scholarly journals Inheritance of Biochemical and Morphological Characters Associated with Two-spotted Spider Mite Resistance in Pelargonium ×hortorum

1997 ◽  
Vol 122 (3) ◽  
pp. 373-379 ◽  
Author(s):  
Richard Grazzini ◽  
Donald Walters ◽  
Jody Harmon ◽  
David J. Hesk ◽  
Diana Cox-Foster ◽  
...  

Diploid zonal geraniums (Pelargonium ×hortorum) are able to resist attack by small arthropod pests such as the two-spotted spider mite (Tetranychus urticae Koch) when exudate produced by tall glandular trichomes contains a high percentage of ω5-unsaturated anacardic acids. Trichomes of susceptible plants exude primarily saturated anacardic acids. Inbred mite-resistant and -susceptible geraniums were reciprocally crossed and the F1, F2, and backcross generations were examined for anacardic acid composition and trichome density. Selected F2 plants were bioassayed for resistance to two-spotted spider mites. High concentrations of ω5-unsaturated anacardic acids in resistant plants are conditioned by a single dominant allele. We propose that inheritance of tall glandular trichome density can be controlled by a small number of loci (possibly as few as one) exhibiting codominance. F2, with low densities of tall glandular trichomes and producing ω5-unsaturated anacardic acids, displayed effective resistance to two-spotted spider mites as measured by mite mortality and fecundity. A genetic model for the biosynthesis of anacardic acids is proposed.

2020 ◽  
Vol 44 ◽  
Author(s):  
Juliano Tadeu Vilela de Resende ◽  
Renato Barros de Lima Filho ◽  
Luana Karolline Ribeiro ◽  
Jéssica Vanessa Wosniak Corrêa ◽  
Cleber Daniel de Goes Maciel ◽  
...  

ABSTRACT The two-spotted spider mite (Tetranychus urticae) is the main pest encountered in strawberry cultivation in protected environments, causing damage and increasing the cost of production associated with chemical control. Breeding programs are essential for obtaining new cultivars that are more tolerant to two-spotted spider mites. The objective was to evaluate whether the leaf trichomes mediatethe resistance of intraspecific strawberry hybrids to two-spotted spider mites. Preselected hybrids were subjected to infestation by two-spotted spider mites and evaluated via the no-choice assay and the travel test. Resistance was correlated with the density of trichomes, both glandular and non-glandular, present on the surface of the leaflets of strawberry genotypes. The results indicated that there is an influence of hybrids and cultivars on the behavior of the pest, allowing the verification of the existence of resistant genotypes (RVDA#16, RVCS#44 and Camino Real). These treatments resulted in low numbers of eggs deposited and hatched compared with the other treatments and shorter distances traveled by two-spotted spider mites on the surface of leaflets. It was also verified that the glandular trichomes presented a significant negative correlation with the average distance traveled by two-spotted spider mites on the surface of the leaf discs, indicating that these structures alter the behavior of these arthropods. Genotype resistance was associated with the presence of glandular trichomes. In addition to the superiority of the agronomic and postharvest attributes of the preselected hybrids (RVDA#16 and RVCS#44) identified in the previous selection efforts, they proved to be promising materials for achieving resistance to the spider mite, revealing important genotypes for use as cultivars and particularly as parents in breeding programs.


2020 ◽  
Vol 25 (8) ◽  
pp. 1359-1372
Author(s):  
Matheus S. Rocha ◽  
Lívia A. Celada ◽  
Everton N. L. Rodrigues ◽  
Luiz E. Costa-schmidt

The emergence of anti-predatory strategies for prey survival are ruled by the minimization of the encounters/interactions with potential predators, but at the same time by maximizing the access to limiting resources such as food or mating partners. Cues indicating predatory activity influence decision-making activities in the two-spotted spider mite Tetranychus urticae, such as dispersion, foraging activities, and reproductive effort.  However, anti-predatory strategies studied in spider mites generally considers mainly the female perspective (e.g. oviposition), leaving a gap in how T. urticae couples deal with predatory risk. Here, through laboratory experiments, we observed that matured spider mite couples were only affected by predation risk during the pre-copulatory stages of the mating process, especially when deciding to proceed in a mating opportunity. The mating performance of individuals was independent of their exposure to predation risk, suggesting that couples would adopt full investment behavior after opting to proceed in a mating attempt. Though our working hypothesis predicted predation risk interference throughout the entire mating process, we conclude that decision-making activities by spider mite during pre-copulatory stages act independently from copulatory stages associated to insemination.


2011 ◽  
Vol 48 (2) ◽  
pp. 193-205 ◽  
Author(s):  
Anna Tomczyk ◽  
Magdalena Suszko

The role of phenols in the influence of herbal extracts fromSalvia officinalisL. andMatricaria chamomillaL. on two-spotted spider miteTetranychus urticaeKochExtracts prepared from 2 medicinal herbs (common sageSalvia officinalisL. and German chamomileMatricaria chamomillaL.) were used in this study for biological control of spider mites. Their effect on mortality, fecundity, and development ofTetranychus urticaeKoch on English ivy (Hedera helixL.) was studied under laboratory and greenhouse conditions. The extracts were prepared by soaking freshSalvialeaves or dryMatricariaflowers in ethanol for 24 h, followed by evaporation, and finally suspension of the pellets in water. Full extracts and extracts without phenols were tested. TheSalviaextracts had a higher acaricidal activity thanMatricariaextracts, but the toxicity of both extracts to spider mite eggs was low. The toxic effect of fullSalviaextracts on larval stages and females ofT. urticaewas evident. More than 50% of larvae and females were killed by this treatment in 4 days. Besides, total fecundity of survived females was evidently lower. Mortality and low fecundity after fullSalviaextract application decreased the spider mite population by 76%. The toxicity ofSalviaextracts after removal of phenols strongly declined, so the negative effect of the fullSalviaextract on spider mites was connected with a high concentration of phenolic compounds. The toxic effect ofMatricariaextracts in all tests was much lower and no evident role of phenolic compounds in its extracts was observed.


HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 831C-831
Author(s):  
Shahrokh Khanizadeh ◽  
Andre Belanger

Considerable variability in susceptibility to two-spotted spider mite (TSSM) were observed for the strawberry cultivars used as parents and some of our promising selections. Large variation was observed for 9-octadecenal oil composition followed by linalool, C9H1002, decanal, β-cyclocitral, α-terpineol and (Z)-3-hexenol. The purpose of this research was to identify the relative susceptibility of selected strawberry lines to TSSM in relation to leaf essential oil composition. One objective of our breeding program is the early identification of susceptible lines and/or seedlings so that they can be eliminated prior to field trials.


2011 ◽  
Vol 48 (2) ◽  
pp. 213-223 ◽  
Author(s):  
Monika Godzina ◽  
Małgorzata Kiełkiewicz ◽  
Katarzyna Szymczykiewicz

Varying abundance and dispersal of the two-spotted spider mite (Tetranychus urticaeKoch, 1836, Acari: Prostigmata: Tetranychidae) onMi-tomato plants differing in allelic combinationIt is well known that the presence of theMi-1.2gene determines the resistance of tomato plants (Solanum lycopersicumL.) to 3 root-knot nematode species and some insect herbivores of the order Hemiptera. In this study, the density and dispersal of two-spotted spider mites (Tetranychus urticae) on tomato plants of 4 cultivars were evaluated under greenhouse conditions, to find out whether tomatoes differing in allelic combination of theMi-1.2gene exhibit similar or different resistance to the mite pest. The results show, for the first time, that the same initial number of mites develops into populations that vary in abundance and distribution depending on tomato allelic composition of theMi-1.2gene. The results indicate that the mite-pest develops more slowly on tomato plants of cultivar ‘Motelle’, carrying 2 dominant alleles for theMi-1.2gene, than on heterozygous ‘Altess F1’ tomatoes and both cultivars carrying only recessive alleles of this gene: ‘Moneymaker’ and ‘Plaisence F1’. This suggests that theMi-1.2gene may be involved in tomato resistance against spider mites when this dominant gene is expressed homozygously, but this needs to be verified by further research.


2020 ◽  
Author(s):  
Karla Gasparini ◽  
Ana Carolina R. Souto ◽  
Mateus F. da Silva ◽  
Lucas C. Costa ◽  
Cássia Regina Fernandes Figueiredo ◽  
...  

ABSTRACTBackground and aimsTrichomes are epidermal structures with an enormous variety of ecological functions and economic applications. Glandular trichomes produce a rich repertoire of secondary metabolites, whereas non-glandular trichomes create a physical barrier against biotic and abiotic stressors. Intense research is underway to understand trichome development and function and enable breeding of more resilient crops. However, little is known on how enhanced trichome density would impinge on leaf photosynthesis, gas exchange and energy balance.MethodsPrevious work has compared multiple species differing in trichome density, instead here we analyzed monogenic trichome mutants in a single tomato genetic background (cv. Micro-Tom). We determined growth parameters, leaf spectral properties, gas exchange and leaf temperature in the hairs absent (h), Lanata (Ln) and Woolly (Wo) trichome mutants.Key resultsShoot dry mass, leaf area, leaf spectral properties and cuticular conductance were not affected by the mutations. However, the Ln mutant showed increased carbon assimilation (A) possibly associated with higher stomatal conductance (gs), since there were no differences in stomatal density or stomatal index between genotypes. Leaf temperature was furthermore reduced in Ln in the early hours of the afternoon.ConclusionsWe show that a single monogenic mutation can increase glandular trichome density, a desirable trait for crop breeding, whilst concomitantly improving leaf gas exchange and reducing leaf temperature.HIGHLIGHTA monogenic mutation in tomato increases trichome density and optimizes gas exchange and leaf temperature


2020 ◽  
Vol 11 (1) ◽  
pp. 118
Author(s):  
Matej Vidrih ◽  
Anja Turnšek ◽  
Magda Rak Cizej ◽  
Tanja Bohinc ◽  
Stanislav Trdan

In 2015, we studied the efficiency of the predatory mite Neoseiulus californicus (McGregor) for suppression of the two-spotted spider mite Tetranychus urticae in a field experiment at a hop plantation. We randomly arranged four treatments in a three-block experiment. Fungicides were used in all treatments; insecticides were used in all treatments except the predatory mite treatment and acaricides were used in only two treatments. A single inundative release of the mite N. californicus was carried out on 4 July. On four different dates (10 June, 17 July, 29 July and 9 August), we counted the eggs and the mobile stages (larvae, nymphs and adults) of the two-spotted spider mite in all four treatments. In the treatment with the predatory mite, we established the fewest eggs and mobile stages of T. urticae 14 days after the release of the predator. The selected acaricides in our research acted in a primarily ovicidal manner, but we did not detect satisfactory effects on the mobile stages of the two-spotted spider mite. This result suggests the emergence of resistance of two-spotted spider mites to the acaricides hexythiazox and abamectin. Our research established comparable effects of the predatory mite N. californicus and acaricides, and further improvement of the efficiency would require release of the natural enemy into a hop plantation in mid-June, followed by a second release three weeks later. The costs of acaricide use in our experiment were from 12.7-fold (two sprayings of hexythiazox, and a single spraying with abamectin) to 17.8-fold (single treatments of hexythiazox and abamectin) lower than those of a single release of the biological control agent in question. The results of our study represent a starting point for future research, which could achieve satisfactory results in suppressing two-spotted spider mites on a hop plantation by repeated use of the predatory mite N. californicus.


2005 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
Douglas B. Walsh ◽  
Gary G. Grove

Leaf disk and whole leaf bioassays were conducted to evaluate the repellency and repulsiveness of selected fungicides, insecticides, spray adjuvants, and petroleum-derived spray oils (PDSO) to the two-spotted spider mite, Tetranychus Urticae Koch (Acari: Tetranychidae). Compounds were evaluated for their ability to stimulate the movement of T. urticae from treated to nontreated grape tissue (repellency) and to inhibit their movement from untreated to treated tissue (repulsiveness). All insecticides other than Bacillus thuringiensis and some fungicides were highly repellent. Several insecticides and fungicides, and all spray adjuvants, were highly repulsive. We conclude that many agrichemicals are irritating to two-spotted spider mites and may impact their spatial dynamics within plant canopies. Accepted for publication 7 November 2005. Published 28 December 2005.


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