Cornel Adler

Bioactivity of fenchone and Plectranthus glandulosus oil against Prostephanus truncatus and two strains of Sitophilus zeamais

The toxic, repellent and reproduction inhibitory effects of Plectranthus glandulosus essential oil and one of its major compounds, fenchone, were evaluated against adult Prostephanus truncatus (Horn) and for two strains of Sitophilus zeamais Motschulsky from Cameroon and Germany. Maize grains were coated with the oil at 0, 10, 20, 40 and 80 μl/40 g grain and fenchone at 0, 20, 40, 80 and 120 μl/40 g grain. Mortality was assessed over a 7‐day period, followed by the determination of F1 progeny production. The repellence of the two products was evaluated at five rates (0.5, 1, 3, 5, 10 μl/half disc) in a choice bioassay on filter paper. The oil and fenchone caused significant dose‐dependent mortality to the three insects, with the oil achieving 100% and 90% mortality for the two S. zeamais strains and P. truncatus, respectively, within 1 day of exposure at the dosage of 80 μl/40 g grain. The insects were less susceptible to fenchone compared with the crude oil. The German strain of S. zeamais was susceptible to the oil than the Cameroonian strain. At the dosage of 20 μl/40 g grain, S. zeamais F1 progeny emergency was completely inhibited by the oil, while 80 μl/40 g grain treatment with fenchone prevented also insect emergence. Plectranthus glandulosus oil generally evoked a maximum per cent repellency of 100% for the three insects, but fenchone caused 55–60% to S. zeamais and 80% to P. truncatus. These results suggest that fenchone, though a major constituent of P. glandulosus oil, may only be a minor component of its bioactivity.

Tolerance of pupae and pharate adults of Callosobruchus subinnotatus Pic. (Coleoptera: Bruchidae) to modified atmospheres: a function of metabolic rate.

Three developmental stages (pupae, early pharate and late pharate adults) of Callosobruchus subinnotatus (Pic.) were investigated for their tolerance or susceptibility to four modified atmospheres. Two of these atmospheres were hypercarbic and two were hypoxic. The hypercarbic atmospheres were found to cause mortality earlier than hypoxic atmospheres. Late pharate adults died earlier than pupae or early pharate adults. Late pharate adults that survived the exposure took a longer time to eclose than the pupae or early pharate adult.Using high resolution microrespirometric techniques, it was possible to record the oxygen consumption rate and CO(2) output of different developmental stages in air. The metabolic rate was determined manometrically as the oxygen uptake rate at an ambient temperature of 25 degrees C. The oxygen uptake rate differed significantly between groups of 20 individuals of different stages (p<0.01; t-test). The lowest rate of oxygen uptake (510.6+/-52.2 &mgr;l g(-1) h(-1)) was recorded in pupae. Higher oxygen uptake rates were found in early pharate adults (668.4+/-45.6 &mgr;l g(-1) h(-1)) and late pharate adults (1171.2+/-45.0 &mgr;l g(-1) h(-1)), and adult beetles (1310.4+/-53.4 &mgr;l g(-1) h(-1)). The patterns of CO(2) release were similar to those of oxygen uptake. CO(2) release was highest in eclosed adults and late pharate adults followed by early pharate adults, and lowest in pupae. The mode of CO(2) release ranged from continuous CO(2) release in pupae to discontinuous CO(2) release in late pharate and eclosed adults. Thus, high metabolic rates, and perhaps, in conjunction with discontinuous CO(2) of late pharate adults are responsible for their higher susceptibility to modified atmospheres than pupae and early pharate adults.

Ancient symbiosis confers desiccation resistance to stored grain pest beetles

Microbial symbionts of insects provide a range of ecological traits to their hosts that are beneficial in the context of biotic interactions. However, little is known about insect symbiont‐mediated adaptation to the abiotic environment, for example, temperature and humidity. Here, we report on an ancient clade of intracellular, bacteriome‐located Bacteroidetes symbionts that are associated with grain and wood pest beetles of the phylogenetically distant families Silvanidae and Bostrichidae. In the saw‐toothed grain beetle Oryzaephilus surinamensis, we demonstrate that the symbionts affect cuticle thickness, melanization and hydrocarbon profile, enhancing desiccation resistance and thereby strongly improving fitness under dry conditions. Together with earlier observations on symbiont contributions to cuticle biosynthesis in weevils, our findings indicate that convergent acquisitions of bacterial mutualists represented key adaptations enabling diverse pest beetle groups to survive and proliferate under the low ambient humidity that characterizes dry grain storage facilities.

Behavioral responses of Callosobruchus maculatus to volatile organic compounds found in the headspace of dried green pea seeds

Abstract There is growing evidence that insects rely on chemical cues to locate food, hosts, predators, and potential mates. The pulse beetle Callosobruchus maculatus has been recognized for decades as the major post-harvest insect pest of legume seeds. In a previous study, we identified five volatile organic compounds in the headspace of dried green pea seeds as electroantennographically active in C. maculatus antennae: 1-pentanol, 1-octen-3-ol, (E)-2-octenal, nonanal, and 3-carene. Some of these compounds used individually elicited attraction toward C. maculatus adults. However, since volatile compounds are generally perceived by insects as blends, we hypothesized that C. maculatus might particularly show attraction to different mixtures of the aforementioned compounds. To test this, we examined the behavioral response of C. maculatus toward a quinary, a quaternary, two ternary, and three binary mixtures in a dual choice Y-tube olfactometer. The results seem to indicate that in a dual choice situation, the first choice made by the beetles is an indication of the attractive or repellent properties of the mixture tested. In most cases, a positive response of C. maculatus to the mixtures of volatiles was observed. Females were attracted to five mixtures, while males were attracted only to two binary mixtures consisting exclusively of aldehydes. The other mixtures caused C. maculatus to respond negatively, suggesting they were repellent. Further investigations with the attractive mixtures should be done in real storage conditions with the aim of developing a trap for the pulse beetle, C. maculatus.

Efficacy of Plectranthus glandulosus (Lamiaceae) and Callistemon rigidus (Myrtaceae) Leaf Extract Fractions to Callosobruchus maculatus (Coleoptera: Bruchidae)

As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, methanol crude extracts of Plectranthus glandulosus and Callistemon rigidus leaves were sequentially fractionated in hexane, chloroform, ethyl acetate, and methanol to establish the most active fraction(s) against Callosobruchus maculatus in cowpea. Cowpea seeds (25 g) were treated with 0.5, 1, 2, and 4 g/kg of extract to evaluate the contact toxicity and F1 progeny production of the beetles in the laboratory. Mortality was recorded 1, 3, and 7 d postexposure. P. glandulosus hexane fraction was more toxic than the other fractions recording 100% mortality at 4 g/kg, within 7 d with LC50 of 0.39 g/kg. Hexane fraction of C. rigidus showed superior toxicity, causing 100% mortality at 4 g/kg within only 1 d of exposure with LC50 of 1.02 g/kg. All the fractions greatly reduced progeny emergence, with C. rigidus hexane fraction being the best progeny inhibitor. Fractions of P. glandulosus and C. rigidus leaves had sufficient efficacy to be a component of storage pest management package for C. maculatus.

Efficacy of Calneem derived from Ghanaian neem seeds and seed oils from two locations in Cameroon against Sitophilus zeamais (Coleoptera: Curculionidae) on maize

Botanical insecticides are among the most promising alternatives to synthetic insecticides for stored product protection. Calneem oil from Ghana and local neem oils from two localities in northern Cameroon (Garoua and Maroua) were tested at 0 (untreated control), 2, 4, 6, 8 and 12 ml/kg, on the adult and immature stages of the maize weevil Sitophilus zeamais (Motschulsky), for mortality and reproduction inhibition. The neem oils from Cameroon were extracted using the traditional kneading method and a hydraulic press in the laboratory (refined). Maize grains were coated with the five neem seed oils (Calneem, Garoua traditional and refined, and Maroua traditional and refined, respectively) and adult mortality was recorded at 1, 3, 7 and 14 days after exposure. Within 1 day of exposure, the highest tested concentration (12 ml/kg) of Calneem, Garoua traditional, Garoua refined, Maroua traditional and Maroua refined oils caused similar weevil mortality of 86.3, 93.8, 93.8, 97.5 and 97.5%, respectively. The 24-h LC50 values for the oils in the same order were 7.0, 6.0,5.0, 5.0 and 4.8 ml/kg, respectively. The lowest (2 ml/kg) and highest (12 ml/kg) concentrations of the oils suppressed progeny production by over 80 and 98%, respectively. The oils arrested the development of the hidden eggs and immature stages in the maize grains. The results suggested that neem seed oils from different localities of northern Cameroon, irrespective of the method of extraction, were effective for the protection of stored maize against S. zeamais. The promotion of natural neem seed oils as stored grain protectants in Cameroon would boost food security, alleviate poverty and reduce environmental degradation.

Vorhabenbezeichnung: Vermeidung von Befall bei der Langzeitlagerung von Getreide

Zuwendungsempfanger: Julius Kuhn-Institut (JKI) ; Autoren: Dr. Cornel Adler, Dr. Agnes Moualeu, Dr. Jens Begemann (Max Rubner-Institut, MRI), Dr. Klaus Munzing (MRI), Dr. Tina Gasch, Rene Grunwald, Tobias Hoffmann, mit Unterstutzung durch Dr. Hartwig Schulz und Dr. Bernd Hommel

Robuste Klassifizierung von Lagerschädlingen anhand ihrer Geräuschsignatur - Grundlage für die Umsetzung eines akustischen Detektionsverfahrens

Die Daten der Vergleichsbetriebe stellen den Status quo im Pflanzenschutz in Deutschland dar. Der Behandlungsindex in Mohre und Frischkohl betrug im Durchschnitt der Jahre (2007-2014) bei 6,2 bzw. 9,2. Mohren wurden vorrangig mit Herbiziden und Frischkohl mit Insektiziden behandelt. Unter dem Aspekt des Pflanzenschutzes und zur Reduktion der Behandlungsintensitat mit Insektiziden kann Abbildung 1: Behandlungsindex der Herbizide (Herbizid-BI) in Abhangigkeit der Vorfrucht in den Vergleichsbetrieben fur Mohre, 2007-2014, in Deutschland, ungleiche Buchstaben symbolisieren signifikante Unterschiede (p<0,05), nBlattfrucht=58, nGemuse=28, nHalmfruchte=115 208 72. ALVA-Tagung, Seminarhotel Wesenufer, 2017 der Fruhkohlanbau empfohlen werden. Im Kohl- und Mohrenanbau konnen Halmvorfruchte Schadlingsbefall vorbeugen. Die Mittelaufwandmengen wurden vorrangig bei Herbizidanwendungen reduziert In beiden Kulturen wurden Abweichungen vom notwendigen Mas verzeichnet. Die Pflanzenschutzberatung sowie die regelmasige Durchfuhrung von Bonituren konnen Pflanzenschutzmittelanwendungen dem notwendigen Mas naher bringen und die Umsetzung des IPS in der Praxis verbessern. Fur die Ausschopfung nichtchemischer Masnahmen sind Praxisdemonstrationen und der intensive Austausch zwischen Wissenschaft und Praxis notig, genauso wie Forschungsforderung zur Entwicklung neuer und Optimierung bestehender integrierter Verfahren und neuer Wirkstoffe. Vorbildhaft wird der IPS von den Demonstrationsbetrieben u. a. in den Kulturen Mohre und Weiskohl, seit 2014 umgesetzt. Die Betriebe werden individuell und intensiv betraten, um Pflanzenschutzmittelanwendungen auf das notwendige Mas zu beschranken. Hierfur werden Bonituren unter Nutzung von Schadschwellen, Warndiensthinweisen und Monitoringverfahren durchgefuhrt.

Schädlingsdichte Getreidelagerung verhindert Insektenbefall inLangzeitlägern

Die Daten der Vergleichsbetriebe stellen den Status quo im Pflanzenschutz in Deutschland dar. Der Behandlungsindex in Mohre und Frischkohl betrug im Durchschnitt der Jahre (2007-2014) bei 6,2 bzw. 9,2. Mohren wurden vorrangig mit Herbiziden und Frischkohl mit Insektiziden behandelt. Unter dem Aspekt des Pflanzenschutzes und zur Reduktion der Behandlungsintensitat mit Insektiziden kann Abbildung 1: Behandlungsindex der Herbizide (Herbizid-BI) in Abhangigkeit der Vorfrucht in den Vergleichsbetrieben fur Mohre, 2007-2014, in Deutschland, ungleiche Buchstaben symbolisieren signifikante Unterschiede (p<0,05), nBlattfrucht=58, nGemuse=28, nHalmfruchte=115 208 72. ALVA-Tagung, Seminarhotel Wesenufer, 2017 der Fruhkohlanbau empfohlen werden. Im Kohl- und Mohrenanbau konnen Halmvorfruchte Schadlingsbefall vorbeugen. Die Mittelaufwandmengen wurden vorrangig bei Herbizidanwendungen reduziert In beiden Kulturen wurden Abweichungen vom notwendigen Mas verzeichnet. Die Pflanzenschutzberatung sowie die regelmasige Durchfuhrung von Bonituren konnen Pflanzenschutzmittelanwendungen dem notwendigen Mas naher bringen und die Umsetzung des IPS in der Praxis verbessern. Fur die Ausschopfung nichtchemischer Masnahmen sind Praxisdemonstrationen und der intensive Austausch zwischen Wissenschaft und Praxis notig, genauso wie Forschungsforderung zur Entwicklung neuer und Optimierung bestehender integrierter Verfahren und neuer Wirkstoffe. Vorbildhaft wird der IPS von den Demonstrationsbetrieben u. a. in den Kulturen Mohre und Weiskohl, seit 2014 umgesetzt. Die Betriebe werden individuell und intensiv betraten, um Pflanzenschutzmittelanwendungen auf das notwendige Mas zu beschranken. Hierfur werden Bonituren unter Nutzung von Schadschwellen, Warndiensthinweisen und Monitoringverfahren durchgefuhrt.

Akustische Früherkennung von Schadinsekten in Vorräten (InsectTap)

Die Daten der Vergleichsbetriebe stellen den Status quo im Pflanzenschutz in Deutschland dar. Der Behandlungsindex in Mohre und Frischkohl betrug im Durchschnitt der Jahre (2007-2014) bei 6,2 bzw. 9,2. Mohren wurden vorrangig mit Herbiziden und Frischkohl mit Insektiziden behandelt. Unter dem Aspekt des Pflanzenschutzes und zur Reduktion der Behandlungsintensitat mit Insektiziden kann Abbildung 1: Behandlungsindex der Herbizide (Herbizid-BI) in Abhangigkeit der Vorfrucht in den Vergleichsbetrieben fur Mohre, 2007-2014, in Deutschland, ungleiche Buchstaben symbolisieren signifikante Unterschiede (p<0,05), nBlattfrucht=58, nGemuse=28, nHalmfruchte=115 208 72. ALVA-Tagung, Seminarhotel Wesenufer, 2017 der Fruhkohlanbau empfohlen werden. Im Kohl- und Mohrenanbau konnen Halmvorfruchte Schadlingsbefall vorbeugen. Die Mittelaufwandmengen wurden vorrangig bei Herbizidanwendungen reduziert In beiden Kulturen wurden Abweichungen vom notwendigen Mas verzeichnet. Die Pflanzenschutzberatung sowie die regelmasige Durchfuhrung von Bonituren konnen Pflanzenschutzmittelanwendungen dem notwendigen Mas naher bringen und die Umsetzung des IPS in der Praxis verbessern. Fur die Ausschopfung nichtchemischer Masnahmen sind Praxisdemonstrationen und der intensive Austausch zwischen Wissenschaft und Praxis notig, genauso wie Forschungsforderung zur Entwicklung neuer und Optimierung bestehender integrierter Verfahren und neuer Wirkstoffe. Vorbildhaft wird der IPS von den Demonstrationsbetrieben u. a. in den Kulturen Mohre und Weiskohl, seit 2014 umgesetzt. Die Betriebe werden individuell und intensiv betraten, um Pflanzenschutzmittelanwendungen auf das notwendige Mas zu beschranken. Hierfur werden Bonituren unter Nutzung von Schadschwellen, Warndiensthinweisen und Monitoringverfahren durchgefuhrt.