Predators induce egg retention in prey

To prevent predation on their eggs, prey often avoid patches occupied by predators. As a result, they need to delay oviposition until they reach predator-free patches. Because many species allocate energy to egg production in a continuous fashion, it is not clear what kind of mechanism prey use to delay oviposition. We used females of the phytoseiid mite Neoseiulus cucumeris to study these mechanisms. Females were placed in patches with pollen, a food source they use for egg production, and they were exposed to another phytoseiid mite, Iphiseius degenerans, which is an intraguild predator of N. cucumeris juveniles. We found that the oviposition of N. cucumeris females on patches with the predator was lower than on patches without the predator. Cues left by the intraguild predator were not sufficient to elicit such behaviour. Females of N. cucumeris reduced oviposition when exposed to the predator by retaining the egg inside their body, resulting in a lower developmental rate once these eggs were laid. Hence, females are capable of retaining eggs, but the development of these eggs continues inside the mother’s body. In this way, females gain some time to search for less risky oviposition sites.     

New species of the Hygrobates salamandrarum-group (Acari, Hydrachnidia, Hygrobatidae) from Southeast Asia

Two new water mite species of the genus Hygrobates Koch, 1837 (Acari, Hydrachnidia, Hygrobatidae) were found to live parasitic on newts of the genus Paramesotriton Chang, 1935 (Amphibia, Caudata, Salamandridae) from Vietnam and Laos: Hygrobates forcipifer sp. nov. and H. ancistrophorus sp. nov. The H. salamandrarum-group is defined, that now includes three species from Southeast Asia. Males and females of both new species are described, as well as larvae and deutonymphs of the Vietnamese species. These data provide the first record of males, nymphs and larvae of the species-group. The systematic position of the group, as well as the parasite-host association and the lifecycle of the species are discussed. Furthermore, the character states of the striking mouthparts, particularly modified as an adaptation for penetrating the amphibian skin, the genital skeleton and the larval morphology are examined.     

Low parasite loads accompany the invading population of the bumblebee, Bombus terrestris in Tasmania

In its native Europe, the bumblebee, Bombus terrestris (L.) has co-evolved with a large array of parasites whose numbers are negatively linked to the genetic diversity of the colony. In Tasmania B. terrestris was first detected in 1992 and has since spread over much of the state. In order to understand the bee’s invasive success and as part of a wider study into the genetic diversity of bumblebees across Tasmania, we screened bees for co-invasions of ectoparasitic and endoparasitic mites, nematodes and micro-organisms, and searched their nests for brood parasites. The only bee parasite detected was the relatively benign acarid mite Kuzinia laevis (Dujardin) whose numbers per bee did not vary according to region. Nests supported no brood parasites, but did contain the pollen-feeding life stages of K. laevis. Upon summer-autumn collected drones and queens, mites were present on over 80% of bees, averaged ca. 350–400 per bee and were more abundant on younger bees. Nest searching spring queens had similar mite numbers to those collected in summer-autumn but mite numbers dropped significantly once spring queens began foraging for pollen. The average number of mites per queen bee was over 30 fold greater than that reported in Europe. Mite incidence and mite numbers were significantly lower on worker bees than drones or queens, being present on just 51% of bees and averaging 38 mites per bee. Our reported incidence of worker bee parasitism by this mite is 5–50 times higher than reported in Europe. That only one parasite species co-invaded Tasmania supports the notion that a small number of queens founded the Tasmanian population. However, it is clearly evident that both the bee in the absence of parasites, and the mite have been extraordinarily successful invaders. Received 12 April 2006; revised 10 November 2006; accepted 15 November 2006.     

Recent non‐native invertebrate plant pest establishments in Great Britain: origins,pathways, and trends

1 An appraisal of non‐native invertebrate plant pest establishments in Great Britain, between 1970 and 2004, was carried out to improve our understanding of current invasion processes by non‐native plant pests, and to assist national strategies in managing the risks they pose. 2 A total of 164 establishments, comprising 50 natural colonists and 114 human‐assisted introductions, were recorded across 13 major taxonomic groups. 3 The mean rate of establishment was 22.1 species per 5‐year period: 19.1 and 3.0 species outside and inside protected cultivation, respectively. Despite the continuing rapid growth in international trade and a general perception that rates of pest invasions are accelerating, no significant temporal trends in the rate of establishments in Great Britain were detected, either for natural colonists or human‐assisted introductions, or for pests of plants grown indoors or outside. 4 The plant trade, particularly in ornamental plants, accounted for nearly 90% of human‐assisted introductions; apiculture, biological control, timber imports, transport stowaways and intentional releases each contributed less than 5%. Only eight (4.9%) of the establishments could be considered as having no direct potential economic impact because all other species have been recorded as feeding on cultivated plants. A greater proportion of establishments by both natural colonists and human‐assisted introductions occurred on non‐native, woody plants. 5 The present study confirms previous work in other European countries that highlight the predominant role of the ornamental plant trade in introducing new plant pests to the European continent, mainly from Asia and North America.     

Assaying three new fungi against citrus mites in the laboratory,and a field trial

The Basidiomycotine fungi Meira geulakonigii, Meira argovae and Acaromyces ingoldii were assayed in the laboratory against five species of herbivorous mites: Phyllocoptruta oleivora (Eriophyidae), Panonychus citri, Eutetranychus orientalis, Tetranychus urticae and Tetranychus cinnabarinus (all four Tetranychidae). All fungi caused significantly high mortality rates (as compared to controls) after 14 days, some after 1 week. Phyllocoptruta oleivora was the most susceptible, showing >80% mortality even after 1 week. In a field trial, grapefruits sprayed either once a month or once a season with M. geulakonigii had significantly fewer P. oleivora and less damage than unsprayed fruit. These results suggest that M. geulakonigii may protect grapefruits against the injurious P. oleivora.     

一种捕食螨饲养观察装置

【目的】为在室内防止捕食螨逃逸,设计一种防止逃逸行为的饲养观察装置。【方法】对比研究了传统隔水式饲养装置和改进型装置在防止逃逸行为中的效果,及改进型装置对捕食螨发育及繁殖能力有无影响。【结果】改进型装置通过添加瓶塞、棉线、盖玻片组成密闭小室,可有效防止捕食螨的逃逸,逃逸率仅为3.3%。另外,使用该装置后的捕食螨生长发育及繁殖等能力与隔水式饲养法相比未受到显著影响。【结论】本文设计的饲养观察装置可在捕食螨生物学、生态学及农药抗性等基础研究中应用。     

Do leaf domatia mediate intraguild predation and host plant resistance to Oligonychus aceris (Shimer) on Red Sunset Maple (Acer rubrum)?

The predatory mites Neoseiulus fallacis (Garman) (Acarina: Phytoseiidae) and Zetzellia mali (Ewing) (Acarina: Stigmaeidae) have the potential to suppress populations of Oligonychus aceris (Shimer) (Acarina: Tetranychidae) on maple cultivars under field conditions. Red Sunset red maples (Acer rubrum) are more resistant to O. aceris than ‘Autumn Blaze’ Freeman maple (Acer × fremanii). Examination of leaves indicated that the mite resistant Red Sunset trees had more leaf domatia than those from Autumn Blaze. Laboratory assays found that maple cultivars did not affect rates of O. aceris consumption by N. fallacis or Z. mali in a 24 h period. Each predator exhibited distinct preferences for O. aceris life stages. N. fallacis consumed significantly more protonymphs and adults of O. aceris, whereas Z. mali consumed more eggs. In contrast, maple cultivars significantly influenced rates of intraguild predation between phytoseiids and stigmaeids. Adult N. fallacis consumed more immature stages of Z. mali on Autumn Blaze than on Red Sunset maple, but adult Z. mali consumed the same numbers of N. fallacis nymphs on both cultivars. These findings provide a potential mechanism to explain the resistance of Red Sunset maples to O. aceris. On Red Sunset maples, where domatia provide Z. mali with refugia from predation by N. fallacis, both predators can contribute to the mortality of O. aceris. In contrast on Autumn Blaze maples Z. mali have no place to hide from N. fallacis, so the contribution of this stigmaeid to O. aceris mortality is greatly diminished. Thus, differential susceptibility of these cultivars to spider mites may be mediated by the capacity of leaf domatia to influence rates of intraguild predation among phytoseiid and stigmaeid predators.     

The genus Scapheremaeus (Acari,Oribatida, Cymbaeremaeidae) in the oribatid mite fauna of New Zealand,with description of two new species

Two new species of oribatid mites of the genus Scapheremaeus (Oribatida, Cymbaeremaeidae), Scapheremaeus gibbus sp. n. and Scapheremaeus luxtoni sp. n., are described from New Zealand. Scapheremaeus gibbus sp. n. is morphologically most similar to Scapheremaeus humeratus Balogh & Mahunka, 1967, but differs from the latter by the number of notogastral, genital and adanal setae, morphology of bothridial setae, position of adanal lyrifissures and absence of humeral processes. Scapheremaeus luxtoni sp. n. is morphologically most similar to Scapheremaeus yamashitai Aoki, 1970, but differs from the latter by the morphology of notogastral and rostral setae, morphology of leg solenidia φ₂ and development of humeral processes. The species Scapheremaeus zephyrus Colloff, 2010 is recorded for the first time in New Zealand. An identification key to the known New Zealand species of Scapheremaeus is provided.     

Contributions to the knowledge of oribatid mites (Acari,Oribatida) of Indonesia. 3. The genus Galumna (Galumnidae) with description of a new subgenus and seven new species

Seven new species of oribatid mites of the genus Galumna are described from litter and soil materials of Sumatra, Indonesia. A new subgenus, Galumna (Atypicogalumna) subgen. n., is proposed; it differs from all galumnid genera and subgenera by the simultaneous presence of porose areas and sacculi on the notogaster (vs. either porose areas or sacculi present). Galumna (Galumna) calva Starý, 1997 is recorded for the first time in the Oriental region, and Galumna (Galumna) sabahna Mahunka, 1995 is recorded for the first time in the Indonesian fauna.