Abstract. At five sites in Hungary and Italy, traps baited with phenylacetaldehyde caught significantly higher numbers (10 to 100 times more) of green lacewings than unbaited traps, which demonstrates that this compound is an attractant. Traps with three bait dispensers usually caught more than those with one dispenser, but the difference was significant only at two out of five test sites. There was no difference in the numbers caught by sticky delta and funnel traps baited with phenylacetaldehyde. However, funnel traps could be adapted to catch living green lacewings. The vast majority of the specimens belonged to the Chrysoperla carnea species complex. Ch. carnea sensu lato dominated the catches at all sites. At some sites 3-11% of the insects caught were Ch. lucasina Lacroix. Phenylacetaldehyde-baited traps were attractive to both sexes, but generally more females were caught than males. Funnel traps baited with three dispensers of phenylacetaldehyde caught green lacewing adults throughout the season in Hungary.

In field trapping tests, the catch of Chrysoperla carnea sensu lato (Neuroptera: Chrysopidae) increased when acetic acid was added to lures with phenylacetaldehyde. The addition of methyl salicylate to the binary mixture of phenylacetaldehyde plus acetic acid increased catches even further. The ternary blend proved to be more attractive than beta-caryophyllene, 2-phenylethanol, or 3-methyl eugenol (compounds previously described as attractants for chrysopids) on their own, and no influence on catches was recorded when these compounds were added as fourth components to the ternary blend. There were minimal changes in activity when (E)-cinnamaldehyde or methyl anthranylate (both evoking large responses from female or male antennae of C. carnea in this study) were added, although both compounds showed significant attraction on their own when compared to unbaited traps. In subtractive field bioassays with the ternary mixture, it appeared that the presence of either phenylacetaldehyde or methyl salicylate was important, whereas acetic acid was less so in the ternary mixture. The ternary blend attracted both female and male lacewings at sites in southern, central, and northern Europe. Possible applications of a synthetic attractant for lacewings are discussed.

As the floral bait alone attracted both sexes of the carnea complex, it showed potential to manipulate the location of larval density via altering the site of oviposition. Aphid sex pheromone compounds alone attracted predatory males of Chrysopa spp. and can potentially be used to enhance biological control of aphids. For the carnea complex, however, a combination of both baits is not advantageous because of the decrease in adults attracted. Assumptions of intraguild avoidance underlying this phenomenon are discussed.

No abstract

The variance in apple blossom weevil, Anthonomus pomorum L., populations was studied in two experimental orchards in Hungary. Over a 15 year period there were four peaks in abundance, at three to six year intervals. Blossom infestation was greatest in the six orchard rows closest to a mixed oak forest. Variance in percent blossoms infested was as great between adjacent branches as between branches on opposite sides of the tree. There was greater variance in infestation percent between adjacent trees than between clusters of trees in different parts of the orchard. There was a slight positive correlation (r = 0.18) between blossom density and the percent infested blossoms. A recommended sampling plan of three branches from ten trees would give a precision of ± 3 % infested blossoms with an error of 0.05. Sampling should be in a stratified random pattern with concentration of samples near the orchard edge, especially edges adjacent to forests. Zusammenfassung Untersuchungen über räumliche und zeitliche Variation von Apfelblütenstecher‐Populationen (Col., Curculionidae) und Empfehlungen für die stichprobenartige Probenahme In zwei ungarischen Versuchsgärten wurde die Variation von Apfelblütenstecher‐Populationen untersucht. In einem Zeitraum von 15 Jahren gab es vier Häufigkeitsspitzen, in drei‐ bis sechsjährigen Intervallen. Der Befall durch Anthonomus pomorum L. war in den sechs Obstbaumreihen, die einem Eichenmischbestand am nächsten standen, am höchsten. Der Unterschied zwischen dem prozentualen Anteil befallener Knospen war zwischen benachbarten Zweigen genauso groß wie zwischen Zweigen von entgegengesetzten Baumseiten. Der prozentuale Befallsunterschied zwischen benachbarten Bäumen war größer als zwischen Gruppen von Bäumen aus verschiedenen Teilen der Obstbaumplantage. Es konnte eine schwach positive Korrelation (r = 0.18) zwischen der Knospendichte und dem Knospenbefallsprozent festgestellt werden. Die empfohlene stichprobenartige Entnahme von drei Asten von zehn Bäumen bringt eine Genauigkeit von ± 3 % mit einem Fehler von 0,05. Die stichprobenartige Entnahme sollte nach einem zufällig gegliederten Muster erfolgen, wobei vor allem Bäume nahe dem Rand der Obstbaumplantagen und insbesondere solche, die an Wälder angrenzen, beprobt werden sollten.