scholarly journals Adaptive aggregation by spider mites under predation risk

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Lena Dittmann ◽  
Peter Schausberger
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.


2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.


ENTOMON ◽  
2020 ◽  
Vol 45 (1) ◽  
pp. 81-86
Author(s):  
Mohammad Yosof Amini ◽  
Ahamad Shah Mohammadi ◽  
Srinivasa N ◽  
Onkarappa S

False spider mites are serious pests of pomegranate and frequently cause considerable economic losses in other fruit crops as well. A field experiment conducted to evaluate eleven acaricides against Tenuipalpus aboharensis infesting pomegranate plants, revealed that wettable sulphur at 2.5 g and dicofol at 2.5 ml per litre were very effective and other acaricides viz. propargite, fenpyroximate, chlorfenapyr and buprofezin were also found effective against T. aboharensis.


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