Observations on different methods of aphid trapping

Cylindrical and horizontal sticky traps painted in a range of spectral colours were used to determine the flight and landing behaviour of aphids. Data are also presented on aphid catches in suction traps at two heights and in light traps. Apart from colour sensitivity (yellow versus white) there was apparently a separate response to colour which in some species varied with season. Within yellow-sensitive species there was also a differential response to colour. With the experimental methods used, it was not possible to define mathematically the active and passive landing components on cylindrical traps. Though the active landing component was large it varied between aphid species. Most species caught on horizontal traps at ground level had been flying above 1 m. In some species the response of males to colour and their landing behaviour differed from that of viviparae and oviparae. Four years data from suction traps suggest that aphid species can be divided into three categories on the basis of the height at which they normally fly. One group, mostly tree-feeders, always show the greatest density at a high level (12.2 m) throughout the season. The second group always have the highest density at a low level (1 m) whilst a third group of species change at a specific date each autumn from a maximum density at 1–12.2 m. Attraction to light (moth trap) appeared to be linked with the grouping of species by height of flight. The interpretation of catch data is discussed in the light of these observations.     

Observations on two races of the groundnut aphid, Aphis craccivora

Two clones of Aphis craccivora, one from Nigeria and one from Kenya, differed in their ability to transmit the GRVW₁ strain of the rosette virus (Okusanya, 1965). Comparison of body measurements of the two clones showed them to be two distinct but overlapping populations. The Nigerian clone formed colonies on Onobrychus viciifolia, Gomphrena globosa and young Soya max more readily than the Kenya clone. The fecundity of single viviparous females of the two clones on groundnut and bean does not differ significantly. Alatae produce half as many young as apterae.

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Zusammenfassung Zwei Klone von Aphis craccivora, einer von Nigeria und einer aus Kenia, unterscheiden sich in der Fähigkeit, Erdnußvirus-Stämme zu übertragen (Okusanya, 1965). Maße der Körpergröße und die Längen der Siphonen, Hintertibien, Antennenglieder und Vordertibien zeigen, daß sie zwei sich überlappenden Populationen angehören. Jungpflanzen von Soya max, Gomphrena globosa und Onobrychis viciifolia werden von dem nigerischen Stamm viel leichter besiedelt als von dem aus Kenia. Einzelne Aptere der beiden Klone produzierten an Erdnuß und Ackerbohnen ähnliche Nachkommenzahlen. Eine einzelne Aptere gebar an Erdnuß 230 Junge; die meisten Larven wurden während der ersten 12 Tage der Fortpflanzungsperiode geboren. Geflügelte beider Klone produzierten nur halb so viele Larven (im Mittel 57 und 52) wie Ungeflügelte (im Mittel 118 und 110). Die beiden Klone sind biologische Rassen von A. craccivora.

     

Horticultural mineral oil treatments in nurseries during aphid flights reduce Plum pox virus incidence under different ecological conditions

The application of horticultural mineral oil (HMO) treatments has been reported as a possible control strategy to reduce Plum pox virus (PPV) incidence in Prunus nurseries. The effect of Sunspray Ultrafine HMO at 1% on the natural viral spread was evaluated in experimental nursery plots of Nemaguard and Mariana GF8‐1 Prunus rootstock blocks established under high natural inoculum pressure of the most prevalent PPV‐types. Tests were conducted in experimental nursery plots in Plovdiv, Bulgaria (PPV‐M and PPV‐Rec), in Bistrita, Romania (PPV‐D and PPV‐Rec) and in Llíria, Spain (PPV‐D). Horticultural mineral oil treatments were applied weekly during the vegetative period from spring to fall (treatments were interrupted in the summer). Nursery plants were analysed yearly by double‐antibody sandwich enzyme‐linked immunosorbent assay with 5B‐IVIA/AMR monoclonal antibodies. The population dynamics of the aphids visiting plants in each experimental nursery plot was monitored by the sticky‐shoot method and also by Moericke yellow water traps. At all three locations, the aphid population first peaked in the springtime. Furthermore, a variable second peak of aphid population was observed in Plovdiv and Bistrita in autumn. The treatments reduced PPV incidence in the three experimental locations and plots and in both assayed Prunus rootstocks grown under high PPV‐inoculum pressure. A reduction from 10% to 20% of PPV‐incidence between treated and control plants (P < 0.05) in Plovdiv and Bistrita, respectively, was observed at the end of the tests. However, HMO treatments did not prevent PPV infection altogether, probably because of the high PPV prevalence in the area near the experimental nursery blocks. The control of PPV in nursery blocks based on HMO is presented as an environmentally friendly strategy based on the physical action of the treatments.     

Rearing of Diatraea saccharalis on diets in Surinam

Mass rearing of the borer Diatraea saccharalis (F.) was attempted on a limited scale. Out of nine non-aseptic artificial diets tested fair results were obtained with the medium containing kidney bean meal (35 g), corn plant powder (10 g), carrot powder (5 g), brewer's yeast (10 g), casein (1 g), ascorbic acid (0.5 g), agar (3 g), water (210 g) and the antimicrobial agents methylparahydroxybenzoate (1 g), streptomycine sulphate (0.1 g), penicillin (0.2 g) and sorbic acid (0.2 g).the borer was also reared satisfactorily on cut corn stalks.

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Résumé L'élevage de Diatraea saccharalis sur une huitaine de régimes artificiels a été étudié sous des conditions non-aseptiques. Des résultats favorables sont obtenus avec un milieu composé de: haricots rouges pulvérisées (35 g), tiges et feuilles de maïs réduites en poudre (10 g), farine de carottes (5 g), levure (10 g), caséine (1 g), acide ascorbique (0,5 g), agar (3 g), eau (210 g) et les antibiotiques: methylparahydroxybenzoate (1 g), streptomycine sulfate (0.1 g), pénicilline (0.2 g) et acide sorbique (0.2 g).L'élevage en bocaux contenant des fragments de tiges de maïa a également donné de bons résultats.

     

Dieback of Passion Fruit in Surinam

In Surinam, the commercial cultivation of the yellow passion fruit (Passiflora edulis f. flavicarpa) is difficult due to the occurrence of dieback. Symptoms referred to as dieback include a decrease in elongation of the shoot end internodes after a period of normal growth leading to wilting and death of the shoots. Fruits from plants showing dieback symptoms are much smaller than those from healthy plants. From shoots with dieback symptoms, three fungi were isolated including Colletotrichum gloeosporioides. However, inoculation experiments with these fungi on shoots of vigorously growing plants were negative, even after wound inoculation. It appeared that plants with dieback symptoms had a poorly developed root system, From these roots Fusarium solani was isolated, which appeared to be highly pathogenic to roots of the yellow passion fruit. After inoculation of the roots of 3-month-old plants, roots became infected and the aerial plant parts showed typical dieback symptoms. Plants with their root system reduced either by inoculating with F. solani or by clipping, and subsequently inoculated with C. gloeosporioides on the aerial parts 2 weeks later, showed dieback symptoms and infection by C. gloeosporioides in shoots with these symptoms. Thus, a badly functioning root system, for example caused by infection of F. solani leads to dieback and predisposes plants to infection by C. gloeosporioides. The latter fungus itself is not a primary pathogen of shoots of the yellow passion fruit in Surinam.     

Accipiter poliogaster in Surinam

Ohne Zusammenfassung     

Measuring and modelling the effects of inoculation date and aphid flights on the secondary spread of Beet mosaic virus in sugar beet

The effect of the inoculation date on the spread of Beet mosaic virus (BtMV) in sugar beet field plots was studied. Two plants in the centre of each plot were inoculated with BtMV using Myzus persicae. The spread of the infection around these sources was monitored by inspecting the plants on two diagonal transects through the centre of the plot. Early inoculations resulted in a greater spread than late inoculations, but any inoculation before the onset of the aphid migration resulted in a similar‐sized spread. The spread was concentrated in patches around the inoculated plants, and its rate was explained by vector pressure, as shown by regression analysis and a mechanistic simulation model. This vector pressure was quantified using data obtained by catching aphids in a green water trap in the crop, catching aphids in a 12 m high suction trap at a distant location, and infection of bait plants from adjacent virus source plants. The daily total aphid catches obtained by a suction trap provided the best statistical explanation for the spread of this virus. The parameter r, describing the relationship between vector pressure and the rate of disease progress, was remarkably robust. This parameter varied less than 10% between treatments (infection date) within a single experiment, and less than a factor two between four experiments performed at different sites in two years. The robustness of this parameter suggests that the spread of a potyvirus may be predicted on the basis of the initial infection date and vector abundance.     

Observations on the number of cereal aphids on the soil in relation to aphid density in winter wheat

The numbers of cereal aphids on the soil surface was assessed by soil samples and by counting the numbers captured in pitfall traps. A relationship was found by both methods between the density of aphids on the plants and the numbers of aphids on the soil. This relationship indicated that a higher proportion of the aphid population was on the soil surface at the lower densities on the plant. Reasons for this relationship are suggested and discussed.     

Observations of preferential feeding by the aphid,Rhopalosiphum maidis on abaxial phloem ofCucurbita maxima

Summary Seventy-four of 83 stylet tracks, and 20 of 22 pairs of stylets of the aphid,Rhopalosiphum maidis were observed terminating in abaxial phloem of matureCucurbita maxima leaves. These results indicate that the abaxial phloem is more important in vein loading and the export of assimilates from mature leaves than the adaxial phloem.     

Lymphocytes on sounding rocket flights

Cell-cell interactions and the formation of cell aggregates are important events in the mitogen-induced lymphocyte activation. The fact that the formation of cell aggregates is only slightly reduced in microgravity suggests that cells are moving and interacting also in space, but direct evidence was still lacking. Here we report on two experiments carried out on a flight of the sounding rocket MAXUS 1B, launched in November 1992 from the base of Esrange in Sweden. The rocket reached the altitude of 716 km and provided 12.5 min of microgravity conditions.     

Nachbarschaft von Vogelnestern und Wespennestern in Surinam

Zusammenfassung In Surinam baut eine Anzahl von Vogelarten ihre Nester in der Regel in enger Nachbarschaft von Wespennestern. Es sind dies die ArtenCacicus cela, Pachyramphus polychopterus, Tolmomyias flaviventris. Es kommt aber auch häufig vor, daß diese Arten ohne Nachbarschaft von Wespen nisten.BeiTodirostrum maculatum ist es gerade umgekehrt; als Regel nistet dieser Tyrannide ohne ein Wespennest in der Nähe, es kommt aber auch ziemlich oft vor, daß die Nachbarschaft besteht.BeiLegatus leucophaius ist es wieder anders, er baut nicht selbst, sondern okkupiert taschenförmige oder beutelförmige Nester anderer Vögel und wird auf diese Weise Nachbar von Wespennestern.Es steht weiter fest, daß das Wespennest immer schon da ist, wenn die Vögel ihr Nest bauen.Als Wespen kommen vor allem in Betracht die Arten:Polybia liliacea, Polybia occidentalis, Synoeca surinama undNectarina bilineolata (nur ein Fall).Das Nest vonSynoeca surinama, das wie ein längliches Geschwulst gegen den Hauptstamm angeklebt ist, kann bisweilen keinen Schutz geben, da das Vogelnest, das am Ende eines Astes gebaut ist, bequem zu erreichen ist, ohne daß die Wespen dabei gestört werden.Einwandfreie Beobachtungen über das Verhalten von Nestfeinden gegenüber den Wespennestern und die in enger Nachbarschaft gebauten Vogelnester fehlen noch immer.Es steht also immer noch nicht genau fest, wie diese Nachbarschaft zu erklären ist.mit 2 Aufnahmen des Verfassers     

Some data on the occurrence of Salmonella in animals in Surinam

Summary During an investigation in Surinam 18Salmonella types were isolated from material obtained from cattle, pigs, dogs, rats, awaris, fowl and toads.     

Blood pressure of Amerindians from Surinam

Blood pressures of members of the Trio and Wajana tribes from Surinam have been analysed in relation to age, stature and weight. The sample is representative of a group living in a hunting and gathering economy but beginning to come into jarring contact with an alien culture. Diastolic pressure does not alter significantly with age in adults of either sex. There is a small but significant increase in systolic pressure with age in adult females but in males there is an apparent decrease. This decrease is probably an artifact of the cross-sectional survey approach. The high pressure in some young adults is discussed with reference to psychosocial stress. Mean blood pressures are given for children from five years of age onwards.     

Zur Brutbiologie vonThraupis episcopus in Surinam

Zusammenfassung Thraupis episcopus gehört in Surinam zu den gemeinsten Singvogelarten und kommt in der Parklandschaft und in Gärten zahlreich vor. Die Nahrung ist sowohl pflanzlich (Früchte und Beeren) wie tierisch (Insekten). In allen Monaten des Jahres sind Nester mit Eiern zu finden. Es werden mindestens zwei Bruten gemacht. Das Nest wird von beiden Geschlechtern gebaut. Das Gelege besteht meist aus 2 Eiern, 3er-Gelege sind selten, es kommen sogar Gelege mit nur einem Ei vor.Nur das Weibchen brütet, es wird vom Männchen nicht gefüttert. Die Brutdauer beträgt 14 Tage.Beide Gatten füttern die Jungvögel aus dem Schnabel mit Beeren und Insekten. Die tägliche Gewichtszunahme eines Jungvogels wurde ermittelt und eine Übersicht der Huderzeiten und Futterfrequenz pro Stunde während 15 Beobachtungsstunden gegeben.Der Jungvogel wurde vom Weibchen bis zum 11. Lebenstag zeitweise am Tage und während der Nacht gehudert. Er verließ das Nest am 16. Lebenstag.     

Simulating transmeridian flights

Sleep and Biological Rhythms -