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.     

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.     

Potential of fungi as biocontrol agents of polyphagotarsonemus latus (Acari: Tarsonemidae)

Infection of broad mites, Polyphagotarsonemus latus, by conidia of Beauveria bassiana, Hirsutella thompsonii, and Paecilomyces fumosoroseus conidia was investigated in the laboratory under controlled temperature and moisture conditions. Infection of P. latus by the fungus (LC₅₀) was related positively to the 1.16 × 10⁶ B. bassiana conidia per ml, 2.39 × 10³ H. thompsonii conidia per ml, and 1.29 × 10⁵ P. fumosoroseus conidia per ml. Mortality caused by B. bassiana occurred the fastest among densities fluctuating between 65 and 125 mites per leaf. The pathogens B. bassiana and P. fumosoroseus, adjuvants (oil and molasses), and the acaricide ABG6364, a microbial insecticide containing the Beta-exotoxin of Bacillus thuringiensis were evaluated for efficacy against P. latus in a greenhouse test. The B. bassiana treated plants had the greatest and most persistent effect on percentage mortality of total broad mites present per leaf (88 %) followed by the acaricide ABG6364. Use of adjuvants (oil and molasses) did not increase infection of P. latus.     

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.     

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.     

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.     

Biology, ecology and control of the Penthaleus species complex (Acari: Penthaleidae)

Blue oat mites, Penthaleus spp. (Acari: Penthaleidae), are major agricultural pests in southern Australia and other parts of the world, attacking various pasture, vegetable and crop plants. Management of these mites has been complicated by the recent discovery of three cryptic pest species of Penthaleus, whereas prior research had assumed a single species. The taxonomy, population genetics, ecology, biology and control of the Penthaleus spp. complex are reviewed. Adult Penthaleus have a dark blue-black body approximately 1 mm in length, and eight red-orange legs. Within Australia, they are winter pests completing two or three generations a season, depending on conditions. The summer is passed as diapausing eggs, when long-distance dispersal is thought to occur. The Penthaleus spp. reproduce by thelytokous parthenogenesis, with populations comprising clones that differ ecologically. The three pest Penthaleus spp. differ markedly in their distributions, plant hosts, timing of diapause egg production and response to pesticides, highlighting the need to develop control strategies that consider each species separately. Chemicals are the main weapons used in current control programs, however research continues into alternative more sustainable management options. Host plant resistance, crop rotations, conservation of natural enemies, and improved timing of pesticide application would improve the management of these pests. The most cost-effective and environmentally acceptable means of control will result from the integration of these practices combined with the development of a simple field-based kit to distinguish the different mite species.     

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.     

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.     

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.     

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.     

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...     

Field evaluation of neem and canola oil for the selective control of the honey bee (Hymenoptera: Apidae) mite parasites Varroa jacobsoni (Acari: Varroidae) and Acarapis woodi (Acari: Tarsonemidae)

Neem oil, neem extract (neem-aza), and canola oil were evaluated for the management of the honey bee mite parasites Varroa jacobsoni (Oudemans) and Acarapis woodi (Rennie) in field experiments. Spraying neem oil on bees was more effective at controlling V. jacobsoni than feeding oil in a sucrose-based matrix (patty), feeding neem-aza in syrup, or spraying canola oil. Neem oil sprays also protected susceptible bees from A. woodi infestation. Only neem oil provided V. jacobsoni control comparable to the known varroacide formic acid, but it was not as effective as the synthetic product Apistan (tau-fluvalinate). Neem oil was effective only when sprayed six times at 4-d intervals and not when applied three times at 8-d intervals. Neem oil spray treatments had no effect on adult honey bee populations, but treatments reduced the amount of sealed brood in colonies by 50% and caused queen loss at higher doses. Taken together, the results suggest that neem and canola oil show some promise for managing honey bee parasitic mites, but the negative effects of treatments to colonies and the lower efficacy against V. jacobsoni compared with synthetic acaricides may limit their usefulness to beekeepers.     

Molecular phylogenetics of a South Pacific sap beetle species complex (Carpophilus spp., Coleoptera: Nitidulidae)

Several species of sap beetles in the genus Carpophilus are minor pests of fresh produce and stored products, and are frequently intercepted in biosecurity operations. In the South Pacific region, the superficially similar species C. maculatus and C. oculatus are frequently encountered in these situations. Three subspecies of C. oculatus have been described, and the complex of these four taxa has led to inaccurate identification and questions regarding the validity of these taxa. A molecular phylogenetic study using the mitochondrial gene cytochrome c oxidase I (COI) and two nuclear markers comprising the rDNA internal transcribed spacer 2 (ITS2) and the D1-D2 region of the large (28S) ribosomal RNA subunit showed that C. maculatus, and C. o. cheesmani were easily differentiated from the two other subspecies of C. oculatus. COI also showed differentiation between C. o. gilloglyi and C. o. oculatus, but this was not shown when third codon positions were removed and when RY-coding analyses were conducted. Generalised mixed Yule-Coalescent (GMYC) models were fitted to trees estimated from the COI data and were analysed using a multimodel approach to consider the evidence for three taxonomic groupings of the C. oculatus group. While the arrangement with the highest cumulative weight was not the arrangement ultimately accepted, the accepted taxonomy also had an acceptable level of support. ITS2 showed structure within C. oculatus, however C. o. oculatus was resolved as paraphyletic with respect to C. o. gilloglyi. COI showed evidence of sequence saturation and did not adequately resolve higher relationships between species represented in the dataset. 28S resolved higher relationships, but did not perform well at the species level. This study supports the validity of C. maculatus as a separate species, and provides sufficient evidence to raise C. o. cheesmani to the level of species. This study also shows significant structure within and between C. o. gilloglyi and C. o. oculatus, giving an indication of recent speciation events occurring. To highlight the interesting biology between these two taxa, C. o. gilloglyi is retained as a subspecies of C. oculatus. These results give clarity regarding the taxonomic status of C. maculatus and the subspecies of C. oculatus and provide a platform for future systematic research on Carpophilus.