Storage conditions and storage pests in grain stores of ecological farming in Baden-Württemberg

Im Ökologischen Landbau sind zur Bekämpfung von Schädlingen nur umweltfreundliche Methoden erlaubt. Entsprechend gibt es eine Reihe von etablierten biologischen oder physikalischen Methoden zum Schutz von Nutzpflanzen auf dem Acker oder in Gewächshäusern. Nutzpflanzen sind aber auch nach der Ernte im Vorratslager und bei der Verarbeitung von Schädlingen bedroht. In diesem Bereich gibt es allerdings nur wenige etablierte umweltfreundliche Bekämpfungsverfahren. Dazu zählen die Bekämpfung von Motten in Vorratslagern, Bäckereien und Haushalten mit Wespen der Gattung Trichogramma (SCHÖLLER & PROZELL 2003) und die kürzlich eingeführte Kontrolle des Kornkäfers Sitophilus granarius L. mit der Lagererzwespe Lariophagus distinguendus FÖRSTER (STEIDLE & REICHMUTH 2003). Ein Problem bei der Entwicklung neuer, umweltfreundlicher Methoden der Schädlingsbekämpfung im Vorratsschutz besteht darin, dass nur wenig über die Bedingungen bekannt ist, unter denen die Lagerung stattfindet. Um diese Wissenslücke zu schließen, wurden die Lagerbedingungen im Ökologischen Landbau am Beispiel von Getreidelagern in Baden-Württemberg untersucht. Im Mittelpunkt standen die Art und die Größe der Lagerstrukturen, die eingelagerten Güter, die Identität der vorherrschenden Schädlinge sowie die momentan durchgeführten Maßnahmen zur Befallsvorsorge und Schädlingsbekämpfung.As basic requirement for the development of environmentally friendly methods of pest control, storage conditions were determined in grain stores of ecological farming in Baden-Württemberg / Southern Germany. The survey reveals that many different types of storage devices are used, with capacities ranging from 25 kg to 550 t. The main storage commodities are different types of grain with wheat, triticale and German wheat being most abundant. Almost all stores contained storage pests. Granary weevils and Indian meal moth were found to be the most abundant primary pests. Important secondary pests were mites, psocids, Cryptolestes sp. and Oryzaephilus surinamensis. The implications of the results are discussed with respect to the biological control of pests in grain stores

Some like it hot – some not: Differences in temperature preference of two parasitic wasp species

Insect pests not only cause damage to crops in the field but also to stored products. One of the major pests in stored grain in Europe is the granary weevil Sitophilus granarius (L.). The most commonly used biocontrol agent against this and other pests developing inside kernels or cocoons is Lariophagus distinguendus (Förster) a parasitic wasp belonging to the family of Pteromalidae. Another parasitic wasp of that family is Anisopteromalus calandrae (Howard). Even though the two wasp species show very similar host finding and parasitisation behaviour, field experiments reveal that L. distinguendus and A. calandrae have different temperature requirements. Whereas parasitisation in L. distinguendus can already be observed at weekly mean temperatures of 9°C to 10°C, A. calandrae needs weekly mean temperatures of at least 11°C to 12°C. On the other hand, L. distinguendus is affected by high temperatures more easily than A. calandrae. Laboratory experiments under different constant temperatures confirm this finding. These findings suggest a temperature dependent release of either L. distinguendus or A. calandrae. At mean temperatures below 19°C, L. distinguendus should be used, at higher temperatures A. calandrae performs better

Pheromone glands in the click beetle genus Athous (Elateridae)

Sexualpheromone sind im gesamten Tierreich weit verbreitet. Vor allem Insekten nutzen diese Art der Partnerfindung. Im Vergleich zu vielen Insektenarten, bei welchen die Art der pheromonbildenden Drüsenzellen, ihre Lage im Körper sowie die chemische Zusammensetzung ihrer Pheromone identifiziert wurde (s. Review von Blomquist & Vogt 2003) ist bei Schnellkäfern (Elateridae) noch sehr wenig bekannt. Die verschiedenen mitteleuropäischen Schnellkäferarten lassen sich anhand ihrer Pheromonspeicherung in zwei unterschiedliche Gruppen unterteilen. Die Weibchen der Unterfamilie Elaterinae, besitzen im letzten von außen sichtbaren Abdominalsegment ein paariges Drüsenreservoir in welchem das produzierte Sexualpheromon gespeichert wird. Im Gegensatz dazu fehlt bei den Weibchen der übrigen Unterfamilien ein solches Pheromonreservoir und es ist unklar, wo bei diesen Arten die Pheromone produziert werden. Beobachtungen von Ivastschenko & Adamenko (1980) deuten darauf hin, dass sich bei diesen Arten die pheromonproduzierenden Zellen im Bereich der Intersegmentalmembran zwischen dem Abdominalsegment VIII und IX befinden. Um zu klären, ob die Pheromondrüsen tatsächlich in diesem Bereich zu finden sind, wurden im Rahmen der vorliegenden Arbeit die Intersegmentalmembranen bei Weibchen und Männchen von Athous haemorrhoidalis und A. subfuscus auf mögliche Drüsenzellvorkommen untersucht.Although it is well known, that click beetles (Elateridae) use pheromones to find their mating partners, only from 10 out of approximately 170 Elateridae species in Central Europe sexual pheromones have been identified. This was successful only with members of the subfamily Elaterinae, where females have an adenoid pheromone reservoir in the abdominal tip. However, all other subfamilies which represent the majority of all Central European click beetle species do not posses such a reservoir. In this study we examine the hypothesis that in these species pheromone glands have no reservoir and are situated on the intersegmental membrane between the 8th and 9th abdominal segment. Using REM, a large number of type III gland cells were found in this area in females of Athous haemorrhoidalis und A. subfuscus. In males these glands are absent. Together with literature data this strongly suggests that these glandular structures represent the source of the sexual pheromones in the genus Athous

Potential of the parasitic wasp Lariophagus distinguendus (FÖRSTER) (Hymenoptera: Pteromalidae) to control the tobacco beetle Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

Die Lagererzwespe Lariophagus distinguendus ist eine generalistische Parasitoidenart, welche die Larven von mindestens 11 verschiedenen Käferarten parasitiert. Die Wirte leben alle entweder endophytisch in Samen oder in Kokons (STEIDLE & SCHÖLLER 1997). Bei der Parasitierung stechen die Weibchen die Samen oder Kokons an und legen jeweils ein Ei an die Außenseite der Wirtslarve (Abb. 1). Die Parasitioidenlarve frisst von außen an dem Wirt, der dabei abgetötet wird. Die Parasitoidenlarve verpuppt sich im Samen oder Kokon, aus dem schließlich eine erwachsene Wespe schlüpft. ...Lariophagus distinguendus (FÖRSTER) (Hymenoptera: Pteromalidae) is a parasitoid of larvae and pupae of a number of beetle species that are pests of stored products. For biological control of the granary weevil Sitophilus granarius (L.) (Coleoptera: Curculionidae) L. distinguendus is currently commercially available in Germany. To study the ability of this strain to parasitize the tobacco beetle and develop on this host, pairs of L. distinguendus were offered larvae of the tobacco beetle of three different age classes. The results reveal that L. distinguendus is able to develop on larvae of the tobacco beetle. Obviously, the oldest larval stage of the beetle is most suitable for development. This makes the strain of L. distinguendus utilised in this experiment generally suitable for the biological control of the tobacco beetle

Einfluss von Extremtemperaturen in Getreidelagern auf die Parasitierungsleistung von Nützlingen im Vorratsschutz

The application of parasitic wasps against stored pests is a common method for the protection of stored products in ecological farming. Temperature measurements in stores show that there are extreme temperatures during a year (extreme cold/hot). Field tests were made to show the influence of these extreme temperatures on the parasitation ability of beneficial insects

Sexy Mouth Odour? Male Oral Gland Pheromone in the Grain Beetle Parasitoid Lariophagus distinguendus (Förster) (Hymenoptera: Pteromalidae)

Throughout the animal kingdom, sexual pheromones are used for the attraction of mates and as courtship signals but also enable sexual isolation between species. In the parasitic wasp Lariophagus distinguendus, male courtship behaviour consisting of wing fanning, antennal stroking of the female antenna, and head nodding stimulates female receptivity leading to copulation. Recently L. distinguendus was reported to consist of two different lineages, which are sexually isolated because males fail to elicit receptivity in foreign females. It is unclear, however, which part of the courtship behaviour triggers female receptivity and therefore could be a mechanism causing sexual isolation. Here we show that in L. distinguendus a nonvolatile male oral pheromone is essential to release the female receptivity signal. In contrast, male wing fanning and antennal contact play a minor role. Additionally, the composition of the oral pheromone depends on the developmental host and females learn the composition upon emergence from the host substrate. These results will enable more detailed work on oral sexual pheromones to answer the question of how they are involved in the speciation process of L. distinguendus and other parasitoid species, for a better understanding of the huge biodiversity in this group

The Tergal Gland Secretion of the Two Rare Myrmecophilous Species Zyras collaris and Z. haworthi (Coleoptera: Staphylinidae) and the Effect on Lasius fuliginosus

The beetle species Zyras collaris and Z. haworthi belong to the rove beetle tribe Myrmedoniini (Staphylinidae: Aleocharinae), which comprises many myrmecophilous species. Due to their rareness, it is unknown how the two species interact with their host ants. GC-MS analyses revealed that both species release α-pinene, β-pinene, myrcene and limonene from their defensive tergal glands. This composition of tergal gland secretion is unique within the subfamily Aleocharinae. In biotests, Lasius fuliginosus ants showed increased antennation towards filter paper balls treated with mixtures of these substances in natural concentrations. Because these monoterpenes are also present in some aphid species which are attended by ants, we hypothesize that Zyras beetles mimic the presence of aphids and thereby achieve acceptance by their host ants

Sex pheromone of the rare click beetle Betarmon bisbimaculatus

The click beetle Betarmon bisbimaculatus (Fabricius, 1803) (Coleoptera: Elateridae) has a scattered distribution throughout a large area in Europe and the near East. Due to its scarcity, little is known about the ecology, biology, and development of this peculiar species. Here, we studied the composition of the female-released sex pheromone of B. bisbimaculatus. Neryl hexanoate, neryl octanoate, and neryl decanoate, in a ratio of approximately 3:1:6, were the only volatile compounds present in the extracts of pheromone glands. A synthetic mixture of all three compounds in the natural ratio was highly attractive to males in field traps. When the compounds were tested individually, only traps baited with neryl hexanoate were attractive, but they caught only a sixth of the males compared to the mixture. Based on the similarity of their sex pheromones, we propose that the tribe Pomachiliini with B. bisbimaculatus is closely related to the tribe Agriotini. This study shows the potential of sex pheromone studies for monitoring of rare and threatened insects as well as for elucidating phylogenetic relationships