Predators of the nest-making spider mite &lt;i&gt;Schizotetranychus brevisetosus&lt;/i&gt; (Acari: Tetranychidae)

Ito, Katsura

doi:10.2300/acari.29.59

Cited by 4 publications

(2 citation statements)

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“…Living on evergreen hosts provides the reproductive advantage of earlier initiation of reproduction than on deciduous hosts, especially where predation pressure in winter is minimal (Ito and Hamada 2018). However, predation pressure of spider mites increases early in winter, with predators of S. breviestosus disappearing in mid-winter (Ito 2020). In this situation, higher cold hardiness of eggs is important during winter.…”

Section: Discussionmentioning

confidence: 99%

“…This style is distinct from S. akitanus, whose females cease producing diapausing eggs and overwinter themselves and adults of different generations interbreed in spring (Gotoh 1986a). Predators are almost absent during winter in S. brevisetosus (Ito 2020), and this low predation pressure enables the overwintering of winter eggs. This inter-speci c difference in overwintering styles may be partly explained by climatic conditions; S. brevisetosus individuals can act even during winter.…”

Section: Introductionmentioning

confidence: 99%

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Overwintering at multiple life stages in Schizotetranychus shii (Acari: Tetranychidae), a specialist of evergreen chinquapin

Nagata,

Negoro,

Ito

2024

Preprint

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Host availability in winter affects the overwintering strategies of herbivorous arthropods. Spider mites (Acari: Tetranychidae) overwinter as eggs or adult females, but some do so as multiple life stages on evergreen hosts. For example, in Schizotetranychus brevisetosus, adult females and their eggs stay on host leaves in mid-winter. However, few studies have focused on proximate factors generating such overwintering stages. Here, we investigated photoperiodic responses and life-stage compositions in winter in a population of Schizotetranychus shii, a specialist of Japanese chinquapin (Fagaceae). The proportion of non-ovipositing females at 20°C followed a sigmoid curve with increasing photoperiod, and the critical day length (CDL) was estimated as 11.8L, which corresponds to the environments from late September to early October. Although females grown under 10–11L conditions never oviposited within 7 days, 90–96% of them started oviposition within only 30 days without chilling (n = 23–31). In the field, all life stages were observed to occur throughout winter, but their proportions varied drastically. The proportion of eggs declined from early October (62%) to early December (12%), as predicted by CDL, but steeply increased toward late February (96%), during which only adult females and eggs remained. In summary, a short photoperiod in October arrests oviposition in emerging females, but they soon commence oviposition in November while immature stages are still growing, and individuals at all life stages (including a new generation) coexist until all immature stages mature in February. This novel pattern suggests that evergreen hosts allow spider mites to evolve overwintering strategies with little phylogenetic constraint.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%