Oviposition deterring pheromone influences dispersal distance in tephritid fruit flies

We tested the hypothesis that Rhagoletis pomonella females exhibit a greater propensity for engaging in long distance (i.e.1000 m) flight following encounters with egg-infested oviposition-deterring-pheromone (ODP) marked host fruit than similar females that encounter uninfested, clean (i.e. no ODP) fruit. Female flies which were first tethered to flight mills were presented with and permitted to explore (a) ODP-marked or (b) clean fruit and then stimulated to fly. Results showed that females that had encountered a high rate of infested, ODP-marked fruit displayed long distance flight more frequently and flew greater average distances than females that had searched uninfested fruit. We discuss there results in light of contemporary foraging theory.

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Résumé La réponse d'insectes à leurs phéromones de dissuasion (ODP) est examinée généralement à un seul niveau de prospection, c'est-à-dire celui de la ressource individuelle elle-même. Ces marqueurs chimiques peuvent, cependant, fournir aussi des informations au prospecteur sur la disponibilité en ressources, tant au niveau de l'inflorescence qu'au niveau de l'habitat. Une telle information influence vraisemblablement le comportement de prospection à différents niveaux.Dans cette note, nous vérifions l'hypothèse que la rencontre avec des hôtes marqués par ODP influence la tendance de Rhagoletis pomonella (Dipt: Tephrit) à entreprendre des vols importants (c'est-à-dire interhabitats). Nous avons montré dans des expériences de laboratoire que les femelles lors de trois rencontres consécutives avec des fruits marqués par ODP: 1) entreprenaient plus fréquemment (19 cas sur 81 contre 6 sur 81) un vol à longue distance (c'est-à-dire 1000 m) et 2) parcourient des distances moyennes supérieures à celles couvertes par des femelles ayant eu la possibilité de prospecter successivement trois fruits propres (sans ODP).Nous engageons le lecteur à examiner nos résultats d'un point de vue qualitatif. Nous ne pouvons nous attendre à ce qu'un vol à longue distance se produise aussi facilement dans la nature qu'au laboratoire, étant donné le plus grand nombre de variables (par exemple, la taille de l'arbre) qui peuvent y modifier le vol réel.Pour terminer, nous discutons les coûts et bénéfices potentiels qui peuvent résulter de ce comportement.

     

Influence of protein hydrolysate baits on oviposition in the apple maggot, Rhagoletis pomonella

Ovipositional responses of apple maggot (AM), Rhagoletis pomonella (Walsh), females were studied in the laboratory on apples (var: Golden Delicious) treated with different rates of four protein hydrolysate baits in choice and no-choice tests. Protein hydrolysate baits at rates of 0.5 and 1% had no significant effect, but oviposition was greatly reduced at higher rates of 5 and 10%. Apple maggot females exposed to apples treated with protein hydrolysate baits at a rate of 10% made 41–71% fewer punctures and laid 41–73% fewer eggs than in untreated control. No oviposition activity was shown on apples treated with 25 and 100% Nulure®. In no-choice tests the AM females laid 75–96% fewer eggs in apples treated with 10 and 25% Nulure compared to controls and no oviposition occurred in apples treated with 100% Nulure. Apple maggot females arrived in similar numbers on apples treated with 10% Nulure and untreated apples, but only 5% of those arriving on Nulure-treated apples showed ovipositor boring with no egg deposition while 60% of females arriving on untreated apples showed ovipositor boring activity and laid an average of 2.5 eggs per apple. In another experiment, individual AM females displayed similar behavioral responses to 10% Nulure-treated apples; none of the 56 females tested on treated apples displayed ovipositor boring activity, but 59% of the females (N=56) tested on untreated apples displayed ovipositor boring within 5 min of their arrival. Ninetyeight percent of AM females stayed and fed on fruit surfaces for 5 min on Nulure-treated apples without ovipositor boring compared to only 2% on untreated apples. Of the females that arrived on untreated apples, 39% flew away within 5 min without ovipositor boring compared to only 2% of those that arrived on Nulure-treated apples. Results of these two behavioral experiments suggest that upon arrival on a protein bait-treated apple, an apparent change of behavior occurs in AM females and instead of attempting to oviposit, they attempt to feed on fruit surfaces resulting in reduced oviposition activity. These results indicate that the feeding and oviposition-related activities of AM females are probably mutually exclusive and that the feeding behavior preempts oviposition activities on host fruits treated with higher rates of protein hydrolysate baits.     

真正柑桔果树群植物的分支学研究

本文用相容性分析方法(Compatability snalysis)分析了真正柑桔果树群(芸香科Rutaceae-柑桔亚科Aurantioideae-柑桔族(Citreae)-柑桔亚族(Citrinae)植物内各属间的分支学关系。给出了建立在7个相容性性状组成的最大族所决定的分支图。性状极性的确定使用了外群法。结果表明,柑桔属(Citrus L.)和多蕊桔属(Clymenia Swing)构成一个单系类群,他们的姐妹群是金柑属(Fortunella Swing.)。被认为起源于中国的3个属,柑桔属(Citrus)、金柑属(Fortunella)和积属(Poncirus Raf.)并未构成一个单系类群。本文还利用分支关系分析和讨论了真正柑桔果树群的种系发生关系。     

FGR对水涨龙眼座果及枝梢生长的效应

1990～1991年的研究结果表明,FGR 1000～3000ppm 4月中旬处理水涨龙眼,对提高果实座果数有明显效果,两年呈一致结果。高浓度(3000ppm)处理,1990年及1991年的座果数比对照分别增加1.38倍和1.07倍(P≤0.05),具有显著的保果效应。FGR各处理对龙眼果实品质及结果期间的夏延秋梢生长发育两年均未见不良影响。     

Effect of excess boron on summer and winter squash

The boron tolerance of two summer squash cultivars (Cucurbita pepo L. Aristocrat Zucchini and Peter Pan Scallop) and one winter squash cultivar (Cucurbita moschata Poir. Butter boy) was determined in large, outdoor sand cultures. Boron treatments were imposed by irrigation with culture solutions that contained 1.0, 3.0, 6.0, 9.0, 12.0, or 15.0 mg B L^-1. Relative fruit yields of Zucchini, Scallop, and Butter boy were reduced 5.2%, 9.8%, and 4.3% with each unit (mg L^-1) increase in soil solution B (B_sw)>2.7, 4.9, and 1.0 mg B L^-1, respectively. Reduced yields of all cultivars were attributed to a reduction in fruit number and not fruit size. Boron concentrations in leaves and fruit were directly correlated to B_sw.     

Effect of mutual shading on the emergence of nodal roots and the root/shoot ratio of maize

The effect of mutual shading on the root/shoot ratio and on the number of nodal roots of maize was studied. Plants of two varieties (Dea and LG2281) were grown in individual pots of 9 L, at three plant densities: 7.5, 11 and 15 plants m^–2. A control experiment was carried out in order to study if root growth was affected by the small size of the pots. Maize plants (cv Dea) were grown at a low plant density (7.5 plants m^–2) in pots of two different volumes (9 and 25 L respectively). In both experiments plants were watered every two hours with a nutrient solution. Some plants were sampled at five dates in the main experiment and the following data were recorded: foliar stage; root, stem and leaf dry weight; number of root primordia and number of emerged roots per phytomer. The final sampling date occurred at silking.Results of the control experiment showed that the root biomass was lower in small pots but the number of nodal roots per phytomer was not affected.Results of the main experiment showed that the total plant biomass and the root/shoot ratio were lower at high plant density. The number of emerged roots was strongly reduced on the upper phytomer (P₈). This reduction was mainly due to a lower percentage of root primordia which elongated. A proposed interpretation is that the number of roots which emerge on upper phytomers is controlled by carbohydrate availability.     

A model for light-limited continuous cultures: growth, shading, and maintenance

Light-limited growth in continuous cultures of phototrophic organisms is modeled. It is assumed that light energy up-take rate depends hyperbolically on light intensity and that the maintenance costs are proportional to biomass. Modeling the light distribution caused by shading within the vessel is necessary to explain the existence of steady state in light-limited chemostats. The model fits well to experimental data from literature on light-limited chemostats and turbidostats. Attention is given to the implications of the model for the estimation of the specific maintenance rate constant in light-limited continuous cultures.     

Morphology of Heliotropium (Boraginaceae) Dispersal Units1

In flowers of Heliotropium s.l. the primary carpel tips are overtopped by commissural outgrowths. Therefore the stylar cleft mimics a lateral orientation of the carpels. In species in which the fruit splits into four diaspores the separation tissues run through both the median and the transverse fruit planes. In species where only two two-seeded nutlets are developed the fruit splits within the false septa and each half is composed of parts of both carpels (“syn-mericarpids”).     

Mass rearingCeratitis capitata: reuse of the finisher larval diet

The standard finisher larval diet used at Seibersdorf for rearing the Mediterranean fruit fly,Ceratitis capitata (Wiedemann), was reused following autoclave heat-treatment to kill larvae or pupae remaining from its first use. Only when the spent diet was mixed with water (about 40% of final diet, w/w) to reconstitute fresh-diet texture, and combined with fresh starter, a similar, but still inferior in respect to larval duration and pupal recovery and size, to the fresh finisher diet production of flies was achieved. Enrichment of the autoclaved spent finisher with small quantities of nutrients gave inconclusive results. Although spent-diet pupae were significantly smaller than fresh-diet control pupae, their adults survived significantly longer than control adults.

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Zur massenaufzucht vonCeratitis capitata: die wiesderverwendung der endkomponente der larvendiät

Zusammenfassung Die in Seibersdorf zur Aufzucht der Mittelmeerfruchtfliege,Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), verwendete Standardendkomponente der Larvendiät konnte nach Abtötung der von der Erstverwendung verbliebenen Larven oder Puppen mittels Autoklavensterilisation wiederverwendet werden. Eine zur frischen Kontrolldiät vergleichbare, jedoch bezüglich der Länge des Larvenstadiums, der Entwicklung der Puppen nach dem Schlüpfen sowie der Größe der Puppen noch immer schlechtere Fliegenproduktion wurde erreicht, wenn die wiederverwendete, autoklavierte Diät mit Wasser (ca. 40% der Enddiät, w/w) zwecks Rekonstitution zur frischen Diättexture gemischt und mit frischem Starter kombiniert wurde. Eine Anreicherung der wiederverwendeten Diätendkomponente mit geringen Mengen von Nährstoffen ergab keine schlüssigen Resultate. Obwohl Puppen der wiederverwendeten Diät signifikant kleiner als Puppen der Frischdiät-Kontrolle waren, überlebten deren Erwachsene signifikant länger als die Erwachsenen der Kontrolle.