Within-plant vertical distributions of the scale insect Nipponaclerda biwakoensis and its five parasitoids that exhibit frequent successful multiparasitism on the common reed

Within‐shoot vertical distributions of the scale insect Nipponaclerda biwakoensis, five species of gregarious parasitoid wasps attacking the scale, and successful multiparasitism (emergence of multiple parasitoid species from a single host) by the parasitoids on the common reed were investigated. Each reed shoot collected was longer than 2.0 m, and was divided into pieces of 0.5 m each from the base of the shoot. The mean number of adult female scales per 0.5 m of shoot increased with height, but the mean rate of overall parasitism of the female scales decreased with height. The five parasitoids showed species‐specific within‐shoot distribution patterns, with respect to the rate of parasitism: Astymachus japonicus, Boucekiella depressa and Encyrtidae sp. 2 showed the greatest rates of parasitism at heights of 0–0.5, 0.5–1.0 and 1.0–1.5 m, respectively. The parasitism rate by Aprostocetus sp. was higher at the lower half of the shoots, whereas that by Encyrtidae sp. 1 was higher at the central positions. The distribution of the five parasitoids largely overlapped with each other at the level of scale aggregations. Nevertheless, successful multiparasitism occurred frequently only in several types of species combinations that involved two parasitoid species showing similar within‐shoot distribution patterns. The rate of successful multiparasitism by B. depressa with A. japonicus or Aprostocetus sp., and that by Encyrtidae sp. 2 with Encyrtidae sp. 1 was constantly high at different vertical positions on the shoots. This may be because B. depressa and Encyrtidae sp. 2 preferentially oviposit into scales previously parasitized by these other species.     

芦苇收割对宫苍仁蚧密度及其五种寄生蜂共寄生关系的影响

【目的】本文旨在揭示芦苇Phragmites australis(Cav.)Trin.ex Steudel收割对宫苍仁蚧Nipponaclerda biwakoensis Kuwana密度及其5种寄生蜂寄生率和共寄生关系的影响及作用机制。【方法】在上海九段沙湿地上沙的芦苇未收割区和收割区分别设置16个和20个样方,于2011年7月和9月进行重复采样,对未收割区和收割区的蚧虫密度、寄生蜂寄生率、共寄生关系和雌性比率分别进行比较分析。【结果】芦苇收割能够显著降低蚧虫密度(P<0.001);从7月到9月,寄生蜂总寄生率呈增高趋势,但7月芦苇未收割区和收割区间寄生蜂总寄生率差异不显著(P>0.05),而9月芦苇收割区寄生蜂总寄生率则显著高于未收割区(P<0.001);而寄生蜂总寄生率与蚧虫密度相关性并不显著。不同寄生蜂对芦苇收割的响应不同,且存在时间差异性。7月,Aprotocetus sp.的寄生率最高,且在收割区的寄生率显著高于未收割区(P<0.05),而其他寄生蜂寄生率均较低。9月,Aprotocetus sp.的寄生率呈下降趋势,而其余寄生蜂寄生率则呈升高趋势;而且除Encyrtidae sp.外,其他寄生蜂寄生率在未收割区和收割区间存在显著差异(P<0.001)。此外,芦苇收割还显著增加Boucekiella depressa与Astymachus japonicus的共寄生率(P<0.001),并显著减少B.depressa与Aprotocetus sp.的共寄生率(P<0.001)。除Aprotocetus sp.(P<0.05)外,芦苇收割对寄生蜂的雌性比率无显著影响。【结论】不同寄生蜂对芦苇收割的响应,不仅依赖于蚧虫密度,而且还与寄生蜂的扩散能力和竞争能力等生物学特性有关。因此,芦苇收割能通过多种途径影响寄生天敌和宫苍仁蚧的高营养级互作关系,需引起足够的重视。     

Abundances of five parasitoids attacking the scale insect <Emphasis Type="Italic">Nipponaclerda biwakoensis</Emphasis> on morphologically changed reed shoots due to damage by a stem-boring caterpillar

Abundances of the scale insect Nipponaclerda biwakoensis and its five parasitoids per shoot of the common reed, Phragmites australis, were compared between shoots damaged by a stem-boring caterpillar and undamaged shoots. Reed shoots that were damaged by the stem-borer in spring change morphologically during summer, inducing tillers from the nodes beneath the damaged part. The number of female scales per shoot did not differ significantly between damaged and undamaged shoots in the second scale generation (September), but was significantly lower on damaged shoots in the third generation (November). Three parasitoid species attacking the scale exhibited different responses to the shoot damage, with the response by each parasitoid being constant in the two scale generations: the parasitism rate by Aprostocetus sp. per shoot was higher on damaged shoots, whereas that by Astymachus japonicus was lower on damaged shoots, and no difference was detected for Boucekiella depressa. In the third scale generation, the parasitism rate by Encyrtidae sp. 1 showed no difference, with respect to shoot damage, whereas that by Encyrtidae sp. 2 was lower on damaged shoots. In three dominant parasitoids, shoot damage had no effect on the number of emerging adults per host, and the sex ratio and body size of the adults. The number of emerging adults per shoot differed significantly between damaged and undamaged shoots for four parasitoids, except B. depressa. These results suggest that shoot damage by the stem-borer exerts a delayed negative impact on the scale numbers and affects the parasitism rate of the scales by three parasitoids and the emerging adult numbers of four parasitoids.     

Effect of oil emulsion sprays on parasitoids of the black parlatoria, Parlatoria ziziphi, in grapefruit

The black parlatoria, Parlatoria ziziphi, a common pest of citrus in the tropics and subtropics, has become the most important citrus pest in Upper Egypt. Spray oils may be a relatively safe alternative to harmful synthetic insecticides. However, the effect of spray oils on black parlatoria and associated parasitoids is unknown. Field studies were conducted in Giza, Egypt to assess the effect of two experimental spray oils on P. ziziphi and three associated parasitoid species on grapefruit (Citrus paradisi). Triona oil was more effective than Shecrona oil and reduced scale populations by up to 99% 75 days after application. The parasitoid Encarsia citrina was not affected significantly by either spray oil. Triona oil was slightly harmful to the other primary parasitoid, Habrolepis aspidioti and reduced parasitism rate by Marietta leopardina. However, because the latter species is a hyperparasitoid, the reduction in its number by Triona was beneficial. Triona application is therefore highly effective in controlling the black parlatoria and it reduced the rate of hyperparasitism by M. leopardina. The oils had only a minor negative impact and only on the less important primary parasitoid in the system.     

Effects of external iron concentration upon seedling growth and uptake of Fe and phosphate by the common reed, Phragmites australis (Cav.) Trin ex. Steudel

The objectives of this study were to determine whether, and to what degree, the aqueous iron concentration in the growing medium affects the growth of, and Fe uptake by, Phragmites australis, and whether the presence of iron in the growing environment affects the uptake of the essential element phosphate. The wetland macrophyte P. australis was grown under laboratory conditions in nutrient solution (0.31 mg L(-1) phosphate) containing a range of iron concentrations (0-50 mg L(-1) Fe). A threshold of iron concentration (1 mg L(-1)) was found, above which growth of P. australis was significantly inhibited. No direct causal relationship between iron content in aerial tissues and growth inhibition was found, which strongly suggests that iron toxicity cannot explain these results. Phosphate concentrations in aerial tissues were consistently sufficient for growth and development (2-3 % d. wt) despite significant variation in concentration of phosphate associated with roots. External Fe concentration had a significant effect on the growth of P. australis and on both Fe and phosphate concentrations associated with roots. However, neither direct toxicity nor phosphate deficiency could explain the reduction in growth above 1 mg L(-1) external Fe concentration     

Analysis of brood development in the ant Amblyopone silvestrii, with special reference to colony bionomics

There are five larval instars in the temperate, subterranean ponerine ant, Amblyopone silvestrii (Wheeler). An examination of the seasonal developmental patterns of immatures collected from more than 100 colonies collected in the field revealed that most or all of the newly hatched individuals overwintered as second to fifth instar larvae and emerged as adults in the next summer. The fifth instar larvae were most abundant in the colony's larval population all year round. The number of eggs present in the nest diminished temporarily in midsummer, although queens collected during this period maintained fully developed ovaries with mature oocytes. When the larvae matured, they were usually moved to temporary nests away from the nest area of the colony and finished pupation and eclosion there, while accompanied by a small number of workers. Pupation of sexuals occurred in the more distant cocoon chambers compared with pupation of workers.     

Seasonal changes in soil arthropod abundance in the dry evergreen forest of north-east Thailand,with special reference to collembolan communities

A soil arthropod community was studied in a dry evergreen forest over a 3-year period from May 1998 to April 2001. Population abundance, species composition, and community structure were investigated over the 3-year study period. The soil arthropods consisted of Acari (75.38%), Collembola (16.11%), and others (8.51%), and their abundances showed a clear difference between the rainy and dry seasons. Population abundance of Collembola and Acari were low during drought conditions. The humidity was the most important factor determining distribution, abundance, and survival of soil Collembola in this tropical forest. High predation and low accumulation of organic matter caused low population abundance of Collembola in the tropical habitat. The collembolan community was dominated by a few dominant species over the study period. The pattern of seasonal changes in numbers of Collembola was similar over the 3-year study period. The species composition of the collembolan community was constant and persistent throughout a 3-year study period. Thus, the collembolan community showed constancy in its species composition with seasonal variability over the 3-year study period.     

Studies on gut pigment in skin-parasitic monogeneans, with special reference to the monocotylid Dendromonocotyle kuhlii

Adults and immature specimens of the monocotylid, monogenean parasite Dendromonocotyle kuhlii contain brown gut pigment and are found on the upper skin of the stingray Amphotistius kuhlii. No indication was found that the living parasites had been feeding on blood. Tests showed that the gut pigment of the parasites is not haematin. The upper epidermis of the stingray contains pigment cells, possibly of two kinds. Although the evidence is not conclusive, it seems likely that the gut pigment of the parasite is derived from host skin pigment ingested when the parasite browses on the fish's skin. Observations on Entobdella australis, from the same host and from Taeniura lymma, support this view. The microbothriid skin parasite Pseudoleptobothrium aptychotremae also contains gut pigment which is not haematin and may be derived from pigment in the skin of its host, Aptychotrema banks.

Experimental evidence is given in support of earlier observations that Entobdella soleae does not damage host dermis during feeding.     

Differential mortality of wintering shorebirds on the Banc d'Arguin, Mauritania, due to predation by large falcons

Predators may influence many aspects of the daily life and seasonal movements of their prey. Here we quantify direct, and evaluate indirect effects of predation by three falcon species (Lanner Falcon Falco biarmicus , Barbary Falcon Falco pelegrinoides and Peregrine Falcon Falco peregrinus ) on coastal shorebirds wintering on the Banc d'Arguin, Mauritania, an area hosting approximately 30% of the East Atlantic Flyway population of shorebirds. On the basis of 754 h of observation over five winters, 97 witnessed attacks and 585 collected prey remains, we show that shorebirds were safer in larger flocks, which tended to be attacked less often. Furthermore, species that forage relatively close to shore and in small flocks were depredated more often than expected from their relative abundance. In three species, Red Knot Calidris canutus canutus , Bar-tailed Godwit Limosa lapponica taymyrensis and Dunlin Calidris alpina , the juveniles were more vulnerable than adults. We estimated that on average 1% of the juvenile and 0.1% of the adult Red Knots present were killed by large falcons each winter. For Red Knots we simultaneously quantified annual survival on the basis of an individual colour-marking programme: mortality due to predation by falcons accounted for an estimated 6.2% (juveniles) and 0.8% (adults) of annual mortality. We suggest that juvenile Red Knots are 10 times as likely to be killed by falcons because they use riskier habitats, i.e. early and late tide foraging areas closer to shores where surprise attacks are both more common and more successful. These results indicate that the strength of indirect effects of predation operating in a shorebird population largely outweigh the effects of mortality per se .     

Determination the population trends of cereal aphids and associated parasitoids by yellow sticky traps with reference to aphid management on wheat

Population trends of cereal aphids and their associated parasitoids inhabiting wheat plantations were monitored by yellow sticky traps. The identified aphids exhibited one seasonal peak for each and were found to be active during the first half of March. Data revealed that, Rhopalosiphum padi L peak occurred one week later than both of Schizaphis graminum (Rondani) and Rhopalosiphum maidis (Fitch). The numbers of aphid complex was recorded more at 90 than at 30 and 60 cm height. Hymenopterous parasitoids activity is synchronised with aphid species, whereas they appeared in small numbers at early and late wheat season and showed their peak on March, with a positive correlation coefficient with aphid populations. The tested compounds (Karate, Biscaya, Match 5% EC, Tracer 24% SC and Neem Azal T/S) showed 100% reduction in aphid numbers after 24 h post application. However, the general reduction percentages indicated 99.31 > 98.32 > 97.97 > 97.06 > 95.66%, by using the abovementioned compounds, respectively.     

Seasonal changes in a population of Menacanthus eurysternus (Mallophaga, Amblycera) on the common myna Acridotheres tristis

Seasonal changes in a population of Menacanthus eurysternus (Mallophaga, Amblycera) on the common myna Acridotheres trislis. International Journal for Parasitology 20: 1063–1065. Seasonal variations in a population of an amblyceran louse, Menacanthus eurysternus, infesting the common myna have been studied. Incidence of infestation, lice, index, and population structure of this species have been recorded in different months of the year; reasons for the population fluctuations are discussed.     

Age-related changes in antioxidant enzymes and prooxidant generation in tissues of the rat with special reference to parameters in two insect species

The objective of this study was to explore the relationship between partially reduced oxygen species and the aging process. Effect of age on antioxidant defenses and prooxidant generation was evaluated by comparing the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, and rates of mitochondrial O-₂ and H₂O₂ generation in the liver, heart, and brain of 3-month and 18-month-old Sprague-Dawley rats. In addition, comparisons of antioxidant defenses and mitochondrial prooxidant generation were made between short-lived insects and the rat tissues. Results indicated that antioxidant enzymes exhibit a mixed pattern of age-related alterations. In each organ of the rat examines, activities of some enzymes were up with age and of others down with age. The overall magnitude of decline in antioxidant defenses observed here and elsewhere in the literature was deemed to be unlikely to be functionally significant. In contrast, the rate of mitochondrial O-₂ and H₂O₂ generation increased in various tissues of the rat. Antioxidant defenses in insects were comparable to tissues in the rat but rates of O-₂ and H₂O₂ generations were notably higher. Results are interpreted to suggest that rates of prooxidant generation may be more crucial than antioxidant levels as possible longevity determinants.     

Comparative observations on AChE distribution in pancreas of some amphibians,reptiles and birds,with special reference to the islets of langerhans

Summary AChE activity in pancreas of some amphibians, reptiles and birds was investigated with light microscope using Karnovsky's technique.A nervous and an extranervous localization of the enzyme showing considerable qualitative and quantitative differences depending on the systematic group, could be discerned. Pancreatic peripheral cholinergic autonomic system comprises nerve fibers and perikarya. The latter seem to occur in newt and frogs as Cajal's interstitial cells (CIC) and are undoubtedly present in birds as CIC and as ganglionic cells. In lizard and snakes they were not present.The extranervous localization of AChE activity was observed in islet cells in frogs, lizards and snakes, also in the walls of blood vessels of all investigated poikilotherms.The findings are compared with results previously obtained in mammalian pancreas or in other organs. Some hypotheses on the physiological significance of enzyme presence in endocrine cells, as well as their belonging to APUD cell series are discussed.This work was supported by a fellowship of the Alexander von Humboldt-Stiftung, Bonn-Bad Godesberg and by the Deutsche Forschungsgemeinschaft (La 229-3). The author expresses his thanks to Prof. Dr. R. H. Lange for scientific advice.     

Ecological studies on the population of isaza,Chaenogobius Isaza Tanaka,in Lake Biwa,with special reference to the effects of population density upon its growth

1. In order to get the knowledge on the age composition of “isaza” population in Lake Biwa and the effect of population density on growth, monthly distribution of mean body length and mean body weight has been analyzed on the basis of monthly haul by “isazabiki” trawl during 1949 to 1953 and also 1960 to 1965.
2. There is no apparent sex difference in the growth in the first and second years of life.
3. “Isaza” population is composed of two age groups, age 0 and 1 groups (1+fish), the latter occupying by far the greater part in commercial catch.
4. During the growth season fishes of both ages feed mainly on zooplankton, though in winter frequently take chironomid larvae, gammaridae and others in volume.
5. The growth season falls in the period from April to October in both age groups.
6. A considerable yearly variation occurring in growth is in close connection with the fluctuation of population density of all ages.
7. The influence affected by the density of age 1 group is larger than that by age 0 group.

     

Colchicine effects on neurosecretory neurons and other hypothalamic and hypophysial cells,with special reference to changes in the cytoplasmic membranes

Summary The morphological effects of colchicine on the entire neurosecretory (NS) tract and on various hypothalamic nuclei have been studied. The perturbation in axonal flow, indicated by the accumulation of NS material, coincide with fragmentation of the cytoplasmic membranes, i. e. the Golgi apparatus and the endoplasmic reticulum, whereas the neurotubules remain relatively well preserved. Autophagic destruction of NS material is observed along the entire length of the NS fibres. The rapid and systematic changes in the axoplasmic reticulum, known to store calcium, lead us to envisage a role for this system — similar to that of the sarcoplasmic reticulum — in controlling the transport of NS vesicles. The junctional zone between the stalk and the neural lobe seems to play a particular rôle in the transport of NS material to the posthypophysial terminals of the NS axons. Colchicine provokes an increase in dense-cored vesicles in most of the neurons of the other hypothalamic nuclei studied: arcuate, suprachiasmatic, periventricular and ventromedial. Membranous alterations are also observed in these sites. Colchicine administered to animals which were hypothyroid, castrated or adrenalectomized, reveals stimulated neurons, identified by their excessive content of dense-cored vesicles. These neurons display no specific localization, for they occur in all hypothalamic nuclei, irrespective of the stimulation. The frequency of stimulation of neurons of the periventricular nucleus is striking.     

The growth form of populations in some aphids,with special reference to the relation between population density and the movements

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National Institute of Agricultural Sciences