<p class="Body"><strong>Effect of foundress population density and size on reproduction and population growth of a haplodiploid mite</strong></p>

Abstract

Tetranychus ludeni Zacher (Acari: Tetranychidae) is an invasive polyphagous haplodiploid pest mite of many vegetable crops in many parts of the world. This study investigated the effects of simultaneous variations in the local foundress population density and size on the reproduction and population growth of T. ludeni. We show that negative population-density and -size dependency limited the reproduction of foundresses, where the effects of population size on population growth overweighed that of population density. We further demonstrate that ovipositing females could accelerate population growth rate (intrinsic rate of increase, rm) at higher population sizes by producing more daughters early during their lifespan, which can be an adaptive strategy to allow more daughters to complete development and disperse to reduce future food competition intensity. This study provided knowledge on population dynamics in response to foundress population density and size in general and T. ludeni population forecast and precise timing of pest management in particular.

Resource relocations in relation to dispersal in Tetranychus ludeni Zacher

“…These findings suggest that the mites adjust their resource allocation to reproduction and movement depending on whether and how far they intend to disperse. In another word, although dispersed and resident mites had similar lifetime fecundity, dispersed mites spread their resources for reproduction in a wider range, prolonging generation time and population doubling time (Weerawansha et al 2020). Similar phenomenon has also been reported in butterflies Proclossiana eunomia Esper, Boloria aquilonaris Stichel, Euphydryas editha bayensis Sternitsky, E. aurinia Rottemburg, and Lopinga achine Scopoli (Lepidoptera: Nymphalidae) (Baguette & Schtickzelle 2006).…”

Comparing the effects of social environments and life history traits on sex allocation in a haplodiploid spider mite

“…We further reveal that maternal age had both significant positive direct and indirect effects on sex ratio (Figure 2). The results suggest that the mated mothers did not experience any sperm depletion as single mating can lead to extremely female-biased sex ratios (Weerawansha et al 2022b), and the aging mothers tend to increase fecundity as well as daughter production continuously, especially during their early life (Table 3; Weerawansha et al 2020). Moreover, maternal age had significant positive effects on egg number (effect=0.…”

“…Moreover, previous studies reveal that in haplodiploid species (i.e., whose fertilized eggs give rise to diploid female offspring and unfertilized eggs to haploid male offspring), life history traits such as the maternal age can also directly affect sex allocation due to the age-specific fertilization (i.e., more daughters produced at specific ages) (Roy et al 2003;Ueno 2014;Weerawansha et al 2020). Nevertheless, maternal age may also affect offspring sex ratio indirectly through age-specific investment in clutch size (Weerawansha et al 2020) and egg size (Reviewed in Mousseau & Fox 1998). Therefore, multiple factors of social environments and life history traits may simultaneously act on offspring sex ratio during the females' reproductive period.…”

Reproductive plasticity in response to the changing cluster size during the breeding period: a case study in a spider mite

“…However, cluster size often changes while individuals are reproducing due to frequent deaths, births, aggregation (immigration) and dispersal (emigration) (Roeder 1992 ; Roff 1992 ; Stearns 1992 ; Price and Hunter 1995 ; Bowman et al 2002 ; Schausberger et al 2021 ). As a result, animals must have developed reproductive plasticity to adapt to dynamic social environment to maximize the fitness of their offspring and their own (Ross et al 2013 ; Radwan et al 2014 ; De Roissart 2016 ; Weerawansha et al 2020 , 2022a , b ; Tinsley Johnson et al 2021 ). To date, it is still unknown how changes of cluster size during female reproductive phase affect their reproductive strategies.…”

“…Spider mites (Acari: Tetranychidae), such as invasive pests Tetranychus ludeni Zacher and Tetranychus urticae Koch, have been used as model species to examine changes of reproductive strategies mediated by social environment (Le Goff et al 2010 ; Macke et al 2012a ; Weerawansha et al 2020 , 2022a , b , c , d ). They live in patchy clusters of varying size and density and produce silk webs for dispersal and protection against predation and environmental hazards (Le Goff et al 2010 ; Yano 2012 ; Schausberger et al 2021 ).…”