Predation of Galendromus helveolus (Acari: Phytoseiidae) on Brevipalpus californicus (Acari: Tenuipalpidae)

The false spider mite, Brevipalpus californicus (Banks), is a major citrus pest in Texas. This phytophagous mite causes damage to fruit, leaves and stems of citrus, and is also a vector of citrus leprosis virus. Galendromus helveolus (Chant) is one of the most prevalent predacious mite species found on Texas citrus. The predation potential of G. helveolus on different stages of B. californicus was evaluated in the laboratory. An individual immature G. helveolus mite consumed an average of 30.7 eggs, 53.6 larvae, or 22.7 nymphs of B. californicus before developing to an adult. An individual adult female G. helveolus consumed an average of 164.8 eggs, 369.6 larvae, or 80.9 nymphs of B. californicus. Both immature and adult G. helveolus never fed on adult stage of B. californicus and never completed development. The development times of the immature stages of G. helveolus were 4.5, 4.1 and 4.6 days when fed on eggs, larvae and nymphs of B. californicus, respectively. When G. helveolus fed on the larval stage of B. californicus, the adults had the longest longevity (18.5 days) and the highest fecundity (14.0 eggs/female).     

芬兰真绥螨对苹果全爪螨的捕食作用研究

在实验条件下,系统研究了芬兰真绥螨Euseius finlandicus Oudemans对苹果全爪螨Panony-chus ulmi Koch的控制能力。研究结果表明:(1)在15～32℃的温度条件下,芬兰真绥螨雌成螨的捕食量随着温度的上升呈线型正相关。在15～25℃的温度内芬兰真绥螨的产卵量随温度升高而增加,在15℃下平均单雌产卵0.42粒,25℃时平均单雌产卵2.56粒;当温度升到32℃时单雌产卵下降为1.62粒,雌成螨的产卵量与温度的关系呈抛物线型。(2)在5～15头/叶的猎物密度下,雌成螨的捕食量随着猎物的密度增加呈线型正相关,而当猎物密度达到30头/叶时,芬兰真绥螨雌成螨的捕食量处于平稳状态。在5～15头/叶的猎物密度下,芬兰真绥螨的产卵量和产卵量均与猎物的密度呈线型正相关;当每头雌成螨捕食量为1.8～3.5头时,产卵量为1.0～1.5粒。(3)不同温度下,芬兰真绥螨对猎物的不同密度和虫态的功能反应可用圆盘方程II型进行拟合;在25℃条件下捕食效率最高且喜好捕食的虫态是卵和幼螨。     

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.     

Testing prey DNA fingerprinting on Amblyseius largoensis (Acari: Phytoseiidae) predation of Raoiella indica (Acari: Tenuipalpidae)

Molecular detection of predation by identifying prey markers in the digestive tract of predators has developed into a powerful tool to assess predator-prey systems in which diet identification is too time consuming or impossible. Here we explore its utility for detecting predation of the pest mite Raoiella indica Hirst by the predatory mite Amblyseius largoensis Muma, taking advantage of the color the predator acquires after eating this mite to cross-reference our results. For this, a ~410?bp segment of the cytochrome c oxidase subunit I (COI) mitochondrial gene marker specific for the subfamily Tetranychoidea was used. Amblyseius largoensis that had recently eaten were collected from greenhouse colonies containing both mites, and isolated from any other food source. Predator mites were taken for fingerprinting at 24, 48, 72 and 96?h of starving after collection, and the same process was repeated a second time, offering pollen as an alternative food source to see whether detection changed. Lastly, a sampling trial was conducted in the greenhouse, in which mites were collected regardless of their color and frozen immediately for fingerprinting. Raoiella indica DNA was detected for 48 h on starving predators, and for 96 h on those who had eaten pollen. The segment was detected in 26?% of the samples collected on the trial. This technique needs refinement specific for this system, but the results obtained here confirm that it could turn into a very useful tool for assessing aspects of this predator-prey system.     

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leaves

Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (‘Maehyang’ and ‘Sulhyang’ varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least‐squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non‐glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970 h) against T. urticae nymphs. The attack rate did not change much at 15–30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15–35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511 h).     

土耳其斯坦叶螨对胡瓜钝绥螨的吸引反应

土耳其斯坦叶螨（Tetranychus turkestani Ugarov ＆ Nikolski）对胡瓜钝绥螨（Amblyseius cucumeris Oudemans）的吸引测试表明,胡瓜钝绥螨对不同螨态的土耳其斯坦叶螨的刺激均能产生显著的吸引反应。胡瓜钝绥螨能捕食土耳其斯坦叶螨的卵,但对土耳其斯坦叶螨的“卵＋丝网＋粪便＋取食斑”没有明显的反应,土耳其斯坦叶螨的若螨I和幼螨是胡瓜钝绥螨最喜欢的猎物。土耳其斯坦叶螨主要通过活动螨对胡瓜钝绥螨产生吸引反应,这种吸引反应能明显提高胡瓜钝绥螨在田间搜索土耳其斯坦叶螨的能力。     

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.     

Biological parameters of the predatory mite Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae)

Developmental periods of egg, larva and nymphal stages and fecundity as well as predation of Cheletomimus bakeri (Acari: Cheyletidae) feeding on Tetranychus cinnabarinus (Acari: Tetranychidae) were evaluated at different temperatures (15, 20, 25, 30 and 35°C) at 65 ± 10% relative humidity and 16 L: 8D in the laboratory. The development periods of C. bakeri from egg through adult decreased significantly when the temperature was increased from 20°C to 35°C. Egg and total development periods of C. bakeri at 20, 25, 30 and 35°C were 13.86, 7.98, 5.07, 4.08 days and 58.66, 41.51, 21.21, 22.92 days, respectively. The highest numbers of total and daily egg production were found at 20°C and 30°C, respectively. Net reproductive rate (R₀ = 13.29), mean generation time (T = 88.30), gross reproductive rate (GRR = 17.46) and doubling time (DT = 23.66) were the highest at 20°C. The intrinsic rate of increase (r_m = 0.0592) and finite capacity for increase (λ = 1.061) for C. bakeri were the highest at 30°C. Predation of C. bakeri increased throughout the range of prey densities. The highest consumption number of C. bakeri feeding on T. cinnabarinus males per day was 4.63, 4.70 and 4.60 when confined to 40, 80 and 160 individuals, respectively. Our data suggest that C. bakeri does not appear to have much promise for the control of spider mites because of the characteristics of the predator such as slow development period, poor searching capacity and low intrinsic rate of increase.     

Prey preference of predatory mite Amblyseius swirskii (Acari: Phytoseiidae) on Tetranychus urticae (Acari: Tetranychidae) and Bemisia tabaci (Hemiptera: Aleyrodidae)

Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) are major pests in greenhouse crops. Recently, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was shown to be an effective biological control agent of both pests. Therefore, the prey preference of A. swirskii was determined using immature stages of T. urticae and B. tabaci in three various treatments based on Manly's β preference index (β). These treatments consisted of immature stages of two prey species (egg, first and second instar nymphs) with densities 12:12, 6:6 and 3:3, respectively, and with 13 replicates. After 24?h starvation, same-aged females of A. swirskii were added to the leaf discs. All experiments were done on bean leaf discs in Petri dishes (8?cm in diameter) in laboratory conditions with 25?±?2°C, 70?±?5% relative humidity and the photoperiod of 16L:8D hours. Comparing the preference indices using t-tests indicates a significant preference of the predator on eggs (t?=?10.80, df?=?24, P?t?=?8.17, df?=?24, P?T. urticae than B. tabaci. Our findings suggest that developmental stages of prey have effect on the prey selection by A. swirskii.     

Cytogenetics of ticks (Acari: Ixodoidea)

Chromosomes and sex determination of 9 species of Haemaphysalis assigned to 4 subgenera are described. H. (tAlloceraea) kitaokai possesses an XX∶XO sex chromosome system with 18 autosomes plus XX in females; 18 plus X in males. H. (Kaiseriana) hystricis has 18 +XX and 18 + XY in females and males, respectively, in most specimens, but a supernumerary chromosome is present in some individuals. A supernumerary chromosome was also observed in 1 male H. (Aborphysalis) formosensis. These two species are the second and third species of ticks reported to have supernumerary chromosomes. H. formosensis, H. (Kaiseriana) bispinosa, H. (Haemaphysalis) campanulata, H. (H.) flava, H. (H.) megaspinosa, H. (H.) japonica, and H. (H.) pentalagi possess 20 autosomes plus 2 sex chromosomes in females and 20+1 sex chromosomes in males. Phylogenetic relationships within the genus Haemaphysalis are briefly discussed.     

Cytogenetics of ticks (Acari: Ixodoidea)

Haemaphysalis longicornis consists of diploid bisexual races (20+ XX; 20+X), triploid obligatory parthenogenetic races (30–35 chromosomes) and an aneuploid race capable of bisexual and parthenogenetic reproduction (22–28 chromosomes). Karyotypes were analyzed for each race. Hybridization failed between diploid and triploid races, but succeeded between bisexual diploid males and parthenogenetic aneuploid females. F₁ and F₂ progeny were produced and their chromosomes studied. Crossing of F₁ progeny to a bisexual race was successful. Parthenogenetic ability was almost completely lost in F₁ and F₂ females. Several possible modes of evolution from diploid bisexual individuals to triploid parthenogenetic ones are discussed as is species characterization in taxa with races reproducing bisexually, parthenogenetically and by a combination of both methods.Supported in part by National Science Foundation Research Grant GB-21008, National Institute of Allergy and Infectious Diseases (NIH) Grant 09556 and the United States Army Medical Research and Development Command, Office of The Surgeon General, Department of the Army, Washington, D. C. 20315, U.S.A.     

Cytogenetics of ticks (Acari: Ixodoidea)

Summary Prior to this paper there have been no reports of a multiple sex chromosome mechanism operative in any tick. The present paper deals with two species of Ixodidae, Amblyomma moreliae and Amblyomma limbatum that exhibit an X₁X₁X₂X₂:X₁X₂Y type of sex chromosome mechanism. Cells from males of both species show nine bivalents plus one sex trivalent. Eleven bivalents were observed in one female A. moreliae. The sex trivalent probably evolved through reciprocal translocation from a system that included ten autosomal bivalents and one sex univalent (the system found in most ixodid species). As a result of the translocation, there are now two X chromosomes (X₁ and X₂) segregating from an unaltered autosome, the neo-Y. A large X chromosome is characteristic of many ticks; in this instance the reciprocal translocation did not change appreciably its relative size.The opinions and assertions contained herein are the private ones of the author and are not to be construed as official or reflecting the views of the Navy Department or the Naval service at large.This study was begun during the tenure of a North Alantic Treaty Organization (National Science Foundation) Postdoctoral Fellowship.     

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.     

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on pollen or mite diets and predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28 degrees +/- 1 degrees C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 +/- 0.47 and 3.5 +/- 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.     

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.     

Toxicity of plant essential oils to Tetranychus urticae (Acari: Tetranychidae) and Phytoseiulus persimilis (Acari: Phytoseiidae)

Fifty-three plant essential oils were tested for their toxicity against eggs and adults of Tetranychus urticae Koch as well as adults of Phytoseiulus persimilis Athias-Henriot, by using a filter paper diffusion bioassay without allowing direct contact. Responses varied according to oil type and dose, and mite species. In a plastic container (4.5 by 9.5 cm) bioassay at 14 x 10(-3) microl/ml air, caraway seed, citronella java, lemon eucalyptus, pennyroyal, and peppermint oils gave > 90% mortality against adult T. urticae, whereas 82 and 81% mortality was observed with sage and spearmint oils, respectively. With the exception of sage oil, the other six essential oils were highly effective against T. urticae eggs at 9.3 x 10(-3) microl/ml air. Against adult P. persimilis, these six test oils caused > 90% mortality at 7.1 x 10(-3) microl/ml air. Particularly peppermint oil at 4.7 x 10(-3) microl/ml air was highly toxic. In an acrylic cage (30 by 30 by 40 cm ) test, lemon eucalyptus, pennyroyal, peppermint, and spearmint oils were highly effective against adult T. urticae at 1.4 x 10(-3) microl/ml air. These results indicate that the mode of delivery of these essential oils was largely a result of action in the vapor phase via the respiratory system. The essential oils described herein merit further study as potential fumigants for T. urticae control.     

Population characteristics of Macrocheles glaber (Acari: Macrochelidae) and Stratiolaelaps scimitus (Acari: Laelapidae) reared on a mushroom fly Coboldia fuscipes (Diptera: Scatopsidae)

Subterranean predatory mites are important biological control agents of pests in soil. In order to understand the population characteristics of two predatory mites, Macrocheles glaber Miiller and Stratiolaelaps scimitus Womersley, we studied their development, survival and fecundity data under laboratory conditions using Coboldia fuscipes Meigen as a food source and analyzed them with the age-stage, two-sex life table. Macrocheles glaber had a significantly shorter developmental time, oviposition period, longevity and lower fecundity than those of S. scimitus. The intrinsic rate of increase (λ), finite rate of increase (r), net reproductive rate (C0),net predation rate (C0), and finite predation rate (ω) of M. glaber were significantly lower than those of S. scimitus. Both population parameters and computer simulation implied that S. scimitus is a potential powerful biocontrol agent compared to M. glaber.     

Biology of Amblyseius largoensis (Muma) (Acari: Phytoseiidae), a potential predator of Aceria guerreronis Keifer (Acari: Eriophyidae) on coconut trees

Aceria guerreronis Keifer is considered one of the main pests of coconuts around the world. Amongst the Phytoseiidae recorded on this crop, Amblyseius largoensis (Muma) has been reported in association with A. guerreronis. In order to verify whether A. largoensis feeds on A. guerreronis, the biology of this predator was evaluated on different food sources, including A. guerreronis. Three types of diet were tested [Tetranychus urticae Koch + castor bean (Ricinus communis L.) pollen + honey at 10%, A. guerreronis + pollen + honey, and only A. guerreronis], determining its development, survivorship, oviposition, sex ratio and longevity at 27 degrees C, 60 +/- 5% RH 12 h photophase. Fertility life tables were constructed. The duration of the immature phase was lower when feeding only on A. guerreronis, while fecundity was higher when feeding on a prey + pollen + honey. There was no difference in relation to survivorship of the immature stages between the three diets. Parameters of fertility life tables were higher when the diet included A. guerreronis or T. urticae + pollen + honey, although the predator was able to complete its life cycle and reproduce when feeding exclusively on A. guerreronis. The results suggest that A. largoensis preys upon A. guerreronis under natural condition and that it might play some role in the control of the latter.     

Biology of Agistemus brasiliensis Matioli, Ueckermann & Oliveira (Acari: Stigmaeidae) and its predation potential on Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae)

The present work aimed to study the biology of Agistemus brasiliensis Matioli, Ueckermann & Oliveira at the following temperatures, namely 15, 20, 25, 30 and 35 degrees C, fed with Brevipalpus phoenicis (Geijskes) and Typha pollen, in laboratory conditions. Life tables were calculated to evaluate the biological parameters. The optimal development of A. brasiliensis took place at 29 degrees C. The values of T (time of generation - days), R0 and r m at 30 degrees C were, 13.95, 16.25 and 0.20, respectively. The prey consumption of A. brasiliensis was studied at the densities of 5, 10, 20, 40 and 60 leprosis mite females per cage (3 cm in diameter) on citrus fruits at 29 degrees C. The maximum prey, namely 7.6 B. phoenicis females per day, were consumed at a density of 20 leprosis mites. At densities of above 40 leprosis mites per cage, A. brasiliensis oviposits 4.7 eggs per day, in comparison to 2.5 eggs per day at 20 mites per cage.