The broad mite,Polyphagotarsonemus latus,as a potential prey for phytoseiid mites in California

In laboratory studies, individuals ofEuseius stipulatus Athias-Henriot,Typhlodromus rickeri Chant,T. porresi McMurtry andT. annectens DeLeon offered broad mite,Polyphagotarsonemus latus (Banks), as prey had developmental and ovipositional rates comparable to those offered a known favorable food (tetranychid mites or pollen).Euseius hibisci (Chant) had a longer developmental period and a markedly lower oviposition rate onP. latus than on the control food. Immature survival and ovipositional rates ofEuseius concordis Chant,Typhlodromus occidentalis Nesbitt,Amblyseius limonicus Garman and McGregor andIphiseius degenerans (Berlese) were very low onP. latus compared to control foods.     

Some predaceous mites [Phytoseiidae] on citrus in the mediterranean region

Seven species of phytoseiid mites were collected from citrus trees in the Mediterranean region during a survey in 1971.Amblyseius stipulatus Athias-Henriot was the most abundant and widespread species in all countries surveyed (Turkey, Greece, Italy, Spain).A. californicus (McGregor) was collected only in Spain;A. potentillae (Garman) andPhytoseiulus persimilis. A.-H. only in Italy.Typhlodromus talbii A.-H. was collected in Greece and Spain,T. athiasae Porath & Swirski in Greece and Turkey, andIphiseius degenerans (Berl.) in Greece and Italy. Living material of all species exceptT. talbii was successfully shipped to California and insectary cultures established. Biologies were studied in the laboratory under 2 food regimes:Tetranychus pacificus McGregor eggs and larvae, and pollen ofMalephora crocea (Jacq.). Pollen was not a satisfactory food forp. persimilis, A. californicus andT. athiasae. Pollen was slightly less satisfactory than tetranychid mites fora. potentillae, but was equally or more favorable than mites forA. stipulatus andI. degenerans. A. stipulatus has become established in southern California.

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Résumé Sept espèces d'acariens de la famille desPhytoseiidae ont été récoltées sur des plants d'agrumes dans la région méditerranéenne au cours d'une étude effectuée en 1971.Amblyseius stipulatus Athias-Henriot est l'espèce la plus abondante et la plus répandue dans tous les pays visités (Turquie, Grèce, Italie, Espagne).A. californicus (McGregor) n'a été trouvé qu'en Espagne.A. potentillae (Garman) etPhytoseiulus persimilis A.-H. n'ont été trouvés qu'en Italie.Typhlodromus talbii. A.-H. a été récolté en Grèce et en Espagne,T. athiasae Porath & Swirski en Grèce et en Turquie, etIphiseius degenerans (Berl.) en Grèce et en Italie. Des spécimens vivants de toutes ces espèces, saufT. talbii, ont été réalisés avec succès en Californie où des élevages en laboratoire ont été réalisés. Ces élevages ont été réalisés avec deux régimes: œufs et larves deTetranychus pacificus, d'une part, pollen deMalephora crocea, d'autre part; ils ont permis de faire les observations biologiques suivantes. Le pollen n'est pas une nourriture satisfaisante pourP. persimilis, A. californicus etT. athiasae. Le pollen convient un peu moins que les tétranyques àA. potentillae; il est aussi favorable ou plus favorable que les tétranyques àA. stipulatus etI. degenerans. A la suite de son introduction dans le sud de la Californie,A. stipulatus semble s'y maintenir.

     

Comparison ofMononychellus progresivus andTetranychus urticae as prey for five species of phytoseiid mites

The present study reports life-table parameters and compares the longevity, fecundity, egg-to-adult development times and the length of the reproductive periods for five phytoseiid species (Typhlodromus annectens, Amblyseius californicus, A. idaeus, Euseius concordis, andPhytoseiulus macropilis) when reared onMononychellus progresivus orTetranychus urticae. Recommendations regarding the use of these species for classical biological control ofM. tanajoa in Africa are made.     

Comparison ofTetranychus evansi andT. urticae [Acari: Tetranychidae] as prey for eight species of phytoseiid mites

Eight phytoseiid species were tested to evaluate and compare their potential as predators ofTetranychus evansi Baker & Pritchard andT. urticae (Koch). The study was conducted using arenas of excised nightshade (Solanum douglasii Dunal) and Lima bean (Phaseolus vulgaris L.) leaves infested with eitherTetranychus species. When the prey wasT. evansi, the predatorsAmblyseius californicus (McGregor) andPhytoseiulus persimilis Athias-Henriot from Ventura, California, showed the highest oviposition rates. However, those rates were 4 to 6 times lower than rates for the same predators feeding onT. urticae. OnlyA. californicus and the strain ofP. persimilis from Beni-Mellal, Morocco, had survivorship higher than 50% 8 days after the beginning of the experiment. The results indicated thatT. evansi is an unfavorable prey for all the phytoseiids tested.

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Résumé Huit espèces d'Acariens phytoseiides étaient testées en vue de comparer leurs potentialités prédatrices vis-à-vis deTetranychus evansi Baker & Pritchard et deTetranychus urticae (Koch). L'étude était réalisée sur des feuilles détachées deSolanum douglasii Dunal et dePhaseolus vulgaris L. Les feuilles avaient été infestées avec l'une ou l'autre des espèces deTetranychus. Amblyseius californicus (McGregor) etPhytoseiulus persimilis Athias-Henriot, de Ventura, ont donné les taux d'oviposition les plus élevés avecT. evansi, mais ces taux étaient 4 à 6 fois inférieurs à ceux obtenus lorsque la proie étaitT. urticae. SeulsA. californicus et la souche deP. persimilis de Beni-Mellal avaient une survie supérieure à 50%, 8 jours après le début du test. Les résultats indiquent queT. evansi n'est pas une proie favorable pour toutes les espèces testées.

     

Population growth and predation interference between two species of predatory phytoseiid mites (Acarina: Phytoseiidae) in interactive systems

Summary Populations of two species of phytoseiid mite predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius degenerans (Berlese), feeding on a tetranychid prey, Tetranychus pacificus McGregor, were allowed to grow separately as well as together on bush lima bean (Phaseolus lunatus Var.) arenas in the laboratory. The population plateau attained by P. persimilis was nearly 5 times higher than that for A. degenerans when each species was on separate leaf arenas. When they were on the same arena, P. persimilis was outcompeted by A. degenerans after about 70 days of population growth. When dispersal to other arenas was necessary for the predators to find prey in another experiment, P. persimilis survived well but not A. degenerans. The mechanisms underlying species displacement were explored further. The differential mortality of immature predators at different developmental stages due to interspecific predation was concluded to be responsible for the population decline of P. persimilis, and the decline of A. degenerans in another experiment was attributed to its sedentary tendency regardless of prey distribution and to the lack of alternative food sources in the system. The implications to biological control of mutual predation between predator species is discussed briefly.     

Specificity of a strain ofNeozygites sp. (Zygomycetes: Entomophthorales) toMononychellus tanajoa (Acari: Tetranychidae)

Neozygites sp. is commonly found infecting the cassava green mite,Mononychellus tanajoa (Bondar), in parts of northeast Brazil. The introduction of this fungus into other regions requires the knowledge of its specificity, especially in relation to natural enemies of different cassava pests. Laboratory tests indicated the development of germination tubes ofNeozygites in some females ofTetranychus bastosi Tuttle et al. andT. urticae Koch, with subsequent formation of a reduced number of hyphal bodies in someT. bastosi. No females of the phytoseiid predatorsAmblyseius idaeus (Denmark & Muma) andAmblyseius limonicus Garman & McGregor s.l. were infected byNeozygites sp.     

Evaluation of phytoseiid predators for control of western flower thrips on greenhouse cucumber

Ten predatory mite species, all phytoseiids, were evaluated for control of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), on greenhouse cucumber. This study was done to further improve biological control of thrips on this crop. Neoseiulus cucumeris (Oudemans) is at present used for biological control of thrips in greenhouses. Compared to this species, Typhlodromalus limonicus (Garman & McGregor), Typhlodromips swirskii (Athias-Henriot) and Euseius ovalis (Evans) reached much higher population levels resulting in a significantly better control of thrips. T. limonicus was clearly the best predator of WFT. Also Euseius scutalis (Athias-Henriot) increased to higher populations levels than N. cucumeris, but without controlling the thrips, probably because of an unequal distribution of this predator on the plant. Iphiseius degenerans (Berlese), Neoseiulus barkeri (Hughes), Euseius finlandicus (Oudemans) and Typhlodromus pyri (Scheuten) did not establish better than N. cucumeris. A non-diapausing exotic strain of N. cucumeris did not differ from the North European strain. The best performers in this study were all of sub-tropical origin. T. limonicus, T. swirskii and E. ovalis have good potentials for controlling not only thrips but also whiteflies. Factors affecting the efficacy of phytoseiids on greenhouse cucumbers are discussed.     

Changes in body weight of two species of predatory mites (Acarina: Phytoseiidae) as a consequence of feeding in an interactive system

Changes in body weight of two species of predatory mites,Phytoseiulus persimilis Athias-Henriot andAmblyseius degenerans (Berlese), when each species was feeding alone on the prey miteTetranychus pacificus McGregor, were determined in the laboratory. The body weight of a starved adult femaleP. persimilis could increase 105.6% (13.05 g) to full satiation, whereasA. degenerans increased 43.2% (7.6 g). A simple model is used to describe the weight changes of each species. Changes in body weight also were determined when each of the two species fed with conspecifics at a high and low predator density. WithP. persimilis there was a reduction in body weight as well as in reproduction and in the number of prey killed when feeding at a high density of conspecifics. These reductions were not observed withA. degenerans. WhenP. persimilis fed with heterospecifics (A. degenerans), reductions in these three variables were less marked. The reductions are attributed primarily to the effect of sharing prey meals with conspecifics. Possible mechanisms for these reductions through meal-sharing are discussed.     

Influence of prey species and stages on predatory efficiency and development of two phytoseiid mites

The effect of prey species and the different stages of prey on the predatory efficiency and biology of the phytoseiid mites,Amblyseius gossipi Elbadry andTyphlodromus mangiferus sp. n. was studied. It was found that feeding either predator onTetranychus cucurbitacearum (Sayed) promoted faster development and a higher rate of oviposition than rearing on the twospotted spider mite,T. urticae (Koch). Different stages of both prey species also produced different responses in the biological activities of these predaceous mites.

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Résumé On a étudié l'effet de l'espèce de la proie et de ses différents stades sur l'efficacité et la biologie des acariens phytoseiides,Amblyseius gossipi Elbadry etTyphlodromus mangiferus sp. n. Il a été constaté que l'alimentation des 2 prédateurs avecTetranychus cucurbitacearus (Sayed) assure un dévelopment plus rapide et une fécondité plus élevée que leur élevage surT. urticae (Koch). Les différents stades de ces 2 proies produisent des réponses différentes dans les activités biologiques des 2 acariens prédateurs.

     

Preselection of predatory mites to improve year-round biological control of western flower thrips in greenhouse crops

In spring and summer, two groups of natural enemies are successfully used for biological control of western flower thrips,Frankliniella occidentalis (Pergande) in greenhouses: phytoseiid mites (Amblyseius cucumeris (Oudemans) and, to a lesser extent,A. barkeri (Hughes)) and anthocorid bugs (Orius spp.). During winter, however, these predators often fail to control the pest. One likely cause for failure is the predators' tendency to enter diapause under short day conditions. In addition, eggs of predatory mites are generally susceptible to low humidity conditions, which often arise in greenhouses when outside temperatures drop below zero, or at bright, hot days in summer. In search for a thrips predator that is not hampered by these conditions, five subtropical phytoseiid species were selected which were known to feed on thrips:A. hibisci (Chant),A. degenerans Berlese,A. limonicus s.s. Garman and McGregor,A. scutalis (Athias-Henriot) andA. tularensis (Congdon). These species were compared toA. cucumeris andA. barkeri, with respect to the following features: (1) predation and oviposition rate with youngF. occidentalis larvae as prey, (2) oviposition rate on a diet of sweet pepper pollen, (3) drought tolerance spectrum of eggs, and (4) incidence of reproductive diapause under short day conditions. The results showed thatA. limonicus exhibited the highest predation and oviposition rates on a diet of thrips larvae. Moreover,A. limonicus females showed total absence of diapause under the conditions tested. A major disadvantage of this species was, however, that its eggs were most sensitive to low air humidity conditions. Least sensitive to low air humidity were eggs ofA. degenerans andA. hibisci. Females ofA. degenerans andA. hibisci also showed total absence of diapause, and intermediate rates of predation and oviposition, on both thrips larvae and pollen. In conclusion, we argue thatA. degenerans andA. hibisci are the most promising candidates for biological control ofF. occidentalis under conditions of low humidity and short day length. The success of these candidates remains to be shown in greenhouse experiments.     

Alternative plant habitats for common phytoseiid predators of the cassava green mite (Acari: Phytoseiidae,Tetranychidae) in northeast Brazil

A survey was conducted to identify possible alternative plant habitats of the most common phytoseiid predators associated with the cassava green mite, Mononychellus tanajoa (Bondar), in their native environment in northeast Brazil. Thirty-two phytoseiid species were collected, including Amblyseius aripo (DeLeon), Amblyseius idaeus (Denmark and Muma) and Amblyseius limonicus Garman and McGregor s.l., the three predators previously shown as the most common on cassava. In increasing order, A. idaeus, Phytoseius guianensis DeLeon and A. aripo were the most common phytoseiids collected on the plant habitats examined. A. limonicus s.l. was one of the least common phytoseiids on plants other than cassava. Altermative plant habitats seem important in harboring A. aripo and A. idaeus, but not A. limonicus s.l..     

Predation byIridomyrmex humilis [Hym.: Formicidae] on eggs ofChrysoperla carnea [Neu.: Chrysopidae] released for inundative control ofIllinoia liriodendri [Hom.: Aphididae] infestingLiriodendron tulipifera

In an effort to suppress the tuliptree aphidIllinoia liriodendri (Monell), approximately 2,000 eggs ofChrysoperla carnea (Stephens) from a commercial insectary were released 4 times on each of 8 tuliptreesLiriodendron tulipifera L. in Berkeley, California, during the spring of 1984. On trees foraged by the Argentine antIridomyrmex humilis (Mayr), 98% of the eggs ofC. carnea were removed from the egg release tapes by the ants. A total of about 1,250 larvae per tree eclosed from the 8,000 eggs released on each tree without ants. Fifty percent of the larvae that did eclose died due to cannibalism or entrapment in the sticky egg release tapes and approximately 625 first instar larvae on each tree were free to forage for aphids. Inundative lacewing releases ofC. carnea did not suppress populations ofI. liriodendri due to ant predation, the low viability of commercial eggs (0–73% eclosion),

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Résumé Dans le but de limiter les populations du puceron du tulipierIllinoia liriodendri (Monell), 4 lachers d'environ 2.000 œufs de provenance commerciale deChrysoperla carnea (Stephens) ont été réalisés au cours du printemps 1984 sur 8 tulipiersLiriodendron tulipifera L., à Berkeley en Californie. cannibalism by emerged larvae, and inadequate release technology. Sur les arbres visités par la fourmi d'ArgentineIridomyrmex humilis (Mayr), 98% des œufs deC. carnea ont été enlevés du support artificiel par les fourmis. Sur les arbres exempts de fourmis, la mortalité de 50% des larves est due au cannibalisme ou à leur engluement sur le support de lacher. A partir de 8.000 œufs déposés sur chaque arbre sans fourmi, on aboutit à environ 625 larves de 1^er stade susceptibles de rechercher des pucerons. Les lachers inondatifs deC. carnea n'ont pas limité les populations d'I. liriodendri. Les raisons en sont: la consommation par les fourmis, une faible viabilité de la plus grande partie des œufs commercialisés (0–73% d'éclosions), une technique inadaptée pour le lacher des œufs et le cannibalisme par les larves elles-mêmes deC. carnea.

     

Establishment ofPhytoseiulus persimilis [Acari: Phytoseiidae] in Southern California

Annual releases ofPhytoseiulus persimilis A.-H. in commercial strawberry fields in Ventura County, California, beginning in 1971, have resulted in the establishment of this predator on strawberry, lima beans, and weeds such asMalva, Solanum andConvolvulus spp., throughout the Oxnard area. These weed species apparently are important reservoirs from whichP. persimilis disperses to new plantings of strawberries each season. This predator is now an important factor in the suppression ofTetranychus urticae (Koch) on strawberry and probably on lima beans in Ventura County.

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Résumé Des lachers annuels dePhytoseiulus persimilis A.-H. dans des cultures commerciales de fraisiers dans le comté de Ventura en Californie, à partir de 1971, ont abouti à l'installation du prédateur dans les fraisiers, les haricots de Lima et des mauvaises herbes telles queMalva, Solanum etConvolvulus spp. dans toute la région d'Oxnard. Ces mauvaises herbes constituent, semble-t-il, d'importants réservoirs à partir desquelsP. persimilis se disperse chaque saison vers les nouvelles plantations de fraisiers. Ce prédateur est maintenant un facteur important de lutte contreTetranychus urticae (Koch) sur fraisier et probablement sur haricot de lima dans le comté de Ventura.

     

Predation ofOligonychus pratensis [Aca.: Tetranychidae] byPhytoseiulus persimilis andAmblyseius californicus [Aca.: Phytoseiidae] under controlled laboratory conditions

The predator efficacy ofPhytoseiulus persimilis Athias-Henriot andAmblyseius californicus (McGregor) (Acarina: Phytoseiidae) when feeding on the Banks grass mite (BGM),Oligonychus pratensis (Banks) (Tetranychidae), was compared under controlled laboratory conditions. Predation byP. persimilis andA. californicus reduced the BGM densities by 60% and 28%, respectively. In general, phytoseiids preferentially fed upon the more abundant instars. Ovipositional rates forP. persimilis while feeding on BGM approximated rates when feeding onTetranychus spp. The use of a trade name is not an endorsement by Texas A&M University.     

Biological control of creeping thistle (Cirsium arvense): Analysis of the releases ofAltica carduorum [Col.: Chrysomelidae] in Canada

Altica carduorum Guérin-Méneville, a biological control agent against creeping thistle (Cirsium arvense (L.)Scop.) was released in Canada on 2 climatically contrasting release sites. Predation at the southern site, aggravated by slow egg and larval development, and low temperatures at the northern site prevented establishment. Reports from other releases in Canada, Britain and South Dakota are discussed.

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Résumé Altica carduorum Guérin-Melville, ennemi naturel du chardon des champsCirsium arvense (L.)Scop. a été laché au Canada dans 2 régions de climat différent. Il n'y a pas eu d'acclimatation à cause de la prédation dans la localité méridionale; dans le site septentrional ce phénomène a été aggravé par un développement embryonnaire et larvaire lent et par de basses températures. Les données sur d'autres lachers faits au Canada, en Grande-Bretagne et dans le Dakota du Sud sont discutées.

     

Effect of different foods on development,reproduction and survival ofPhytoseiulus longipes [Acarina: Phytoseiidae]

The effect of different prey mite species on development of the immature stages and on survival and oviposition of adult predator femalePhytoseiulus longipes Evans was studied.P. longipes completed its development onTetranychus pacificus McGregor,Oligonychus punicae (Hirst), andPanonychus citri (McGregor), but not onPetrobia harti (Ewing). Females oviposited while feeding onT. pacificus andO. punicae, but not onP. citri orP. harti. The highest percent survival was observed onT. pacificus, followed byO. punicae andP. citri. The longevity ofP. longipes onP. harti (vial arenas) and on pollen (leaf arenas) was the same as that on leaves with no food. The provision of 10% sucrose solution and clover honey doubled the longevity ofP. longipes females compared with no food.     

Oviposition and development in predaceous mites fed with artificial and natural diets (Acari: Phytoseiidae)

Oviposition rate and developmental capacity was determined for Amblyseius hibisci (Chant), A. limonicus Garman and McGregor, A. largoensis (Muma), Metaseiulus pomoides Schuster & Pritchard, M. occidentalis (Nesbitt), Typhloseiopsis arboreus (Chant), Typhodromus pyri Scheuten, Phytoseiulus persimilis Athias-Henriot, and Iphiseius degenerans (Berlese) on both artificial and natural diets. Oviposition and development occurred in seven of nine species when fed artificial diet and in all species when fed natural diets (phytophagous mites or pollen). The combined mean oviposition rate (21-d tests) for all species which oviposited on artificial diet was ca. one third the rate achieved by these species when tested on natural diets. Eggs and immature stages derived from oviposition tests with artificial diet showed no abnormalities and developmental times (egg to egg) were similar to those observed on natural diets. Predator cultures maintained on artificial diet showed gradual declines in viability within 2–3 months and only A. hibisci survived longer than 6 months. Adult predators of species which failed to oviposit when fed artificial diet survived longer than adults tested in the absence of food and water. Immature stages of these species failed to develop on artificial diet.

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Ponte et developpement d'acariens predateurs alimentes a partir d'un regime artificiel et d'un regime naturel (Acari: Phytoseiidae)

Résumé Le nombre d'ufs pondus par 7 espèces de Phytoseiidae nourries sur milieu artificiel a varié de 0,1 à 1,2 uf/femelle/jour. Pour l'ensemble des espèces, le nombre moyen d'ufs pondus a été de 0,5 uf/femelle/jour pour une période de ponte moyenne de 18,5 jours.Deux espèces, Phytoseiulus persimilis et Metaseiulus occidentalis nourries sur milieu artificiel, n'ont pas pondu; leurs longévités moyennes ont été respectivement de 11,3 et de 10,3 jours.Avec un régime naturel (acariens phytophages ou pollen), le nombre d'ufs pondus, pour 9 espèces de Phytoseiidae a varié de 0,8 à 3,2 ufs/femelle/jour. Pour l'ensemble des espèces, le nombre moyen d'ufs pondus a été de 1,7 uf/femelle/jour pour une durée moyenne de la période de ponte de 19,0 jours.La viabilité des ufs provenant des expériences de ponte avec régime artificiel était elevée chez toutes les espèces prédatrices et les durées du développement sur milieu artificiel étaient semblables à celles observées avec régime naturel. La viabilité des élevages de prédateurs maintenus sur milieu artificiel a diminué progressivement et la plupart des élevages avaient disparu en moins de 6 mois. Les tentatives d'élevage de P. persimilis et M. occidentalis sur milieu artificiel ont été négatives bien que les prédateurs adultes femelles aient eu une plus grande longévité sur milieu artificiel qu'en absence de nourriture et d'eau.

     

Research advances on pesticide resistance in natural enemies

Recent research on the factors governing resistance development among arthropod natural enemies is reviewed, including selection studies of resistance development in the predatory miteAmblyseius fallacis (Garman) andTetranychus urticae Koch and patterns of toxicity to pesticides and mixed function oxidase activity in a group of pests, predators and parasites. New areas of resistance development in the speciesPhytoseiulus persimilis A. H. andTyphlodromus pyri Scheuten are discussed as are genetic studies of resistance inP. persimilis and the toxicology of resistance inA. fallacis. Lastly, the widespread documentation of resistance inA. fallacis, a predator of plant-feeding mites, the cecidomyidAphidoletes aphidimyza (Rond.), a predator of aphids and 2 parasites of leafhopper in orchards of North America, is discussed relative to the long-term use of organophosphate-based insecticides and programs of integrated pest control.

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Résumé Les récentes recherches sur les facteurs déterminant le développement d'une résistance aux pesticides chez les arthropodes ennemis naturels des ravageurs sont rappelées, y compris les études sur la sélection pour cette résistance de l'acarien prédateur,Amblyseius fallacis (Garman) et deTetranychus urticae Koch, ainsi que les types de toxicité des pesticides pour un ensemble de ravageurs et de leurs parasites et prédateurs. De nouveaux domaines dans les phénomènes de la résistance chezPhytoseiulus persimilis A.H. etTyphlodromus pyri Scheuten sont discutés, telles que les études génétiques de la résistance chezP. persimilis et la toxicologie de la résistance chezA. fallacis. Enfin la très abondante documentation sur la résistance deA. fallacis, prédateur d'acariens phytophages, deAphidoletes aphidimyza (Rond), cecidomyie prédatrice de pucerons et de deux parasites de cicadelles en vergers en Amérique du Nord, est discutée en fonction de l'utilisation prolongée d'insecticides à base d'organophosphorés et de programmes de lutte intégrée.

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Published as article No. 8498 of the Michigan Agricultural Experiment Station, Michigan State University, East Lansing, Michigan 48824.     

Karyotypes and sex determination of ten species of phytoseiid mites (acarina: Mesostigmata)

The chromosomal picture was studied on early cleayage divisiona of 10 phytoseiid mites, using the aceto-orcein smear technique. Eggs of 9 species have either a haploid (4) or a diploid (8) number of chromosomes:Amblyseius rubini Swirski & Amitai,A. swirskii Athias,A. hibisci Chant,A. ohilenensis (Dosse),A. largoensis (Muma),Typhlodromus athiasae Porath and SwirskiT. rhenanus (Oud.) sensu latiore,Phytoseiulus persimilis Athias, andI phiseius degeneraus (Berlese).Typhlodromus oceidentalis Nesbitt has 3 and 6 chromosomes. In sections and smears of post embryonic stages belonging to mites representative of the four genera, a haploid number was found in males, whereas in females somatic cells contained 2n and ovaries n as well as 2n. Thus it is shown that sex is determined by the haplo-diploid (arrhenotokous) mechanism. Males differ from females in the structure of the interphase nuclei belonging to the central nervous system. Contribution from The Volcani Institute of Agricultural Research (NUIA.) Bet Dagan, Israel, 1968 Series, No. 1331-E.     

Biosystematics of phytoseiid mites (Acari: Phytoseiidae) associated with cassava

Laboratory crossing experiments indicate that populations of A. limonicus sensu lato collected from cassava (Manihot esculenta Crantz) in Brazil (Cruz das Almas) and Colombia (Palmira and Monteria) are conspecific and different from A. limonicus Garman & McGregor sensu stricto collected in Riverside, California, USA and Jaguariuna, Brazil. A. limonicus s.l. did not cross with A. tenuiscutus, A. rapax or A. limonicus s.s.. A. limonicus s.s. did not cross with A. rapax. Populations of A. aerialis, A. anonymus and A. idaeus from Colombia are conspecific with Brazilian populations of these species.