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1.
This paper suggests that the nymphs of a specialist predator, Kirkaldyia (=Lethocerus) deyrolli (Belostomatidae: Heteroptera), are indirectly affected by their tadpoles’ prey. K.
deyrolli nymphs and the predator Laccotrephes japonensis (Nepidae: Heteroptera) adults coexist in rice paddy fields. It was predicted that the difference in tadpole density may influence
the K. deyrolli nymph survival rate. We first compared survival rates of the first instar nymphs of K. deyrolli in June (high tadpole density period) and July (low tadpole density period). Secondly, we investigated the survival rate
of K. deyrolli nymphs at different tadpole densities and under the presence or absence of L. japonensis adults to examine whether higher tadpole density moderates predation pressure from L. japonensis adults to K. deyrolli nymphs, e.g., density-mediated indirect effects. As a result of the comparison, the survival rate of K. deyrolli nymphs in June was higher than that in July. For the field experiment, the slopes between the survival rate of K. deyrolli nymphs and tadpole density were positive under both predator presence and absence. However, the slope under the presence
of a predator was steeper than that under absence of the predator (“predator-by-tadpole density interaction” was significant).
These results suggest that a higher tadpole density in June provides an abundant food resource for K. deyrolli nymphs and also moderates predation pressure from L. japonensis. 相似文献
2.
The soybean aphid, Aphis glycines Matsumura is a new invasive pest of soybean in North America. We studied the ability of the existing predator community in soybean to reduce A. glycines establishment in field studies using either predator exclusion, open, or leaky cages that allowed aphid emigration but limited predation. Cages were infested with uniform initial densities of A. glycines adults and subsequent populations of aphids and predators were monitored over 24 h. The most abundant predators in these trials included the carabid beetles Elaphropus anceps (Le Conte), Clavina impressefrons Le Conte, Bembidion quadrimaculatum Say and spiders (Salticidae and Lycosidae). Foliar predators were less abundant and included; Harmonia axyridis Pallas, Coccinella septempunctata (L.), and Orius insidious (Say). Over the 2-year study, we found statistically significant predation on adult A. glycines in one out of six trials at 15 h and two out of six trials at 24 h. There was never significant evidence for predation of nymphs in any trial, however overall survival (adults + nymphs) was significantly reduced in one out of six trials at 15 h and three out of six trials at 24 h. Based on these results we suggest that generalist predators can be a significant but variable factor influencing the establishment of A. glycines populations in soybean. The impact of existing predator communities should be further investigated as a means of managing A.␣glycines populations in North American soybean production systems. 相似文献
3.
The Palaearctic stinkbug Picromerus bidens L. (Heteroptera: Pentatomidae) has been considered as a potential biocontrol agent of several defoliator pests in various
agricultural and forest ecosystems. It may therefore be a valuable alternative for the Nearctic pentatomid Podisus maculiventris (Say) (Heteroptera: Pentatomidae), the augmentative use of which has largely been abandoned in Europe given its possible
environmental impact as an exotic polyphagous predator. However, no study has yet documented the impact of insecticides on
P. bidens, which is essential to evaluate the possible combination of this predatory pentatomid with current insecticide applications
in integrated pest management (IPM) programmes. This study reports on laboratory experiments investigating the susceptibility
of P. bidens to five insecticides with different modes of action: the pyrethroid deltamethrin, the diacylhydrazine methoxyfenozide, the
juvenile hormone mimic pyriproxyfen, the spinosyn spinosad, and the neonicotinoid imidacloprid, all of which are used to control
defoliator pests. Fourth-instar nymphs and female adults of the predator were exposed to formulated materials of the insecticides
by residual contact. Methoxyfenozide and spinosad did not cause significant mortality to 4th instars and female adults of
P. bidens. In contrast, deltamethrin and imidacloprid were harmful to nymphs and adults of the predator, with LC50 values ranging between 1.5 and 9.9 mg a.i./l. Pyriproxyfen was toxic to 4th instars with an LC50 value of 13.9 mg a.i./l but did not affect female adults. Reproduction and longevity of P. bidens were not adversely affected when the predator was exposed to field concentrations of spinosad, methoxyfenozide, or pyriproxyfen,
or sublethal concentrations (around LC10) of deltamethrin and imidacloprid. The results from residual contact experiments suggest that methoxyfenozide, spinosad,
and to a lesser extent, pyriproxyfen may be compatible with P. bidens in an IPM programme. Further experiments assessing food chain toxicity of these compounds should offer a more complete picture
of their selectivity. 相似文献
4.
Shin-ya Ohba 《Limnology》2008,9(1):71-73
Giant water bug Kirkaldyia (=Lethocerus) deyrolli (Belostomatidae: Heteroptera) nymphs consume many individuals of anuran larvae (tadpoles) before they reach adulthood. However,
no quantitative data on the number of tadpoles consumed have been made available until now, despite the importance of this
data for the conservation of this species. The number of tree frog, Hyla japonica (Hylidae: Anura), tadpoles consumed by nymphs of K. deyrolli was examined under laboratory conditions. The number increased according to the developmental stage of the nymphs; the fifth
instar nymphs were the highest consumers. The total numbers consumed by the nymphs throughout development were 155.0 ± 12.8
(average ± SD) and 172.8 ± 9.6 for the males and the females, respectively. Thus, it might be important to maintain high densities
of frogs in fields to conserve the population of K. deyrolli into the future. 相似文献
5.
Tetranychus evansi Baker and Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are important pests of Solanaceae in many countries. Several studies have demonstrated that T. urticae is an acceptable prey to many predatory mites, although the suitability of this prey depends on the host plant. T. evansi, has been shown to be an unfavorable prey to most predatory mites that have been tested against it. The predator Phytoseiulus fragariae Denmark and Schicha (Acari: Phytoseiidae) has been found in association with the two species in Brazil. The objective of
this work was to compare biological parameters of P. fragariae on T. evansi and on T. urticae as prey. The study was conducted under laboratory conditions at 10, 15, 20, 25 and 30°C. At all temperatures, survivorship
was lower on T. evansi than on T. urticae. No predator reached adulthood at 10°C on the former species; even on the latter species, only about 36% of the predators
reached adulthood at 10°C. For both prey, in general, duration of each life stage was shorter, total fecundity was lower and
intrinsic rate of population increase (r
m
) was higher with increasing temperatures. The slower rate of development of P. fragariae on T. evansi resulted in a slightly higher thermal requirement (103.9 degree-days) on that prey than on T. urticae (97.1 degree-days). The values of net reproduction rate (R
0), intrinsic rate of increase (r
m
) and finite rate of increase (λ) were significantly higher on T. urticae, indicating faster population increase of the predator on this prey species. The highest value of r
m
of the predator was 0.154 and 0.337 female per female per day on T. evansi and on T. urticae, respectively. The results suggested that P. fragariae cannot be considered a good predator of T. evansi. 相似文献
6.
7.
Fawzeia H. Elmhalli Katinka Pålsson Jan Örberg Thomas G. T. Jaenson 《Experimental & applied acarology》2009,48(3):251-262
The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A–E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs
at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate
increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results
obtained by methods A, C and E, the LC50 range was 0.035–0.037 mg PMD/cm2 and the LC95 range was 0.095–0.097 mg PMD/cm2 at 4 h of exposure; the LT50 range was 2.1–2.8 h and the LT95 range was 3.9–4.2 h at 0.1 mg PMD/cm2. To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm2) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed
that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic
to nymphs of I. ricinus and may be useful for tick control. 相似文献
8.
Carolina Calderón Alvarez Charlotte E. Causton Mark S. Hoddle Christina D. Hoddle Roy van Driesche Edward J. StanekIII 《BioControl》2012,57(2):167-179
In January 2002, the first biological control program was implemented on the Galapagos Islands with the release of the Australian
coccinellid Rodolia cardinalis Mulsant to control the invasive cottony cushion scale, Icerya purchasi Maskell. This was the first time that Galapagos authorities had approved the introduction of a biological control agent to this iconic
archipelago and, because of this precedent, it was important to monitor and evaluate its behaviour soon after its introduction.
Surveys were carried out after the release of R. cardinalis in 2002 to confirm establishment on Santa Cruz Island. In 2009, seven years post-release, a broader survey was done to document
spread throughout the archipelago. Directly after the release of R. cardinalis in 2002, a predator exclusion study and field observations were carried out on scale insect populations on white mangrove (Laguncularia racemosa [L.] Gaertn. F.) on Santa Cruz Island to document impact. In less than three months after R. cardinalis was released in 2002, populations of I. purchasi on white mangrove that were exposed to the predator in the exclusion experiment, or were monitored in the field, had declined
by 99–100%. Results suggest that R. cardinalis played a key role in this decline, possibly in combination with high rainfall. Rodolia cardinalis dispersed quickly after its release and by 2009 was found in a wide variety of habitats on seven of the eight islands surveyed
that had records of I. purchasi. Two of these were self-introductions. Further monitoring is recommended to determine whether this biological control agent
has successfully reduced scale insect numbers on other valued plant species. 相似文献
9.
As physiological factors may influence the predatory behavior of insects, this study was designed to evaluate the possible impact that hunger has on the search path of a polyphagous predator: Deraeocoris lutescens Schilling (Heteroptera: Miridae). D. lutescens was fed a diet of Rhopalosiphum padi (Linné) (Homoptera: Aphididae) nymphs and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs at 21±1 °C and a photoperiod of 16:8 (L:D). After moulting, third and fifth instar nymphs and adults were placed in Petri dishes containing an abundant food source for 24 h. After 24 h, the food was removed and groups were randomly assigned to increasing periods of prey deprivation. Each D. lutescens nymph or adult was placed at the center of an empty arena and its searching path was recorded to calculate different path parameters and to determine the type of movement mode adopted. Results show an effect of starvation on both nymphal and adult D. lutescens searching paths. Satiated third instar nymphs manifested an intensive search path whereas fifth instar nymphs and adults adopted an intermediate one. When starved, the extensive search path appeared early in young nymphs, and later in the last instar nymphs and adults, according to the degree of prey deprivation. 相似文献
10.
Jeong Jun Kim 《BioControl》2007,52(6):789-799
The activity of entomopathogens on insect pests has been investigated for many species but the influence of entomopathogenic
fungi on factors other than mortality relating to population increase has not been frequently studied. The influence of Lecanicillium attenuatum CS625 (=Verticillium lecanii CS625) on development and reproduction of cotton aphid (Aphis gossypii) was investigated. A conidia suspension of the isolate was applied onto first instar nymphs. Increased spore concentration
did not significantly affect each nymphal stage, total nymphal period, pre-reproductive period and the age of first larviposition.
A significant dose effect on reduction of life span, reproductive period and fecundity was observed in 1st and 3rd instars
after spore application. When conidia were applied to 1st instars, life span was significantly reduced to 10.8 and 8.4 days
at 1 × 104 and 1 × 108 conidia/ml, respectively from 12.2 days in the control. During the life span, total fecundity was 41 ± 7.3, 26 ± 0.8 and
22 ± 5.7 nymphs per female at 1 × 104, 1 × 106 and 1 × 108 conidia/ml, respectively compared with 51 ± 2.0 nymphs per untreated female. Reproduction period was also significantly shortened
with increasing spore concentration. Application of spores to 3rd instars showed a similar trend. However, daily fecundity
of individual aphids was not affected by spore dose. It was concluded that the isolate of L.
attenuatum is able to affect populations of cotton aphid by reducing life span and total fecundity as well as by killing the aphids
directly. 相似文献
11.
The inhibition of mycelial growth of Lagenidium giganteum by neem oil was lower than that of Metarhizium anisopliae in PYG and Emerson’s YpSs agar media. However, neem oil did not inhibit the mycelial growth of L. giganteum in sunflower seed extract agar medium, but did it inhibit the mycelial growth of M. anisopliae. The minimum inhibitory concentration of neem oil for L. giganteum was higher than that for M. anisopliae. The minimum fungicidal concentration of neem oil in PYG medium was lower than in YpSs for both fungi. The spores of L. giganteum grown in SFE medium could be used with neem oil for vector control. 相似文献
12.
Hornbostel VL Zhioua E Benjamin MA Ginsberg HS Ostfeldt RS 《Experimental & applied acarology》2005,35(4):301-316
Effectiveness of the entomopathogenic fungus Metarhizium anisopliae, for controlling nymphal Ixodes scapularis, was tested in laboratory and field trials. In the laboratory, M. anisopliae (Metschnikoff) Sorokin strain ESC1 was moderately pathogenic, with an LC50 of 107 spores/ml and induced 70% mortality at 109 spores/ml. In a field study, however, 109 spores/ml M. anisopliae did not effectively control questing I. scapularis nymphs, and significant differences were not detected in pre- and post-treatment densities. For nymphs collected and returned to the laboratory for observation, mortality was low in treatment groups, ranging from 20 to 36%. To assess whether a chemical acaricide would synergistically enhance pathogenicity of the fungus, we challenged unfed nymphal I. scapularis with combinations of M. anisopliae and permethrin, a relatively safe pyrethroid acaricide, in two separate bioassays. Significant interactions between M. anisopliae and permethrin were not observed, supporting neither synergism nor antagonism. 相似文献
13.
14.
Herbivory can be an important factor structuring coastal algal communities. Herbivores may preferentially graze particular
algal species or tissue types. Mesograzers, despite their small size, can critically weaken kelp thalli and impact entire
kelp beds. We propose that when kelp beds are composed of several kelp cohorts, mesograzers will selectively choose to inhabit
younger plants and grazing activities will have a greater impact on younger plants. This study investigated the effects of
grazing by the littorinid gastropod, Lacuna vincta, on different age classes of the bull kelp, Nereocystis luetkeana by (1) testing food preference of L. vincta on juvenile, first-year adult, and second-year adult Nereocystis blades in the laboratory, (2) determining substrate (blades of different ages) preference of L. vincta in the laboratory, and by (3) estimating in-situ herbivore abundances and densities on juvenile and adult Nereocystis. Results demonstrated that grazing by L. vincta produced greater damage on juvenile than older Nereocystis tissues. Although L. vincta did not select juvenile versus older kelps as substrate in the laboratory, in situ surveys showed that differences existed
between age classes with higher L. vincta densities on juvenile than adult kelp. We conclude that at a local scale, L. vincta can be an important structuring factor in Nereocystis populations due to its high density and grazing ability.
Handling editor: K. Martens 相似文献
15.
We examined the toxicity of a fungicide, sulfur, to the egg parasitoid Anagrus erythroneurae (Hymenoptera: Mymaridae) Trjapitsyn and Chiapini and the vineyard leafhopper pest Erythroneura elegantula Osborn (Homoptera: Cicadellidae) and tested whether or not the use of sulfur in the field affects biological control of E. elegantula. Using field cage bioassays, we demonstrated that sulfur is toxic to adult A. erythroneurae parasitoids, but not toxic to adult E. elegantula leafhoppers. We nonetheless found in a field experiment that sulfur produced no changes in rates of parasitism or E. elegantula egg density, and generated only a very small increase in the density of E. elegantula nymphs. These results suggest that sulfur, although toxic to A. erythroneurae, is not highly disruptive of E. elegantula biological control in vineyards. Our results suggest that simple bioassays of acute toxicity may not accurately predict the
impact of agricultural chemicals on biological control. 相似文献
16.
Callicarpenal (13, 14, 15, 16-tetranor-3-cleroden-12-al) and intermedeol [(4S,5S,7R,10S)-eudesm-11-en-4-ol], isolated from American beautyberry, Callicarpa americana (Lamiaceae), were evaluated in laboratory bioassays for repellent activity against host-seeking nymphs of the blacklegged
tick, Ixodes scapularis, and lone star tick, Amblyomma americanum. A strip of organdy cloth treated with test solution was doubly wrapped (treatment on outer layer) around the middle phalanx
of a forefinger and ticks released on the fingertip. Callicarpenal and intermedeol, at 155 nmole/cm2 cloth repelled 98 and 96% of I. scapularis nymphs, respectively. Dose response tests with I. scapularis nymphs showed no difference in repellency among callicarpenal, intermedeol and Deet (N,N-diethyl-3-methylbenzamide), however, SS220 ((1S,2′S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide) was significantly more repellent than the other compounds. Callicarpenal,
at 155 nmole/cm2 cloth, repelled 100 and 53.3% of I. scapularis nymphs at 3 and 4 h, respectively, after the cloth was treated, whereas intermedeol repelled 72.5% of I. scapularis nymphs 3 h after treatment. In comparison with the results obtained with I. scapularis, callicarpenal, intermedeol, Deet and SS220 were less effective against A. americanum. Only intermedeol and SS220 repelled significantly more A. americanum than ethanol controls at 155 nmole compound/cm2 cloth. At 1,240 nmole/cm2 cloth, callicarpenal and intermedeol repelled 20 and 40% of A. americanum nymphs. 相似文献
17.
To narrow the differences between the results obtained from radionuclides and heavy metal ecotoxicity investigations in the laboratory and in the abandoned uranium mines, a few standardised plant bioassay procedures were selected from the literature for testing with Lemna gibba L. The bioassay procedures were tested in situ and ex situ. The laboratory culturing was performed in batch and semicontinuous modes. The results revealed that most of the standardised plant bioassay procedures require modification for the L. gibba bioassay to predict the actual effects under field conditions. L. gibba performed relatively better in the field than laboratory batch cultures despite that the batch cultures had many-fold higher nutrient concentrations than in the field. For instance, the phosphorus concentration of the mine tailing water was 0.13 ± 0.09 μg l−1 in the field, while the literature range for phosphorus in the laboratory culture media is 13.6–40 mg l−1. L. gibba growth in the laboratory batch culture was influenced by speciation changes due to consumption of nutrients, CO2 and O2 phase exchanges, and excretion of organic substances by the test plants. Semicontinuous culture modes performed significantly better than batch cultivation even after 10× dilution of the nutrient solution. The growth behaviour revealed that L. gibba exhibited intrapopulation and probiotic interaction for best performance. Growth performance of L. gibba was influenced by the anions that balanced essential cations despite equal cation concentration in the culture media; e.g., the best growth was observed in culture media that had more SO42− than Cl−. Water samples from the field had higher SO42− concentrations than Cl−. The test vessel material, sterilisation and axenic culturing procedures also influenced the sensitivity of the bioassay. These, for instance, and a few others are neither described nor reported in most standard Lemna tests or the literature. Thus, this work presents results of a series of tests conducted on the selected methods. Common and possible errors and corrective measures in assigning L. gibba bioassay from laboratory population levels to field community levels are discussed. 相似文献
18.
Stefanie Kimbacher Ingrid Gerstl Branko Velimirov Sylvia Hagemann 《Molecular genetics and genomics : MGG》2009,282(2):165-172
P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding
region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Genome sequence analysis of Xanthomonas
oryzae pv. oryzae has revealed a cluster of 12 ORFs that are closely related to the gum gene cluster of Xanthomonas campestris pv. campestris. The gum gene cluster of X. oryzae encodes proteins involved in xanthan production; however, there is little experimental evidence supporting this. In this
study, biochemical analyses of xanthan produced by a defined set of X. oryzae
gum mutant strains allowed us to preliminarily assign functions to most of the gum gene products: biosynthesis of the pentasaccharide repeating unit for GumD, GumM, GumH, GumK, and GumI, xanthan polymerization
and transport for GumB, GumC, GumE, and GumJ, and modification of the pentasaccharide repeating unit for GumF, GumG, and GumL.
In addition, we found that the exopolysaccharides are essential but not specific for the virulence of X. oryzae.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Sang-Yoon Kim and Jeong-Gu Kim contributed equally to this work. 相似文献
20.
Summary
Linaria khalkhalensis Hamdi & Assadi is described as a new species from Azerbaijan and Guilan provinces (northern Iran), belonging to Linaria sect. Linaria. It is close to Linaria lineolata Boiss. and L. elymaitica (Boiss.) Kuprian., which it resembles in habit and vegetative features. However, floral and seed characters together with
a distinctive geographical distribution, warrant recognition at the species rank. An illustration of the new species, a distribution
map, scanning electron micrographs of seed and capsule surfaces, and an identification key are also included. 相似文献