A comparison of the water balance characteristics of Typhlodromus occidentalis and Amblyseius finlandicus mites (Acari: Phytoseiidae) and evidence for the site of water vapour uptake

To determine how adult Typhlodromus occidentalis, a mite used in the biological control of spider mites, thrive in arid western North America, the water balance characteristics of adult females were compared to those of a laboratory colony of Amblyseius finlandicus originating from Finnish apple orchards. The mites contained comparable amounts of water (73.6 and 74.9%, respectively, for T. occidentalis and A. finlandicus), absorbed water from the air between 86% and 92% relative humidity (RH) (critical equilibrium humidity) and drank free water from droplets. Typhlodromus occidentalis were distinguished, however, by having lower net water loss rates (0.8% versus 1.3% h–1 at 0% RH, 20°C for A. finlandicus), a feature that enables them to retain water more effectively. Above the critical equilibrium humidity water was lost by adult female T. occidentalis whose mouth parts had been blocked with wax, implying an oral uptake mechanism for the absorption of water vapour. © Rapid Science Ltd. 1998     

Biological Control of Tetranychus Urticae (Acari: Tetranychidae) With Naturally Occurring Predators in Strawberry Plantings in Valenica, Spain

Naturally occurring beneficials, such as the phytoseiid mite Amblyseius californicus McGregor and the insects Stethorus punctillum Weise, Conwentzia psociformis (Curtis) and others, controlled Tetranychus urticae Koch in 11 strawberry plots near Valencia, Spain, during 1989–1992. The population levels of spider mites in 17 subplots under biological control were low or moderate, usually below 3000 mite days and similar to seven subplots with chemical control. In most of the crops A. californicus was the main predator, acting either alone or together with other beneficials. Predaceous insects colonized the crop when tetranychids reached medium to high levels. For levels above one spider mite per leaflet, a ratio of one A. californicus per five to ten T. urticae resulted in a decline of the prey population in the following sample (1–2 weeks later). These results suggest that naturally occurring predators are able to control spider mites and maintain them below damaging levels in strawberry crops from the Valencia area.     

胡瓜钝绥螨捕食茶橙瘿螨的实验种群生命表及捕食作用初探

本在25℃条件下初步研究了胡瓜钝绥螨捕食茶橙瘿螨的实验种群生命表、各螨态取食量及猎物－－卵转化率。25℃时胡瓜钝绥螨的净增殖率R0＝21．7862,世代平均周期T＝16．1822,内禀增长率rm＝0．1904,周限增长率λ＝1．2097,种群倍增所需时间t＝3．6405。日平均产卵量2．19粒／天,总产卵量36－48粒／雌,平均38．97粒／雌。胡瓜钝绥螨雌螨－生取食量1978．49头。雄螨取食量879．56头。猎物：卵转化率为79．78头茶橙瘿螨：2．19粒胡瓜钝绥螨卵。     

Suppressing Establishment of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) in Cucumber Crops by Prophylactic Release of Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae)

Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is the most damaging pest of protected cucumbers in the UK and reliable control measures are required that are compatible with other components in the IPM programme. Although the predatory mite, Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), has been used for thrips control for many years, results against F.occidentalis in cucumbers during the early 1990s were frequently unacceptable. Three experiments in 1994/95 evaluated a prophylactic approach to the control of F.occidentalis. This involved placing one A. cucumeris culture sachet on each plant immediately after planting. F. occidentalis was released in all crops to ensure that the biocontrol measure received a severe test. Treatment was compared to untreated controls and the delayed release of culture sachets. The cultures remained active and produced populations of A. cucumeris on leaves for at least nine weeks. Establishment of F. occidentalis populations was almost entirely suppressed when the culture sachets were placed immediately after planting. Thrips damage was reduced compared to untreated controls when introduction of culture sachets was delayed by 2-4 weeks but this increased the risk of control failure.     

Patch-Leaving Decision of the Predatory Mite Amblyseius womersleyi (Acari: Phytoseiidae) Based on Multiple Signals from Both Inside and Outside a Prey Patch

We compared the emigration rates of Amblyseius womersleyi from prey patches (leaf disks) of different conditions in airflow containing either infested plant volatiles (volatiles airflow) or uninfested plant volatiles (control airflow). Both airflow and prey patch conditions significantly affected the emigration rates. Emigration rates from patches carrying prey products (feces, exuviae, webs, etc.) and prey eggs were significantly lower in control airflow than in volatiles airflow. Under other patch conditions, the rates were lower in control airflow than in volatiles airflow, although the difference was not significant. In both airflows, the lowest emigration rates were observed when predators were in a heavily infested patch. Patches carrying prey products and prey eggs resulted in lower emigration rates than patches carrying eggs alone and patches emitting prey-infested plant volatiles but carrying no prey. Thus, A. womersleyi appears to decide the timing of emigration based on two criteria: prey products in the patch and prey-infested plant volatiles from outside.     

猎物对巴氏钝绥螨生长发育和繁殖的影响

在(25±1)℃、90%RH以上、无光照实验条件下,以腐食酪螨和刺足根螨为猎物,研究了巴氏钝绥螨的生长发育和繁殖情况。结果表明,以腐食酪螨幼螨为猎物,巴氏钝绥螨可正常发育和繁殖,雌、雄成螨寿命分别为(34.250±1.361)和(23.950±1.606)d;以刺足根螨为猎物时,无法发育到成螨;成螨寿命明显缩短,雌、雄分别为(7.300±0.619)和(6.567±0.609)d,显著短于捕食腐食酪螨的巴氏钝绥螨,而且雌螨不能产卵。     

Review of Australian Asperoseius Chant, Euseius Wainstein, Okiseius Ehara and Phytoscutus Muma (Acari: Mesostigmata: Phytoseiidae) with a key to the genera of Australian Amblyseiinae and descriptions of two new species

Previous workers have used a conservative generic classification of the subfamily Amblyseiinae that treated most Australian Phytoseiidae as species in the genus Amblyseius Berlese. However, this lumping masks the occurrence of a number of genera recognised overseas, including some that contain important biological control agents. In this review, a key to the genera of Australian Amblyseiinae is provided and the Australian species in four amblyseiine genera are reviewed and keyed. Asperoseius Chant is represented by a single known Australian species, A. australiensis Fain and Krantz collected from a Culicoides midge in South Australia. Six species of Euseius Wainstein are recognised in Australia, including four endemics: E. dowdi (Schicha), E. elinae (Schicha), E. neovictoriensis (Schicha), and E. victoriensis (Schicha), and two Asia–Pacific species: E. noumeae (Schicha) and E. ovalis (Evans). Okiseius Ehara is represented in Australia by the previously described O. morenoi Schicha and O. domatorum (Schicha); the Asian species O. subtropicus Ehara (new record); and two new species, O. tribulation and O. cowbay described from tropical rainforest in Far North Queensland. Phytoscutus acaridophagus Collyer, a mite described from New Zealand, is reported in association with acarid mites ( Neotropacarus sp.) in Victoria and in Queensland.     

Survival, horizontal distribution, and economics of releasing predatory mites (Acari: Phytoseiidae) using mechanical blowers

The predatory mites Phytoseiulus persimilis and Amblyseius cucumeris are commonly used in commercial greenhouses for augmentative biological control of spider mites and thrips, respectively. One disincentive for growers to use biological control is the cost of manually distributing predators. Therefore, we tested the efficiency of two types of mechanical blowers for dispensing predatory mites. One blower had a metering device to control the flow of material (MBWMD); the other had no metering device (MBWOMD). Predator survival was measured at various distances after dispensing them with blowers. Survival also was compared with a manual-sprinkling method. When blowers were held horizontally, the distribution of predators was uneven for both blowers. For P. persimilis, 77% were found at 1.52 and 2.44 m with the MBWOMD, whereas 75% were located at 2.44, 3.35, and 4.27 m with the MBWMD. For A. cucumeris, 97% were found at 1.52, 2.44, and 3.35 m with the MBWOMD, while 81% landed at 2.44 and 3.35 m with the MBWMD. Percentages of live P. persimilis found using the MBWMD, MBWOMD, and manual-sprinkling were 31 ± 4, 49 ± 3, and 68 ± 8%, respectively. For A. cucumeris, percentages of survival were 61 ± 4, 79 ± 4, and 83 ± 7%, respectively. The MBWOMD dispensed P. persimilis 22 and 44 times faster than the MBWMD and manual-sprinkling, respectively. Mechanical blowers have the advantage of better coverage, substantially less labor, and estimated total costs to growers that are approximately half that of the manual release method.     

Imidacloprid increases egg production in Amblyseius victoriensis (Acari: Phytoseiidae)

The chloronicotinyl insecticide, imidacloprid, recommended for aphid control in Australian stone fruit orchards, was examined for its impact on survival and egg production in Amblyseius victoriensis Womersley. Imidacloprid at the field rate (0.0053% a.i.) was non-toxic, but repellent to A. victoriensis in laboratory bioassays. Females treated with imidacloprid showed increased egg production, producing 1.9–2.0 eggs per day compared with 1.3–1.6 eggs per day for the untreated individuals. A population of A. victoriensis in an apricot orchard was significantly reduced for 4 weeks following the application of imidacloprid. However, the population recovered after 5–6 weeks and was significantly larger (more than twice) than that in the untreated section of the orchard during weeks 9–12. The imidacloprid-mediated enhancement of the fecundity and population development of A. victoriensis is discussed with respect to integration in existing biological control programmes in the Australian stone fruit. This revised version was published online in November 2006 with corrections to the Cover Date.