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Ana Mabel Martínez - One of the best experts on this subject based on the ideXlab platform.
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Susceptibility of the Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae) to endemic isolates of Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae)
Journal of Pest Science, 2011Co-Authors: Jaime A. Ocampo-hernández, Patricia Tamez-guerra, Samuel Pineda, Fernando Tamayo-mejía, Ariel Guzmán-franco, José I. Figueroa La Rosa, Ana Mabel MartínezAbstract:Entomopathogenic fungi represent excellent candidates for biological insecticides. Among the many entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) is one of the most promising species. Here, we report the results of infection studies performed using four B. bassiana native isolates (Bb37, Bb38, Bb40, and Bb45) compared with the commercial product Mycotrol^® (strain GHA) on adult Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae), one of the most important pests of bean production in Mexico. First, single concentration (1 × 10^8 conidia mL^−1) assays were carried out using all isolates applied using an immersion method. Examinations at 10 days after inoculation indicated that isolates Bb37, Bb38, and Bb40 significantly reduced adult survival, causing 60–75% mortality compared to the commercial strain GHA (33%) and control (29%). Second, using two selected isolates (Bb37 and Bb40), the mean lethal concentration values (LC_50) were estimated for third instar larvae and adult E. Varivestis . The LC_50 values for Bb37 and Bb40 isolates decreased 5.26-fold and 3.19-fold, respectively, in third instars compared with adults. However, such difference for Bb40 isolate was not significant. Finally, an experiment, to compare the median survival time (MST) values between third instar and adult E. Varivestis , was conducted using Bb37 and Bb40 at 1 × 10^9 conidia mL^−1. MST values were significantly reduced against larvae (87 and 100 h) compared with adults (130 and 134 h) by Bb37 and Bb40, respectively. We conclude that native isolates of B. bassiana represent an important alternative for the control of E. Varivestis . However, to demonstrate its effectiveness under field conditions, detailed studies are needed.
H. Schmutterer - One of the best experts on this subject based on the ideXlab platform.
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die wirkung von rohpressaften und rohextrakten aus ajuga arten auf frasaktivitat und metamorphose von Epilachna Varivestis muls
Journal of Applied Entomology, 2009Co-Authors: H. Schmutterer, Gisela TervoorenAbstract:The effect of squeezed juices and crude extracts of Ajuga species on feeding activity and metamorphosis of Epilachna Varivestis (Col., Coccinellidae) The effect of fresh, squeezed plant juices and that of crude extracts from dried parts of Ajuga reptans and A. remota on the feeding activity and metamorphosis of Epilachna Varivestis was investigated by means of various testing methods. Squeezed plant juices and crude plant extracts cause a strong antifeedant effect. The causal agents are most probably ajugarins, at least in case of A. remota. Furthermore, the metamorphosis is strongly influenced by the extracts, leading to high larval and pupal mortalities, the appearance of pupal-adult specimens and of beetles showing more or less deformed wings. The growth-regulating effect is presumedly caused by ecdysoids, primarily ecdysterone. Zusammenfassung Die Wirkung von Pressaften aus frischen und von Rohextrakten aus getrockneten Teilen von Ajuga reptans und A. remota auf die Frasaktivitat und Metamorphose von Epilachna Varivestis wurde mit Hilfe verschiedener Testmethoden untersucht. Pressafte und Rohextrakte bewirken eine deutliche Frashemmung, die zumindest bei A. remota wahrscheinlich auf Ajugarine zuruckgefuhrt werden konnen. Auserdem wird die Metamorphose stark beeinflust, was zu hoher Larven- und Puppenmortalitat sowie zur Entstehung sog. pupal-adulter Tiere und zu Kafern mit mehr oder weniger stark deformierten Flugeln fuhrt. Die metamorphosestorende Wirkung ist mit groser Wahrscheinlichkeit auf die in den Ajuga-Arten enthaltenen Ecdysoide, insbesondere das Ecdysteron zuruckzufuhren.
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zur wirkung einiger reinfraktionen aus samen von azadirachta indica auf frasaktivitat und metamorphose von Epilachna Varivestis col coccinellidae
Journal of Applied Entomology, 2009Co-Authors: H. Schmutterer, Heinz RemboldAbstract:Effects of some pure fractions of extracts from neem (Azadirachta indica) seeds on feeding activity and metamorphosis of Epilachna Varivestis (Col. Coccinellidae) In a number of publications of various authors on the ingredients of neem tree (Azadirachta indica) seeds only azadirachtin was mentioned as an effective growth regulator in insects of various orders. This triterpenoid was also identified as a potent phagorepellent and sterilant. In the present investigation some fractions of extracts from neem seeds of West African origin (Togo) were purified. Four finally obtained pure fractions showed strong to very strong growth disruption effects in Epilachna Varivestis, a fifthone was somewhat less active. After uptake of the neem seed ingredients by feeding on treated bean leaves various more-or-less typical symptoms appeared in fourth instar larvae. They can be described as follows: Under the influence of fractions 18-79a I and 18-79a II the larvae gradually shriveled until they died; fraction 18-79b I caused blackish legs in the shriveling test insects. After the uptake of fractions 18-80b and 18-80d reddish-brown spots appeared in the dorso-lateral zones of the thorax. The larvae showing this type of symptoms were very large and died not before about three weeks after appearance of such spots. Only fraction 18-79a I showed obvious phagorepellent properties mainly during the first day of the so-called “petri dish test”. Fractions 18-79a I, 18-79a II and 18-80b also prevented moulting from the 3rd to the 4th instar larva even in very low concentrations. After uptake of fraction 18-79b I and 18-80d the majority of 3rd instar larvae was able to moult but the resulting 4the instar larvae refused to feed on untreated bean leaves and died some days afterwards. Zusammenfassung In bisherigen Veroffentlichungen uber Inhaltsstoffe aus Neem-(Azadirachta indica-) Samen wurde lediglich das Triterpenoid Azadirachtin als metamorphosestorender Stoff bei Insekten verschiedener Ordnungen erwahnt. Gleichzeitig wurde es als sehr wirksames Phagorepellent identifiziert. Eine von laufenden Biotesten begleitete Fraktionierung der Extrakte aus Neem-Samen westafrikanischer Herkunft ergab, das insgesamt vier stark bis sehr stark und ein weiterer, schwacher wirksamer Inhaltsstoff vorhanden sind, die tiefgreifende Einflusse auf die Metamorphose von Epilachna Varivestis ausuben konnen. An Viertlarven treten nach oraler Aufnahme der Wirkstoffe unterschiedliche, mehr oder weniger typische Symptome auf, die sich in drei Gruppen einteilen lassen: Bei den Reinfraktionen 18-79a I und 18-79a II schrumpfen die Testtiere allmahlich zusammen, bei 18-79b I werden vor dem Einschrumpfen des Korpers die Beine schwarz. Bei den Fraktionen 18-80b und 18-80d treten auf dem Thorax 1–4 rotbraune Flecke auf und die Larven sterben erst nach mehreren Wochen ab. Lediglich die Fraktion 18-79a I zeigt eine deutliche frasabschreckende Wirkung, besonders wahrend des 1. Versuchstages. Die Fraktionen 18-79a I, 18-79a II und 18-80b verhindern selbst in sehr niedriger Konzentration die Hautung von der L3 zur L4. Die Reinfraktionen 18-79b I und 18-80d konnen die Hautung zwar bei den meisten L3 nicht verhindern, doch sterben die L4 dann wenige Tage spater, meist ohne vorher noch Futter aufgenommen zu haben.
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azadirachtin a potent insect growth regulator of plant origin
Journal of Applied Entomology, 2009Co-Authors: H Rembold, G K Sharma, Ch Czoppelt, H. SchmuttererAbstract:Azadirachtin, a potent antifeedant and growth regulator from the neem tree, Azadirachta indica A. Juss, was tested against three holometabolous insects belonging to different orders: Mexican bean beetle, Epilachna Varivestis Muls.; Mediterranean flour moth, Ephestia kuehniella Zell.; and honeybee, Apis mellifera L. Different amounts of azadirachtin were either fed (E. Varivestis, fourth instar larvae) or topically applied (E. kuehniella, last larval instar, spinning stage; A. mellifera, third instar larvae) to the test insects. The larval development to adults was greatly reduced and the reduction was dose-dependent; pupal mortality was also observed. However, weight gains were comparable with control larvae, indicating no feeding inhibition. The strong effect of azadirachtin on larval-pupal and pupal-adult moults is interpreted as an interference with moulting hormone pools. Zusammenfassung Azadirachtin, ein starker Wachstumsregler pflanzlichen Ursprungs bei Insekten Azadirachtin ist ein starker Frashemmer und Wachstumsregler bei vielen Insekten. Es kommt als wichtigster aktiver Bestandteil im Samen des Neembaums, Azadirachta indica A. Juss, vor. Die reine Substanz wurde an drei holometabolen Insekten, die unterschiedlichen Ordnungen angehoren, auf seine fras- und entwicklungshemmende Wirkung gepruft: am mexikanischen Bohnenkafer, Epilachna Varivestis Muls., der Mittelmeer-Mehlmotte, Ephestia kuehniella Zell., und der Honigbiene, Apis mellifica L. Azadirachtin wurde in verschiedenen Dosen entweder verfuttert (E. Varivestis, viertes Larvenstadium) oder topikal appliziert (E. kuehniella, letztes Larvenstadium; A. mellifica, drittes Larvenstadium). Die Larvenentwicklung bis zum Adultstadium war reduziert, wobei Mortalitat auch im Puppenstadium beobachtet wurde. Der Gewichtszuwachs entsprach dem der Kontrolltiere und schliest eine Frashemmung aus. Die starke Wirkung von Azadirachtin auf die Larven-Puppen- und Puppen-Adult-Hautung wird als eine Storung des Hautungshormonpools interpretiert.
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Effect of Substituent and Ring Changes in Naturally Occurring Naphthoquinones on the Feeding Response of Larvae of the Mexican Bean Beetle, Epilachna Varivestis
Journal of Chemical Ecology, 1997Co-Authors: Marian Weissenberg, I. Schaeffler, M. Eliyahu, H. Schmutterer, M. Klein, Jan Meisner, K. R. S. AscherAbstract:Behavioral evaluation of the antifeedant effect of 10 naturally occurring 1,4-naphthoquinones on larvae of the Mexican bean beetle, Epilachna Varivestis Mulsant, was undertaken concurrently with that of a series of synthetic analogs and model compounds in order to assess structure–activity relationships. Plumbagin, 1,4-naphthoquinone, juglone, menadione, and naphthazarin, which were found to be active at 0.3% concentrations, were also bioassayed at 0.1, 0.05, and 0.01% at which concentration 1,4-naphthoquinone still retained some activity. The model studies suggest that two structural features might be operative independently against E. Varivestis : one consisting of a properly substituted naphthoquinone moiety and the other requiring a benzo- or naphthohydroquinone. Within the naphthoquinone group, the relative activity is determined by a substituent effect which is the outcome of a complex interplay of electronic, steric, electrochemical, and positional requirements. Among the model compounds, 2-chloro-3-amino-1,4-naphthoquinone and α-naphthylamine displayed appreciable activity even at 0.01% The results should enable selection of plant sources for naphthoquinones possessing larval inhibition properties.
Jaime A. Ocampo-hernández - One of the best experts on this subject based on the ideXlab platform.
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Susceptibility of the Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae) to endemic isolates of Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae)
Journal of Pest Science, 2011Co-Authors: Jaime A. Ocampo-hernández, Patricia Tamez-guerra, Samuel Pineda, Fernando Tamayo-mejía, Ariel Guzmán-franco, José I. Figueroa La Rosa, Ana Mabel MartínezAbstract:Entomopathogenic fungi represent excellent candidates for biological insecticides. Among the many entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) is one of the most promising species. Here, we report the results of infection studies performed using four B. bassiana native isolates (Bb37, Bb38, Bb40, and Bb45) compared with the commercial product Mycotrol^® (strain GHA) on adult Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae), one of the most important pests of bean production in Mexico. First, single concentration (1 × 10^8 conidia mL^−1) assays were carried out using all isolates applied using an immersion method. Examinations at 10 days after inoculation indicated that isolates Bb37, Bb38, and Bb40 significantly reduced adult survival, causing 60–75% mortality compared to the commercial strain GHA (33%) and control (29%). Second, using two selected isolates (Bb37 and Bb40), the mean lethal concentration values (LC_50) were estimated for third instar larvae and adult E. Varivestis . The LC_50 values for Bb37 and Bb40 isolates decreased 5.26-fold and 3.19-fold, respectively, in third instars compared with adults. However, such difference for Bb40 isolate was not significant. Finally, an experiment, to compare the median survival time (MST) values between third instar and adult E. Varivestis , was conducted using Bb37 and Bb40 at 1 × 10^9 conidia mL^−1. MST values were significantly reduced against larvae (87 and 100 h) compared with adults (130 and 134 h) by Bb37 and Bb40, respectively. We conclude that native isolates of B. bassiana represent an important alternative for the control of E. Varivestis . However, to demonstrate its effectiveness under field conditions, detailed studies are needed.
Daniel J Ballhorn - One of the best experts on this subject based on the ideXlab platform.
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Constraints of Simultaneous Resistance to a Fungal Pathogen and an Insect Herbivore in Lima Bean (Phaseolus lunatus L.)
Journal of Chemical Ecology, 2011Co-Authors: Daniel J BallhornAbstract:The existence of tradeoffs among plant defenses is commonly accepted, however, actual evidence for these tradeoffs is scarce. In this study, I analyzed effects of different direct defenses of wild lima bean plants ( Phaseolus lunatus ) that were simultaneously exposed to a fungal pathogen ( Colletotrichum lindemuthianum ) and an insect herbivore, the Mexican bean beetle ( Epilachna Varivestis ). Although plants were derived from spatially widely separated populations, I observed a common tradeoff between resistance to pathogens and herbivores. Plants with high levels of anti-herbivore defense (cyanogenesis) showed low levels of resistance to pathogens (polyphenol oxidase activity and phenolic compounds), and vice versa . Competition for resources generally is considered to be the basis for tradeoffs. However, I report direct inhibition of polyphenol oxidase by cyanide, making simultaneous expression of both defenses at high levels impossible. I argue that populations composed of individuals investing in one type of defense have an advantage in environments that periodically favor either pathogen or herbivore plant antagonists.
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Quantitative Variability of Direct Chemical Defense in Primary and Secondary Leaves of Lima Bean (Phaseolus lunatus) and Consequences for a Natural Herbivore
Journal of Chemical Ecology, 2008Co-Authors: Daniel J Ballhorn, Susann Schiwy, Manfred Jensen, Martin HeilAbstract:Ontogenetic variability in chemical plant defenses against herbivores is a common phenomenon, but the effects of this variability on herbivore–plant interactions are little understood. In a previous study on lima bean ( Phaseolus lunatus ), we found a trade-off between cyanogenesis, a direct defense, and the release of herbivore-induced volatile organic compounds (VOCs; mainly functioning as an indirect defense). Moreover, the expression of these two defenses could change during plant ontogeny. The present study aimed at elucidating whether such ontogenetic changes in plant defense can affect herbivore–plant interactions. We quantified feeding rates of a natural insect herbivore, the Mexican bean beetle ( Epilachna Varivestis ), on primary and secondary leaves of individual lima bean plants. These insects strongly preferred low cyanogenic primary leaves over high cyanogenic secondary leaves. Although weakly defended by cyanogenesis, lima beans’ primary leaves showed protein concentrations and photosynthetic activities that did not differ significantly from secondary leaves at the time of analysis. Based on our findings, we suggest that lima beans’ long-lived primary leaves function as efficient source organs, even beyond the stage of seedlings. This hypothesis may explain why primary leaves express a strong indirect defense by the release of herbivore induced VOCs.
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oviposition choice of mexican bean beetle Epilachna Varivestis depends on host plants cyanogenic capacity
Journal of Chemical Ecology, 2006Co-Authors: Daniel J Ballhorn, Reinhard LiebereiAbstract:The choice of insect females as to where to lay their eggs strongly affects progeny survival and, thus, fitness. We conducted choice experiments with female Mexican bean beetles, which were offered lima bean plants differing in their cyanogenic capacity (HCNc), i.e., in the intensity of hydrogen cyanide release per time unit from damaged plant tissue. Females preferred to lay their eggs on plants with low HCNc. In contrast, the mere concentration of cyanide-containing precursors (the cyanogenic potential, HCNp) did not affect oviposition choices. Plant cyanogenesis occurs after tissue damage, which brings specific β-glucosidases in contact with their substrates, cyanogenic glycosides, from which they are separated by compartmentation in the intact plant tissue. Plants commonly store toxic compounds in an inactive form. Our results demonstrate that for cyanogenesis, which is widespread in plants, it is the toxic product itself rather than the precursor that affects oviposition choices of a specialized herbivore.
José I. Figueroa La Rosa - One of the best experts on this subject based on the ideXlab platform.
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Susceptibility of the Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae) to endemic isolates of Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae)
Journal of Pest Science, 2011Co-Authors: Jaime A. Ocampo-hernández, Patricia Tamez-guerra, Samuel Pineda, Fernando Tamayo-mejía, Ariel Guzmán-franco, José I. Figueroa La Rosa, Ana Mabel MartínezAbstract:Entomopathogenic fungi represent excellent candidates for biological insecticides. Among the many entomopathogenic fungi, Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Clavicipitaceae) is one of the most promising species. Here, we report the results of infection studies performed using four B. bassiana native isolates (Bb37, Bb38, Bb40, and Bb45) compared with the commercial product Mycotrol^® (strain GHA) on adult Mexican bean beetle Epilachna Varivestis Mulsant (Coleoptera: Coccinellidae), one of the most important pests of bean production in Mexico. First, single concentration (1 × 10^8 conidia mL^−1) assays were carried out using all isolates applied using an immersion method. Examinations at 10 days after inoculation indicated that isolates Bb37, Bb38, and Bb40 significantly reduced adult survival, causing 60–75% mortality compared to the commercial strain GHA (33%) and control (29%). Second, using two selected isolates (Bb37 and Bb40), the mean lethal concentration values (LC_50) were estimated for third instar larvae and adult E. Varivestis . The LC_50 values for Bb37 and Bb40 isolates decreased 5.26-fold and 3.19-fold, respectively, in third instars compared with adults. However, such difference for Bb40 isolate was not significant. Finally, an experiment, to compare the median survival time (MST) values between third instar and adult E. Varivestis , was conducted using Bb37 and Bb40 at 1 × 10^9 conidia mL^−1. MST values were significantly reduced against larvae (87 and 100 h) compared with adults (130 and 134 h) by Bb37 and Bb40, respectively. We conclude that native isolates of B. bassiana represent an important alternative for the control of E. Varivestis . However, to demonstrate its effectiveness under field conditions, detailed studies are needed.