Effect of synthetic pyrethroids and other compounds on the susceptibility and development of the egg stage of the predacious miteAmblyseius gossipi [Mesostigmata: Phytoseiidae]

Eggs from a laboratory culture ofAmblyseius gossipi El-Badry laid on cotton strands were placed on leaf discs and sprayed with various pesticides or water for 40 s. The eggs were allowed to dry and then transferred to new discs. Compounds tested were cypermethrin, flucythrinate, fenvalerate, cyfluthrin, pyridaphenthion, methamidophos, dichlorvos and dicofol. Only methamidophos was inactive on the egg stage. When sprayed at a level of 400 ppm, eggs were highly susceptible to flucythrinate, cyfluthrin, pyridaphenthion, and fenvalerate and were slightly susceptible to dichlorvos and dicofol. Viability of eggs decreased as the concentration of the effective compounds increased. Older eggs were more sensitive than younger ones. None of the larvae from eggs treated with flucythrinate and pyridaphenthion were able to develop beyond the larval stage.

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Résumé Les œufs d'un élevage de laboratoire d'Amblyseius gossipi El-Badry pondus sur des fibres de coton furent placés sur des disques de feuille et traités avec des produits phytosanitaires variés ou de l'eau durant 40 s. Les œufs une fois ressuyés furent transférés sur de nouveaux disques. Les composés testés furent la cypermethrine, le flucythrinate, le fenvalerate, le cyfluthrine, le pyridaphenthion, le metamidophos, le dichlorvos et le dicofol. Seul le methamidophos était inactif sur le stade œuf. Traités à la dose de 400 ppm, les œufs furent très sensibles au flucythrinate, au cyfluthrine, au pyridaphenthion et au fenvalerate et légèrement sensible au dichlorvos et au dicofol. La variabilité des œufs décroissait comme augmentait la concentration des composés efficaces. Des œufs agés furent plus sensibles que des œufs plus jeunes. Aucune des larves issues d'œufs traités au flucythrinate et au pyridaphenthion n'étaient capables de se développer au-delà du stade larvaire.

     

Growth inhibition of the predacious miteAmblyseius brazilli [Mesostigmata: Phytoseiidae] by a synthetic juvenile hormone under laboratory conditions

The predacious miteAmblyseius brazilli El-Banhawy was exposed to the synthetic juvenile hormone methoprene to see the biological differences resulting from the application of the compound and its toxicity. Methoprene was applied as leaf residues or incorporated with the diet (pollen or prey). By contact methoprene was less toxic. Only at the highest concentration (1000p pm) the number of individuals reaching maturity, the percentage of survival and the number of eggs decreased while the duration of the developing individuals increased. The compound was more effective when injested. Feeding on pollen mixed with 100p pm methoprene block the development of all the individuals and a negligible number of eggs was laid. A diet containing 10p pm methoprene permitted a percentage of the individuals to reach maturity and oviposit. The survival and reproduction of the females fed on a diet containing 10p pm methoprene were also low. All the delivered eggs hatched under the different treatments, which indicates that methoprene did not interrupt the hatching process.

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Résumé L'acarien prédateurAmblyseius brazilli El-Banhawy a été exposé à l'hormone juvénile synthétique, le methoprène, afin de voir les différences biolgiques résultant de l'application du composé ainsi que sa toxicité. Le methoprène a été appliqué sur les feuilles ou incorporé dans l'alimentation (pollen ou proie). Par contact, le methoprène est moins toxique. C'est seulement dans le cas des concentrations les plus élevées (1000 ppm), que le nombre d'individus atteignant la maturité, le pourcentage de survie et le nombre d'œufs sont diminués; la durée de développement des individus, cependant, augmente. Le composé est plus actif lorsqu 'il est injecté. L'alimentation avec du pollen mélangé de 100 ppm de methoprène arrête le développement de tous les individus et le nombre d'œufs pondus est négligeable. Un aliment contenant 10 ppm de methoprène permet à une partie des individus d'atteindre la maturité et de pondre. De même, la survie et la reproduction des femelles nourries avec un aliment contenant 10 ppm de methoprène sont faibles. Tous les œufs pondus éclosent, dans les différents traitements: le methoprène n'inhibe pas l'éclosion.

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This work was conducted as part of a program of research on the predacious mites of Brazil, under support of a National Research Council grant to Dr.E. M. El-Banhawy     

Studies on the mating behaviour of the predaceous miteAmblyseius gossipi [Acarina,Phytoseiidae]

Résumé Le comportement sexuel de l'Acarien prédateurAmblyseius gossipi Elbadry a été étudié en laboratoire. Il a été reconnu que l'accouplement est nécessaire pour que les femelles pondent. Des accouplements successifs prolongent les périodes de préoviposition, d'oviposition et de postoviposition et accroissent la longévité des femelles. Les femelles accouplées plusieurs fois pondent davantage d'œufs que les femelles qui ont eu seulement un accouplement. Dans les techniques d'élevage en masse, des accouplements successifs favoriseraient beaucoup le rapide accroissement de la population du prédateur. Le taux sexuel de la descendance des femelles accouplées une seule fois est de 1,5 femelles pour 1 male, tandis que pour la descendance de femelles ayant eu des accouplements répétés il est de 2 femelles pour 1 male.      

Effect of avermectin and dicofol on the immatures of the predacious miteAmblyseius gossipi with a special reference to the secondary poisoning effect on the adult female [Acari: Phytoseiidae]

Avermectin at 1 ppm was slightly toxic by contact to the different immature stages of the predacious miteAmblyseius gossipi El-Badry. When immatures ofA. gossipi ingested treated prey on clean leaf discs, the toxicity increased and the resulted ΦΦ oviposited at a significantly lower rate. In contrast, dicofol at 250 ppm was extremely toxic by contact and caused a significant mortality to the immatures when it was ingested. Female mortality increased and fecundity decreased as the time of feeding treated prey increased from 24 h to 192 h. In case of dicofol a permanent depression in reproduction was recorded after feeding treated prey for 144 h. Females ofA. gossipi suffered a depression in reproduction when fed on prey formerly kept on plant leaves treated with avermectin. This depression was reported, only, after 192 h of feeding on prey previously reared on leaves treated with dicofol.      

Residual toxicity of some common acaricides in Brazil to the predacious miteAmblyseius brazilli

The direct toxicity of 5 common acaricides toAmblyseius brazilli El-Banhawy was tested. Omethoate proved to be the most toxic and Chlorobenzilate the least toxic. LC₅₀ were 1.2ppm, 220ppm, 720ppm and 1250ppm for Omethoate, Mexacarbate, Dicofol, Mitran and Chlorobenzilate respectively. The indirect toxicity was also studied by providing the female predators with the phytophagous miteAponicus spinosus (Banks) previously treated by Chlorobenzilate and Mexacarbate. The females were fed on the treated as well as the untreated prey. The eg laying was interrupted and almost stopped in the case of Mexacarbate.

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Résumé La toxicité directe de 5 acaricides communs surAmblyseius brazilli El-Banhawy a été examinée. L'Ométhoate est le plus toxique et le Chlorobenzilate le moins toxique. Les CL₅₀ sont respectivement de 1,2ppm, 4,7ppm, 220ppm, 720ppm et 1250ppm pour l'Ométhoate, le Mexacarbate, le Dicofol, le Mitran et le Chlorobenzilate. De même la toxicité indirecte des acaricides a été examinée en fournissant aux prédanteus femelles l'acarien phytophageAponicus spinosus (Banks) traité par le Chlorobenzilate et le Mexacarbate. Les femelles on été nourries de proies traitées et non traitées. La ponte a été interrompue; elle a été presque arrêtée dans le cas du Mexacarbate.

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This work was conducted as part of a program of research on the predadcious mites of Brazil, under support of a National Research Council grant to Dr.E. M. El-Banhawy.     

Cold-hardiness in the predatory miteAmblyseius potentillae (Acari: Phytoseiidae)

Cold-hardiness was studied in the predatory miteAmblyseius potentillae (Garman) by determining the mortality after exposure to –5°C. Predators reared under diapause-inducing conditions were more cold-resistant than mites that had been kept under long-day conditions. An acclimatization period at 4°C prior to exposure to sub-zero temperatures had a positive effect on the cold-hardiness of the predator, and was remarkable in diapausing mites.Lower temperatures during diapause induction had a positive effect on cold resistance in this predator; mites in which diapause was induced at 15°C were more cold-resistant than mites that had been subjected to short-day conditions at 18 and 20°C.A day/night temperature rhythm did not increase the cold-hardiness of the mite when grown under long-day conditions. Such a rhythm did increase the cold-hardiness of the diapausing predator when given a short acclimatization period, but this effect disappeared after longer acclimatization periods.     

Biogeographic distribution of the Phytoseiidae (Acari: Mesostigmata)

More than 1982 species in 90 genera were included in an analysis of the biogeography of the Phytoseiidae, a family of predatory mites. Seven biogeographic regions were taken into account: Nearctic, Neotropical, Ethiopian, West Palaearctic, East Palaearctic, Oriental, and Australasian. The number of species was particularly high in the Neotropical, Oriental, and West Palaearctic regions. These regions also present the highest levels of species endemism. The number of genera was quite similar in all regions except for the Neotropics, which also had a high level of endemism. The possible Gondwanian (Neotropical, Ethiopian, Australasian, and Oriental regions) origin of the Phytoseiidae, most probably in the Neotropics, and their possible radiation to Laurasia (Nearctic, West Palaearctic, and East Palaearctic regions) are discussed. The comparison between genera and species in the different biogeographic regions indicate the importance of both dispersal and vicariance events in the evolution of the group. Dispersal is assumed to have been most important between Neotropical and Nearctic regions and between East Palaearctic and Oriental regions, whereas vicariance could have been the dominating process between Australasian, Ethiopian, and Oriental regions, as well as between West and East Palaearctic regions. A parsimony analysis of endemicity showed the Neotropical and the Nearctic regions to be isolated from the other regions. This is certainly due to a diversification after the continents drifted apart and then a high dispersal between Nearctic and Neotropical regions. Different phylogenetic hypotheses and scenarios are proposed for each subfamily based on the results obtained and further investigations are proposed.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 845–856.     

Arthropods in biodiversity hotspots: the case of the Phytoseiidae (Acari: Mesostigmata)

The biodiversity hotspot concept was defined by Myers in 1988 to determine priority areas for conservation. They have high endemism levels and have lost more than 70% of their original vegetated area. To date, there is little information on arthropod diversity in these zones. This work focuses on the biodiversity of the Phytoseiidae (Acari), one of the best known among the order Mesostigmata, in these threatened areas. These mites are usually predators and they are worldwide spread. Geographic distribution of phytoseiids in 27 biodiversity hostspots was assessed from data of the last world catalogue published in 2004. One thousand two hundred and thirty species are reported from at least one hotspot (62% of the total species number) and 604 species (30% of the total species number) are endemic to the 27 hotspots considered. The number of reports/publication in hotspot areas (2.6) is higher than in non-hotspot zones (1.5). Hotspots areas could be thus considered as a great reservoir of the Phytoseiidae diversity, just as they are for vertebrates and plants. Correlations between plant, vertebrate, mite diversity and endemism, as well as congruence rates between endemism levels of these three organisms suggest that the biodiversity patterns of plants and vertebrates mirror well those of the Phytoseiidae (both for endemicity and species richness). More intense conservation efforts in biodiversity hotspots would thus be assumed to affect plant and vertebrate biodiversity, as already known, but also arthropod biodiversity, as it was assumed. These results further support thus the importance of these zones in biodiversity conservation, even for organisms like mites, very small and poorly studied in this regards. More data on arthropods are, however, required to confirm these preliminary observations.     

Three new species of phytoseiid mites from Kenya (Mesostigmata: Phytoseiidae)

The following 13 species of predacious mites of the family Phytoseiidae are recorded from various plants in Kenya: Amblyseius albizziae sp. nov., A. kenyae sp. nov., A. natalensis Van der Merwe, A. lokele Pritchard & Baker, A. largoensis (Muma), A. rykei Pritchard & Baker, A. teke Pritchard & Baker, Typholdromus kikuyuensis sp. nov., T. magdalenae Pritchard & Baker, Phytoseius amba Pritchard & Baker, p. ferox Pritchard & Baker, Iphiseius degenerans (Berlese), I. gongylus Pritchard & Baker. The new species and the male of A. natalensis are described.     

Feeding habits,post-embryonic and adult survival,mating, virility and fecundity of the predacious miteAmblyseius swirskii [Acarina: Phytoseiidae] on some coccids and mealybugs

The nutritional value forAmblyseius swirskii Athias-Henriot, of eggs or crawlers ofCoccus hesperidum L.,Saissetia oleae (Olivier),S. coffeae (Walker),Pseudococcus citriculus Green, andP. longispinus Targ.-Tozz, even with the addition of honeydew, was low; only a few young reached adulthood and the oviposition rate was negligible. However, addition of honeydew toTetranychus cinnabarinus Boisd. enhanced the oviposition rate ofAmblyseius swirskii. Honeydew was a favourite food forA. swirskii, whereas the eggs and crawlers tested were not eagerly attacked and consumed. Females and males fed honeydew ofSaissetia oleae mated readily and the females were inseminated, but fecundity was negligible.

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Résumé La valeur nutritive des aliments suivants a été faible même lorsqu'à du miellat ont été additionnés: des œufs ou des larves nouvelles nées deCoccus hesperidum L.,Saissetia oleae (Olivier),S. coffeae (Walker),Pseudococcus citriculus Green etP. longispinus Targ.-Tozz.; seulement une faible proportion est arrivée au stade adulte, le taux d'oviposition de ceux-ci étant négligeable. Cependant la ponte deAmblyseius swirskii a été accrue lorsque du miellat fut ajouté àTetranychus cinnabarinus Boisd. Le miellat est un aliment préféré deA. swirskii, tandis que les œufs et larves nouvelles nées des espèces testées ne sont pas attaqués ni dévorés avec appétit. Des femelles et des males élevés sur du miellat s'accouplent facilement, les femelles sont fécondées, mais la quantité d'œufs pondue reste négligeable.

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Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel, 1976 Series, No. 196-E.     

Statistical approaches for morphological continuous characters: a conceptual model applied to Phytoseiidae (Acari: Mesostigmata)

Marie‐Stephane, T. (2012). Statistical approaches for morphological continuous characters: a conceptual model applied to Phytoseiidae (Acari: Mesostigmata). —Zoologica Scripta, 42, 327–334. Species discrimination is certainly the most current and essential taxonomic task. Despite molecular development, species continue to be delimited using morphological characters. This study provides statistical approaches to assess decision rules, using continuous morphological characters, to determine whether specimens examined belong or not to a same species. As species discrimination is usually based on no overlapping between intraspecific distributions, a general statistical approach has been developed to assess, for a character x, the relation between intraspecific overlapping and (i) the differences between the means of specimen lots corresponding to two species and (ii) the differences between the values borne by two specimens belonging to two species. Then, this conceptual approach was applied to the predatory mite family Phytoseiidae, highlighting that the minimal difference between means of two specimen lots belonging to two species should be of 10.58 μm (for setae <65 μm) and 33.99 μm (for setae >65 μm). When no specimen sets are available but only two specimens compared, the model shows that a difference of 13.24 μm (for setae <65 μm) and 31.74 μm (for setae >65 μm) would be sufficient to conclude that these specimens belong to two species. The presently proposed decision rules are assumed to improve species discrimination and to limit synonymies. Further developments will consist in applying this approach to databases containing species features in order to automatically extract the putative synonyms. Furthermore, such decision rules would also be useful to determine whether a species newly described is really new for science.     

Some factors affecting reproduction and sex-ratio of the predacious mite Amblyseius deleoni (Muma and Denmark) (Acari: Phytoseiidae)

Abstract

Several factors were examined to determine their effect on the reproduction and sex ratio in the predacious mite Amblyseius deleoni (Muma and Denmark), in the laboratory. The factors investigated included multiple matings, duration of copulation, capacity of male for mating in excess of females and age of mating females and males. The factors included also, the host plant leaf texture, food deprivation during immature and adult stages, and prey (Tetranychus urticae Koch) density. The results indicated that females of A. deleoni require multiple matings to maximize their reproductive potential, also when copulation was allowed for increasing periods of time, there was a gradual increase in total egg production and oviposition period. A male showed a high reproductive ability for more than 15 days and was able to mate more than once in excess of females. Age of females has an influence on fecundity and sex ratio; old females decreased egg production and produced proportionally more male progeny compared with young females. Similarly, the highest number of eggs deposited per female A. deleoni was reported, when female mated with a young male (0-day old). In addition, males of A. deleoni (at any age) were able to inseminate the females. Results from host plant leaf texture indicated that guava leaf gave the highest reproduction rate, while the fig leaf gave the least female fecundity. Neither the reproductive rate nor the sex ratio of the progeny of females crossed by normal or experimental males had been influenced by the food deprivation during immature stages. A significant lower fecundity was recorded on female's A. deleoni when exposed to different food deprivation programmes during adult stage. The number of eggs laid by the predator female increased with increasing prey density of T. urtice to a maximum of 2.04 eggs deposited per day at a prey density of 30 protonymphs of T. urticae as a prey. As the level of prey density was increased, there was a shift in sex ratio towards an increased proportion of females.     

Effect of posttreatment temperature on the toxicity of five synthetic pyrethroids toTetranychus urticae Koch (Acari: Tetranychidae)

The synthetic pyrethroids bioallethrin,d-phenothrin, and fenvalerate, when tested by the slidedip technique, were more toxic to female two-spotted spider mites,Tetranychus urticae Koch, at 30°C than at 20°C. LC₅₀ values differed by 1.7-, 3.8-, and 5.3-fold, respectively. Two other synthetic pyrethroids, flucythrinate and cyfluthrin, gave similar toxicity values at these two temperatures. The greater sensitivity ofT. urticae at a warmer temperature to the first three pyrethroids differs from insect toxicity studies, which often show negative temperature relationships.University of Minnesota Scientific Journal Series No. 14954     

Comparative life-history studies on the predaceous mitesTyphlodromus annectens andT. porresi (Acari: Mesostigmata: Phytoseiidae)

Some aspects of the biologies ofTyphlodromus annectens De Leon andT. porresi McMurtry were studied at 25°C. The tetranychid mitesOligonychus punicae (Hirst),Panonychus citri (McGregor) andTetranychus pacificus McGregor were all favorable foods for development ofTy. annectens, whereas a low survival rate of immatures and no oviposition occurred on pollen.Tetranychus pacificus appeared to be a less favorable prey than the other two tetranychids forTy. porresi. Typhlodromus annectens, a very small species, andTy. occidentalis, a medium-sized species used for comparison, consumed significantly moreTe. pacificus larvae than did the medium-sizedTy. porreso. Comparing weights of fed and starved individuals suggested thatTy. occidentalis consumed the greatest volume of food material per time unit. The results are compared with those of previous studies of species in theoccidentalis species group ofTyphlodromus.     

Idiosomal setae in the family Phytoseiidae (Acari: Mesostigmata): variation,geographical distribution and taxonomic considerations

Phytoseiidae classification is based on idiosoma chaetotaxy and the assumed evolutionary process is seta suppression. This article aims to determine how depilation could have taken place depending on seta position, subfamily and region. For this, the occurrence of 21 variable setae on dorsal and ventral shields was determined for 1996 species in seven biogeographical regions. The occurrence of eight rare setae assumed to be past relics and 11 rarely absent setae (assumed to be undergoing a loss process) was analysed. The subfamily Phytoseiinae has ‘lost’ the highest number of primitive setae, the subfamily Amblyseiinae has ‘retained’ the highest number and Typhlodrominae has an intermediate position, except for the seta z6. The subfamily Phytoseiinae shows the highest number of setae undergoing a loss process, whereas the subfamily Typhlodrominae has lost these setae in 674 species and subfamily Amblyseiinae in 415 species, making this latter subfamily that with the most retained dorsal setae. According to spatial seta occurrence, it could be hypothesized that Amblyseiinae originated from South Gondwana, Typhlodrominae from the Euro‐America region (Laurasia zone) and Phytoseiinae from the Ethiopian area. The presently admitted classification of Phytoseiidae is discussed with regard to the occurrence of rarely present setae (assumed to have been lost in high frequency). © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 606–624.     

Statistical approaches to assess intraspecific variations of morphological continuous characters: the case study of the family Phytoseiidae (Acari: Mesostigmata)

Statistical methods for delimiting species with morphological data remain woefully understudied. The present study presents statistical approaches to study the intraspecific variations of continuous characters used in species diagnosis. For this, the data set comprised 14 species of the mite family Phytoseiidae (Acari: Mesostigmata) and 23 continuous characters (seta lengths). The statistical approaches aim to determine (i) how intraspecific variations differ depending on the characters and species considered, and (ii) how to choose the number of specimens to be considered for characterizing intraspecific boundaries. The means of the related confident limits at 95% (rCL₉₅) of the 14 species and the 23 setae are around 20%, suggesting that 95% of the specimens of a same species are included in the interval μ ± 0.2μ. No relationship was found between seta variations and the number of specimens considered for each species, nor for seta variations and their position on the mite body. However, a correlation between seta lengths and rCL₉₅ means was observed. An abacus was proposed to determine the coefficient that must be applied to mean seta length to calculate the lower and upper limits of the interval that will include 95% of the specimens of a same species. The higher the precision around the mean, the higher the number of specimens considered. Furthermore, this number varies considerably depending on the characters and species considered for high precisions. However, for a priori error around the mean of 15%, the number of specimens needed to characterize the intraspecific variation is quite homogeneous and ten specimens would be required. I discuss the utility of such results to resolve some persistent problems in the alpha‐taxonomy of the family Phytoseiidae but also of other taxa. © The Willi Hennig Society 2012.     

植绥螨科3新种和似巨钝绥螨特征补充(蜱螨亚纲:中气门目)

记述植绥螨科Phytoseiidae3新种:永安钝绥螨Amblyseius yonganensis sp.nov.,仿盾钝绥螨Ambly-seius imitopeltatus sp.nov.和尤溪盲走螨Typhlodromus youxiensis sp.nov.,并补充似巨钝绥螨Amblyseius grandisimilis Ma,2004特征。     

Rates of Development, Survival and Predation of Immature Stages of Phytoseiulus Longipes (Acari: Mesostigmata: Phytoseiidae)

Larvae of Phytoseiulus longipes do not feed. Thus, the purpose of this research was to determine the functional response as well as developmental and survival rates of the nymphal stages of this predator on the egg stage of the prey Tetranychus pacificus. The egg consumption for both immature stages increased smoothly with a negative rate reaching a plateau (type II response). To complete their development, the protonymphs and deutonymphs consumed mean minimums of 3.15 and 3.56 eggs, respectively, at a prey density of 20 per excised leaf arena. The mean daily developmental and survival rates also showed a curvilinear rise to a plateau. These plateaus for both developmental (71%) and survival rates (100%) were obtained at a prey egg density of 20 for both nymphal stages. Attack coefficients and handling times for both predator stages were estimated using several curve fitting models. All these models indicated a higher value of attack coefficient and a lower value of handling time for deutonymphs as compared to protonymphs. These findings, combined with the knowledge of adults' predation response, foraging behaviour and prey preference, indicate this predator's overall potential as a biological control agent against web-spinning spider mites such as the Pacific spider mite.     

Seasonal history ofTyphlodromus pyri (Acari: Mesostigmata: Phytoseiidae) in a commercial apple orchard in Czechoslovakia

The seasonal history and phenology of an indigenous field population ofTyphlodromus pyri Scheuten inhabiting a commercial apple orchard in South Bohemia are described. Data on population dynamics, number of generations, feeding, mating and reproductive habits as well as seasonal distribution within the apple tree canopy are discussed. Recommendations for mass retrieval ofT. pyri from apple orchards, their transfer to, and release in other orchards, are given. The conclusions and recommendations can be used for improving integrated pest management strategies in commercial apple orchards.