Insect Growth Regulatory Activity Research Articles

Insect growth inhibition by tocotrienols and hydroquinones from Roldana barba-johannis

The methanol extract from the aerial parts of Roldana barba-johannis (Asteraceae) afforded sargachromenol, sargahydroquinoic acid, and sargaquinoic acid. These natural products and their corresponding acetylated and methylated derivatives showed insecticidal and insect growth regulatory activities against the Fall Armyworm [ Spodoptera frugiperda J.E. Smith, (Lepidoptera: Noctuidae)], an important insect pest of corn. The most active compounds were sargachromenol and its acetylated derivative; sargahydroquinoic acid and its acetylated derivative; and a mixture of sargachromenol, sargahydroquinoic acid, and sargaquinoic acid (6:3:1) and the acetylated form of this mixture. All these compounds and mixtures had significant inhibitory effects between 5.0 and 20.0 ppm in diets. Most compounds were insecticidal to larvae, with lethal doses between 20 and 35 ppm. In addition, these substances also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl radical in TLC autographic and spectrophotometric assays. These compounds appear to have selective effects on the pre-emergence metabolism of the insect. The results from these compounds were fully comparable in activity to those known natural insect growth inhibitors such as gedunin and methanol extracts of Cedrela salvadorensis and Yucca periculosa. These substances may be useful as natural insecticidal agents.

Antioxidant and insect growth regulatory activities of stilbenes and extracts from Yucca periculosa

The methanol extract from the bark of Yucca periculosa F. Baker afforded 4,4′-dihydroxstilbene, resveratrol and 3,3′,5,5′-tetrahydroxy-4-methoxystilbene and had growth regulatory activity against the Fall Army worm ( Spodoptera frugiperda J.E. Smith, Lepidoptera:Noctuidae) an insect pest of corn. The most active compound was 3,3′,5,5′-tetrahydroxy-4-methoxystilbene which had significant effects at 3 μg/g in diets. In addition to the inhibitory activity on bleaching of crocin induced by alkoxyl radicals, these compounds also demonstrated scavenging properties toward 2,2-diphenyl-1-picrylhydrazyl in TLC autographic and spectrophotometric assays. Our results indicate that these compounds could be involved in interference of sclerotization and moulting. These compounds appear to have selective effects on the pre-emergence metabolism of the insect. The results were fully comparable to known natural insect growth inhibitors such as gedunin and Cedrela extracts and have had a possible role as natural insecticidal agents.

Photostabilizers for Azadirachtin‐A (A Neem‐Based Pesticide)

Photostability of azadirachtin‐A (a neem based pesticide) has been studied without and with adding stabilizers such as ter. butyl‐p‐cresol, 8‐hydroxy quinoline and ter. butyl hydroquinone as thin film on glass surface and on leaf surface under sunlight and UV light. Half‐life of azadirachtin has been found to be 48 min and 3.98 days as thin film under UV light and sunlight and 2.47 days on leaf surface, respectively. 8‐Hydroxy quinoline and ter. butyl hydroquinone have been found effective in controlling degradation of azadirachtin under both sunlight and UV light with half‐life of 44.42 and 35.90 days under sunlight, and 55.80 and 48.50 h under UV light, respectively. Whereas ter. butyl‐p‐cresol has been found effective A only under sunlight. Significant decreases in antifeedant and insect growth regulatory activity against third instar larvae of Spodoptera litura has been observed with azadirachtin when exposed to sunlight and UV light. However, by the addition of above stabilizers, the biological activity of azadirachtin‐A has been retained even after 24 h of irradiation under UV light and up to 30 days of exposure to sunlight.

Insect antifeedant and growth regulating activities of quassinoids from Samadera indica

Four quassinoids, indaquassin C (1), samaderins C (2), B (3) and A (4), isolated from the seeds and bark of Samadera indica, were tested for insect antifeedant and growth regulatory activities against the tobacco cutworm, Spodoptera litura. Indaquassin C was the most effective antifeedant. Samaderin C increased pupal duration and induced pupal mortality.

Insect growth inhibition, antifeedant and antifungal activity of compounds isolated/derived from Zingiber officinale Roscoe (ginger) rhizomes.

Fresh rhizomes of Zingiber officinale (ginger), when subjected to steam distillation, yielded ginger oil in which curcumene was found to be the major constituent. The thermally labile zingiberene-rich fraction was obtained from its diethyl ether extract. Column chromatography of ginger oleoresin furnished a fraction from which [6]-gingerol was obtained by preparative TLC. Naturally occurring [6]-dehydroshogaol was synthesised following condensation of dehydrozingerone with hexanal, whereas zingerone and 3-hydroxy-1-(4-hydroxy-3-methoxyphenyl)butane were obtained by hydrogenation of dehydrozingerone with 10% Pd/C. The structures of the compounds were established by 1H NMR, 13C NMR and mass (EI-MS and ES-MS) spectral analysis. The test compounds exhibited moderate insect growth regulatory (IGR) and antifeedant activity against Spilosoma obliqua, and significant antifungal activity against Rhizoctonia solani. Among the various compounds, [6]-dehydroshogaol exhibited maximum IGR activity (EC50 3.55 mg ml-1), while dehydrozingerone imparted maximum antifungal activity (EC50 86.49 mg litre-1).

Insect growth regulatory activity of naturally occurring quinones and their derivatives in Dysdercus koenigii Fabr. (Hem., Pyrrhocoridae)

Insect growth regulatory activity of naturally occurring quinones and their derivatives in Dysdercus koenigii Fabr. (Hem., Pyrrhocoridae)

Insect growth regulatory activity of naturally occurring quinones and their derivatives in Dysdercus koenigii Fabr. (Hem., Pyrrhocoridae)

Plumbagin, a naphthoquinone occurring in the plants belonging to Plumbago sp. is known to have insect growth disrupting activities. In the present study, a comparative evaluation of bioactivities of related naphthoquinones, juglone and menadione and benzoquinones, 2,6‐dimethylbenzoquinone and 2,3,6‐trimethylbenzoquinone along with 2,6‐dimethylhydroquinone have been undertaken using Dysdercus koenigii. The LD50 values of the compounds showed wide variation. Although all the test compounds disrupted the normal growth at sublethal doses, 2,6‐dimethylbenzoquinone and menadione showed activity at low doses.

Insect growth regulatory activity of some extracts and compounds from Parthenium argentatum on fall armyworm Spodoptera frugiperda.

The methanolic extract from aerial parts of Parthenium argentatum, afforded argentatin A and B. These compounds were evaluated for their effect on the fall armyworm (Spodoptera frugiperda). Toosendanin, a commercial insecticide derived from Melia azedarach was used as positive control. When tested for activity, using neonate larvae into the no-choice artificial diet bioassays, argentatin A, argentatin B and methanol extract caused significant growth inhibitory activity with GC50 of 17.8, 36.1 and 6.4 ppm at 7 days, respectively, and increased the development time of surviving larvae in a concentration-dependent manner with RGI values of 0.40, 0.60 and 0.26, at 25.0, 25.0 and 5.0 ppm, respectively. In addition, it was possible to observe in most of the treated groups a significant delay in the time of pupation, adult emergence and deformities. Acute toxicity against adults of S. frugiperda was also found, MeOH extract had the most potent activity with LD50 value of 3.10 ppm. In addition, MeOH extract and argentatin A caused acetylcholinesterase inhibition of 93.7% and 90.0%, at 5.0 and 50.0 ppm, respectively; whereas argentatin B had only slight inhibitory activity. Therefore, the MeOH extract was identified as insecticidal extract from P. argentatum with activity at concentrations above 15.0 ppm.

Synthesis and Quantitative Structure−Activity Relationships of New 2,5-Disubstituted-1,3,4-oxadiazoles

Fourteen new 2,5-disubstituted-1,3,4-oxadiazoles, namely (i) six 2-[2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropyl]-5-substituted-1,3,4-oxadiazoles and (ii) eight 2-substituted-phenoxymethyl-5-substituted-aryl-1,3,4-oxadiazoles, were synthesized and evaluated for their insect growth regulatory activity against second-instar larvae of armyworm (Pseudaletia separata Walker). Two of these compounds (7 and 8) showed good insecticidal activities, with LC(50) values of 14.33 and 15.85 microg/mL, respectively. Steric parameters (e.g., the molecular length d and the ratio of the nonpolar surface area and polar surface area V(1)/V(2)) and semiempirical quantum parameters (e.g., the molecular total energy E(t) and the lowest unoccupied molecular orbital energy E(LUMO) and so on) of these compounds, as well as those of six other 2,5-disubstituted-1,3,4-oxadiazoles reported, were acquired by the molecular modeling method and the PM3-SCF-MO method, respectively. With the help of the synthons' activity contribution method based on the Free-Wilson approach in its Fujita-Ban variant, quantitative structure-activity relationships were studied by regressing half-lethal concentrations against the above parameters.

Insect antifeedant and growth regulating activities of neem seed oil – the role of major tetranortriterpenoids

Abstract: An attempt was made to correlate insect antifeedant and growth regulatory activities of neem (Azadirachta indica) seed oil with the major tetranortriterpenoids. Selective elimination of triterpenoids by preparative high‐performance liquid chromatography, incorporation of the eliminated compounds in defined concentrations and bioassaying the resultant fractions against Spodoptera litura indicated the necessity to quantify major triterpenoids for correlation of bioactivity of neem oil.

Patterns of bioactivity and herbivory on Nothofagus species from Chile and New Zealand

Nothofagus species from Chile and New Zealand were surveyed in the field for invertebrate abundance and leaf feeding damage and in the laboratory for antifeedant activity against leafrollers (Ctenopsteustis obliquana, Epiphyas postvittana), deterrent activity against pea aphid (Acyrthosiphon pisum), insect growth regulatory activity (Oncopeltus fasciatus), nematicidal activity (Caenorhabditis elegans), antibiotic activity (Pseudomonas solanaciarium), and general toxicity. A data matrix indicated that N. alessandri and N. pumilio most likely have a chemical barrier to insect attack as leaves showed low faunal abundance, low herbivory, and activity in the leafroller antifeedant, aphid deterrent, and nematicidal assays. A chemical examination of N. alessandri that used the leafroller antifeedant test to guide the separation yielded an active fraction containing the flavonoid, galangin, and the stilbene, pinosylvin, which appear to act in concert to deter leafroller feeding. The discovery of the phytoalexin, pinosylvin, in the leaves, raises the possibility that Nothofagus in general, and N. alessandri in particular, may have induced chemical defense mechanisms.

The commercial use of azadirachtin and its integration into viable pest control programmes

With the continued robust growth of the global biopesticide market, azadirachtin is uniquely positioned to become a key insecticide to expand in this market segment. In the USA the actual or impending cancellation of some organophosphate and carbamate insecticides that have either lost patent protection or are not being re-registered in many markets because of the Food Quality Protection Act of 1996, has opened new opportunities for biopesticides and reduced-risk pesticides in general. The broad-spectrum activity of azadirachtin at low use rates (12·5 to 40 g AI ha-1) coupled with the insect growth regulator activity (in all larval/nymphal instars including the pupal stage) and unique mode of action (ecdysone disruptor), make azadirachtin an ideal candidate for insecticide resistance, integrated pest control and organic pest control programmes. Azadirachtin has been exempted from residue tolerance requirements by the US Environmental Protection Agency for food crop applications. Azadirachtin exhibits good efficacy against key pests such as whiteflies, leafminers, fungus gnats, thrips, aphids and many leaf-eating caterpillars. Azadirachtin has minimal to no impact on non-target organisms, is compatible with other biological control agents and has a good fit into classical Integrated Pest Management programmes. The world's largest azadirachtin extraction facility has been fully commissioned in India to process over 10,000 tonnes neem seeds per annum. This will ensure the wide availability of azadirachtin technical grade material in the future. © 1998 Society of Chemical Industry.

Synthesis and Insect Growth Regulatory Activity of Alkoxy-Substituted Benzaldoxime Ethers.

Alkoxy-substituted benzaldoxime ethers, namely (i) 3-methoxy-4-ethoxybenzaldoxime N-O-alkyl ethers, (ii) 3,4-dimethoxybenzaldoxime N-O-alkyl ethers, and (iii) 3,4-methylenedioxybenzaldoxime N-O-alkyl ethers, have been synthesized and evaluated for their insect growth regulatory activity against fifth-instar nymphs of the desert locust Schistocerca gregaria F. When injected into insect hemolymph at the lowest dose level of 3 µg/nymph, 3,4-methylenedioxybenzaldoxime N-O-methyl ether and 3,4-methylenedioxybenzaldoxime N-O-isopropyl ether showed 40 and 50% growth deformities respectively. On topical application (at 20 µg/nymph) 3-methoxy-4-ethoxybenzaldoxime N-O-methyl ether inflicted 100% abnormalties in insect growth. Structure-activity relationship studies revealed that maximum activity was associated with compounds having three carbons in the oxime ether moiety.

Insect antifeedant and growth-regulating activities of Salannin and other c-seco limonoids from neem oil in relation to Azadirachtin

The antifeedant and insect growth-regulating activities of salannin, nimbin, and 6-deacetylnimbin, in comparison with azadirachtin-A, have been studied againstSpodoptera litura, Pericallia ricini, andOxya fuscovittata. Salannin deterred feeding, delayed molt by increasing larval duration, caused larval and pupal mortalities, and decreased pupal weights in the two lepidopterans. Salannin also caused molt delays and nymphal mortalities inOxya fuscovittata. The role of salannin and other compounds in conferring bioactivity, along with azadirachtin-A, to neem oil/neem seed extracts is emphasized.

Structure-related insect antifeedant and growth regulating activities of some limonoids

Insect antifeedant and growth-regulating activities of 22 limonoids (both natural and their derivatives) againstSpodoptera litura were studied to understand the structure-related bioactivities of the limonoids. The C-seco limonoids (azadirachtins A, B, D, H, and I) were the most effective compounds as a group, while the intact limonoids (cedrelone and its derivatives) were the least effective. The cyclohexenone A ring and theα-hydroxy enone group in the B ring appear to be important for antifeedant activity. The presence of a cyclohexenone or 1,2-epoxide in the A ring coupled with anα-hydroxy enone in the B ring correlated well with growth regulatory activity. An acetoxy at C-7 instead ofα-hydroxy enone and perhaps the carbonyl at C-16 increase growth regulatory activity. Absence of 14-15 epoxide may not drastically reduce antifeedant activity and growth regulatory activity.

Susceptibility of neem to attack by the Formosan subterranean termite, Coptotermes formosanus Shir. (Isopt., Rhinotermitidae)

AbstractThe neem tree, Azadirachta indica, is a source of natural compounds with potent insecticidal, feeding deterrent and insect growth regulator activity. However, little information is available on the effects of these natural products on termites. We assessed the effects of mulches made from ground neem branches and roots on survival of the Formosan subterranean termite, Coptotermes formosanus, and compared termite feeding and survival on neem wood and bark to that on susceptible Pseudotsuga menziesii wood. Termite survival was fairly low in both P. menziesii heartwood and neem mulches over the 14 day test period, and did not differ significantly among those treatments. However, termites exposed to either P. menziesii wood, neem wood, or neem bark for 4 weeks fed significantly less on neem wood and bark. Feeding on neem bark caused significant termite mortality (56.4%) in comparison to that induced by feeding on neem wood (27.1%) or P. menziesii wood (12.5%). Thus, although neem is not entirely resistant to termite attack, the antifeedant properties of its wood and bark and the toxicity of neem bark support the use of neem trees for arboriculture in areas where termites are a problem.

Control of Soybean Looper with Experimental Chemistry in Louisiana, 1994

Abstract The efficacy of several experimental insecticides that consist of pyrrole or avermectin chemistry, or exhibit insect growth regulator activity were evaluated against the soybean looper (SBL) on soybean in a small plot insecticide screening trial at the Macon Ridge Branch of the Northeast Research Station near Winnsboro, Louisiana. Activity of these materials was compared to that of the standard recommended insecticide Larvin at 0.6 lb (AI)/acre. Plots measured 50 ft by 5 rows (40 inch spacing) and were arranged in a RCB with 4 replications. Insecticides were applied on 23 Aug (R5, beginning seed stage) with a tractor and compressed air sprayer calibrated to deliver 10 gpa at 38 psi through TX8 hollow cone nozzles. Treatments were evaluated using 25 sweeps (15 inch diameter sweep net) per plot at 2, 5, and 7 DAT. No precipitation occurred throughout the duration of this experiment.

Biologically active constituents of tropical and subtropical plants

Abstract

Behavioural effects of a neem insecticide onCoptotermes formosanus(Isoptera: Rhinotermitidae)

Abstract The neem tree, Azadirachta indica is the source of azadirachtin and other compounds with potent insecticidal, feeding deterrent, and insect growth regulator activity. This study investigated the effects of a commercial insecticide formulation (Margosan‐O) containing 0.3% azadirachtin and 14% neem oil on orientation, tunnelling, and feeding behaviour of the Formosan subterranean termite, Coptotermes formosanus. In short‐term orientation assays, termite workers did not avoid papers treated with a 1000 ppm solution of azadirachtin. Termite workers also readily penetrated sand containing 20, 100, or 500 ppm azadirachtin, although significant mortality occurred in the 100 ppm treatment. However, subsequent observations indicated that termites avoided long‐term contact with the treated sand. In two multiple‐choice feeding assays, C. formosanus workers fed significantly less on papers containing azadirachtin concentrations >100 ppm. Azadirachtin, and possibly other neem oil components, thus show some to...

Insect growth regulating activity of 1,5‐disubstituted imidazoles against Bombyx mori and Oncopeltus fasciatus

AbstractSeventeen 1,5‐disubstituted imidazoles possessing a variety of substituents were tested on Bombyx mori and Oncopeltus fasciatus. All compounds induced precocious metamorphosis from 4th‐instar larvae of B. mori. Of the compounds tested, 1‐benzyl‐5‐[(E)‐2,6‐dimethyl‐1,5‐heptadienyl]imidazole (KK‐42) was the most active against B. mori larvae. However, none of the compounds induced precocious metamorphosis in O. fasciatus nymphs, although several showed delayed toxicity. Treated nymphs died during or immediately after the moult. A series of 1‐isobutylimidazoles exhibited high activity against O. fasciatus, whereas KK‐42 was inactive even at high doses. There was no apparent correlation between the ability of imidazoles to cause precocious metamorphosis in B. mori and the delayed toxicity for O. fasciatus.