Resistance to organophosphates in red spider mite, Tetranychus urticae, from English hop gardens

Two strains of Tetranychus urticae, collected in 1969 from hops in Kent (strain RK) and Wisbech, Cambridgeshire (RW), showed a similar pattern of resistance to organophosphates, high to parathion (> 100 ×), low to azinphos-ethyl (7 ×) and intermediate to demeton-S-methyl (21–27 ×); they were both fully susceptible to tetradifon, dicofol and formetanate. RK showed greatei than 50 × resistance to fourteen other organophosphates; exceptions were azinphos-methyl (11 ×), phosphamidon (21 ×) and methidathion (31 ×). Resistance in RK was shown to be controlled by a single major gene, incompletely dominant with parathion but nearer to intermediate in expression to demeton-S-methyl and azinphos-ethyl. A test for allelism showed that the major genes for O.P. resistance in RK and the Dutch strain Baardse reside at the same locus or are closely linked. The results are compared with other work on T. urticae and on Panonychus ulmi.     

Historical tests of the toxicity of pesticides to Typhlodromus pyri (Acari: Phytoseiidae) and their relevance to current pest management in New Zealand apple orchards 1. Laboratory tests with eggs and larvae

A two-part review is presented relating historical tests of the toxicity of pesticides to Typhlodromus pyri and their relevance to modern pest management in New Zealand pome-fruit orchards. Over the past thirty years, the initial need for T. pyri resistance to broad-spectrum pesticides has substantially declined as a growing array of new selective chemicals have come into use. In Part 1, a laboratory bioassay is described for determining the toxicity of pesticides to the eggs and larvae of an organophosphate (OP)-resistant strain of Typhlodromus pyri from New Zealand. Apple leaves bearing T. pyri and its prey Panonychus ulmi were collected from the field. Leaf discs with known numbers of eggs (no active stages) of T. pyri and prey were cut from the leaves and sprayed with selected pesticides at recommended field rates to simulate field application. The survival of eggs, and the larvae which hatched from them, were recorded for seven days. Thirteen acaricides, 16 fungicides and 15 insecticides were evaluated. Toxic chemicals were aminocarb, amitraz, benomyl, binapacryl, chlordimeform, ethion, omethoate, oxamyl, permethrin, pirimiphos-methyl and triazophos. Slight and variable toxicity was caused by azinphos-methyl, chlorpyrifos, dinocap, mancozeb + dinocap, metiram + nitrothal-isopropyl, and sulphur. No toxicity was detected with the other 24 pesticides. A comparison of the test results with those from field trials in New Zealand showed good agreement, except that the laboratory tests failed to detect the known field toxicity of dithiocarbamate fungicides and the insecticide vamidothion. Most of the chemicals tested are no longer used in commercial pome-fruit orchards in New Zealand, all of which now practise integrated (IFP) or organic (OFP) fruit production based on selective pest management methods. The tested pesticides of continuing importance are identified, and a summary is presented of the international literature describing the impact on T. pyri of the current pesticides used in New Zealand IFP and OFP. The changes in pesticide use in New Zealand are paralleled by similar changes in most pome-fruit growing areas of the world.     

Resistance to organophosphates, and the genetic background, in fruit tree red spider mite, Panonychus ulmi, from English apple orchards

Assays on adult females and eggs of Panonychus ulmi , on leaf discs of Myrobalan plum, were used to characterise and establish homogenous organophosphateresistant (OR) and susceptible strains. Reciprocal crosses of these strains, and assays on adult mites and eggs of the parent, F₁ and F₂ generations confirmed that resistance was controlled by a single major gene, the expression of which was dominant in the response to parathion, and incompletely dominant to vamidothion, dimethoate and demeton-S-methyl. Reproductive incompatibility, between strains, as in Tetranychus urticae , was not found.
Bioassays on larvae hatched from winter eggs, collected from several orchards in Kent, Essex and Somerset, were used to evaluate the spectrum of cross-resistance to a range of 20 organophosphates (OPs). Together with assays on adult females, these tests showed 10- to 100-fold resistance to most of the OPs used for several years including those noted above, but less than 10-fold to azinphos compounds and to several recently-introduced OPs, e. g. dialifos, triazophos, dioxathion. The resistance spectrum in strain OR and five field strains was similar, but some had higher levels to parathion and demeton-S-methyl, and others to dioxathion after 3–4 years' exposure. Resistance levels to individual OPs may be enhanced by specific selection. Strains resistant to OPs showed only 2- to 5-fold resistance to two carbamates, and were fully susceptible to dicofol.     

Integrated control of apple pests in New Zealand 16. Progress with integrated control of European red mite

Abstract

Studies were made in an orchard near Nelson from 1974 to 1978 on integrated control of Panonychus ulmi (Koch) using the organophosphate-resistant predator Typhlodromus pyri Scheuten. Correct timing of selective acaricides during the October-January period is essential, and can be achieved by close observation of P. ulmi development. When the majority of winter eggs have hatched (late October to early November), or the majority of the summer eggs laid by the first generation (very late November to early or mid December), there is a short period when a maximum of immature mites occurs. This is before many adult females have matured, and is the most effective time for application of an acaricide such as cyhexatin. The development of P. ulmi, in particular the incubation period of the summer eggs, is controlled by temperature, and in seasons when mean temperatures are well below average in November and December the delayed mite development makes accurate timing of the December spray more difficult. Other factors which also affect mite development are the use of dormant oil, cultivar, and orchard aspect and shelter.

On the block of trees where no acaricides were used since 1968, although regular applications of azinphos-methyl were made, T. pyri maintained P. ulmi at acceptable levels over the 5 years 1973-78, a maximum of P. ulmi occurring each season in January with the third generation. In three seasons the peak was well below the threshold for commercial spraying; in two seasons this threshold was exceeded, but despite the absence of acaricides P. ulmi numbers soon fell.

A further experiment demonstrated the utility of mineral oil and cyhexatin as selective acaricides in integrated programmes. Cycloprate, tricyclotin, and fenbutatin oxide were shown to be as effective and selective as cyhexatin, a single application in early December giving good survival of T. pyri and season-long control of P. ulmi. In another experiment propargite was as effective and selective as cyhexatin; amitraz was more toxic to T. pyri and less persistent against P. ulmi, and resulted in a poor P. ulmi : T. pyri ratio; and chlorpyrifos, though not more toxic than cyhexatin to T. pyri, was less effective against P. ulmi.

Mancozeb, and dinocap + mancozeb, used in a summer-long programme of 12 treatments, were more toxic to T. pyri than were binapacryl or dinocap alone.     

Boophilus microplus: strain differences of the cholinesterase system.

Cholinesterase (EC 31.1.7 and EC 31.1.8) activity was determined for homogenates of two Argentinian strains of larval ticks, Boophilus microplus. One strain (strain A) was sensitive to organophosphate acaricides. The other strain (strain G) was insensitive to coumaphos and to a lesser degree to other acaricides. For both strains maximal activity was found at 8 × 10^?3M substrate, showing inhibition by excess substrate. Maximal activity was recorded at pH 6.7 and 7.8, the latter peak being more evident for strain G. Values of Q₁₀ of 1.15 and 1.25 were obtained for strains A and G, respectively. Centrifugation at 27,000g resulted in the separation of the total cholinesterase activity into two fractions, one soluble and one particulate; the soluble fraction in strain G showed marked resistance to inhibition by an organophosphate ester and to heat inactivation.     

Resistance status of the carmine spider mite,Tetranychus cinnabarinus and the twospotted spider mite,Tetranychus urticae to selected acaricides on strawberries

The carmine spider mite, Tetranychus cinnabarinus (Boisduval) and the twospotted spider mite, Tetranychus urticae Koch, are serious pests of strawberries and many other horticultural crops. Control of these pests has been heavily dependent upon chemical acaricides. Objectives of this study were to determine the resistance status of these two pest species to commonly used acaricides on strawberries in a year‐round intensive horticultural production region. LC₉₀ of abamectin for adult carmine spider mites was 4% whereas that for adult twospotted spider mites was 24% of the top label rate. LC_90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 0.5%, 0.5%, 1.4% and 83% of their respective highest label rates for carmine spider mite eggs, 0.7%, 2.7%, 12.1% and 347% of their respective highest label rates for the nymphs. LC_90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 4.6%, 11.1%, 310% and 62% of their respective highest label rates for twospotted spider mite eggs, 3%, 13%, 432,214% and 15% of their respective highest label rates for the nymphs. Our results suggest that T. cinnabarinus have developed resistance to bifenazate and that the T. urticae have developed resistance to hexythiazox. These results strongly emphasize the need to develop resistance management strategies in the region.     

Development of a genetic sexing strain of Anopheles arabiensis for KwaZulu‐Natal,South Africa

An efficient sexing system is important for the release of sterile males for any control programme using the sterile insect technique. This study describes the development and characterization of a new genetic sexing strain from South Africa (GMK), needed for the planned implementation of such a programme in northern KwaZulu‐Natal Province. The base colony used was a locally modified laboratory strain of Anopheles arabiensis containing a sex‐linked gene conferring dieldrin resistance to male mosquitoes. Female A. arabiensis mosquitoes from northern KwaZulu‐Natal were mated with these males and backcrossed to introduce the dieldrin resistance gene to the Y chromosome. The resulting strain therefore had an overall genotype representing the local population but with the Y chromosome containing the dieldrin resistance gene. Life‐history characteristics, stability of the sex‐linked resistance marker, and reduction in dieldrin waste were investigated. The strain showed semi‐sterility exhibited by low egg hatch rates, faster development in the immature stages and longer adult survivorship compared with the parental strains. While the GMK strain carrying the dieldrin‐resistant gene was successfully established, the stability of the gene is limited, requiring periodic purification. Dieldrin waste can be limited by treating many more eggs than currently recommended.     

Insecticide resistance in Brazilian Triatoma infestans and Venezuelan Rhodnius prolixus

Resistance levels to insecticides used in control of Chagas Disease vectors were assessed in two species of bugs (Hemiptera: Reduviidae): Triatoma infestans (Klug) from Brazil and Rhodnius prolixus Stål from Venezuela. The resistance ratios, compared to susceptible laboratory strains, were determined by topical application bioassays. The T. infestans PA strain exhibited resistance ratios of 7× to deltamethrin, 3.6× to β‐cyfluthrin and 3.3× to cypermethrin, but was susceptible to β‐cypermethrin and lambda‐cyhalothrin. Rhodnius prolixus CA strain showed resistance to all the pyrethroids evaluated, the resistance ratios ranging between 4.5× to lambda‐cyhalothrin and 12.4× to cypermethrin. Deltamethrin resistance in both strains was decreased by piperonyl butoxide, suggesting oxidative metabolism as cause of resistance.     

A cereal cyst nematode (Heterodera avenae Woll.) resistance gene transferred from Aegilops triuncialis to hexaploid wheat

 The cereal cyst nematode (Heterodera avenae) is an important root parasite of common wheat. A high level of resistance was transferred to wheat from Aegilops triuncialis (TR lines) using the cross [(T. turgidum×Ae. triuncialis)×T. aestivum]. Low fertility (3–5 viable kernels per plant) was observed during the process but the surviving hybrid plants were highly vigorous. To obtain stable resistant lines further crosses to T. aestivum were performed. The resistance in TR lines seems to be transferred from the C genome of Ae. triuncialis (genomes CCUU). Ae. triuncialis was highly resistant to the two Spanish populations of H. avenae tested, as well as to four French races and two Swedish populations. The histological analysis showed a hypersensitive reaction in the roots of a resistant TR line inoculated with the Ha71 pathotype of H. avenae, whereas well-formed syncytia were observed in the roots of the susceptible control. Resistance to the H. avenae Ha71 pathotype seemed to be inherited as determined by a single dominant factor in the crosses between resistant TR lines and susceptible cultivars. Received: 11 November 1997 / Accepted: 9 December 1997     

Proteomic Analysis of the Lake Trout (Salvelinus namaycush) Liver Identifies Proteins from Evolutionarily Close and ‐Distant Fish Relatives

Lake trout are used as bioindicators for toxics exposure in the Great Lakes ecosystem. Here the first lake trout (Salvelinus namaycush) liver proteomics study is performed and searched against specific databases: (NCBI and UniProtKB) Salvelinus, Salmonidae, Actinopterygii, and Oncorhynchus mykiss, and the more distant relative, Danio rerio. In the biological replicate 1 (BR1), technical replicate 1 (TR1), (BR1TR1), a large number of lake trout liver proteins are not in the Salvelinus protein database, suggesting that lake trout liver proteins have homology to some proteins from the Salmonidae family and Actinopterygii class, and to Oncorhynchus mykiss and Danio rerio, two more highly studied fish. In the NCBI search, 4194 proteins are identified: 3069 proteins in Actinopterygii, 1617 in Salmonidae, 68 in Salvelinus, 568 in Oncorhynchus mykiss, and 946 in Danio rerio protein databases. Similar results are observed in the UniProtKB searches of BR1RT1, as well as in a technical replicate (BR1TR2), and then in a second biological replicate experiment, with two technical replicates (BR2TR1 and BR2TR2). This study opens the possibility of identifying evolutionary relationships (i.e., adaptive mutations) between various groups (i.e., zebrafish, rainbow trout, Salmonidae, Salvelinus and lake trout) through evolutionary proteomics. Data are available via the PRIDE Q2 (PXD011924).     

Resistance to HSV-1 in the mouse is governed by two major,independently segregating,non-H-2 loci

Earlier studies showed that genetic resistance of adult, inbred strains of mice to Herpes Simplex Virus-type 1 (HSV-1) is a dominant genetic trait. The present studies were undertaken to determine the number of genetic loci involved and whether they were found within the major histocompatibility complex,H-2, of the mouse. Challenge with HSV-1 of progeny of mice backcrossed to moderately susceptible BALB/c mice, of progeny of mice backcrossed to very susceptible A/J strain mice, and of progeny of the F-2 cross using (C57BL/6 × A/J)F₁ mice indicated that two major loci were responsible for resistance. The backcrosses to BALB/c mice suggested that additional genes on this background enhanced resistance, while further backcrosses with the A/J mice indicated that other genes on the A/J background (or the lack thereof) reduced resistance. Studies with congenic mice showed that genes within theH-2 did not influence resistance or susceptibility.     

Establishment of an acaricide-susceptible Tetranychus urticae strain and its species confirmation based on morphological and molecular characters

Acquisition of a reference Tetranychus strain that is completely susceptible to acaricides and retains an identical genetic background to acaricide-resistant strains is an essential step in elucidating mechanisms of resistance. To establish a strain completely susceptible to various acaricides, we collected Tetranychus mite populations from several regions in South Korea, including both remote and heavily cultivated regions. We tested their suitability as a susceptible reference strain by determining baseline susceptibility to six acaricides and by determining species identity as Tetranychus urticae. The UD strain, originally collected from a remote island region, was found to be most susceptible to all five major acaricides tested and was confirmed to as T. urticae on the basis of both morphological and molecular evidence. Moreover, molecular phylogenetic analysis revealed that the UD strain is an ancestral strain of other prevalently collected green-type strains. Taken together, we propose that the UD strain can be used as a susceptible reference strain for T. urticae resistance studies as it provides baseline susceptibility to acaricides and possesses a common genetic background with most other acaricide-resistant strains.     

Genetic specificity and potential for local adaptation between dengue viruses and mosquito vectors

Background  

Several observations support the hypothesis that vector-driven selection plays an important role in shaping dengue virus (DENV) genetic diversity. Clustering of DENV genetic diversity at a particular location may reflect underlying genetic structure of vector populations, which combined with specific vector genotype × virus genotype (G × G) interactions may promote adaptation of viral lineages to local mosquito vector genotypes. Although spatial structure of vector polymorphism at neutral genetic loci is well-documented, existence of G × G interactions between mosquito and virus genotypes has not been formally demonstrated in natural populations. Here we measure G × G interactions in a system representative of a natural situation in Thailand by challenging three isofemale families from field-derived Aedes aegypti with three contemporaneous low-passage isolates of DENV-1.     

Phytoextraction Potential of Wild Type and 35S-GSHI Transgenic Poplar Trees (Populus × Canescens) for Environmental Pollutants Herbicide Paraquat,Salt Sodium,Zinc Sulfate and Nitric Oxide In Vitro

Phytoextraction potentials of two transgenic (TR) poplar (Populus × canescens) clones TRggs11 and TRlgl6 were compared with that of wild-type (WT) following exposure to paraquat, zinc sulfate, common salt and nitric oxide (NO), using a leaf-disc system incubated for 21 days on EDTA-containing nutritive WPM media in vitro. Glutathione (GSH) contents of leaf discs of TRlgl6 and TRggs11 showed increments to 296% and 190%, respectively, compared with WT. NO exposure led to a twofold GSH content in TRlgl6, which was coupled with a significantly increased sulfate uptake when exposed to 10^?3 M ZnSO₄. The highest mineral contents of Na, Zn, Mn, Cu, and Mo was observed in the TRggs11 clone. Salt-induced activity of catalase enzyme increased in both TR clones significantly compared with WT under NaCl (0.75% and 1.5%) exposure. The in silico sequence analyses of gsh1 genes revealed that P. × canadensis and Salix sachalinensis show the closest sequence similarity to that of P. × canescens, which predicted an active GSH production with high phytoextraction potentials of these species with indication for their use where P. × canescens can not be grown.     

Isolation of a Halophilic,Bacteriorhodopsin-producing Archaeon,Haloferax larsenii RG3D.1 from the Rocky Beach of Malvan,West Coast of India

Haloarchaea live in saline environments and require salt for their growth. The present study reports on the isolation of a haloarchaeal strain RG3D.1 identified as Haloferax larsenii using Sehgal and Gibbons medium with 3.42 M NaCl, from Rock Garden at Malvan in the West Coast of India. The rock type of Malvan Coast is correlated based on geological setting with the basal member of the Bababudan group placed at 2728 ± 102 million years ago (Ma). The haloarchaeal strain produced bacteriorhodopsin (BR) (0.137 g l^?1) and generated electric potential of 49.2 mV when exposed to sunlight. Thus, this is the first report on the isolation of a haloarchaeon, Haloferax larsenii, from red rocky substrate and production of BR.     

QTL mapping for brown rot (Monilinia fructigena) resistance in an intraspecific peach (Prunus persica L. Batsch) F1 progeny

Brown rot (BR) caused by Monilinia spp. leads to significant post-harvest losses in stone fruit production, especially peach. Previous genetic analyses in peach progenies suggested that BR resistance segregates as a quantitative trait. In order to uncover genomic regions associated with this trait and identify molecular markers for assisted selection (MAS) in peach, an F1 progeny from the cross “Contender” (C, resistant)?×?“Elegant Lady” (EL, susceptible) was chosen for quantitative trait loci (QTL) analysis. Over two phenotyping seasons, skin (SK) and flesh (FL) artificial infections were performed on fruits using a Monilinia fructigena isolate. For each treatment, infection frequency (if) and average rot diameter (rd) were scored. Significant seasonal and intertrait correlations were found. Maturity date (MD) was significantly correlated with disease impact. Sixty-three simple sequence repeats (SSRs) plus 26 single-nucleotide polymorphism (SNP) markers were used to genotype the C?×?EL population and to construct a linkage map. C?×?EL map included the eight Prunus linkage groups (LG), spanning 572.92 cM, with an average interval distance of 6.9 cM, covering 78.73 % of the peach genome (V1.0). Multiple QTL mapping analysis including MD trait as covariate uncovered three genomic regions associated with BR resistance in the two phenotyping seasons: one containing QTLs for SK resistance traits near M1a (LG C?×?EL-2, R ²?=?13.1–31.5 %) and EPPISF032 (LG C?×?EL-4, R ²?=?11–14 %) and the others containing QTLs for FL resistance, near markers SNP_IGA_320761 and SNP_IGA_321601 (LG3, R ²?=?3.0–11.0 %). These results suggest that in the C?×?EL F1 progeny, skin resistance to fungal penetration and flesh resistance to rot spread are distinguishable mechanisms constituting BR resistance trait, associated with different genomic regions. Discovered QTLs and their associated markers could assist selection of new cultivars with enhanced resistance to Monilinia spp. in fruit.     

Infectivity and Early Antibody Response to Borrelia burgdorferi Sensu Lato Isolated in Japan in Outbred Mice

Borrelia burgdorferi sensu lato isolated from Ixodes ovatus (B. japonica), I. persulcatus and patients with erythema migrans (EM) in Japan were determined on infectivity and arthritis induction-activity in outbred mice. Infectivity of B. japonica was weak and did not induce the development of footpad swelling by subcutaneous (s.c.) inoculation into the footpad. Challenged strain, NO129-M of B. japonica, to ddY mice were reinoculated to the mice at various cell numbers (1 × 10-1 × 10⁶ cells/mouse). The strain isolated from the mouse did not reinfect ddY mice and did not induce the production of specific antibody to the homologous strain. On the other hand, strains from I. persulcatus and patients with EM in Japan infected the mice and induced a serious inflammatory response in Borrelia-inoculated footpad as well as strains belonging to the three genospecies, B. burgdorferi sensu stricto, B. garinii, and B. afzelii, related to Lyme disease, from North America and Europe. The mice were infected with 10 cells of strain HP1 isolated from I. persulcatus in Hokkaido and of strain 297 isolated from a patient in the U.S.A. by subcutaneous inoculation into the hind footpad, or by intradermal inoculation into the back. Antigens of ca. 20, 23–24 (Osp C), 29, 39, 41 (flagellin) and 45 kDa reacted with the pooled sera from mice inoculated with strains HP1 and 297, but Osp A and Osp B did not.