An integrative morphological and molecular diagnostics for Typhlodromus pyri (Acari: Phytoseiidae)

Tixier, M‐S., Okassa, M. & Kreiter, S. (2011). An integrative morphological and molecular diagnostics for Typhlodromus pyri (Acari: Phytoseiidae). —Zoologica Scripta, 41, 68–78. Phytoseiidae species are predators used in biological control programmes to limit mite pests out‐breaks in the world. Specific diagnostic is thus very important to ensure the success of pest management. This study aims to determine the species status of populations within the main species in vineyards and orchards: Typhlodromus (Typhlodromus) pyri, considering four molecular markers (COI, Cytb mtDNAs, 12SrRNA, ITSS) and 34 morphometrical characters. With the three mitochondrial DNA fragments considered, unexpected high genetic distances were observed between two groups, whereas both nuclear DNA and morphological analyses did not show such distinction. Furthermore, the GYMC and the 4 × rule tests emphasised the existence of a single species. Similarly, cross‐breeding experiments between specimens of the two groups showed no reproductive incompatibility. Therefore, despite the great intraspecific variation emphasised by the three mtDNA markers, we conclude that all the specimens considered belong to the same species. The present study clearly underlines the difficulty to conclude on species status using only mt markers and genetic distances, and stresses the necessity to apply multiple approaches for species definition. It also shows the confidence of the morphology for delineating this species.     

Status of two cryptic species, Typhlodromus exhilaratus Ragusa and Typhlodromus phialatus Athias-Henriot (Acari: Phytoseiidae): consequences for taxonomy

Typhlodromus phialatus and T. exhilaratus are morphologically close species. Their differentiation is based on the shape of the insemination apparatus and on idiosomal setae length. However, the setae length values are often intermediate between these two species and do not allow accurate identification. Furthermore, the handful of differences in insemination apparatus shape are also questionable as a means of differentiation. Synonymy between these species has thus been questioned. Three experiments were carried out. Idiosomal seta length measurements, molecular tests and cross experiments were conducted for three populations, identified as T. exhilaratus and T. phialatus according to the shape of their insemination apparatus. The results show that the variation range of seta lengths is great and that these criteria do not allow accurate separation of these populations into two species. However, molecular tests show a species-level nucleotide differentiation between them. Cross experiments confirm this result, showing complete reproduction incompatibility between the mites bearing different insemination apparatus shapes. Therefore, T. exhilaratus and T. phialatus could be considered to be two valid species and the insemination apparatus could be considered as a pertinent diagnostic criterion at the specific level.     

Temperature and diet effects on immature development of predatory mite Typhlodromus athenas Swirski and Ragusa (Acari: Phyotseiidae)

Temperature and food quality both can influence growth rates and developmental time of herbivorous insects and mites. Typhlodromus athenas Swirski and Ragusa is an indigenous mite in the Mediterranean region and data on its temperature dependent development are lacking. In the current study, temperature-dependent development and survival of T. athenas immature stages were evaluated on eggs and all stages of Tetranychus urticae Koch, as well as on almond (Prunus amygdalis Batsch) pollen, under seven constant temperatures ranging from 15 to 35°C, 65% RH, and a photoperiod of 16:8 (L:D) h. On both diets survival was considerably high at all temperatures. The longest developmental period of immature stages was recorded at 15°C, whereas the shortest was at 30°C. Female immatures on almond pollen had shorter developmental time compared to that on twospotted spider mites. Food had a significant effect on female total developmental time at temperatures lower than 25°C. The lower developmental thresholds, estimated by a linear model, for egg-to-adult of females and males fed on pollen were 8.60 and 8.77°C, respectively, whereas on T. urticae they were 10.15 and 10.62°C, respectively. Higher values of tmin for total development were estimated by a nonlinear model (Lactin-2), and ranged from 10.21°C for both females and males on almond, to 11.07 for females and 10.78°C for males on prey. Moreover, this model estimated optimal and lethal temperatures accurately. The results of this study indicate that T. athenas appears better adapted to higher temperatures that occur in the Mediterranean region and may be a useful biological control agent.     

Effect of seven different pollens on bio-ecological parameters of the predatory mite Typhlodromus foenilis (Acari: Phytoseiidae)

Development, immature survival, reproduction, and life table parameters of the predatory mite Typhlodromus foenilis Oudemans were evaluated on seven different plant pollens (almond, apple, pear, cherry, apricot, plum, and walnut). Experiments were conducted in environmental chambers at 20 +/- 1 degrees C with 65 +/- 5% RH and a photoperiod of 16:8 (L:D). T. foenilis successfully completed its development on all pollen diets. Female mean developmental time from egg to adult emergence ranged from 11.3 +/- 0.12 to 14.28 +/- 0.23 d, whereas that of males was from 10.81 +/- 0.17 to 14.17 +/- 0.17 d. The average life span of adult females varied from 41.0 +/- 1.46 to 65.45 +/- 3.89 d, and total fecundity ranged from 11.78 +/- 0.65 to 39.09 +/- 2.38 eggs/female. The intrinsic rate of increase of T. foenilis was highest on almond pollen (r(m) = 0.104/d) and was the shortest on walnut pollen (r(m) = 0.055/d). The results show that this predatory mite develops well on all pollens, with almond and apricot pollens being of high nutritional value. This study provides further information for mass rearing of T. foenilis, and these findings are discussed in relevance with the establishment of this species in the field.     

Intraspecific competition in immature Amblyseius fallacis,Amblyseius andersoni,Typhlodromus occidentalis and Typhlodromus pyri (Acari: Phytoseiidae)

Intraspecific competition in immature Amblyseius fallacis, Amblyseius andersoni, Typhlodromus occidentalis and Typhlodromus pyri was examined in the laboratory using small cages at five different predator densities (two, four, eight, 16 and 32) in the absence and presence of prey 100 eggs of two-spotted spider mite, Tetranychus urticae (Koch), at 25 ± 1°C, 80% RH and 16L:8D photoperiod. In the absence of spider mite prey, some individuals of immature phytoseiids showed increased development and surival with increasing predator densities up to certain limits, but none survived to the adult stage, except for a single male each of A. andersoni and A. fallacis who completed development by cannibalizing on conspecifics at a density of 32 predators per cage. In the absence of spider mite prey, the mean immature survival time was independent of the initial predator density, but the variance of survival time increased with predator density. In the presence of prey, the proportion of immatures surviving to adulthood generally decreased with initial predator density and dropped sharply to almost none at the predator density of 32 for A. fallacis, eight for A. andersoni, 16 for T. occidentalis and four for T. pyri. The number of prey consumed per predator during the first day generally decreased with predator density in all four species, as prey available per predator decreased and the competition for food increased with predator density. Our data indicate that scramble competition is operating in these four species. Although cannibalism was occasionally observed, especially after the exhaustion of prey and in the generalist predators such as A. andersoni, the immatures of these phytoseiids were less influenced by the interference of conspecifics than by the increasing difficulty of finding food at high predator densities. The implications of this study for understanding phytoseiid population dynamics and their use in biological control are discussed.     

Interspecific competition and predation between immature Amblyseius fallacis,Amblyseius andersoni,Typhlodromus occidentalis and Typhlodromus pyri (Acari: Phytoseiidae)

Interspecific competition and predation in immature Amblyseius fallacis (Garman), Amblyseius andersoni Chant, Typhlodromus occidentalis (Nesbitt) and Typhlodromus pyri Scheuten were examined in small cages at three egg densities (0, 20 and 80) of two-spotted spider mite, Tetranychus urticae Koch, in the laboratory at 25±1°C,80% RH and 16L: 8D photoperiod. For the six possible between-species comparisons, the large polyphagous A. andersoni always outcompeted the other three predator species, which were either smaller and/or less polyphagous; the small oligophagous T. occidentalis was always eliminated by the other three predator species, which were either larger and/or more polyphagous. The small and polyphagous T. pyri tied with the large and oligophagous A. fallacis. The outcome of the interaction was generally similar at the three prey densities except in (1) the A. fallacis-A. andersoni system where the advantage of A. andersoni over A. fallacis was reduced when 20 or 80 eggs per cage were present at the start of the interaction and (2) the A. fallacis-T. occidentalis system where the advantage of A. fallacis over T. occidentalis increased with prey density. This study indicates that predator size, predator degree of polyphagy and prey density can affect the competitiveness of immature phytoseiids.     

DNA preparation method in eggs, immature stages, and diapausing females of Tetranychus spider mites (Acari: Tetranychidae) for diagnostic PCR-RFLP

A DNA preparation method for diapausing females, immature stages, and eggs of spider mites for diagnostic analyses using restriction fragment length polymorphisms after polymerase chain reaction (PCR-RFLP analysis) of the internal transcribed spacer (ITS) region including 5.8 S of the nucleic ribosomal DNA was developed using Tetranychus urticae Koch as a typical example of tetranychid mites. In diapausing females and deutonymphs, the method of crushing an individual mite with a glass rod was eminently successful and a useful method to obtain the DNA template for PCR. For protonymphs, larvae, and eggs older than 48?h after oviposition at 24?°C, the DNA preparation method for a single nematode, crushing a tiny sample with a filter paper chip, was also successful and a useful method to obtain the DNA template from mite individuals (eggs) for PCR. Consequently, we found a single distinctive band of an amplified DNA fragment after electrophoresis in all developmental stages, and digestion of the PCR product by a restriction endonuclease, DraI, resulted in identical banding patterns being exhibited in all developmental stages. Our findings indicate that PCR-RFLP analysis of the ITS region can be used for species identification of diapausing females, immature stages, and eggs of Tetranychus species.     

Inter- and intraspecific predation on immatures by adult females in Euseius finlandicus, Typhlodromus pyri and Kampimo dromus aberrans (Acari: Phytoseiidae)

In a series of experiments, the interspecific predation and cannibalism on immatures by the adult females of Euseius finlandicus, Kampimodromus aberrans and Typhlodromus pyri were examined under laboratory conditions. The three species showed differing tendencies to prey on each other's motile immature stages. Euseius finlandicus females consumed more larvae and protonymphs than the females of T. pyri and K. aberrans. In cages without free water E. finlandicus ate a range of 6.51 larvae or 5.31 protonymphs of T. pyri and 5.27 larvae or 5.95 protonymphs of K. aberrans per female per day. Kampimodromus aberrans and T. pyri females exhibited a greater tendency to prey on heterospecifics than on conspecifics. When feeding on phytoseiid immatures and without free water, T. pyri females survived longer and laid more eggs than the females of E. finlandicus and K. aberrans. Adult females of E. finlandicus and T. pyri having free water and preying on heterospecific protonymphs were able to maintain egg laying during the whole experimental period of 12 days. The females of all three species had difficulties in piercing phytoseiid eggs, and the number of sucked eggs per female per day was low. Kampimodromus aberrans females ate 0.48 eggs of T. pyri daily, which was the highest recorded number. The great tendency to interspecific predation on motile immature phytoseiids by the females of E. finlandicus is discussed with regard to the dominance of this species on deciduous trees and bushes in Austria.     

Sublethal effects of esfenvalerate residues on pyrethroid resistant Typhlodromus pyri (Acari: Phytoseiidae) and its prey Panonychus ulmi and Tetranychus urticae (Acari: Tetranychidae)

The effect of residues of esfenvalerate on oviposition of the resistant strain of the predatory mite Typhlodromus pyri and its main prey, European red mite Panonychus ulmi and two-spotted spider mite Tetranychus urticae, were investigated. T. pyri showed a significant linear reduction in oviposition after 24h in the presence of increasing levels of esfenvalerate residue applied at the field rate. Furthermore, when given a choice, T. pyri preferred to lay eggs on residue-free surfaces. Of the two prey species, only P. ulmi showed significant avoidance of increasing levels of residues of the field rate concentration of esfenvalerate, as measured by runoff mortality, however both P. ulmi and T. urticae, when given a choice, showed a preference for esfenvalerate-free surfaces. As with the predatory mite T. pyri, both prey species showed a significant linear reduction of oviposition with increasing esfenvalerate residues and a preference to lay eggs on esfenvalerate-free surfaces. Esfenvalerate residues as high as 15X field rate were not repellent to pyrethroid-resistant T. pyri. The possible effects of these sublethal effects on predator-prey dynamics and implications for integrated mite control programmes in apple orchards are discussed.     

A comparative life history study of immature Amblyseius fallacis,Amblyseius andersoni,Typhlodromus occidentalis and Typhlodromus pyri (Acari: Phytoseiidae) with a review of larval feeding patterns in the family

Survival, developmental time, activity, feeding rates, and other biological aspects of immatures of Amblyseius fallacis, Amblyseius andersoni, Typhlodromus occidentalis and Typhlodromus pyri were examined in the laboratory in small arenas (2×2 cm) with different egg densities (0, 5, 10, 20 per 12 h) of the twospotted spider mite, Tetranychus urticae (Koch), at 25±1°C, ≈80% RH, and 16L: 8D photoperiod. Egg survival was high (86–100%) in all four species. Larval survival was similarly high except for T. occidentalis which all died in the absence of food. Survival rates of protonymphs and deutonymphs were also high except that up to 50% of A. andersoni died at 5 prey eggs per 1/2 day. Developmental time did not vary significantly with prey density and was similar for males and females in the oligophagous predators (A. fallacis and T. occidentalis), but was longer at lower prey densities and in females than males in the polyphagous predators (A. andersoni and T. pyri). In general, the time allocated to three active instars (=stases) decreased in the order: A. andersoni (81%), T. pyri (78%), A. fallacis (69%), and T. occidentalis (64%). The polyphagous predator species had a shorter larval stage and much longer deutonymphal stage than the oligophagous species. The proportion of time allocated to the protonymphal stage was the least variable among the four species. The interspecific differences in walking activities also appeared greater in larval and deutonymphal stages than in the protonymphal stage. The larvae of the two oligophagous predators (A. fallacis and T. occidentalis, walking activity averaging 36–49%) were more active than the two polyphagous predators (A. andersoni and T. pyri), which spent 80% or more time resting. In deutonymphs, walking activity increased in the order: T. occidentalis (14%), A. andersoni (27%), A. fallacis (43%) and T. pyri (59%). Larvae were more active during the first half of their life than the latter half. In general, most life history traits of immature A. andersoni, T. pyri, A. fallacis, and T. occidentalis are not associated with their phylogenetic relatedness or size, but with the feeding specialization of the predator species. Larval feeding patterns in Phytoseiidae are reviewed and a hypothesis about the evolution of larval feeding behavior in Phytoseiidae is proposed.     

南非盲走螨实验种群的发育历期及生命表

在27℃条件下,以粗脚粉螨Acarus siro L.为饲料饲养观察南非盲走螨Typhlodromus(Anthoseius) transvaalensis(Nesbitt)的生长发育和繁殖情况,组建实验种群生命表。结果表明,南非盲走螨行孤雌生殖,卵、幼螨、前若螨、后若螨、成螨产卵前期各阶段发育历期分别为2.00,0.72,1.96,1.53,1.77d,完成1个世代发育需7.98d,雌成螨平均寿命14.82d、平均产卵量25.75粒,各种群生命参数分别为:净增殖率R0=25.01,世代平均周期T=13.71,内禀增长率rm=0.23,周限增长率λ=1.26,种群倍增所需日数t=2.95。采用小空间湿度控制法,测定不同湿度对南非盲走螨卵的孵化和成螨产卵的影响。结果表明,卵发育和孵化的最适湿度为75.0%~85.0%,96.0%的相对高湿度对成螨的产卵和存活均有不利影响。以橘全爪螨Panonychus citri McGregor不同螨态为猎物时,南非盲走螨对橘全爪螨幼螨的捕食量最大,日平均捕食量为5.40头,而对橘全爪螨雌成螨则几乎不取食。     

Predation Preference of Typhlodromus Pyri and Kampimodromus Aberrans (Acari: Phytoseiidae) When Offered Con- and Heterospecific Immature Life Stages

The predation preference of singly caged adult females and nymphs of Typhlodromus pyri and Kampimodromus aberrans for con- or heterospecific immature stages as prey was tested in the laboratory. Both polyphagous predatory mite species have been previously shown to interact directly through predation on each other. The present study demonstrated that the adult females of T. pyri and K. aberrans are able to discriminate between con- and heterospecific larvae and protonymphs and that they prefer to prey upon heterospecifics when given the choice. Hunger did not reduce the propensity of the females to prefer heterospecifics over conspecifics. For proto-and deutonymphs the trends followed the results obtained with the adult females, but the preference for heterospecifics was not distinct enough to be significant. In competitive situations reciprocal predation may be a crucial mechanism in the interaction of polyphagous phytoseiid species and may contribute significantly to population persistence. The results are discussed with regard to possible associations between the ability to discriminate con- and heterospecifics and the type of feeding specialization (generalists versus specialists).     

Effect of several different pollens on the bio-ecological parameters of the predatory mite Typhlodromus athenas Swirski and Ragusa (Acari: Phytoseiidae)

The development, survivorship, and reproduction of the predacious mite Typhlodromus athenas Swirski and Ragusa were studied in the laboratory by rearing the predator on nine different plant pollens [almond(Prunus amygdalis Batsch), apple (Malus domestica Borkh.), apricot (Prunus armeniaca L.), cherry (Prunus avium L.), pear (Pyrus communis L.), plum (Prunus domestica L.), walnut (Juglans regia L.), olive (Olea europaea L.), Typha sp.], and pollen collected from bee hives. All experiments were conducted in environmental chambers at 20 ± 1°C, 65% RH, and a photoperiod of 16:8 (L:D) h. Survival during immature development ranged from 81.1 to 96.0%. The shortest mean developmental time from egg to adult with respect to the range of pollen species was recorded for females and males fed on almond pollen (10.76 ± 0.18 and 10.45 ± 0.21 d, respectively), while the longest was on beehive pollen (26.97 ± 0.23 and 24.00 ± 0.25 d for females and males, respectively). Female longevity varied from 51.63 ± 5.52 d (olive pollen) to 102.81 ± 6.60 d (pear pollen), while fecundity ranged from 5.33 ± 2.35 eggs per female (beehive pollen) to 26.43 ± 1.73 eggs per female (almond pollen). The diet consisting of almond pollen resulted in the highest intrinsic rate of natural increase (r(m)) (1.00 d(-1)) and pollen collected from bee hives resulted in the lowest (0.013 d(-1)). These results showed that various pollen could favor the development of T. athenas, and also support the view that alternative food resources may play an important role in the field for sustaining and increasing the predator's population.     

Temperature-related development and population parameters for Typhlodromus pyri (Acari: Phytoseiidae) found in Oregon vineyards

The beneficial mite Typhlodromus pyri is a key predator of grapevine rust mite Calepitrimerus vitis in Pacific coastal vineyards. Rust mite feeding has been associated with damage such as stunted, deformed shoot growth and reductions in fruit yield. The life history traits of T. pyri were assessed at seven constant temperatures (12.5, 15, 17.5, 20, 25, 30 and 35 °C) to determine population parameters providing data to better predict biological control of C. vitis populations by T. pyri in vineyards. Successful development from the egg to adult stage was observed at temperatures ranging from 15 to 30 °C. Constant exposure to 12.5 and 35 °C resulted in 100 % mortality in immature T. pyri. Developmental times, fecundity and longevity were highest at 25 °C. The estimated minimum and maximum developmental thresholds were 7.24 and 42.56 °C, respectively. Intrinsic rate of increase (r ( m )) was positive from 15 to 30 °C indicating population growth within this range of temperatures. Net reproductive rate and intrinsic rate of increase were greatest at 25 °C. These developmental parameters can be used to estimate population growth, determine seasonal phenology and aid in conservation management of T. pyri. Results presented in this study will aid in evaluating the effectiveness of T. pyri as a key biological control agent of C. vitis during different periods of the growing season in Pacific Northwest vineyards.     

Biparental inheritance of RAPD markers in males of the pseudo-arrhenotokous mite Typhlodromus pyri.

In pseudo-arrhenotokous mites, haploid males develop from fertilized eggs that undergo paternal genome loss (PGL) during early embryogenesis. We present evidence that some of the paternal genome may be retained in males of the predatory mite Typhlodromus pyri Scheuten (Acari: Phytoseiidae). Two reproductively compatible populations were differentiated by two random amplified polymorphic DNA markers and the inheritance pattern in the offspring was analysed. Maternal transmission rates are variable and independent of the sex of the offspring and of the marker. These data suggest a nuclear origin and independent segregation of the markers. One marker (330 base pairs (bp)) was paternally transmitted to male as well as female offspring, the other (990 bp) was paternally transmitted to all females and some of the male offspring. We propose that the paternal set of inactivated chromosomes may be partially retained in some tissues of the haploid males or, alternatively, that a B chromosome does not follow the process of PGL in male embryos, thereby segregating with the maternal set. The possible mechanisms controlling the condensation and the segregation of the chromosome(s) retained are discussed on the basis of current hypotheses on chromosome inactivation in insects.     

Morphological and molecular characterization of a new microsporidian species from the predatory mite Metaseiulus occidentalis (Nesbitt) (Acari,Phytoseiidae)

A new microsporidian species is described from the predatory mite Metaseiulus (formerly Typhlodromus or Galendromus) occidentalis (Nesbitt) (Acari, Phytoseiidae). The ultrastructure of this new species is presented together with the first molecular characterization for a microsporidium of mites. All stages of this new microsporidium are haplokaryotic and develop in direct contact with the host-cell cytoplasm. Sporogony is disporoblastic and spores are formed in eggs, immature stages, and adults of M. occidentalis. There are two morphological classes of spores, one with a short polar filament (3-5 coils) that measured 2.53 x 1.68 microm and one with a longer polar filament (8-9 coils) that measured 3.14 x 1.77 microm. Horizontal transmission of this new species occurs by cannibalism of eggs and other stages and perhaps involves the spores with the long polar filament. Spores with the short polar filament may play a role in autoinfection and vertical (transovarial) transmission that is highly efficient in transferring the microsporidium from adults to progeny. Analysis of the small subunit ribosomal DNA indicated that this species from M. occidentalis is most closely related to the Nosema/Vairimorpha clade of microsporidia. A conflict between the morphological and molecular data is discussed. The species is compared to previously described microsporidia of arachnids resulting in creation of Oligosporidium occidentalis n. sp. in the family Unikaryonidae.     

Intra- and interspecific predation on four life stage groups by the adult females of Metaseiulus occidentalis, Typhlodromus pyri, Neoseiulus fallacis and Amblyseius andersoni

Do adult females of oligophagous species such as Neoseiulus fallacis (Garman) and Metaseiulus occidentalis (Nesbitt) show less intra- and interspecific predation on phytoseiids when other foods are scarce than polyphagous species such as Amblyseius andersoni Chant and Typhlodromus pyri Scheuten? We caged single adult females of each species without food with ten of their own eggs or larvae, with ten eggs or larvae of the other species or with ten nymphs or adult females of M. occidentalis (T. pyri for M. occidentalis). We assessed the ambulatory activity, survival time, egg levels and prey loss in each test. Polyphages (in particular T. pyri) lived longer than oligophages (in particular N. fallacis) without food. The small T. pyri detected its own stages and benefited most by feeding on small active stages of other species. Amblyseius andersoni, the largest mite, fed and gained the most of any species when held with nymphs and female adults. Metaseiulus occidentalis fed on eggs of all four species to enhance survival. The large hyperactive N. fallacis gained the least from these behaviours. Each mite seemed uniquely adapted to survive conditions of scarce prey and these behaviours may explain their roles in phytoseiid mite complexes. Overall, oligophagous adult females fed less and gained less by feeding on phytoseiids than did polyphagous adult females.     

Differential impact of egg predation by Zetzellia mali (Acari: Stigmaeidae) on Metaseiulus occidentalis and Typhlodromus pyri (Acari: Phytoseiidae)

The differential impact of Zetzellia mali on the phytoseiids Metaseiulus occidentalis and Typhlodromus pyri was studied in the laboratory and by analysis of population from orchard plots that contained either phytoseiid, similar numbers of prey mites and high or low densities of Z. mali. Five hypotheses were evaluated to explain why Z. mali had more impact on M. occidentalis in the field than on T. pyri. Given equal opportunity, Z. mali adult females did not consume more M. occidentalis eggs than T. pyri eggs nor did adult females of either phytoseiid inflict greater mortality on Z. mali eggs or larvae through attack or consumption. There was no difference in the within-tree association of Z. mali adult females with eggs of either phytoseiid species nor were there differences in the way prey mites (all life stages) were spatially partitioned between adult female Z. mali as compared with adults and deutonymphs (combined) of either phytoseiid. The foraging area of adult female Z. mali and the oviposition locations of the two phytoseiids from both field and laboratory data were compared using spatial statistics. Metaseiulus occidentalis laid significantly more eggs in the primary foraging area of adult female Z. mali than T. pyri. This was the only factor identified which may explain the greater impact of Z. mali on M. occidentalis. The impact of these interspecific effects on the persistence of predatory mite guilds and biological control are discussed.     

Euseiusfinlandicus (Acari: Phytoseiidae) as a potential biocontrol agent against Tetranychus urticae (Acari: Tetranychidae): life history and feeding habits on three different types of food

Life history and reproductive parameters of the generalist predatory mite Euseius (Amblyseius) finlandicus (Oudemans) were studied in the laboratory at 25 +/- 1 degrees C, with a 16L:8D photoperiod and 60 +/- 15% RH, to investigate its response to different food sources: an eriophyid mite Aceria sp., tulip pollen Tulipa gesnerana L., and two-spotted spider mite Tetranychus urticae Koch. Total developmental time of the immature stages was the shortest on eriophyid mites, followed by pollen, and then spider mites. Fecundity was highest on pollen (43.69 eggs; 1.63 eggs/female/day), then eriophyid mites (39.73 eggs; 1.37 eggs/female/day) and lowest on spider mites (18.16 eggs; 0.80 eggs/female/day). Intrinsic rate of increase (Rm), net reproductive rate (Ro) and finite rate of increase (lambda) followed the same pattern [pollen (0.168, 27.96 and 1.183, respectively), eriophyid mites (0.153, 20.81 and 1.167), spider mites (0.110, 9.44 and 1.119)]. Mean generation time (days) was the shortest on pollen (19.90), followed by eriophyid mites (20.02), and then spider mites (20.59). Average spider mite larvae consumed by E. finlandicus during immature stages were 9.18 for males and 11.85 for females. Adult E. finlandicus females consumed an average of 166.38 spider mite protonymphs during adult stage compared to an average of 66.55 by males. The number of prey protonymphs consumed per day by females was highest in the oviposition period, lower in the pre-oviposition period and the lowest in the post-oviposition period. The eriophyid mite as a prey recorded the shortest developmental time, while pollen as food recorded the highest oviposition rate in E. finlandicus. The potential of this predator as a biocontrol agent against T. urticae is discussed.     

New species of the genus Typhlodromus from Sudan (Acari: Phytoseiidae)

The genus Typhlodromus in Sudan includes five species. Of these, three new species are described and illustrated in this work. Individuals of T. sudanicus Elbadry and T. medanicus Elbadry have been found to play an important role in feeding on phytophagous mites and white fly nymphs infesting cotton crop.
Typhlodromus niloticus sp. n. and T. balanites sp. n. from fruit trees feed on tetranychid and eriophyid mites. T. sennarensis sp. n. has been collected from wild plants.
A key is provided for the identification of members of the genus Typhlodromus in Sudan.