Biological studies of Oligonychus punicae (Acari: Tetranychidae) on grapevine cultivars

Life cycle, fecundity and longevity of the avocado brown mite, Oligonychus punicae (Hirst), were studied on six grapevine cultivars (Tucupita, Villanueva, Red Globe, Sirah, Sauvignon and Chenin Blanc), under laboratory conditions at 27 +/- 2 degrees C, 80 +/- 10% RH, and L12:D12 photoperiod. Mite-infested leaves were collected from vineyards, placed in paper bags and taken to the laboratory. A laboratory mite culture was established using the grape cultivar Criolla Negra as host plant. To elucidate potential effects on avocado brown mite parameters, we assessed levels of secondary metabolites, such as alkaloids, flavonoids, tannins and polyphenols, of leaves of the six grape cultivars, as well as the thickness of the adaxial cuticle-epidermis. The life cycle of O. punicae differed among cultivars with average values ranging between 8.2 days on Tucupita leaves and 9.1 days on Sirah. Relatively high fecundity was found on Tucupita leaves (2.8 eggs/female/day) during 11.4 oviposition days, while low fecundity values occurred on Sirah and Villanueva leaves, with 0.9 and 1.8 eggs/female/day during 7.9 and 6.7 days, respectively. Average longevity of O. punicae females ranged from 8.1 to 17.5 days on Sirah and Sauvignon leaves, respectively. Intrinsic rate of increase (r (m)) was highest on Sauvignon (0.292) and Tucupita (0.261), and lowest on Sirah (0.146) and Villanueva (0.135). Although significant differences in cuticle-epidermis thickness were detected among the six cultivars, it seemed not to affect mite parameters. Secondary metabolite content also varied between the cultivars. Generally, increasing flavonoid content coincided with decreasing reproductive parameters. The natural plant resistance observed in this study could be useful in the development of an integrated pest management program for mite pests in grape production.     

Temperature-dependent life history of Oligonychus mangiferus (Acari: Tetranychidae) on Mangifera indica

The mango red spider mite, Oligonychus mangiferus (Rhaman and Sapra), is a major mango pest in Taiwan. This mite damages the leaves of the mango tree and affects the quality of the fruit. This study investigates the life history of the mango red spider mite on Mangifera indica L. cv. Irwin at five constant temperatures (17, 21, 25, 29, and 33 °C), under 80 ± 5 % RH and L12:D12 photoperiod conditions. An increase in temperature significantly decreased the developmental times for each stage and the overall immature period in females and males. The lower developmental thresholds of the immature stage were 12.5 and 12.4 °C for females and males, respectively. The thermal summations for the development of the immature stage were 185.9 and 175.7 degree-days for females and males, respectively. Based on the annual field temperature, an estimated 26 generations can reproduce in a mango orchard annually. The longevity of adults of both sexes decreased as temperature increased, and adult males lived longer than females. The preoviposition periods were shorter than 1 day when the temperature exceeded 25 °C. The development period and the oviposition period were shortest at 29 °C. At this point, daily fecundity was highest, and fecundity was second highest, resulting in the highest intrinsic rate of increase (r _m ), 0.182 day^?1. These life history traits are applied to improve the management of O. mangiferus.     

Presence-absence sequential sampling plan for northern fowl mite, Ornithonyssus sylviarum (Acari: Macronyssidae), on caged-layer hens

Caged-layer hens were scored as infested or uninfested by visual examination of the vent region, and the number of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago), per hen was estimated. The proportion infested and average number of mites per hen were shown to have a highly significant, positive relationship (r = 0.936). Sampling among houses within a flock, and rows and sections within houses were analyzed to determine the reliability of sampling a representative portion of a flock. Low- and moderate-tolerance treatment thresholds, based on percentage of hens infested with mites, were developed from sampling 1 wk before and 1 wk after acaricide treatments determined necessary by the producer. These thresholds were used to compare a fixed (single) sampling plan, a curtailed procedure of the fixed sampling plan, and a sequential sampling plan based on a sequential probability ratio test, by sampling 174 hens (the maximum number needed for the single sampling plan). The sequential sampling plan required fewer hen examinations on average to reach a treatment decision than did the other plans, depending on the infestation tolerance limits. Using a low tolerance approach in which infestations below 15% are considered noneconomic (safe threshold) and infestations above 25% are considered economically important (action threshold), as few as 5 hens required examination to reach a treatment decision. Sequential sampling plan graphs are presented for 2 tolerance threshold scenarios (a 15% safe-threshold paired with a 25% action threshold and a 35% safe-threshold paired with a 45% action threshold). These sequential sampling plans using presence absence assessments should greatly facilitate monitoring and treatment decisions for this important pest.     

Life table and predation of Neoseiulus longispinosus (Acari: Phytoseiidae) on Oligonychus coffeae (Acari: Tetranychidae) infesting tea

Life table and predation of the predatory mite Neoseiulus longispinosus (Evans) on the red spider mite (RSM), Oligonychus coffeae (Nietner), a major pest of tea in India, were studied in the laboratory. Developmental time from egg to adult varied from 4 to 14 days at 30 to 15 °C, respectively; at 35 °C no larva survived. Survival of immature stages was more than 94 % at all temperatures. Threshold temperature for development of immature stages of females and males was 10 and 9.9 °C, respectively, and thermal constant was 84.03 degree-days for females and 80 for males. Sex ratio was female biased and temperature (20–30 °C) had no clear effect on sex determination. Egg hatchability was 73 % at 35 °C and >97 % at lower temperatures. Average number of eggs laid per female/day was higher at 30 °C than at 20 or 25 °C. The highest net reproductive rate (R ₀) was 40.7, at 20 °C. Mean generation time (T) decreased from 28 to 13 days with temperature increasing from 20 to 30 °C. Weekly multiplication (6.5) and intrinsic rate of natural increase (r _m ) (0.268) were highest at 30 °C. Males lived longer than females at every temperature tested. Longevity was highest at 20 °C (50 days for females and 55 for males). Survival and longevity were adversely affected by temperature above 30 °C. Daily consumption of prey increased with the advancement of predator’s life stages; adult females consumed the highest numbers of prey items, preferably larvae and nymphs.     

Predatory behaviors of Neoseiulus californicus and Galendromus helveolus (Acari: Phytoseiidae) attacking Oligonychus perseae (Acari: Tetranychidae)

Predatory behaviors of Neoseiulus californicus (McGregor) and Galendromus helveolus (Chant) attacking Oligonychus perseae Tuttle, Baker and Abbatiello on avocado leaves were videotaped and analyzed. Behaviors were recorded for “fresh” predators that were used ≤ 48 hr post receipt from a commercial insectary and “cold stored” predators that were maintained at 12°C for ≈ 14 days. Fresh and cold stored G. helveolus were observed to attack O. perseae only after invading webbed nests. Conversely, fresh and cold stored N. californicus employed three different modes of predatory attack: (1) intercepting and attacking migrant O. perseae outside of web nests; (2) attacking prey through nest webbing; or (3) invading and attacking O. perseae inside nests. Predatory efficacy of both N. californicus and G. helveolus was reduced following cold storage, as both species engaged in certain predatory behaviors less frequently in comparison to predators that were not stored at low temperatures. Our observed results for N. californicus and G. helveolus attacking O. perseae are interpreted in relation to the chaetotaxy hypothesis, which proposes that phytoseiid invasion efficiency and propensity of webbed nests is facilitated by dorsal setal lengths. This revised version was published online in July 2006 with corrections to the Cover Date.     

Within-plant distribution of twospotted spider mites (Acari: Tetranychidae) on impatiens: development of a presence-absence sampling plan

The twospotted spider mite, Tetranychus urticae Koch, is an important pest of impatiens, a floricultural crop of increasing economic importance in the United States. The large amount of foliage on individual impatiens plants, the small size of mites, and their ability to quickly build high populations make a reliable sampling method essential when developing a pest management program. In our study, we were particularly interested in using spider mite counts as a basis for releasing biological control agents. The within-plant distribution of mites was established in greenhouse experiments and these data were used to identify the sampling unit. Leaves were divided into three zones according to location on the plant: inner, intermediate, and other. On average, 40, 33, and 27% of the leaves belonged to the inner, intermediate, and other leaf zones, respectively. However, because 60% of the mites consistently were found on the intermediate leaves, intermediate leaves were chosen as the sampling unit. These results lead to the development of a presence-absence sampling method for T. urticae by using Taylor coefficients generic for this pest. The accuracy of this method was verified against an independent data set. By determining numerical or binomial sample sizes for consistently estimating twospotted spider mite populations, growers will now be able to determine the number of predatory mites that should be released to control twospotted spider mites on impatiens.     

比哈小爪螨实验种群生命表的研究

本文研究了比哈小爪螨5个温度梯度的实验种群生命表.结果表明15 ℃时内禀增长率和周限增长率均最小,分别为0.0235和1.0238,种群倍增时间最长(29.47 d);35 ℃时内禀增长率和周限增长率均最大,分别为0.3069和0.3592,种群倍增时间最短(2.26 d),说明高温有利于该螨种群的增长.25 ℃时净增殖率最大(56.30).35 ℃的世代生长周期最短(11.97 d).15 ℃时其寿命最长(98.90±20.77 d),35 ℃时寿命最短(19.00±3.11 d).最高平均产卵量71.60粒/雌和最高日平均产卵量4.10粒/雌/天均在25 ℃时出现.15 ℃时平均产卵量最低(8.80粒/雌),日平均产卵量仅有0.34粒/雌/天.最大日产卵量出现在35 ℃时(12.00粒/雌/天).     

Damage on 'Hass' avocado leaves, webbing and nesting behaviour of Oligonychus perseae (Acari: Tetranychidae)

The damage of Oligonychus perseae Tuttle, Baker and Abbatiello on 'Hass' avocado trees occurs mainly on the underside of the leaves along the midrib, main veins and leaf depressions. The lower epidermal, spongy parenchyma and palisade parenchyma cells of the leaf tissues are destroyed. Large necrotic areas on the underside of the leaves result from feeding when high population levels occur. Feeding and reproduction takes place in 'nests' of silken webbing, which also provide protection from some predator mites and other natural enemies. Oligonychus perseae shows a modification of the earlier defined life-type web nest (WN-c). The greatest number of nests built by a female was 12.17 at 20°C and the greatest number of eggs per female per nest was 5.20 at 25°C.     

Approaches for sampling the twospotted spider mite (Acari: Tetranychidae) on clementines in Spain

Tetranychus urticae Koch (Acari: Tetranychidae) is an important pest of clementine mandarins, Citrus reticulata Blanco, in Spain. As a first step toward the development of an integrated crop management program for clementines, dispersion patterns of T. urticae females were determined for different types of leaves and fruit. The study was carried out between 2001 and 2003 in different commercial clementine orchards in the provinces of Castelló and Tarragona (northeastern Spain). We found that symptomatic leaves (those exhibiting typical chlorotic spots) harbored 57.1% of the total mite counts. Furthermore, these leaves were representative of mite dynamics on other leaf types. Therefore, symptomatic leaves were selected as a sampling unit. Dispersion patterns generated by Taylor's power law demonstrated the occurrence of aggregated patterns of spatial distribution (b > 1.21) on both leaves and fruit. Based on these results, the incidence (proportion of infested samples) and mean density relationship were developed. We found that optimal binomial sample sizes for estimating low populations of T. urticae on leaves (up to 0.2 female per leaf) were very large. Therefore, enumerative sampling would be more reliable within this range of T. urticae densities. However, binomial sampling was the only valid method for estimating mite density on fruit.     

The process of population increase and patterns of resource utilization of two spider mites,Oligonychus ununguis (Jacobi) andPanonychus citri (McGregor), under experimental conditions (Acari: Tetranychidae)

Summary Pattern of population growth and characteristics of habitat utilization and of migration by two species of spider mites were studied under experimental conditions. The population growth ofOligonychus ununguis (Jacobi) on a chestnut occurred only on a single mite-release leaf over a long period, and few individuals moved away. Most of the 2nd progeny generation females of this species emigrated from the mite-release leaf as well as the sapling by means of ballooning threads. During this growth period, population density on the mite-release leaf levelled off, whereas that on the sapling increased. In contrast, the foundress ofPanonychus citri (McGregor) on citrus actively moved over several neighbouring leaves, and until the 2nd progeny generation females emerged, individuals were distributed over all the sapling leaves by means of walking. Emigration from the sapling was not observed until the 2nd progeny females emerged, and after that the mites emigrated by means of ballooning threads. The population density ofP. citri on the sapling levelled off and was rather decreased on the mite-release leaf at the time of mite emigration. Comparing the changing pattern of the relative degree of aggregation (m ^*/m) measured in two different units between these two species, the pattern ofm ^*/m in 1 cm² on the mite release leaf inO. ununguis resembled that of the unit of leaves on the sapling inP. citri. This result as well as behavioural observations indicate that migration ofO. ununguis is the movement from leaf to leaf and that ofP. citri from sapling to sapling. It is, therefore, concluded that the boundary of the microhabitat is a single leaf forO. ununguis but sapling or foliage forP. citri. This work was presented in Annual Meeting of Jap. Soc. Appl. Ent. Zool., 1981 in Okayama.     

Spider mites of sugarcane in Australia: a review of grass-feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae)

Abstract In many areas of the world, spider mites are significant pests of sugarcane. Australia is currently fortunate in lacking the most destructive species, and usually suffers only sporadic damage. Herein, we provide a key to the genera of spider mites associated with sugarcane, review the most significant genus, Oligonychus Berlese, and provide a key to the species of grass-feeding Oligonychus in the Australasian region. The species O. araneum Davis, O. digitatus Davis, O. grypus Baker and Pritchard, O. orthius Rimando, and O. oryzae (Hirst) are redescribed, while the Australian O. zanclopes sp. n. Beard and Walter from sugarcane and rice, O. turbelli sp. n. Beard and Walter, O. ephamnus sp. n. Beard and Walter and O. festucolus sp. n. Beard and Walter from other grasses, are newly described. Previous records of O. grypus in Australia appear to be misidentifications of what is described here as the new species O. zanclopes .     

Factors affecting location of Banks grass mite,Oligonychus pratensis (Acari: Tetranychidae), on corn leaves

The site on which adult female Banks grass mite,Oligonychus pratensis (Banks), settled when placed on corn (Zea mays L.) leaves was significantly influenced by light, leaf surface, and gravity. Mites chose the abaxial side of corn leaves when light was excluded as a factor. With a light source present, the mites went to and stayed on the leaf surface away from light. In the absence of light and leaf-surface influences, gravity showed significant effect on the choice of the under site of corn leaves by the mites; this effect also existed with light present, and acted in concert with normal light conditions (i.e., light from above). Results suggest that both heat and ultraviolet light may be responsible for the observed light effect.     

Notes on the Occurrence of <Emphasis Type="Italic">Oligonychus milleri</Emphasis> (McGregor) and <Emphasis Type="Italic">Oligonychus ununguis</Emphasis> (Jacobi) (Acari: Tetranychidae) in Brazil

We verified infestation of Oligonychus milleri (McGregor) on plantations of Pinus caribaea (Pinaceae) and of Oligonychus ununguis (Jacobi) on plantations of Eucalyptus urophylla x Eucalyptus grandis (Myrtaceae) in State of Rondônia, Northern region of Brazil. This represents the first record of O. milleri in Brazil. Oligonychus ununguis was recorded previously, on cypress. The damage caused by these two spider mites in the plantations is described herein.     

Population dynamics of the citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae) in Japanese pear orchards

In spring a population of the citrus red mite (Panonychus citri),a non-diapausing species, migrated to a Japanese pear orchard, mainly from nearby Japanese holly trees, but in autumn most of the mites starved to death while the rest returned to the holly trees. In the Japanese holly trees, the population of mites reached their maximum density in late May1993 and in mid-June 1994 on overwintered leaves and moved to newly opened leaves in mid-June 1993 and late June 1994. The mites tended to disperse abruptly in early June or mid-June and again towards the end of June. The mites inhabiting the holly trees appeared to migrate to the Japanese pear trees in June but their densities on pear leaves remained low until mid-August. In the pear orchard, the mites initially tended to increase on pear leaves near the holly trees and then gradually spread to other leaves farther away from the holly trees. Their highest density in the pear orchard occurred in mid-October. When pear leaves were inoculated with two or five female adults at different times from May to September, the leaves inoculated before mid-August showed no increase in the number of mites. A possible cause for the suppression of the population increase on pear leaves from June to mid-August is discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

柑橘全爪螨种群空间格局的地学统计学分析

应用地学统计学方法分析了柑橘园主要害螨柑橘全爪螨Panonychus citri（McGregor）种群的空间格局及其动态。结果表明,柑橘全爪螨种群具有空间相关性,变程介于1．10～21．0m,其半变异函数主要符合高斯模型,表现为聚集分布,其中3月、8月和9月的聚集强度较大;种群空间格局动态显示,4月、10月为该种群的两个发生高峰期,柑橘全爪螨种群数量快速上升扩散。地学统计学方法能够应用于柑橘全爪螨种群的空间格局分析,并有助于对该害螨进行发生预测与控制处理。     

Beat sampling accuracy in estimating spruce spider mite (Acari: Tetranychidae) populations and injury on juniper

The use of a standardized beat sampling method for estimating spruce spider mite, Oligonychus ununguis (Jacobi) (Acari: Tetranychidae), densities on a widely used evergreen ornamental plant species, Juniperus chinensis variety 'Sargentii' A. Henry (Cupressaceae), was examined. There was a significant positive relationship between total spruce spider mite densities and spider mite densities from beat sampling on juniper. The slope and intercept of the relationship may be used by pest managers to predict total spider mite densities on plants from beat sample counts. Beat sampling dramatically underestimates the total number of spider mites on a foliage sample. The relationships between spruce spider mite feeding injury and spider mite density estimates from beat sampling juniper foliage and total spider mite counts on foliage were also examined. There was a significant positive relationship between spruce spider mite density as estimated from beat sampling and injury to the plants. There was a similar positive relationship between the total number of spruce spider mites and injury to the plants, suggesting that a pest manager could use beat sampling counts to estimate plant injury and related thresholds. These findings have important implications to decision-making for spruce spider mite control, especially as it relates to threshold levels and determining rates of predator releases. Further assessment of the effectiveness of beat and other sampling methods across multiple spider mite- host plant associations needs to be examined to enable pest managers to select sampling plans that are feasible and reliable.     

Functional response ofAllothrombium pulvinum deutonymphs (Acari: Trombidiidae) on two-spotted spider mites (Acari: Tetranychidae)

Functional responses of deutonymphs of the predatory mite,Allothrombium pulvinum Ewing, on eggs and adult females of two-spotted spider mite,Tetranychus urticae Koch, were determined in the laboratory. Predation experiments were conducted on lima bean leaf discs over a 24-h period at 25±2°C, 30–50% RH and 24L: 0D photoperiod. Prey densities ranged from 10 to 120T. urticae eggs per disc or 2 to 32 adult females per disc.Allothrombium pulvinum deutonymphs were more effective againstT. urticae eggs than its adult females. The role ofA. pulvinum deutonymphs in integrated and biological pest control is discussed.