Host Selection by the Herbivorous Mite Polyphagotarsonemus latus (Acari: Tarsonemidae)

This study examined the host-selection ability of the broad mite Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae). To make long-distance-shifts from one host plant patch to another, broad mites largely depend on phoretic association with whiteflies. However, the host plants of whiteflies and broad mites are not necessarily the same. We determined the host-preference and acceptance of free-moving and phoretic broad mites using two behavioral bioassays. We used a choice test to monitor host selection by free-moving mites. In the case of phoretic mites, we compared their rate of detachment from the phoretic vector Bemisia tabaci placed on leaves taken from various host plants. The suitability of the plant was further determined by monitoring mite’s fecundity and its offspring development. We compared the mites’ responses to young and old cucumber (Cucumis sativus cv. ‘Kfir’) leaves (3rd and 8–9th leaf from the apex, respectively), and two tomato (Solanum lycopersicum cvs. ‘M82’ and ‘Moneymaker’). Free-moving mites of all stages and both sexes preferred young cucumber leaves to old cucumber leaves and preferred young cucumber rather than young tomato leaves, demonstrating for the first time that broad mites are able to choose their host actively. As for phoretic mated females, although eventually most of the mites abandoned the phoretic vector, the rate of detachment from the whitefly vector was host dependent and correlated with the mites’ fitness on the particular host. In general, host preference of phoretic female mites resembled that of the free-moving female. Cues used by mites for host selection remain to be explored.     

Biology and control of the broad mite,Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae)

The broad mite,Polyphagotarsonemus latus (Acari: Tarsonemidae), is an important, and in some cases recent, pest of diverse crops in tropical and subtropical regions. Infested leaves become bronzed with down-curling margins, buds are aborted and flowers distorted, shoots grow twisted and fruit may be misshapen and russeted. Injuries, presumably due to toxins, occur even after the broad mite is killed by pesticides. There is no evidence thatP. latus transmits plant viruses, but injury may be mistaken for virus or herbicide damage. The mite infests plants referable to ca 55 dicotyledone and two monocotyledone families as well as to the Cupressaceae. Changes in horticultural practices, including control measures, could have caused recent pest outbreaks. The mite may raise a generation in 1 week under optimal conditions (ca 25°C and high relative humidities) and deposit ca. 40 eggs/ female. The usual sex ratio is 1:4 male: female and reproduction is arrhenotokous. Dispersal is effected through male carriage of pharate females as well as by winds, insects (especially whiteflies) and man. Field sampling is facilitated by the pest's aggregated distribution. Control options comprise plant resistance, pesticides and biocontrol. Areas for future research include the possible emergence of sibling species or feeding strains, better understanding of the mite's reproduction, the effects of host plants on life history parameters, monitoring for pesticide resistance and exploration for additional natural enemies of the broad mite.     

Temperature-dependent development of the broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) on Rhododendron simsii

The broad mite, Polyphagotarsonemus latus (Banks), is one of the major pests causing severe economic damage in Rhododendron simsii Planch hybrid production in Belgium. In order to optimize biological control programs and to parameterize warning programs, we studied the effect of environmental temperature on the development of P. latus on R. simsii leaves. In combination with a photoperiod of 16:8 h (L:D) and a relative humidity of 80 ± 5 %, six constant temperatures (15, 17, 20, 25, 30 and 33 ± 1 °C), were studied. Total developmental times of 13.3, 10.5, 6.6, 4.2, 3.5 and 4.0 days were measured, respective to each of the aforementioned temperatures. Development of females took significantly longer than that of males at 15, 17, 20 and 30 °C. Survival rates observed between 17 and 30 °C varied between 43.5 and 96.9 %. Lower survival rates were found at 15 and 33 °C, i.e. 31.8 and 23.6 %, respectively. The lower, optimal and upper developmental threshold (t _min , t _opt and t _max , respectively) and thermal constant (K) of the pest were estimated for each life stage by a linear and two non-linear models. Based on measurements of total development of P. latus thermal thresholds of 10.0, 30.1 and 36.0 °C were calculated for t _min , t _opt and t _max , respectively. The number of degree-days needed to complete immature development when feeding on R. simsii was 66.7.     

Dispersal of the broad mite, Polyphagotarsonemus latus (Acari: Tarsonemidae) on Bemisia argentifolii (Homoptera: Aleyrodidae)

The broad mite Polyphagotarsonemus latus (Banks) and silverleaf whitefly Bemisia argentifolii Bellows & Perring (=B strain of Bemisia tabaci (Gennadius)) have many common host plants. It was found that broad mites can attach themselves to B. argentifolii adults and use them as a carrier for their dispersal. In a cage experiment, we observed that more than 80% of B. argentifolii adults had more than one broad mite attached within 4 h after B. argentifolii landed on broad mite-infested plants. Overall, 97.5% of the broad mites examined were attached to the legs, mostly on the tibiae and tarsi of B. argentifolii adults, and 99.5% of the broad mites attached to B. argentifolii were adult females. The successful dispersal of broad mite via B. argentifolii was also demonstrated with a cage experiment.     

Evaluation of the activity of filamentous fungi isolated from soils of the Pampa biome applied in the biological control of Tetranychus urticae (Acari: Tetranychidae) and Polyphagotarsonemus latus (Acari: Tarsonemidae)

Experimental and Applied Acarology - Tetranychus urticae Koch and Polyphagotarsonemus latus Banks are mite species considered capable of attaining pest levels, damaging a range of agricultural...     

Evaluation of Metarhizium anisopliae (Deuteromycota: Hyphomycetes) for control of broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) in mulberry

A study on 12 entomopathogenic fungi for controlling broad mite (Polyphagotarsonemus latus (Banks)) in mulberry found that Metarhizium anisopliae CKM-048 was the most virulent strain in controlling both larvae and adult broad mites at the concentration of 2 x 10(8) conidia/ml. There was no ovicidal effect when tested with broad mite eggs. Median lethal concentrations (LC(50)) of M. anisopliae in killing larvae and adults were 8.7 x 10(6) and 1.3 x 10(7 )conidia/ml, respectively. Median lethal times (LT(50)) of larvae and adults were 2.4 and 3.8 days, respectively, at the concentration of 2 x 10(8) conidia/ml. The fungus was found to produce protease and chitinase. Scanning electron microscope (SEM) studies were done to monitor the infection steps of the fungus on broad mites. A greenhouse test on mulberry trees revealed that M. anisopliae could reduce the broad mite population within 4 days after treatment. However, after 7 days, its efficacy was decreased significantly.     

Factors affecting the potential of phytoseiid mites (Acari: Phytoseiidae) as biocontrol agents in North-Italian vineyards

The results of a 5-year study on the relationships between spider mites and their predators in vineyards in Northern Italy are reported. The efficacy of the two predatory mites appeared to be strongly affected by various factors (grape variety, presence of macropredators, climatic condition, interspecific competition, phytoseiid strain). The phytoseiid mitesAmblyseius aberrans (Oud.) andTyphlodromus pyri Scheuten were released at three different density levels in two vineyards (A, B) infested byEotetranychus carpini (Oud.). One strain ofA. aberrans and two strains ofT. pyri were used for the experiments. In vineyard A,Panonychus ulmi (Koch) was recorded in the second and subsequent years of the experiments and became dominant overE. carpini from the third year onwards. The presence of anthocorids in the same vineyard increased the complexity of the system and gave us the possibility of comparing two very different situations. Release of low numbers ofA. aberrans gave a satisfactory control of spider mite populations in both vineyards. These results were even obtained on a variety non preferred by phytoseiids (Merlot) and with the continuous presence of anthocorids (vineyard A). After 5 years,A. aberrans was observed in 53% of the plots in vineyard A and in all plots of the other vineyard (B). Results of experiments in whichT. pyri was released were similar to those obtained in the experiments withA. aberrans, but only in the first year of the study. In vineyard A, theT. pyri populations declined dramatically from the second year onwards; the use of a non-preferred variety (Merlot) and the continuous presence of anthocorids seemed the most important factors causing the decline of predatory mite density. In vineyard B,T. pyri was capable of controlling spider mites even in the second year of the experiments. A very low density of macropredators and a preferred grape variety (Raboso) positively affected control. The density ofT. pyri in vineyard B decreased at the end of the second year because of adverse climatic conditions (high temperatures in combination with a low relative humidity). The decrease ofT. pyri allowed the displacement of this species byA. aberrans in all plots of vineyard B. It was also shown that the twoT. pyri strains differed in their efficacy to control spider mites. The research was partially supported by a grant from Regione Veneto (“Lotta biologica e integrata nel controllo di insetti ed acari dannosi”). The general lines of the research were planned by C. Duso and the most relevant part of the experiments was carried out by the same author. C. Pasqualetto contributed to the experimental work especially during 1989 and 1990.     

A laboratory-based method to measure relative pesticide and spray oil efficacy against broad mite, Polyphagotarsonemus latus (Banks)(Acari: Tarsonemidae)

Six pesticides and two spray oils were tested against Polyphagotarsonemus latus. The chemicals were evaluated under laboratory conditions, requiring the development of a novel bioassay method, which is reported here. The pesticide toxicities fell into three distinct groups, namely abamectin, conventional pesticides and oils. The relative pesticide toxicities at the LC₅₀ level were abamectin 4.9×10^-8 g ai l^-1, endosulfan 1.1×10^-3 g ai l^-1, fenpyroximate 2.3×10^-3 g ai l^-1, pyridaben 4.1×10^-3 g ai l^-1, tebufenpyrad 4.4×10^-3 g ai l^-1, dicofol 4.5×10^-3 g ai l^-1, petroleum spray oil 3.4×10^-1 g ai l^-1 and canola oil 4.1×10^-1 g ai l^-1. The calculation of the LC_99.9 values allows for resistance monitoring in P. latus and the suggested discriminating concentrations are abamectin 1.0×10^-4 g ai l^-1; endosulfan, pyridaben and dicofol 1.0×10^-1 g ai l^-1 fenpyroximate and tebufenpyrad 5.0×10^-1 g ai l^-1.     

Feeding behavior of some phytoseiid predators on the broad mite,Polyphagotarsonemus latus [Acari: Phytoseiidae,Tarsonemidae]

Feeding behavior of 4 phytoseiid species on the broad mitePolyphagotarsonemus latus (Banks) was studied.Typhlodromus rickeri Chant,T. porresi McMurtry, andT. annectens DeLeon preferred prey larvae over other stages.Euseius stipulatus Athias-Henriot fed on all but the nymphal stage, and showed a decreased preference for prey larvae and females. None of the 4 species fed upon the nymphal stage.

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Résumé Le comportement alimentaire de 4 espèces dePhytoseiidae surPolyphagotarsonemus latus (Banks) a été étudié.Typhlodromus rickeri Chant,T. porresi McMurtry, etT. annectens DeLeon préfèrent les larves de la proie aux autres stades.Euseius stipulatus A.-H. s'alimente sur tous les stades de la proie sauf la nymphe, mais les larves et les femelles de la proie sont moins appréciées. Aucune des 4 espèces ne s'est alimentée aux dépens du stade nymphal.

     

Biology, thermal requirements and fertility life table of the broad mite Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) in grape (Vitis vinifera L.) cv. Italia

The mite Polyphagotarsonemus latus (Banks) constitutes one of the main pest of grape crop at the Submédio S?o Francisco Valley. The objective of this work was to study the biology of the broad mite Polyphagotarsonemus latus (Banks), to determine its thermal requirements and its fertility life table in grape (Vitis vinifera L.) cv. Italy. Acclimatized chambers (BOD) were used, adjusted to the temperatures of 18, 22, 25, 28 and 32 degrees C, relative humidity of 65 +/- 10% and alternated light of 12h. Egg-adult period was 3.4 and 6.8 days for males and 3.5 and 7.4 days for females, respectively at 32 degrees C and 18 degrees C. At the temperatures of 18, 25 and 32 degrees C, each female deposited, respectively, 16.5, 44.3 and 13.3 eggs. The stages of egg, larva and pupa and egg-adult period presented, respectively, thermal thresholds of 11.23, 9.45, 12.19, and 9.71 degrees C and thermal constant of 28.51, 14.59, 8.33, and 62.73 degrees-day. The mean duration of one generation (T) was 25.6, 10.8 and 8.2 days, respectively, at the temperatures of 18, 25 and 32 degrees C. The net reproductive rate (R0) at the temperature of 25 degrees C was the highest, corresponding to an increase of 30.12 times at each generation. The intrinsic rate of population increase (rm) was 0.10 (18 degrees C), 0.31 (25 degrees C) and 0.12 (32 degrees C) and the finite ratio of population increase (lambda) was 1.10 (18 degrees C), 1.36 (25 degrees C) and 1.13 (32 degrees C). According to the mean temperature values, P. latus can have 95 and 99 generations/year, respectively, for the municipal districts of Petrolina, PE and Juazeiro, BA.     

Host-seeking behaviour of tracheal mites (Acari: Tarsonemidae) on honey bees (Hymenoptera: Apidae)

The behaviour of the endoparasitic tracheal mite, Acarapis woodi (Rennie) on honey bees (Apis mellifera L.) is a challenge to observe because of its small size. Through a microscope, we videotaped this mite's movement on young bees, dead bees and bees exposed to vegetable oil. Previous studies have shown that solid vegetable oil decreases mite infestations in a bee colony. We hypothesized that the oil alters mite behaviour to the detriment of the parasite, thus helping to safeguard the host. Habitat-seeking behaviour, identified as necessary for mites to locate a new host environment, was disrupted on both dead and oil-treated bees. Questing behaviour, which is associated with transfer between hosts, increased significantly on the dead and oily bees. The behaviours of mites were significantly different between all three treatments (x ²=494.96, p<0.001 on dead bees and x ²=851.11, p<0.001 on oily bees). Both questing and seeking behaviours were significantly different on each of the thoracic treatments (F _2,66=7.88, p<0.001 and F _2,66=21.28, p<0.001) and mite questing behaviour was not altered between males and females on live or oily bees (F _1,22=0.25, p<0.62), but habitat seeking was (F _1,22=7.42, p<0.012). The male questing and habitat-seeking behaviours were observed. We conclude that oil-treated bees gained protection from habitat-seeking mites because the normal behaviour of the mites seeking an oviposition site is interrupted.     

Biological Control OfPolyphagotarsonemus latus (Acarina:Tarsonemidae) in greenhouses and field trials using introductions of predacious mites (Acarina:Tphytoseiidae)

Effect of prédation of 2 phytoseiid species on the broad mitePolyphagotarsonemus lotus (Banks) was studied on bean and lime plants in the greenhouse and in the field in lime.Neoseiulus californicus (McGregor) maintained mite density at low levels, whereas the effect ofNeoseiulus barken (Hughes) was erratic.N. californicus, together with a complex of indigenous predacious mites, keptP. latus density below economic damaging levels on lime fruits     

A means of determining sex in larval Tarsonemidae (Acari: Heterostigmata) based on external structure

Larval males generally differ from larval females of Tarsonemidae in having three, rather than two, pairs of small pseudanal setae flanking the uropore. This sex-linked difference in larvae correlates with a similar difference in adults: females retain only one pair of them, as setae, whereas males retain two pairs, modified into accessory copulatory structures. The possible usefulness of determining sex in larval tarsonemids is discussed. In some taxa, however, these setae are vestigial or so minute as to not be useful in sex determination.     

Russian honey bee (Hymenoptera: Apidae) colonies: Acarapis woodi (Acari: Tarsonemidae) infestations and overwintering survival

Honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies infested by parasitic mites are more prone to suffer from a variety of stresses, including cold temperature. We evaluated the overwintering ability of candidate breeder lines of Russian honey bees, most of which are resistant to both Varroa destructor Anderson & Trueman and Acarapis woodi (Rennie), during 1999-2001. Our results indicate that Russian honey bee colonies (headed by original and supersedure queens) can successfully overwinter in the north, even during adverse weather conditions, owing to their frugal use of food stores and their resistance to tracheal mite infestations. In contrast, colonies of Italian honey bees consumed more food, had more mites, and lost more adult bees than Russian honey bees, even during unusually mild winter conditions.     

Inheritance of resistance to Acarapis woodi (Acari: Tarsonemidae) in first-generation crosses of honey bees (Hymenoptera: Apidae)

The tendency of honey bees, Apis mellifera L, to become infested with tracheal mites, Acarapis woodi (Rennie), was measured in six different types of F1 colonies. The colonies were produced by mating a stock (Buckfast) known to resist mite infestation to each of five commercially available stocks and to a stock known to be susceptible to mites. Young uninfested bees from progeny and parent colonies were simultaneously exposed to mites in infested colonies, then retrieved and dissected to determine resultant mite infestations. Reduced infestations similar to but numerically greater than those of the resistant parent bees occurred in each of the six crosses made with resistant bees regardless of the relative susceptibility of the other parental stock. Reciprocal crosses between resistant and susceptible queens and drones proved equally effective in improving resistance. Therefore, allowing resistant stock queens to mate naturally with unselected drones, or nonresistant queens to mate with drones produced by pure or outcrossed resistant queens, can be used for improving resistance of production queens.     

Use of endophytes as biocontrol agents

Plant diseases, caused by various microorganisms, including viruses, bacteria, fungi, protozoa and nematodes, affect agricultural practices and result in significant crop losses. Fungal pathogens are the major cause of plant diseases and infect most plants. Agrochemicals play a significant role in plant disease management to ensure a sustainable and productive agricultural system. However, the intensive use of chemicals has adverse effects on humans and ecosystem functioning and also reduces agricultural sustainability. A sustainable agriculture is achieved through reduction or elimination of fertilizers and agrochemicals, resulting in minimal impact to the environment. Recently, the use of antagonistic endophytes as biocontrol agents is drawing special attention as an attractive option for management of some plant diseases, resulting in minimal impact to the environment. Endophytes that resides asymptomatically within a plant, have the potential to provide a source of candidate strains for potential biocontrol applications. This review addresses biocontrol methods using endophytic fungi such as Colletotrichum, Cladosporium, Fusarium, Pestalotiopsis and Trichoderma species as an attractive option for management of some plant diseases. Potential endophytes are screened in vitro and in vivo to test their antagonistic actions by different mechanisms, including mycoparasitism, production of lytic enzymes and/or antibiotics and induction of plant defenses. Currently, efforts are being made to commercialize these biocontrol agents. A continued research pipeline consisting of screening, in vitro and in vivo testing, biomass production and commercialization of endophytes as biocontrol agents may contribute to sustainable agriculture.     

New species of Daidalotarsonemus and Excelsotarsonemus (Acari,Tarsonemidae) from the Brazilian rainforest

Three new species of Tarsonemidae, Daidalotarsonemus oliveirai Rezende, Lofego & Ochoa, sp. n., Excelsotarsonemus caravelis Rezende, Lofego & Ochoa, sp. n. and Excelsotarsonemus tupi Rezende, Lofego & Ochoa, sp. n. are described and illustrated. Measurements for these species are provided, as well as drawings, phase contrast (PC), differential interference contrast (DIC) and low temperature scanning electron microscopy (LT-SEM) micrographs. Some characters, which have not been used or clearly understood, are described herein. Biological, ecological and agricultural aspects about the role of these species in the rainforest and its surrounding environment are briefly discussed.