The poultry red mite,Dermanyssus gallinae,a potential vector of Erysipelothrix rhusiopathiae causing erysipelas in hens

Erysipelas is a bacterial disease caused by Erysipelothrix rhusiopathiae, which may infect swine as well as several other species of mammals and birds, including domestic fowl. In poultry, erysipelas may cause sudden high mortality due to septicemia. This communication describes the first isolation of E. rhusiopathiae from the haematophagous poultry red mite, Dermanyssus gallinae DeGeer (Acari: Dermanyssidae), that was collected on three farms where hen erysipelas was diagnosed. The bacteria were isolated from the integument as well as from the interior of the mites. Serotypes 1a and 1b of E. rhusiopathiae found in the mites corresponded with those isolated from the diseased birds. These findings imply that D. gallinae is a potential vector of E. rhusiopathiae. The current lack of effective measures to control D. gallinae causes recurring mite problems in poultry facilities once afflicted by this parasite. Consequently, mites containing E. rhusiopathiae may act as reservoir hosts of this bacterium, allowing it to persist in the poultry house between flock cycles as a source of infection for the replacement pullets. The zoonotic potentials of both E. rhusiopathiae and D. gallinae should also be considered.     

New Record of Feather Mite,Neopteronyssus bilineatus Mironov, 2003 (Arachnida: Pteronyssidae), from a Grey-Capped Pygmy Woodpecker,Yungipicus canicapillus in Republic of Korea

This study intended to record a species of feather mite, Neopteronyssus bilineatus Mironov, 2003, (Arachnida: Pteronyssidae), from a grey-capped pygmy woodpecker, Yungipicus canicapillus (Blyth, 1845), in the Republic of Korea. Mite samples were collected from the flight feathers of a woodpecker, preserved directly in 95% ethyl alcohol, and then observed by a light microscope after specimen preparation. Morphology of Neopteronyssus bilineatus is distinguished from other pici group species by opisthosoma part with 2 longitudinal bends, tarsal seta rIII 3 times longer than tarsus III in males, and 2 elongated hysteronotal plates extending beyond the level of setae e2 in females. In the present study, a species of feather mite, N. bilineatus, was newly recorded from Y. canicapillus in Korean fauna.     

Biosynthesis of the widely distributed hydrocarbon (Z,Z)-6,9-heptadecadiene in astigmatid mites

ABSTRACT

Using a crude enzyme solution prepared from astigmatid mites, the conversion reaction to (Z,Z)-6,9-heptadecadiene (6,9-C17) using linoleyl aldehyde (LAld) as a substrate was successful. The mass spectrum of the reaction product using ¹³C-labeled LAld as a substrate could be assigned as ¹³C-labeled 6,9-C17. Unlike the findings in other species, the decarbonylase derived from mites did not require a coenzyme.     

Behavioural response of spider mites (Tetranychus urticae) to induced resistance of cotton plants

ABSTRACT.

• 1 Spider mites (Tetranychus urticae Koch) given a choice between a cotton plant previously damaged by mites and an undamaged control preferentially moved to the control plant.
• 2 This host-choice behaviour was seen in adult female mites but not in immatures.
• 3 Adult females were not found to be significantly more fecund on control plants than on previously damaged plants, but the duration of this choice experiment precluded full assessment of effects on fecundity.
• 4 Mites responded very quickly, choosing previously undamaged plants without contacting or feeding on the test plants. This suggests that an olfactory response to a chemical substance(s) is involved.

     

Intraspecific variation in a generalist herbivore accounts for differential induction and impact of host plant defences

Plants and herbivores are thought to be engaged in a coevolutionary arms race: rising frequencies of plants with anti-herbivore defences exert pressure on herbivores to resist or circumvent these defences and vice versa. Owing to its frequency-dependent character, the arms race hypothesis predicts that herbivores exhibit genetic variation for traits that determine how they deal with the defences of a given host plant phenotype. Here, we show the existence of distinct variation within a single herbivore species, the spider mite Tetranychus urticae, in traits that lead to resistance or susceptibility to jasmonate (JA)-dependent defences of a host plant but also in traits responsible for induction or repression of JA defences. We characterized three distinct lines of T. urticae that differentially induced JA-related defence genes and metabolites while feeding on tomato plants (Solanum lycopersicum). These lines were also differently affected by induced JA defences. The first line, which induced JA-dependent tomato defences, was susceptible to those defences; the second line also induced JA defences but was resistant to them; and the third, although susceptible to JA defences, repressed induction. We hypothesize that such intraspecific variation is common among herbivores living in environments with a diversity of plants that impose diverse selection pressure.     

Impact and management of the eriophyoid mite Trisetacus juniperinus on the evergreen cypress Cupressus sempervirens

Abstract 1 In the Mediterranean region, the eriophyoid mite Trisetacus juniperinus causes considerable damage to the evergreen cypress, Cupressus sempervirens L., particularly in nurseries and young stands, disturbing the apical growth of the tree. 2 The impact of mites on survival and apical growth of two commercial clones of cypress (Agrimed and Bolgheri), as well as the results of differently timed pesticide applications to suppress mite population on newly grafted trees, were evaluated. 3 Mites easily infested clonal scions from rootstocks that were previously infested in the nursery, inducing tip deformation and disturbance of the growth. Apical growth was significantly lower in infested than in control trees 2 years following the graft. 4 Deformed apical buds were left early by mites, which dispersed in the crown and may have incurred high mortality. This is interpreted as a defensive reaction of the cypress to the mite attack, which involves costs resulting in reduced apical growth in both clones. However, mites partly overcame tree defences in the Bolgheri clone. 5 Healthy rootstock and graft material should be used to limit damage and maintain plant growth because natural infestations rarely occur. In case of attack, a pesticide should be applied as soon as possible because precocious mite infestation has a log‐lasting effect on tree growth, with considerable economic damage.     

Mouthparts in Leptotrombidium larvae (Acariformes: Trombiculidae)

Mouthparts of Leptotrombidium larvae (Acariformes: Trombiculidae), potential vectors of tsutsugamushi disease agents, were studied in detail using light microscopy, scanning electron microscopy, and transmission electron microscopy. The mouthparts incorporated within the pseudotagma gnathosoma are composed of the infracapitulum ventrally and the chelicerae dorsally. The ventral wall of the infracapitulum is formed by a wide mentum posteriorly and a narrowed malapophysis anteriorly. The malapophysis firmly envelops the distal cheliceral portions by its lateral walls. The lateral lips of the malapophysis are flexible structures hiding the cheliceral blades in inactive condition and turning back forming a type of temporary sucker closely applied to the host skin during feeding. The roof of the infracapitulum is formed by a weakly sclerotized labrum anteriorly and a cervix with the capitular apodemes extending posteriorly. The labral muscles are lacking. The capitular apodemes serve as origin for pharyngeal dilators running to the dorsal wall of the pharynx fused with the bottom of the infracapitulum. The basal cheliceral segments are separated from each other besides the very posterior portions where they are movably joined by the inner walls. The sigmoid pieces serve for insertion of the cheliceral elevators originating at the posterior portions of the basal segments. The movable digits reveal the solid basal sclerite and the cheliceral blade curved upward with a tricuspid cap on its tip. Dendrites of nerve cells run along the digits to their tips. The ganglia are placed within the basal segments just behind the movable digits. The chelicerae also reveal well developed flexible fixed digits overhanging the basal portions of the blades. The gnathosoma possesses several sets of extrinsic muscles originating at the scutum and at the soft cuticle behind it. Laterally, the gnathosoma bears five‐segmented palps with a trifurcate palpal claw. J. Morphol. 277:424–444, 2016. © 2016 Wiley Periodicals, Inc.     

Influence of soil applied nitrogen (NPKS 25: 5: 5:5) on Brevipalpus phoenicis Geijskes (Acari: Tenuipalpidae) mite incidence and damage symptoms on tea

Application of nitrogenous fertilisers (NPKS 25: 5: 5:5) for yield of tea and to induce tolerance to the red crevice ( Brevipalpus phoenicis Geijskes) mite was found to be rates between 150 and 200 Kg N ha^-1 yr^-1 rates above 400 Kg N ha^-1 encouraged the build up of mites on tea. Damage symptoms resulting from mite infestation declined with increase in application of nitrogenous fertilisers.
The levels of nitrogen in the leaf tissues increased with soil applied nitrogen and also was related to the mite numbers found on the leaves suggesting a link. The symptoms of the discoloured necrotic leaf base that accompanied mite infestation was significantly ( P ≤ 0.05) and linearly correlated (r = 0.60) to mite numbers in the control plot. The levels of applied nitrogen were negatively correlated to % leaf necrosis suggesting a tolerance leading to reduction in necrotic symptoms with fertiliser applications.     

Toxicities of 26 pesticides against 10 biological control species

To determine selective effectiveness for specific pesticides on biological control species we evaluated the contact toxicity of 16 insecticides, 2 acaricides, 3 fungicides, and 5 biopesticides. Targeted species included 3 predatory mites (Phytoseiulus persimilis Athias-Henriot, Amblyseius swirskii Athias-Henriot, and Neoseiulus californicus McGregor), 5 hymenopteran parasitoids (Diglyphus isaea Walker, Aphidius colemani Viereck, Encarsia formosa Gahan, Eretmocerus eremicus Rose and Zolnerowich and E. mundus Mercet), and 2 hemipteran predators (Orius laevigatus Fieber and Nesidiocoris tenuis Reuter) in laboratory condition. In addition, residual toxicity was evaluated on P. persimilis, E. formosa, and O. laevigatus. For contact toxicity, five insecticides (spinetoram, spinosad, lepimectin, chlorfenapyr, and dinotefuran + spinetoram) showed high toxicity to predatory mites. Most pesticides tested were highly toxic to all hymenopteran species except for D. isaea which showed low susceptibility to 11 pesticides. Bistrifluron + flubendiamide and B. valismortis were less toxic to A. colemani, and only B. valismortis was safe to both E. mundus and E. eremicus. Insect growth regulators (methoxyfenozide and bistrifluron), chlorantraniliprole, and bistrifuron + flubendiamide were not toxic to hemipteran predators. Fungicides and biopesticides were safe to hemipteran predators except for two biopesticides (B. subtilis and P. fluorescens). Most pesticides had low residual toxicity to P. persimilis, with the exception of chlorfenapyr whose toxicity persisted over 7 days. One insecticide (cyantraniliprole), 2 acaricides (spiromesifen and fenpyroximate), 1 fungicide (metrafenone), and 4 biopesticides (B. subtilis, P. polymyxa, P. fluorescens, and B. valismortis) showed a much lower residual toxicity to E. formosa. Eight insecticides, 2 acaricides, 3 fungicides, and 5 biopesticides showed low residual toxicity to O. laevigatus.     

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.