scholarly journals Evolutionary history determines population spread rate in a stochastic, rather than in a deterministic way

2020 ◽  
Author(s):  
Mortier Frederik ◽  
Masier Stefano ◽  
Bonte Dries
Keyword(s):  
Evolutionary History ◽  
Spider Mite ◽  
Life History Traits ◽  
Fragmented Landscape ◽  
Spread Rate ◽  
Population Spread ◽  
Natural Landscapes ◽  
Experimental Populations ◽  
Two Spotted Spider Mite ◽  
The One

AbstractFragmentation of natural landscapes results in habitat and connectedness loss, making it one of the most impactful avenues of anthropogenic environmental degradation. Populations living in a fragmented landscape can adapt to this context, as witnessed in changing dispersal strategies, levels of local adaptation and changing life-history traits. This evolution, however, can have ecological consequences beyond a fragmented range. Since invasive dynamics are driven by the same traits affected by fragmentation, the question arises whether fragmented populations evolve to be successful invaders.In this study we assess population spread during three generations of two-spotted spider mite (Tetranychus urticae) population in a replicated experiment. Experimental populations evolved independently in replicated experimental metapopulations differing only in the level of habitat connectedness as determined by the inter-patch distance.We find that habitat connectedness did not meaningfully explain variation in population spread rate. Rather, variation within experimental populations that shared the same level of connectedness during evolution was larger than the one across these levels. Therefore, we conclude that experimental populations evolved different population spread capacities as a result of their specific evolutionary background independent but of the connectedness of the landscape. While population spread capacities may be strongly affected by aspects of a population’s evolutionary history, predicting it from identifiable aspects of the evolutionary history may be hard to achieve.

Ethyl formate and phosphine fumigations on the two-spotted spider mite, Tetranychus urticae and their biochemical responses

2019 ◽  
Vol 62 (1) ◽  
Author(s):  
Kyeongnam Kim ◽  
Yong Ho Lee ◽  
Gayoung Kim ◽  
Byung-Ho Lee ◽  
Jeong-Oh Yang ◽  
...  
Keyword(s):  
Tetranychus Urticae ◽  
Respiratory Chain ◽  
Spider Mite ◽  
Ethyl Formate ◽  
Treated Group ◽  
Effective Control ◽  
Molecular Approaches ◽  
Significant Difference ◽  
Target Sites ◽  
Two Spotted Spider Mite

Abstract Two spotted spider mite, Tetranychus urticae, is a polyphagous pest to a variety of plants and they are hard to be controlled due to occurrence of resistance to acaricides. In this study, biochemical evaluation after ethyl formate (EF) and phosphine (PH3) fumigation towards T. urticae might help officials to control them in quarantine purposes. PH3 fumigation controlled eggs (LC50; 0.158 mg/L), nymphs (LC50; 0.030 mg/L), and adults (LC50; 0.059 mg/L) of T. urticae, and EF effectively affected nymphs (LC50; 2.826 mg/L) rather than eggs (LC50; 6.797 mg/L) and adults (LC50; 5.836 mg/L). In a longer exposure time of 20 h, PH3 fumigation was 94.2-fold more effective tool for control of T. urticae than EF fumigant. EF and PH3 inhibited cytochrome c oxidase (COX) activity differently in both nymphs and adults of T. urticae. It confirmed COX is one of target sites of these fumigants in T. urticae and COX is involved in the respiratory chain as complex IV. Molecular approaches showed that EF fumigation completely down-regulated the expression of cox11 gene at the concentration of LC10 value, while PH3 up-regulated several genes greater than twofold in T. urticae nymphs treated with the concentration of LC50 value. These increased genes by PH3 fumigation are ndufv1, atpB, para, and ace, responsible for the expression of NADH dehydrogenase [ubiquinone] flavoprotein 1, ATP synthase, and acetylcholinesterase in insects, respectively. Lipidomic analyses exhibited a significant difference between two fumigants-exposed groups and the control, especially an ion with 815.46 m/z was analyzed less than twofold in the fumigants-treated group. It was identified as PI(15:1/18:3) and it may be used as a biomarker to EF and PH3 toxicity. These findings may contribute to set an effective control strategy on T. urticae by methyl bromide alternatives such as EF and PH3 because they have shared target sites on the respiratory chain in the pest.

scholarly journals Effects of local isolates of Beauveria bassiana (Balsamo) Vuillemin on the two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae)

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Cenk Yucel
Keyword(s):  
Tetranychus Urticae ◽  
Beauveria Bassiana ◽  
Spider Mite ◽  
Lethal Effect ◽  
Probit Analysis ◽  
Plant Feeding ◽  
Wide Range ◽  
Two Spotted Spider Mite ◽  
Short Time ◽  
Tetranychus Urticae Koch

Abstract Background The two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae), is a widely distributed plant-feeding pest that causes significant yield losses in a wide range of crops. Newly developed or improved environmentally friendly biocontrol agents serve as an alternative to traditional pest control tools. Experiment of the effects of 2 local fungal isolates of Beauveria bassiana (BGF14 and BCA32) was carried out against T. urticae under laboratory conditions. Results Both tested isolates had lethal effect in a short time after application, and this effect increased as time progressed. BGF14 and BCA32 isolates caused T. urticae mortality rates ranging from 25.88 to 61.92 and 32.36 to 62.03% when applied at the concentrations between 1×105 and 1×108 conidia/ml, respectively. According to the Probit analysis performed on the effect of fungi on T. urticae adults, the LC50 values of BGF14 and BCA32 isolates on the 7th day after inoculation were 2.6×106 and 6.3×104 conidia/ml, respectively, and the LT50 values for both fungi applied at a concentration of 108 conidia/ml were 2.14 and 2.23 days, respectively. Conclusions The 2 isolates of B. bassiana (BGF14 and BCA32) had the potentials to suppress T. urticae population and can be recommended as promising biocontrol agent candidates for control of T. urticae.

scholarly journals Environmental RNAi pathways in the two-spotted spider mite

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Mosharrof Mondal ◽  
Jacob Peter ◽  
Obrie Scarbrough ◽  
Alex Flynt
Keyword(s):  
Gene Expression ◽  
Small Rna ◽  
Spider Mite ◽  
Genetic Manipulation ◽  
Model Organisms ◽  
Rnai Pathway ◽  
Plant Host ◽  
Rnai Technology ◽  
Two Spotted Spider Mite ◽  
Multicellular Organisms

Abstract Background RNA interference (RNAi) regulates gene expression in most multicellular organisms through binding of small RNA effectors to target transcripts. Exploiting this process is a popular strategy for genetic manipulation and has applications that includes arthropod pest control. RNAi technologies are dependent on delivery method with the most convenient likely being feeding, which is effective in some animals while others are insensitive. The two-spotted spider mite, Tetranychus urticae, is prime candidate for developing RNAi approaches due to frequent occurrence of conventional pesticide resistance. Using a sequencing-based approach, the fate of ingested RNAs was explored to identify features and conditions that affect small RNA biogenesis from external sources to better inform RNAi design. Results Biochemical and sequencing approaches in conjunction with extensive computational assessment were used to evaluate metabolism of ingested RNAs in T. urticae. This chelicerae arthropod shows only modest response to oral RNAi and has biogenesis pathways distinct from model organisms. Processing of synthetic and plant host RNAs ingested during feeding were evaluated to identify active substrates for spider mite RNAi pathways. Through cataloging characteristics of biochemically purified RNA from these sources, trans-acting small RNAs could be distinguished from degradation fragments and their origins documented. Conclusions Using a strategy that delineates small RNA processing, we found many transcripts have the potential to enter spider mite RNAi pathways, however, trans-acting RNAs appear very unstable and rare. This suggests potential RNAi pathway substrates from ingested materials are mostly degraded and infrequently converted into regulators of gene expression. Spider mites infest a variety of plants, and it would be maladaptive to generate diverse gene regulators from dietary RNAs. This study provides a framework for assessing RNAi technology in organisms where genetic and biochemical tools are absent and benefit rationale design of RNAi triggers for T.urticae.

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