Wireworms of Agriotes lineatus, A. obscurus, A. sputator and A. sordidus were exposed to insecticide treated soil using two different control methods. One method consisted of a spray application of ...insecticides at doses of 50, 100, 200, and 300 g a.i. per ha. The other method consisted of a bait treatment at doses of 0.01, 0.1, 1, and 10 g a.i. per ha. Four insecticides were tested: fipronil and the neonicotinoids thiamethoxam, imidacloprid and clothianidin. In the soil treatment trial, chlorpyrifos was added as a reference treatment. The two test methods were conducted at different dates on the various species, but in equally controlled conditions. Mortality was observed after one and two (bait treatment) or three (soil treatment) weeks of exposure. Fipronil was highly lethal to each of the wireworm species tested, regardless of the method used. In general, mortality was higher compared to the neonicotinoids tested, the latter showing low or no mortality at the given dose and exposure variants. Applying fipronil in a bait formulation may decrease the amount of active ingredient per ha considerably, therefore baits may have important environmental benefits.
Efficacité des insecticides par contact ou absorption orale contre quatre espèces de larves de taupins Agriotes en conditions contrôlées
Des larves de taupins appartenant à Agriotes lineatus, A. obscurus, A. sputator et A. sordidus ont été exposées à du sol traité avec des insecticides en employant deux méthodes de lutte différentes. Une méthode consistait à pulvériser des insecticides à des doses de 50, 100, 200 et 300g de substance active par ha. L'autre méthode était de réaliser un traitement par appâtage à des doses de 0,01; 0,1; 1 et 10g de substance active par ha. Quatre insecticides furent testés: le fipronil et les néonécotinoïdes thiamethoxam, imidaclopride, et clothianidine. Dans l'essai de traitement du sol, du chlorpyrifos fut ajouté comme traitement de référence. Les deux méthodologies de test furent conduites à différentes dates sur les espèces différentes, mais dans des conditions contrôlées similaires. La mortalité a été observée au bout de une et deux semaines d'exposition (traitement par appâts) et trois semaines d'exposition (traitement du sol). Le fipronil était hautement létal pour chacune des espèces de taupins, quelle que soit la méthode utilisée. En général, la mortalité était plus élevée que pour les néonicotinoïdes testés, ces derniers ne provoquant peu ou pas de mortalité à la dose donnée, ainsi qu'aux différentes modalités d'exposition. L'application du fipronil au travers d'une formulation de type « appâts » peut permettre de diminuer considérablement la dose de substance active par ha, dès lors, les appâts peuvent avoir un impact environemental positif.
Эффeктивнocть инceктицидoв, вoздeйcтвyющиx кoнтaктнo и чepeз пoглoщeниe, в oтнoшeнии чeтыpex видoв Agriotes wireworm в yпpaвляeмыx ycлoвияx
Пpoвoлoчники Agriotes lineatus, A. obscurus, A. sputator и A. sordidus были пoдвepжeны вoздeйcтвию oбpaбoтaннoй инceктицидoм пoчвe, пpи этoм иcпoльзoвaлиcь двa paзличныx cпocoбa бopьбы. Oдин из ниx зaключaлcя в oпpыcкивaнии инceктицидaми в дoзax 50, 100, 200, и 300 г. д.в. нa гeктap. Дpyгoй зaключaлcя в пpeдcтaвлeнии oтpaвлeнныx пpимaнoк c дoзaми 0,01; 0,1; 1 и 10 г. д.в. нa гeктap. Были пoдвepгнyты пpoвepкe чeтыpe инceктицидa: фипpoнил и нeoникoтинoиды: тиaмeтoкcaм, имидaклoпpид и клoтиaдинин. B oпытax пo oбpaбoткe пoчвы xлopпиpoфoc дoбaвлялcя в кaчecтвe кoнтpoльнoй oбpaбoтки. Эти двa cпocoбa иcпытaний пpoвoдилиcь в paзличныe дни нa paзныx видax, нo в oдинaкoвo yпpaвляeмыx ycлoвияx. Cмepтнocть oпpeдeляли пocлe oднoй и двyx (oтpaвлeнными пpимaнкaми) или тpex (oбpaбoткa пoчвы) нeдeль экcпoзиции. Фипpoнил был выcoкo лeтaлeн пo oтнoшeнию к кaждoмy видy тecтиpoвaвшиxcя пpoвoлoчникoв, нeзaвиcимo oт пpимeняeмoгo cпocoбa. Кaк пpaвилo, лeтaльнocть былa вышe пo cpaвнeнию c тecтиpoвaвшимиcя никoтинoидaми, пpичeм пocлeдниe пoкaзывaли низкyю лeтaльнocть или ee oтcyтcтвиe в дaннoй дoзe и вapиaнтax экcпoзиции. Пpимeнeниe фипpoнилa в видe пpимaнoк пoзвoляeт знaчитeльнo cнизить кoличecтвo дeйcтвyющeгo вeщecтвa нa гeктap, cлeдoвaтeльнo, мoжнo cчитaть, чтo пpимaнки имeют бoльшoe пpeимyщecтвo для oкpyжaющeй cpeды.
In the forestry nurseries, biological material is often heavily damaged by a rich complex of pests thatattack in the soil, or at the level of soil. The purpose of this research was the monitoring of ...the populationstructure of click beetles (wireworms). The monitoring of the wireworms in the larval stage was done bythe method of catching the worms with baited traps. For the bait have been used plastic cups with wheatand barley seeds in the ratio of 1:1 to which was added 15% coniferous sawdust. The larvae capturedwere identified after some aspects of external morphology. In 2011 with the help of 20 traps during themonitoring period have been captured 69 larvae of Elateridae family which is an average of 3.45 larvae/ trap. The species captured were Agriotes lineatus L., Agriotes sputator L., Agriotes obscurus L., Agriotesustulatus Schall., Selatosomus aneus L., Athous niger L., Athous haemorrhoisdalis F., Athous subfuscus Mull.,Prosternon tesselatum L. and Lacon murinum L. but Agriotes lineatus L. was the dominant specie. Thenext dominant specie was Selatosomus aneus L., which participated with 18.9% in the Elateridae faunastructure (13 specimens were caught). In 2012 in the nursery were captured 93 larvae of Elateridaefamily (with 24 larvae more than the previous year, representing an increase by 34.8 captures). In bothexperimental years in the both monitoring locations, the dominant species was Agriotes lineatus L.
The presence of geranyl octanoate, previously found in pheromone gland extracts of Agriotes lineatus females, was also demonstrated in gland extracts of A. proximus females. Similar to A. lineatus, ...geranyl butanoate was present only in trace amounts in A. proximus female gland extracts. In air entrainment samples of female A. lineatus and A. proximus beetles, the relative ratio of geranyl butanoate and geranyl octanoate was higher than that in gland extracts. In addition, comparison of a segment of the mitochondrial cytochrome c oxidase subunit I gene of feral specimens of A. lineatus and A. proximus showed >99% similarity. Both pheromone profile and nucleotide sequence analysis delineate close relationship between the investigated taxa and postulate taxonomic revision. Further studies on sympatric populations of A. lineatus and A. proximus are underway to investigate and better understand possible processes of species diversification.
Root herbivores can have a positive or negative effect on the abundance and/or performance of foliar phytophages. In addition, abiotic factors such as drought can either strengthen or weaken this ...effect, depending on the system under investigation. One explanation for these varying responses lies in differences in the physiological response of host plants to drought and root herbivores. Here, the impacts of root phytophages on a leaf-mining species feeding on annual and perennial plant species (four
Sonchus species) were compared. The responses of plants and leaf-miners to drought and root herbivore treatments were not related to whether the host plant was an annual or perennial. However, where root feeders did affect foliar phytophage performance, this occurred only under a drought treatment, demonstrating the potential for climate change to alter the outcome of plant-mediated interactions.
Wurzelherbivoren können einen positiven, neutralen oder negativen Einfluss auf die Abundanz und/oder Performanz von Blattphytophagen ausüben. Zusätzlich können abiotische Faktoren, z.B. Trockenheit, diese durch die Pflanze vermittelten Interaktionen verstärken oder abschwächen. Eine Erklärung für diese unterschiedlichen Reaktionen liegt in den unterschiedlichen Reaktionen der Wirtspflanzen auf Trockenheit und Wurzelfresser.
Hier vergleichen wir Interaktionen zwischen Blatt- und Wurzelherbivoren (Minierfliegen bzw. Drahtwürmer), die an einjährigen und mehrjährigen Pflanzen (vier
Sonchus-Arten) fraßen. Die Reaktionen der Pflanzen auf Trockenheit und Wurzelfresser und die Ergebnisse der indirekten Interaktionen waren unabhängig davon, ob es sich um eine ein- oder mehrjährige Art handelte. Wenn indessen die Wurzelfresser die Performanz der Minierfliegen beeinflussten, so trat der Effekt nur in der Trockenheitsbehandlung auf. Dies zeigt, dass der Klimawandel potentiell das Resultat von pflanzenvermittelten Interaktionen verändern kann.
1 Wireworms, the soil dwelling larvae of click beetles, Agriotes spp., have recently become a more prevalent pest of potatoes. The present study investigated whether potato varieties showed variable ...susceptibility to wireworm herbivory, and also tested whether increased susceptibility was associated with lower concentrations of glycoalkaloids. Twelve varieties were originally screened across a range of experimental scales, including laboratory and tunnel experiments and a large‐scale field trial involving over 2000 tubers.
2 In laboratory no‐choice tests, Maris Peer, Marfona and Rooster varieties were significantly more susceptible to wireworm attack, with 63% of tubers showing damage, compared with just 15% of the less susceptible varieties of King Edward, Nadine and Maris Piper. There was also greater tissue consumption and weight gain when wireworms were reared on the most susceptible varieties.
3 In choice tests, wireworms showed a significant preference for those varieties previously identified as being the most susceptible to wireworm herbivory (4.2 holes per tuber) compared with the least susceptible (1.2 holes per tuber). Similar patterns of susceptibility were seen in the field trial, although there was generally more variation in susceptibility.
4 In a tunnel experiment, Marfona and Maris Peer were significantly more susceptibile to wireworm attack (47% of tubers showing damage) compared with Nadine, King Edward and Maris Piper (27% of tubers showing damage). Although Nadine, in particular, had the highest glycoalkaloid concentrations (309.33 mg/kg) and lowest amounts of wireworm herbivory, the relationship between susceptibility and glycoalkaloid concentrations was weak, suggesting that this is unlikely to be the sole mechanism underpinning varietal susceptibility.
Based on analysis of pheromone gland extracts, highly attractive new baits have been developed for three click beetle pests. That for Agriotes brevis is a mixture of geranyl butanoate and ...(E,E)-farnesyl butanoate, and that for A rufipalpis and A sordidus contains geranyl hexanoate alone. From known data from species populating Russia, optimized bait compositions for species in Central and Western Europe were developed as follows: geranyl octanoate + geranyl butanoate for A lineatus, geranyl isovalerate for A litigiosus, geranyl hexanoate + geranyl octanoate for A obscurus, geranyl butanoate alone for A sputator and (E,E)-farnesyl acetate alone for A ustulatus. Although slight differences were found in gland contents with A litigiosus var laichartingi and fenotypus typicus, nevertheless there were no differences in response to the optimum bait. There were no differences in pheromone composition or response to the optimized bait between the two morphological forms (‘black’ and ‘red’) of A ustulatus. As a result of these studies, highly effective pheromone baits are now available for monitoring and population reduction in all important pest click beetle species in Central and Western Europe.
A prototype ground-based pheromone trap design, baited with various pheromone lures, was field tested for effectiveness in trapping male Agriotes obscurus and Agriotes lineatus click beetles in ...British Columbia. Pheromone dispensers containing geranyl octanoate and geranyl hexanoate in a 1:1 ratio caught the greatest numbers of A. obscurus, whereas those containing geranyl octanoate and geranyl butanoate in a 9 or 10:1 ratio caught high numbers of A. lineatus. Some differences in A. obscurus attraction to traps were observed between dispensers according to the manufacturer and the number of dispensers deployed in traps. The trap design and optimal pheromone dispensers tested would be suitable for monitoring or surveying A. obscurus and A. lineatus populations in North America.
While testing traps baited with a blend of geranyl octanoate and geranyl butanoate (pheromone components previously identified for Agriotes lineatus, Coleoptera, Elateridae) in Portugal and Bulgaria, ...large numbers of the closely related Agriotes proximus were captured. In the literature, two different compounds, (E,E)-farnesyl acetate and neryl isovalerate had previously been identified as pheromone components of A. proximus. Subsequent field tests, conducted in several European countries, revealed that A. proximus was weakly attracted to geranyl butanoate on its own, while A. lineatus was weakly attracted to geranyl octanoate on its own. However, the largest catches for both species were observed with a blend of both compounds. No A. proximus was caught in traps baited with the blend of (E,E)-farnesyl acetate and neryl isovalerate at any of the test sites. In electroantennographic studies, antennae of male A. proximus and A. lineatus both gave greater responses to geranyl butanoate than to geranyl octanoate, suggesting that the perception of these two compounds was similar for both species. A 1:1 blend of geranyl octanoate and geranyl butanoate can be used as a bait in traps for the detection and monitoring of both A. lineatus and A. proximus in many European countries.
Larvae of
Agriotes obscurus L. and
A. lineatus L. were placed in tubs of soil collected from British Columbia (BC) and flooded with purified water for 4, 7, 11, 14, 18, 25, 39, or 53 days at 5, 10, ...15, or 20
°C. Wireworms submerged at high temperatures died more quickly than those submerged at low temperatures, and wireworms in flooded Delta soil died more quickly than those in flooded Agassiz soil. Soil analysis suggests that soil salinity may affect the effectiveness of flooding as a control strategy. Flooding in fall or summer (higher temperatures) would likely provide more effective control of wireworm populations than flooding in winter.
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