wait for sperm recovery. Females do not discriminate the male state before copulation, and those that mate with sperm-limited males suffer from sperm shortage. Although females can augment their sperm supply by remating, only a portion of females do so, regardless of sperm supply. The lack of a female facultative response suggests weak environmental selection on the species or the existence of sexual conflict over sperm transfer.

  • Influence of body size on fecundity and sperm management in the parasitoid wasp Anisopteromalus calandrae
    Physiological Entomology, 2015
    Co-Authors: Eiichi Kasamatsu, Jun Abe
    Abstract:

    A large body size is considered to be advantageous to the reproductive success of females as a result of several factors, such as the allocation of more resources to reproduction and the efficient management of sperm transferred by males. In the present study, the effects of female body size, female mating status and additional food availability on fecundity and the offspring sex ratio are investigated in the parasitoid wasp Anisopteromalus calandrae Howard (Hymenoptera: Pteromalidae). Because of haplodiploid sex determination, females must fertilize eggs to produce female offspring but not to produce male offspring. As predicted, female fecundity and the number of female offspring are positively correlated with body size. However, although the volume of the spermatheca increases with female body size, the amount of sperm stored in the spermatheca is relatively constant, irrespective of body size. Consequently, larger females produce a greater proportion of male offspring, especially at the end of the oviposition sequence, suggesting that larger females that possess more resources for reproduction and produce a larger number of offspring are more likely to suffer sperm depletion. The results of the present study also show that mated females have an increased fecundity compared with virgin females, although the opportunity to feed on honey along with host feeding has no impact upon fecundity or the sex ratio.

Mun Il Ryoo - One of the best experts on this subject based on the ideXlab platform.

  • biological control of indianmeal moth and rice weevil by parasitoids with reference to the intraspecific competition pattern
    Journal of Economic Entomology, 2011
    Co-Authors: Jeongyeon Ji, Yong Shik Chun, Ja Hyun Na, Mun Il Ryoo
    Abstract:

    Biological control of rice weevil, Sitophilus oryzae (L.), and Indianmeal moth, Plodia interpunctella (Hubner), by their parasitoids Anisopteromalus calandrae (Howard) and Bracon hebetor Say was examined while considering the intraspecific competition pattern of the pests. In both experimental and simulation studies, A. calandrae was shown to suppress the rice weevil population, a contest type competitor, regardless of the parasitoid/weevil ratios tested. In contrast, B. hebetor only significantly suppressed the Indianmeal moth, a scramble type competitor, when the parasitoid/moth ratio was >0.05. At ratios lower than 0.05, the role of B. hebetor was negligible, and the correlation coefficients between the number of moths that had emerged and the parasitoid/moth ratio was estimated to be 0.07. The control efficiency of the two parasitoids with respect to the parasitoid/host ratio was estimated using a ratio-response model. To suppress the weevil density to a level that was only 10% of the current density, the ratio was estimated to be 0.02, whereas this value was 0.14 for the Indianmeal moth. However, for the continuous suppression of the Indianmeal moth, periodic and iterative introduction of B. hebetor was required.

  • Mycoflora of stored rice in relation to the biological control of Sitophilus oryzae by Anisopteromalus calandrae
    Journal of Asia-Pacific Entomology, 2011
    Co-Authors: Youngwoo Nam, Eun Young Yoon, Ki Deok Kim, Mun Il Ryoo
    Abstract:

    In this study, we determined the effect of controlling rice weevils on the mycoflora of stored brown rice by using Anisopteromalus calandrae (Howard), a parasite of the rice weevil. The mycoflora in brown rice with the parasitoid was similar to that without the parasitoid; however, the dominant mold species differed. Without the parasitoid, Aspergillus candidus Link and Penicillium islandicum Sopp were the dominant species, whereas Aspergillus penicilloides Speg. and P. islandicum were dominant when the parasitoid was present. The difference appeared to be due mainly to the difference in the grain moisture content with and without the parasitoid. A. candidus was the dominant species in the communities without the parasitoid and was not observed when the weevils were suppressed. P. islandicum dominated or co-dominated regardless of the presence of the parasitoid which suggested that P. islandicum is tolerant to low grain moisture content or is positively affected by the presence of the rice weevil.

  • effects of biological control of rice weevil by Anisopteromalus calandrae with a population of two aspergillus spp
    Environmental Entomology, 2009
    Co-Authors: Eun Young Yoon, Mun Il Ryoo
    Abstract:

    ABSTRACT In this study, we assessed the interaction occurring between the rice weevil and two storage molds (Aspergillus candidus Link and Aspergillus niger Van Tiegem) that prefer different moisture regimens under rice storage conditions. Rice weevil induced rapid population growth in both of the storage molds. The colony forming units (CFUs) of A. candidus and A. niger peaked at 109.00 ± 0.02 and 107.72 ± 0.03/g, respectively. All of the rice grains were infested with the molds and eventually deteriorated; in the jars infested with A. candidus, no living weevils were found after 135 d. Suppression of the rice weevil by its larval parasitoid, Anisopteromalus calandrae (Howard), significantly retarded the growth of A. candidus but completely halted the growth of A. niger, which was replaced by xerophyllic molds including Aspergillus penicilloides Spegazzini and Wallemia sebi (Fries). Regression analyses showed that the total number of weevils was a significant factor explaining grain moisture content, whi...

  • Host‐size‐dependent feeding behaviour and progeny sex ratio of Anisopteromalus calandrae (Hym., Pteromalidae)
    Journal of Applied Entomology, 2008
    Co-Authors: Won Il Choi, T. J. Yoon, Mun Il Ryoo
    Abstract:

    Host-size related feeding and oviposition behaviour, and allocation of progeny sex by Anisopteromalus calandrae (Howard) were tested on Sitophilus oryzae L. The parasitoid showed a host-size-dependent partition of feeding and oviposition behaviour, preferring small hosts for feeding, but large hosts for oviposition. Neither the mutual interference nor the host density showed any effect on the behaviour of the parasitoid. Allocation of progeny sex by the female parasitoid appeared to be based more likely on absolute than on relative host size encountered. A model for the progeny sex ratio was constructed based on: (1) ovipositional preference of the parasitoid on large hosts; (2) feeding preferentially on small hosts; and (3) host-size-related regulation of progeny sex ratio. The progeny sex ratio of the parasitoid predicted by the model was in close agreement with the observed value.

  • Fitness and Sex Allocation of Anisopteromalus calandrae (Hymenoptera: Pteromalidae): Relative Fitness of Large Females and Males in a Multi-Patch System
    Annals of the Entomological Society of America, 2004
    Co-Authors: Won Il Choi, Mun Il Ryoo
    Abstract:

    The host quality model for explaining the sex ratio of progeny of hymenopterous parasitoids was tested with Anisopteromalus calandrae (Howard) parasitizing Sitophilus oryzae (L.). The life span of females and males did not show any influence of body size: 15.3 ± 6.14 and 15.9 ± 4.16 d for females of small and large size, and 5.4 ± 1.90 and 6.0 ± 2.30 for males. However the reproduction rate of large females was twice as high as for small females (80.9 ± 5.78 versus 37.4 ± 3.16). Large males mated with twice as many females as did small males (19.2 ± 3.8 versus 8.1 ± 3.8), suggesting that females do not gain greater fitness by being large than males. In a system in which the parasitoid was permitted to search among randomly dispersed host patches, large females showed a higher net reproduction rate than small females. This was not influenced by the size of male the females mated with: 132.8 ± 9.81 and 132.5 ± 7.41 for large females mated with large and small males, respectively, and 70.4 ± 13.72 and 54.07 ± 6.17 for small females mated with large and small males. The size-dependent dispersal ability among host patches of females, which is the active dispersal sex, is another factor that influenced oviposition behavior of A. calandrae, which assigns daughters on large hosts and sons on small hosts.

James E. Baker - One of the best experts on this subject based on the ideXlab platform.

  • Molecular differentiation of two strains of the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae) using specific PCR primers
    Journal of Entomological Science, 2004
    Co-Authors: Yu Cheng Zhu, Alan K. Dowdy, James E. Baker
    Abstract:

    Two strains (Sav and Bam) of the parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) showed different sensitivity to organophosphate insecticides. By using polymerase chain reaction (PCR) and DNA sequencing, we demonstrated clear molecular difference between these two strains. DNA markers that are specific for the Bam strain were developed, and PCR-generated DNA fragments were cloned and sequenced. Two DNA fragments unique to the Bam strain contained 365 and 584 nucleotides. A pair of specific primers was designed from each fragment. PCR-amplification of the DNA from individual wasps generated fragments of the expected sizes only in the Bam strain. Studies conducted on F1 and F2 hybrids produced from crossing and backcrossing between resistant and susceptible strains indicated that these DNA markers are located on mitochondria and inherited exclusively maternally. Probes developed from these fragments may be used in assessing genetic information of natural populations and in studies on physiological or biochemical differences between the strains of this beneficial insect.

  • Effects of protect-it on efficacy of Anisopteromalus calandrae (Hymenoptera: Pteromalidae) parasitizing rice weevils (Coleoptera: Curculionidae) in wheat
    Environmental Entomology, 1999
    Co-Authors: Joel Perez-mendoza, James E. Baker, Frank H. Arthur, Paul W. Flinn
    Abstract:

    The parasitoid Anisopteromalus calandrae (Howard) was very sensitive to direct contact with Protect-It, an inert dust formulation containing 90% diatomaceous earth and 10% silica aerogel. LT 50 s at room temperature and humidity were 49 min (95% CL = 48-51) and 72 min (95% CL = 69-74) for males and females, respectively, in petri dishes containing 2.5 mg dust per square centimeter. Under the same conditions, adults of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), a host of A. calandrae, were much less sensitive. Mortality of S. oryzae after a 24-h contact period was 50% for females and 62% for males. When tested in no-choice laboratory bioassays at 27°C, label rates of Protect-It (200 and 400 ppm) dusted onto hard red winter wheat, Triticum aestivum. L. (13.9% moisture content) that was infested with immature rice weevils reduced the longevity of parent A. calandrae females and significantly reduced parasitization of the weevils at 3 tested humidities, 43, 60, and 75% RH. Parasitoid progeny production was also significantly reduced. At 75% RH, 92.8 ± 2.9 parasitoid progeny were produced in untreated wheat compared with 12.6 ± 2.6 progeny in the treated wheat. Sex ratio of parasitoid progeny was not significantly affected by the dust treatments at any relative humidity. In two-choice tests in divided petri dish arenas, single A calandrae females showed a strong avoidance of Protect-It-treated wheat and a significant preference for parasitizing weevils in untreated wheat. However, significantly more parasitoid progeny were produced in dishes in which one-half contained Protect-It-treated wheat and the other half contained untreated wheat compared with dishes in which both halves of the divided dishes held untreated wheat. Reasons for the Protect-It-stimulated oviposition response by A. calandrae are not known, but may be related to stress induced by the dust. In separate tests, there was no significant difference in emergence of weevils from treated or untreated wheat, regardless of the weevil age at time of dusting, or the relative humidity at which the dusted wheat was maintained. Our studies provide evidence that any natural control of pest insects exerted by local populations of parasitoids, or enhanced biological control by augmentative releases of parasitoids, would be adversely affected by the use of Protect-It or other diatomaceous earth products on stored grain.

  • Detection of single‐base substitution in an esterase gene and its linkage to malathion resistance in the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae)
    Pesticide Science, 1999
    Co-Authors: Alan K. Dowdy, James E. Baker
    Abstract:

    Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) is an important parasitoid of stored-grain insect pests. Partial cDNA sequences of an esterase-like enzyme have been obtained from a malathion-resistant (R) strain and a susceptible (S) strain of this wasp. A single-base substitution in the R strain has been confirmed by using PCR amplification of specific allele (PASA) to amplify genomic DNA extracted from individual resistant and susceptible parents, F 1 hybrids from double reciprocal crosses, and progeny from backcrosses. The R allele appeared to be inherited in a strict Mendelian fashion in both diploid female and haploid male progeny. The esterase fragment co-segregated with resistance in these crosses and backcrosses. Female wasps in a mixed population of A calandrae that survived a malathion screen carried the R allele for the esterase-like enzyme, while those wasps that died did not have the R allele. The single base-pair mutation, guanine in the R strain and thymine in the S strain, presumably results in a tryptophan-to-glycine amino acid substitution in the encoded protein. We do not know how these amino acid substitutions may relate to functional differences in the enzyme. However, this esterase gene or another linked esterase gene may encode the resistance-associated malathion detoxifying activity in the R strain.

  • Selection of Cold Injury Treatments to Facilitate Release of the Parasitoid Anisopteromalus calandrae(Hymenoptera: Pteromalidae) Reared on the Rice Weevil (Coleoptera: Curculionidae)
    Journal of Economic Entomology, 1999
    Co-Authors: Charles S. Burks, David W. Hagstrum, James E. Baker
    Abstract:

    The use of cold treatments to kill the rice weevil, Sitophilus oryzae (L.), before eclosion but allow the parasitoid Anisopteromalus calandrae (Howard) to complete development and eclosion was examined. Cold tolerance, crystallization temperature, and developmental stage of rice weevils were examined at 2-d intervals between 18 and 30 d after rice weevil oviposition. The median crystallization temperature dropped from 216 to 2248C over this time, and cold tolerance was lowest between day 20 and 24. Based on these data, rice weevil immatures were exposed on days 18, 19, 21, 22, 23, and 24 after oviposition fo r2ht ovarious subzero temperatures. Hosts were exposed to parasitoids for oviposition on day 20. Before parasitization, rice weevils were either frozen internally by exposure to 2258C, or were subjected to nonfreezing chilling injury by exposure to 2128C. Rice weevils exposed to cold after parasitization were subjected to chilling injury by exposure to either 212 or 2108C. Freezing rice weevil larvae before parasitization resulted in poor production of parasitoids and a sex ratio favoring males. Exposure to 2128C for 2 h, 2 or 3 d after parasitization resulted in production of parasitoids similar to unchilled controls, and a slightly higher female-to- male ratio than the controls. The production of A. calandrae was better after exposure to 2108C, but at this temperature some rice weevils eclosed. The treatment o f2ha t2128C, 3 d after parasitization gave the best parasitoid survival and ensured rice weevil mortality.

  • Differential mRNA expression levels and gene sequences of a putative carboxylesterase-like enzyme from two strains of the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae).
    Insect biochemistry and molecular biology, 1999
    Co-Authors: Yu Cheng Zhu, Alan K. Dowdy, James E. Baker
    Abstract:

    Carboxylesterase-like enzyme cDNAs have been cloned and sequenced from malathion-resistant and susceptible strains of the parasitoid Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae). The cDNAs consist of 1963 nucleotides including a 35 bp untranslated 5'-end, a 1596 bp open reading frame, and a 332 bp untranslated 3'-end. The open reading frame encodes 532 amino acid residues. The predicted protein sequence from these cDNAs includes 2 potential N-glycosylation sites, a carboxylesterase type-B serine active site FGGDSENVTIFGESAG, and conserved residues Ser187, Glu317, and His432 to function as the catalytic triad. The predicted carboxylesterase-like enzyme sequence is most similar to that of the carboxylesterase from the peach-potato aphid, Myzus persicae with 45% sequence identity. Alignment of the parasitoid carboxylesterase-like enzyme cDNAs revealed that there are two nucleotide differences in the open reading frame between the parasitoid strains, including a silent mutation and a point mutation that presumably causes a gene product difference. A nucleotide thymine at position 658 in the susceptible strain cDNA is replaced by a guanine in the resistant strain cDNA. This substitution leads to an amino acid change from tryptophan (Trp220) in the susceptible strain to glycine (Gly220) in the resistant strain. This substitution is genetically linked to resistance but it is not known how or if this amino acid substitution affects detoxification of malathion. Northern blot analyses demonstrated that expression level of the carboxylesterase-like enzyme mRNA in adult A. calandrae is approximately 30-fold higher in the resistant strain relative to that in the susceptible strain. Southern analysis indicated that Pst I or Eco RI restriction sites are different in the two strains. Both a modified gene structure and an increase in expression of carboxylesterase may be responsible for the high level of resistance found in this beneficial wasp.