Control of phytoseiids in a spider mite mass-rearing system (Acari: Phytoseiidae,Tetranychidae)

Phytoseiid mites which contaminated the spider mite colony and interfered with the mass-rearing of spider mites were controlled by dipping in hot water. Immersion for 60 s in water of 50°C killed all stages ofAmblyseius fallacis (Garman),A. womersleyi Schicha andPhytoseiulus persimilis (Athias-Henriot) (Acari: Phytoseiidae). Only approximately 0.3% of theA. womersleyi eggs hatched, and this seems negligible. The populations ofTetranychus kanzawai Kishida andT. urticae (Koch) (Acari: Tetranychidae) were reduced. However, they recovered well. Although this treatment resulted in the withering of some soybean seedlings, the next trifoliate leaf to be produced was normal. A very satisfactory result was obtained when this technique was applied to the mass-rearing system.     

Synergism between different species of proteolytic rumen bacteria

Proteolytic strains ofButyrivibrio alactacidigens, Butyrivibrio fibrisolvens, Selenomonas ruminantium, andStreptococcus bovis grew markedly better in medium containing casein as sole nitrogen source when they were inoculated in pairs rather than singly, when growth was poor or nil. The improved growth ofSelenomonas ruminantium with other species was a consequence of a faster rate of proteolysis by the mixed culture. The cooperativity withStreptococcus bovis was mediated by the extracellular activity ofSelenomonas ruminantium. Synergistic growth betweenBu. alactacidigens and other bacteria was not due to cooperativity between proteolytic activities but probably to nutritional interdependence between the species. Cooperative proteolysis also occurred in mixtures ofSelenomonas ruminantium andBacteroides ruminicola, a proteolytic isolate capable of growth on casein in monoculture.     

Phytoseiid mites (Acari: Phytoseiidae) on apple trees and in surrounding vegetation in southern Finland. Densities and species composition

Leaf samples were collected from sprayed (n=29) and unsprayed (n=19) apple orchards, from the surrounding vegetation (n=58) and from one arboretum (n=12), altogether from 46 plant species (1–5 samples each). The density of phytoseiid mites averaged 1.2 mites/leaf on unsprayed apple trees, but only 0.06 mites/leaf on sprayed trees. The phytoseiid density exceeded 1/leaf onAesculus hippocastani, Aristolochia macrophylla, Corylus avellana, Fragaria vesca, Frxinus excelsior, Juglans cinerea, Pterocarya rhoifolia, Ribes nigrum, Rubus odoratus, Sorbus aucuparia, S. thuringiaca, Tilia×euchlora andUlmus glabra. Other common trees and bushes inhabited by phytoseiids wereCrataegus coccinea (0.2 mites/leaf),Prunus padus (0.7),Salix caprea (0.4), andTilia cordata (0.9).Twelve species of phytoseiid mites were found, of which ten occurred on unsprayed apple trees. The most widely distributed species on apple trees werePhytoseius macropilis (in 79% of unsprayed samples),Euseius finlandicus (74%),Paraseiulus soleiger (53%),Paraseiulus triporus (37%),Amblyseius canadensis (26%) andAnthoseius rhenanus (26%). The highest densities on apple trees were found in populations ofE. finlandicus (mean 0.7 mites/leaf),Ph. macropilis (0.5) andA. canadensis (0.5). On sprayed apple trees,E. finlandicus, Pa. soleiger andPh. macropilis occurred most commonly, but their mean densities were under 0.1/leaf. Almost no phytoseiids were found in orchards sprayed with oxydemetonmethyl before blooming of apple.On other plants,E. finlandicus occurred most commonly (on 33 plant species) and in the highest densities, followed byPh. macropilis (14),Pa. soleiger (12),Pa. triporus (12) andAn. rhenanus (7).Seiulus aceri andParaseiulus talbii were identified as new phytoseiid species in Finland. It is concluded that deciduous trees and bushes in forest margins around orchards can serve as important reservoirs for phytoseiid mites, and that the dominant species in these plants would migrate into and colonize the orchards if the use of harmful chemicals were restricted.     

The effect of the dung pad fauna on the emergence ofMusca tempestiva [Dipt.: Muscidae] from dung pads in southern France

The emergence ofMusca tempestiva Fallèn, from cow pads in southern France was reduced by a mean of 98% and 96% respectively in nine experiments concluded in 1979 and 1981, by the action of the complete dung fauna. Fauna emerging from dung pads and captured in simultaneous trapping using dung baited pitfall traps consisted of 13 Dipterous species (9 Muscidae, 2 Sepsidae and 2 Sphaeroceridae), 25 Coleopterous species (7 Scarabaeidae, 1 Geotrupidae, 2 Aphodiidae, 3 Hydrophilidae, 12 Staphylinidae), 3 Hymenopterous parasites and 1 species of macrochelid and 2 species of parasitoid mites carried phoretically by the dung beetles. The total number of insects and mites per trap was usually small. The Staphylinidae which included 4Aleochara species of whichAleochara tristits Gravenhorst andA. bipustulata (L.) are known parasitoids of Diptera pupae, and 6 predatory species, were the most abundant insects present. Whilst the overall abundance of insects and mites trapped was relatively low it is probable that the most important factor in the control ofM. tempestiva was the combined influence of the different elements making up the dung pad fauna.     

Die Feinde der Raubmilben als Reduzierender Faktor der Spinnmilben

Summary The relations betweenMetatetranychus ulmi living on apple trees and its different predators are complex. The most important natural enemy of this spider mite is the predacious miteTyphlodromus pyri (= T. tiliae). It destroys more spider mites than the beneficial insects do. In the district of Stuttgart-Hohenheim about 38 species of insects and spiders feed onTyphlodromus mites. For instanceT. pyri is reduced considerably byOrius minutus. This bug is a natural enemy of aphids and spider mites, however it prefers the predatory mites. It attacks the spider mites and aphids only ifTyphlodromus mites are not available.Chrysopa vulgaris andAnthocoris nemorum are similar in their feeding habits. These two destroyTyphlodromus pyri also but they are less important thanO. minutus. The other beneficial insects in our orchards have little effect on spider mites or predacious mites. If we have enough pests on our apple trees to make spraying necessary, we should look forTyphlodromus mites and be careful no to destroy them. We should always examine the composition of the biocoenosis applying chemical agents because the populations of insects and predacious mites may vary from one area to the other.      

Ultrastructure of the reproductive system of the house dust mitesDermatophagoides farinae andD. pteronyssinus (Acari,Pyroglyphidae) with remarks on spermatogenesis and oogenesis

Several parts of the reproductive system of both sexes ofDermatophagoides farinae andD. pteronyssinus are investigated and compared by light-, scanning electron-, and transmission electron microscopy. New techniques have been employed for scanning of the internal structures of these mites. The male reproductive system consists of unpaired testis, paired vasa deferentia, an accessory gland, ejaculatory duct, and copulatory organ. The female reproductive system consists of bursa copulatrix, ductus bursae, receptaculum seminis, paired ducti receptaculi, ovaries, oviducts, one chorion gland, ovipositor, and oviporus. Testis as well as ovaries are characterized by syncytia of nutritional function. The specifics of spermatogenesis are discussed in connection with sperm transfer. Similarities between the construction of the ovaries and oogenesis in astigmatic mites and telotrophic meroistic ovaries in insects are discussed.     

The effect of pyrethroid lambdacyhalothrin applications on the spatial distribution of phytophagous and predatory mites in apple orchards

The spatial distribution of three phytophagous mites,Panonychus ulmi (Koch),Tetranychus urticae Koch andAculus schlechtendali (Nalepa), and two predacious mites,Zetzellia mali (Ewing) andAmblyseius fallacis (Garman), and the effect of pyrethroid lambdacyhalothrin applications on mite spatial dispersion were investigated over a 3-year period in an apple orchard in Ontario. The index of dispersion and the slope of Taylor's power law were used to evaluate dispersion patterns of mites. Panonychus ulmi showed that between-tree spatial variation decreased with an increase of population densities, whereas between-leaf variation increased with population densities. With all other four species it appeared that between-tree variation is much greater than between-leaf variation at all field population density levels. The values ofb by Taylor's power law suggested that all five species of mites are aggregated, but that in generalP. ulmi andT. urticae (b=1.427–1.872) are more aggregated than their predators (b=1.254–1.393). Taylor's regression technique suggests that pyrethroid applications causedP. ulmi, T. urticae, Z. mali andA. fallacis to be less aggregated whileA. schlechtendali was more aggregated. The impact of changes in mite spatial distribution following pyrethroid applications on sampling plans is discussed.     

Selection for non-diapause inAmblyseius cucumeris andAmblyseius barkeri and exploration of the effectiveness of selected strains for thrips control

In Europe and North America the western flower thrips,Frankliniella occidentalis, is an important pest in various greenhouse crops, such as sweet pepper and cucumber. Two species of predatory mite are commercially applied for biological control of this pest:Amblyseius cucumeris andA. barkeri. Thrips control is generally successful from March onwards. During winter, however, thrips control by these predatory mites is less effective. An important reason for this is that the commercially applied strains of both mite species enter reproductive diapause under short-day photoperiods, whereas the western flower thrips does not enter diapause. In this paper we report on selection experiments for non-diapause in strains of both mite species, aimed at obtaining predators that do not enter diapause under light- and temperature conditions prevailing in winter. Additional experiments were done to estimate the potential of the selected lines as control agents ofF. occidentalis. Selection for non-diapause proved highly successful in both predatory mite species. In a New Zealand strain ofA. cucumeris diapause incidence decreased from 41% to 0% in about ten generations; in a Dutch strain ofA. barkeri diapause incidence decreased from 67% to 0% in about six generations. Furthermore, selection for non-diapause had no influence on predator performance, measured as predation rate and oviposition rate on a diet of first instar thirps larvae. Rates of predation and oviposition were the same for selected and unselected lines in both species; rates of predation and oviposition were higher forA. cucumeris than forA. barkeri. After 18 months under non-diapause conditions, no less than 92% of a sample of the selected non-diapause line ofA. cucumeris did not enter diapause when tested under diapause-inducing conditions. This indicates that ‘non-diapause’ is a stable trait in these predatory mites. Finally, a small-scale greenhouse experiment in a sweet pepper crop showed that the selected non-diapause line ofA. cucumeris established successfully under diapause-inducing short-day conditions.     

In-feed 0.6% ivermectin formulation for treatment of wild boar in the Moslavina hunting ground in Croatia

An in-feed 0.6% ivermectin formulation was administered for 7 days to wild boar piglets at three sites of the Moslavina hunting ground in Croatia. Examination of internal organs and skin of five piglets that died immediately before the start of administration of the ivermectin formulation revealed the presence of Metastrongylus apri and Metastrongylus pudendotectus in the lungs, and of Ascarops strongylina, Physocephalus sexalatus and Globocephalus urosubulatusin in the gastrointestinal tract. Coccidial oocysts were found in the feces of all animals. Sarcoptes scabiei var. suis was identified in the skin of four piglets. The efficacy of treatment was assessed by examining fecal samples before start of therapy (day 0) and on days 7 and 14. Before treatment strongylid-type eggs were detected in 70–100% of fecal samples (210–505 EpG) The eggs of Strongyloides ransomi, Trichuris suis, Ascaris suum, Ascarops strongylina and Physocephalus sexalatus were identified in 10–50% of fecal samples at an intensity of 5–45 EpG. On day 14 after the start of the treatment, strongylid-type eggs were detected in 10% of fecal samples from one of the three sites only. Eggs of other helminth species were not detected at any of the three sites. This confirmed the successful therapeutic efficacy of the in-feed 0,6% ivermectin formulation.     

An improved method for determining the susceptibility ofRhizoglyphus robini andR. setosus (Acarina:Acaridae) to pesticides

Most bioassays used for determining the susceptibility ofRhizoglyphus mites face the problem of mite escapes, which leads to variation within replicates of treatments. An improved method uses surface tension of water to deter the bulb mites from escaping, and simplifies the food supply during the test with a piece of filter paper only. This method is described in detail and the susceptibility ofR. robini andR. setosus to several compounds measured by this method is demonstrated.     

Does time spent on adult bees affect reproductive success of Varroa mites?

Reproduction ofVarroa jacobsoni Oudemans (Acari: Varroidae) and the number ofVarroa mites that were found dead on the bottom board of the hive, were studied in relation to the period the mites spent on adult honey bees,Apis mellifera L. (Hymenoptera: Apidae), prior to invasion into brood cells. The maximum period on adult bees was 23 days. To introduce mites, combs with emerging worker brood, heavily infested with mites, were placed into a colony and removed the next day. At the beginning of the first day following emergence from brood cells, 18% of the mites introduced into the colony was found on the bottom of the hive. Part of these mites may already have died inside the capped brood cells, and then fallen down after cleaning of cells by the bees. At the second and third day following emergence, respectively 4% and 2% of the mites on adult bees at the previous day was recovered on the bottom, whereas from the fourth day on only 0.6% of the mites on adult bees was recovered on the bottom per day. After invasion into brood cells, 8–12% of the mites did not produce any offspring. Of the mites that did reproduce, the total number of offspring was 4.0–4.4 per mite during one reproductive cycle, part of which may reach maturity resulting in 1.2–1.3 viable daughters, and 8–10% of the mites produced only male offspring. Reproduction was independent of the period the mites had spent on adult bees prior to invasion into brood cells.     

Keratinolytic fungi of wadi Qena in Egypt

Forty-six soil samples collected from different sites of wadi Qena were examined for keratinophilic fungi using the hair baiting technique. Thirty-two species in addition to one variety of each ofA. nidulans andA. flavus which belong to eighteen genera were recovered.Aspergillus, Chrysosporium, Penicillium, Microsporum andFusarium were the most frequent genera developed from baited soils.     

Comparison of the fecundity of three species of grain store mites on fungal diets

The egg production of isolated pairs ofAcarus siro, Glycyphagus destructor andTyrophagus longior fed on a control diet of wheatgerm and yeast was compared with that on mycelial pellets from shake cultures ofCladosporium cladosporiodes, Aspergillus repens, A. ruber andPenicillium cyclopium as well as spores ofP. cyclopium andA. repens. The mites always produced fewer eggs on the fungal diets than on the ideal diet.Tyrophagus longior usually did best of the three mite species on the fungal diets, andG. destructor worst.Aspergillus ruber proved the most suitable fungus for all mite species, whileC. cladosporiodes was the least suitable. Spores were a less suitable diet than mycelial pellets from shake cultures, which were predominantly mycelium.     

Parasites of insects damaging seeds and cones of the European (Larix decidua) and Polish larches (L. polonica) in Poland

It was found thatEupelmus pullus Rusch. parasitized the larvae ofResseliella skuhravyorum Skrzypcz. in Poland. Examination of the ripening seeds and cones ofLarix decidua Mill. andL. polonica Rac. showed that the average larval parasitism was 18.0% and 19.5% respectively. Information on the other parasites of insects damaging seeds and cones ofL. decidua andL. polonica is given.     

The occurrence of keratinophilic fungi in texas soil

Summary A total of 137 soils, 27 coming from caves and 110 from outdoor lands of Texas, were examined for the presence of keratinophilic fungi by the use of the ToKaVa hairbaiting technique. Twenty three and 69 fungal isolates, respectively, were recovered from these areas. Microsporon gypseum was the most common isolate, followed byTrichophyton mentagrophytes, andT. terrestre. M. gypseum was recovered from caves in a very high frequency (67 %), in comparison to its presence in the outdoor soils (10 %).Fifteen strains ofChrysosporium, belonging to four species, were isolated. Fourteen of these isolates were recovered from shady areas under trees. None of these had been isolated from Texas soil before.     

Isolation and characterization of a new ruminal bacteriophage lytic toStreptococcus bovis

A new bacteriophage, designated F4, was isolated from the ruminal fluid of a calf. The host range of F4 phage was limited to five strains ofStreptococcus bovis out of ten tested on which clear plaques 0.6–1.2 mm in diameter were found. Bacteriophage F4 had an elongated head 75 nm long and 33 nm wide with a noncontractile flexible tail 100 nm in length on average. This phage is defective in the generation of plaques at low multiplicities of infection. Its genome consists of double-stranded linear DNA of 60.38 kb lacking cohesive ends. The F4 DNA was analyzed with 13 restriction enzymes. The restriction enzymes that did not cleave it wereBamHI,EcoRI,PvuI, andSmaI. The circular restriction map was constructed with four restriction endonucleases (XbaI,EcoI,SalI, andBglI).     

Laboratory culture of the mitesVarroa jacobsoni andTropilaelaps clareae

A laboratory method was developed for rearing the mitesVarroa jacobsoni Oudemans andTropilaelaps clareae Delfinado and Baker to the adult stage. The method consists of infesting larvae ofApis cerana Fabricius andA. mellifera L. with mites in ELISA microtiter racks.     

Influence of dispersal from almonds on the population dynamics and acaricide resistance frequencies of spider mites infesting neighboring cotton

Neighboring almond and cotton fields were sampled for spider mites in four locations in the San Joaquin Valley of California. The dominant species in the almonds wasTetranychus pacificus McGregor. In three cotton sites.T. pacificus was present in significantly higher densities near the almonds on at least one sampling date. In contrast.T. urticae Koch andT. turkestani Ugarov & Nikolski were equally abundant across the cotton fields. Almonds appeared to act as a continuous early-season source ofT. pacificus for cotton, with peaks in aerial dispersal from almonds occurring due to overcrowding, plant water stress, and applications of repellent acaricides. Cotton, which experienced little water stress, supported very high densities of spider mites and so acted primarily as a sink for spider-mite dispersal from almonds and other field crops throughout the growth-season. The frequencies of resistance expressed byT. pacificus andT. urticae were similar between neighboring crops, even if the acaricide had been registered for use only in almonds (cyhexatin) or cotton (dicofol). Thus, longterm acaricide selection and movement of spider mites between the two crops resulted in similar proportions of resistant individuals. In these study sites, large-scale dispersal ofT. pacificus from almonds rarely directly affected acaricide efficacy in cotton, because resistance frequencies were similar for spider mites from the two crops and because acaricide applications were usually made in cotton after dispersal from almonds was completed. In two cotton sites, field selection with dicofol was reversed by subsequent immigration of spider mites from neighboring field crops.     

Transformation and inheritance of Bt genes inGossypium hirsutum

Transgenic plants offer many unique opportunities for managing pest populations. However, the inheritance, integration, and expression of multiple transgenes are prerequisite for maintaining sustainable resistance against insects in crops. We took a gene-pyramiding approach to produce Bt cotton expressing two Bt genes,cry1Ac andcry2A. Using sonication-assistedAgrobacterium-mediated transformation (SAAT), we achieved an efficiency of 6.26%. Putative transgenic plants were confirmed via PCR, Southern hybridization, and western-blotting. Those showing mortality of 75 to 100% for the second instar ofHeliothis armigera (compared with 0% for the control) were considered Bt-positive. Transgenes were segregated according to a 3:1 Mendelian inheritance pattern in the T1 generation forHeliothis resistance. In our insect bioassay, the control plants showed >95% leaf damage, and insects reached the 4^th instar stage of larval growth. In contrast, leaf damage on transgenic plants was limited to only a few bites, and insect mortality was 75 to 100%. ELISA confirmed transgene expression, and Bt protein was detected in leaf tissue. This performance was consistent with that of the parent transgenics. PCR and Southern blots verified integration of thecry1Ac andcry2A genes into the progeny. Therefore, this strategy provides a pathway toward cotton improvement and the development of durable resistance against insect damage.     

Location of the α-amylase gene in rumenStreptococcus bovis strains distinguished by unstable amylase activity

Genetic stability of amylase activity after serial subcultivation experiments with amylolytic ruminalStreptococcus bovis strains was investigated. Two strains Amy⁺ and Amy⁻ were obtained. Loss of amylase activity connected with the loss of plasmid DNA was not found in these strains. The presence of the gene responible for the amylase activity in the chromosome of these strains was revealed by hybridization of the α-amylase gene on pJK108 against chromosomal DNA ofS. bovis andBacillus subtilis after a complete restriction withEcoRI.