Effects of azadirachtin on levels of ecdysteroids and prothoracicotropic hormone-like activity in Heliothis virescens (Fabr.) larvae

Barnby, Mark A.; Klocke, James A.

doi:10.1016/0022-1910(90)90183-g

Cited by 62 publications

(48 citation statements)

References 23 publications

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“…Azadirachtin has sterilizing activity among different insect species 29,30 . This effect is generally attributed to disturbances in the synthesis or release of hormones or neurohormones involved in the insect reproduction 31,32 . In bumblebees, as well as in distinct insect species, juvenile hormone (JH) and ecdysteroids are the main hormones linked to the behavioural and physiological aspects of the reproduction 33,34 .…”

Section: Discussionmentioning

confidence: 99%

Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae)

et al. 2014

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Background: Lethal and sublethal effects of azadirachtin were studied on Bombus terrestris via oral exposure in the laboratory to bring out the potential risks of the compound to this important pollinator.Results: Microcolonies chronically exposed to azadirachtin via treated sugar water during 11 weeks in the laboratory exhibited a high mortality ranging from 32 to 100 % with a range of concentrations between 3.2 and 320 mg litre , azadirachtin significantly inhibited the egg laying and, consequently, the production of drones during 6 weeks. When azadirachtin was tested under an experimental setup in the laboratory where bumblebees need to forage for food, the sublethal effects were stronger as the numbers of drones were reduced already with a concentration of 0.64 mg litre -1 . Besides, a negative correlation was found between the body mass of male offspring and azadirachtin concentration.Conclusion: Azadirachtin can affect B. terrestris with a range of sublethal effects. This study confirms the need to test compounds on their safety, especially when they have to perform complex tasks such as foraging.

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Section: Discussionmentioning

confidence: 99%

Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae)

et al. 2014

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“…Its antifeedant mode of action is effected through contact chemoreception (primary antifeedancy) and internal feedback mechanisms (secondary antifeedancy) (Schmutterer, 1985). Growth regulatory and sterilant effects, caused mainly by alterations to ecdysteroid and juvenile hormone titres, are the result of blockage of release of morphogenetic peptides (Redfern et al, 1982;Sieber & Rembold, 1983;Mordue (Luntz) et al, 1986;Rembold et al, 1987;Barnby & Klocke, 1990). There may also be direct effects of azadirachtin upon tissues such as muscle, gut epithelia and cells undergoing mitosis which lead to a general loss of fitness and which may also contribute to secondary antifeedant effects (Mordue (Luntz) & Blackwell, 1993;Nasiruddin & Mordue (Luntz), 1993).…”

Section: Introductionmentioning

confidence: 99%

Differential thresholds of azadirachtin for feeding deterrence and toxicity in locusts and an aphid

Mordue

Nisbet

Nasiruddin

et al. 1996

Entomologia Exp Applicata

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“…Sesquiterpenoids are a structurally diverse class of isoprenoids found in plants, some fungi, and bacteria, but not in vertebrates, which have important implications in plantplant (1), plant-insect (2,3), and plant-pathogen (4,5) interactions. Despite an extensive appreciation for the structure-function relationships of plant sesquiterpenoids, the sesquiterpenoid biosynthetic pathway and its regulation are not well understood (4,6).…”

Section: Introductionmentioning

confidence: 99%

Gene family for an elicitor-induced sesquiterpene cyclase in tobacco.

Facchini

Chappell

1992

Proc. Natl. Acad. Sci. U.S.A.

237

174

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The initial step in the conversion of the isoprenoid intermediate farnesyl diphosphate to the sesquiterpenoid phytoalexin capsidiol in elicitor-treated tobacco tissues is catalyzed by an inducible sesquiterpene cyclase [5-epiaristolochene synthase (EAS)]. Two independent cDNA clones (cEAS1 and cEAS2) encoding EAS were isolated from an elicitor-induced tobacco cDNA library by differential hybridization and subsequently were characterized by hybrid selection-in vitro translation. Insertion of cEAS1, a partial cDNA clone encoding 175 C-terminal amino acids, into an Escherchia coli expression vector resulted in accumulation of a fusion protein immunodetectable with EAS-specific polyclonal antibodies. The cDNA clones were used to isolate two full-length EAS genes that mapped 5 kilobases (kb) apart on one 15-kb genomic clone. The nucleotide sequences of the structural gene components were identical from 388 base pairs (bp) upstream of the transcription initiation site to 40 bp downstream of the translation termination codon, suggesting a relatively recent duplication event. The genes consist of 1479-bp open reading frames, each containing five introns and specifying 56,828-Da proteins. The N-terminal amino acid sequence deduced from the genomic clones was identical to the first 16 amino acids of the EAS protein identifuible by Edman degradation. RNA blot hybridization with cEAS1 demonstrated a mRNA induction time course consistent with the induction of the EAS mRNA translational activity with maximum levels 4-6 h after elicitation. EAS mRNA was not detected in control cells. DNA blot-hybridization analysis of genomic DNA revealed a copy number of '12-15 for EAS-like genes in the tetraploid tobacco genome. The conservation of a putative allelic prenyl diphosphate binding motif is also discussed.Sesquiterpenoids are a structurally diverse class of isoprenoids found in plants, some fungi, and bacteria, but not in vertebrates, which have important implications in plantplant (1), plant-insect (2, 3), and plant-pathogen (4, 5) interactions. Despite an extensive appreciation for the structure-function relationships of plant sesquiterpenoids, the sesquiterpenoid biosynthetic pathway and its regulation are not well understood (4, 6). Although many enzymes of general isoprenoid biosynthesis have been measured in plants, few enzymes suspected of being rate-limiting have been identified (4, 6). Moreover, little is known about the mechanisms regulating the activity and absolute levels of plant isoprenoid biosynthetic enzymes with the exception of a diterpene cyclase (7). This is in contrast to the extensive molecular analysis of regulatory mechanisms controlling isoprenoid metabolism in mammalian systems (8).Tobacco cell suspension cultures respond to treatment with elicitors such as fungal cell wall hydrolysates or cellulase by the de novo synthesis and secretion of antibiotic sesquiterpenoids, primarily the phytoalexin capsidiol (9, 10). Central to capsidiol biosynthesis is the induction of a sesquiterpene cyclase [5-epi...

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Effects of azadirachtin on levels of ecdysteroids and prothoracicotropic hormone-like activity in Heliothis virescens (Fabr.) larvae

Cited by 62 publications

References 23 publications

Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae)

Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae)

Differential thresholds of azadirachtin for feeding deterrence and toxicity in locusts and an aphid

Gene family for an elicitor-induced sesquiterpene cyclase in tobacco.

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