Control of mushroom sciarid fly Lycoriella ingenua populations with insect growth regulators applied by soil drench

Mushroom sciarid fly Lycoriella ingenua (Dufour, 1839) comb. nov., is one of the most common fly pests affecting the cultivation of Agaricus bisporus (Lange) Imbach in Turkey. In this study, eight insect growth regulators (IGRs)--diflubenzuron, flufenoxuron, lufenuron, methoprene, novaluron, pyriproxyfen, teflubenzuron, and triflumuron-were tested for their potential to control L. ingenua populations in two successive growing periods. Treatments were targeted at larvae as soil drenches; treatment efficacy was evaluated by assessing adult emergence and larval damage. These products were compared with a control treated with water (negative control) and a conventional chemical insecticide (chlorpyrifos ethyl) (positive control). Treatments with the IGRs caused significant reductions in emerging adult numbers and sporophore damage rates compared with the water-treated control over the two growing periods. Of the IGRs tested, novaluron, diflubenzuron, and teflubenzuron had significantly lower numbers of emerging adults than the rest of the IGRs and chlorpyrifos ethyl-treated control in both periods. Treatments with teflubenzuron, pyriproxyfen, novaluron, and diflubenzuron resulted in significantly lower sporophore damage rates than all other treatments. Compared with negative control, there were no significant yield reductions due to applications of selected IGRs. The results suggest that all the IGRs tested can be used as alternatives to conventional pesticides in controlling L. ingenua populations on mushroom.     

昆虫生长调节剂的毒理机制与抗药性研究进展

昆虫生长调节剂是通过干扰昆虫正常生长发育,致使昆虫个体死亡或活动能力下降,从而导致种群灭绝的一类特异性杀虫剂。本文对3类重要的昆虫生长调节剂（保幼激素类似物、几丁质合成抑制剂和蜕皮激素类似物）的毒理作用机制以及害虫对其抗药性的研究进展进行了综述,叙述了害虫对该类药剂的抗药性发展情况,并对其抗药性机理进行了探讨。目前研究表明,害虫对该类药剂的主要抗性机理是解毒代谢酶增强和表皮穿透率降低。     

Effects of Hexaflumuron and Pyriproxyfen on the purified Phenoloxidase of Chilo suppressalis Walker (Lepidoptera: Crambidae)

Effects of two insect growth regulators (IGRs), hexaflumuron and pyriproxyfen, were studied on the purified phenoloxidase (PO) of Chilo suppressalis. Purification procedure revealed two isozymes of PO, namely POI and POII. IC₅₀ concentrations of hexaflumuron and pyriproxyfen on POI were 0.36, 0.23?μg/ml and on POII were 0.105, 0.42?μg/ml, respectively. Determination of optimal pH and temperature revealed pH 5 and temperature 40?°C as the optimal values for the enzymatic activity. Treating POs with IC₅₀ concentrations of two IGRs was pH and temperature dependent. Effects of these IGRs on POI caused significant increase of K_m value versus control suggesting competitive inhibition. Hexaflumuron and pyriproxyfen cause reduction in V_max value of POII versus control suggesting non-competitive inhibition. The current study shows direct effects of two IGRs on purified PO of C. suppressalis for the first time. These findings could be helpful to develop safe compounds with inhibitory mechanism on PO to neutralise insect immune responses against entomopathogenic agents.     

Improved Conservation of Natural Enemies with Selective Management Systems for Bemisia tabaci (Homoptera: Aleyrodidae) in Cotton

A large-scale study was conducted in 1996 to evaluate and demonstrate strategies for pest management of Bemisia tabaci (Gennadius) in cotton involving different insecticide regimes, application methods, and action thresholds. Here we examined the effects of the various management systems on the abundance and activity of native natural enemies. Population densities of 18 out of 20 taxa of arthropod predators were significantly higher in regimes initiated with the insect growth regulators (IGRs) buprofezin (chitin inhibitor) or pyriproxyfen (juvenile hormone analog) compared with a regime dependent on a rotation of conventional, broad-spectrum insecticides. There were no differences in predator density between the two IGR regimes, and generally no effects due to application method or action threshold level. Predator to prey ratios were significantly higher in regimes utilizing the two IGRs compared with the conventional regime, but were unaffected by application method or threshold level. Rates of parasitism by Eretmocerus eremicus Rose and Zolnerowich and Encarsia meritoria Gahan were higher in the IGR regimes compared with the conventional regime, but were unaffected by insecticide application method, or the action threshold used to initiate applications of the IGRs. Results demonstrate the selective action of these two IGRs and suggest that their use may enhance opportunities for conservation biological control in cotton systems affected by B. tabaci, especially relative to conventional insecticide alternatives.     

Compatibility of Insect Growth Regulators with Eretmocerus eremicus (Hymenoptera: Aphelinidae) for Whitefly (Homoptera: Aleyrodidae) Control on Poinsettias: I. Laboratory Assays

The compatibility of five insect growth regulators (IGRs), buprofezin, pyriproxyfen, fenoxycarb, pymetrozine, and kinoprene, were tested in the laboratory for compatibility with the whitefly parasitoid Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae). The survivorship of adult parasitoids foraging on poinsettia leaves with residues 6, 24, and 96 h of age was determined. The toxicity of Bemisia argentifolii Bellows and Perring (Homoptera: Aleyrodidae) patches treated with IGRs presented to female parasitoids 24 and 96 h posttreatment was quantified. Survivorship of immature E. eremicus developing within B. argentifolii nymphs was determined by treating whitefly nymphs with IGRs 5 and 13 days postoviposition by female parasitoids. Finally, behavioral observations of female parasitoids foraging on IGR-treated and untreated B. argentifolii patches presented simultaneously were quantified to determine whether IGR residues had a repellant effect toward E. eremicus. Averaging ranks for IGRs based on their compatibility with E. eremicus and their ability to kill B. argentifolii nymphs produced the following parasitoid compatibility order: buprofezin > fenoxycarb > pymetrozine = pyriproxyfen > kinoprene. Further work in greenhouses assessing the efficacy of buprofezin with E. eremicus for B. argentifolii control on poinsettias is recommended.     

A systematic review on the eco-safe management of mosquitoes with diflubenzuron: An effective growth regulatory agent

Mosquitoes serve as the major vector transmitting malaria, dengue, yellow fever and several other diseases of human concern. Rising in mosquito-borne diseases and consequent fatalities throughout the world has made the management of mosquitoes of paramount importance. With the use of various insecticidal agents and their indiscriminate application in the fields for vector control; other issues such as multiple insecticide resistance, lethality to non-specific targets and adverse effects on human and environmental health have emerged making the situation more critical. Hence, the focus of researchers has diverted to the use of Insect Growth Regulators (IGRs) that affect the growth and development of the insects without inducing any appreciable toxic effects. The paper comprehensively reviews various IGRs and their potential use against insect pests and mosquito vectors. A special emphasis has been laid on the utilization of diflubenzuron, its larvicidal potency and growth regulatory effects against mosquitoes. The paper also delivers a detailed discussion on various approaches governing with the application of diflubenzuron, a chitin synthesis inhibitor, for its potent effects over a wide range of other insect species, low toxicity to humans, safety to other non-target animals, negligible deleterious environmental impact along with the possible development of resistance in the mosquitoes, thereby providing insights and the direction for the future in terms of the innovative and technological perspective. Keeping in view the role of multifarious mechanisms in the development of resistance; use of various synergistic compounds, such as hydrolase inhibitors - profenofos and S,S,S-tributyl phosphorotrithioate; glutathione S-transferase inhibitor – diethylmaleate; and oxidase inhibitor - piperonyl butoxide (PBO); has been recommended in combination with IGRs to enhance their efficacy, and reduce or reverse the resistance in target mosquitoes. Another compound, verapamil, has been found extremely efficient in imparting synergistic effect to diflubenzuron by inhibiting P-glycoproteins, a transporter of the insecticides causing their efflux from the cell. Recommendations have been made for safe and effective mosquito control measures, adequate policies and increased awareness about the mosquito-borne diseases among the masses. In addition, regular surveillance of mosquitoes is endorsed for the formulation of an efficient mosquito management strategy.     

Insecticide and acaricide molecules and/or combinations to prevent pet infestation by ectoparasites

External antiparasitic drugs used in cats and dogs have evolved in terms of active ingredients but also regarding formulations. Old chemical groups have been supplanted by phenylpyrazoles, neonicotinoids, oxadiazines, spinosyns or others which are entering the veterinary market. In addition to insecticides-acaricides, insect and mite growth inhibitors (IGRs) have emerged. These IGRs are used in animals or in the environment, either alone or in combination with insecticides-acaricides. The notion of antiparasitic treatment has evolved to the concept of prevention of ectoparasite infestation but also of transmitted diseases through the introduction of formulations providing long-lasting activity. At the same time, ease-of-use has been improved with the development of spot-on formulations. Progress has also been achieved through the development of antiparasitic drugs providing control of both external and internal parasites.     

两种昆虫生长调节剂对嗜虫书虱的致死作用

系统测定了灭幼宝（Pyriproxyfen)和烯虫酯（Methoprene) 2种昆虫生长调节剂对储藏物主要害虫嗜虫书虱（Liposcelis entomophila)的生物活性。采用饲料混药法,针对不同浓度的灭幼宝和烯虫酯分别对嗜虫书虱若虫的致死作用,对若虫发育历期,成虫繁殖力和卵孵化率的影响设置不同处理和重复。结果表明,灭幼宝对嗜虫书虱若虫的致死作用非常明显,其效果比烯虫酯好;不同浓度的灭幼宝使若虫的发育历期明显延长; 灭幼宝和烯虫酯对嗜虫书虱的成虫无杀伤作用,但对成虫的产卵量有明显的抑制作用,两者的作用浓度却相差5倍。灭幼宝对卵的孵化率影响更大,因而具有更显著的杀卵效果。     

The use of insect growth regulators - implications for ipm with citrus in southern africa as an example

IGRs have been widely promoted as being ideal IPM compatible pesticides. A number of IGRs have been used extensively on citrus in southern Africa providing excellent control of some target pests. However, field experience has indicated that this has had considerable direct and indirect detrimental effects on IPM. Bioassays confirmed that some of the IGRs used are highly detrimental to certain coccinellid and hymenopteran biocontrol agents of economic importance. Field experience and bioassays have indicated extreme persistence and widespread contamination resulting from agricultural use of some of these products. This presents a serious obstacle to maximisation of biocontrol in IPM and the success of future biocontrol projects using IGR-sensitive species. It also gives rise to concern about potential environmental contamination. In conclusion the use of IGRs should not be considered advantageous to IPM without careful investigation of their potential non-target effects in the particular agro-ecosystem and appropriate consideration for non-target effects in the surrounding environment.     

Toxicity of diflubenzuron and pyriproxyfen to the predatory bugPodisus maculiventris

The susceptibility of the predatory pentatomidPodisus maculiventris (Say) to the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen was investigated in the laboratory. Fifth-instar nymphs were exposed to formulated materials of each compound via direct contact, residual contact and ingestion. Diflubenzuron was harmless toP. maculiventris by direct and residual contact, but was highly toxic when ingested via drinking water. Pyriproxyfen caused severe deformities at ecdysis whatever the method of exposure. Exposure of fifth instars to sublethal concentrations (around LC₁₀) of both compounds had no adverse effects on reproduction of emerging adults. The data suggest that the use of these IGRs in the integrated management of insect pests should be evaluated with caution.     

Effect of 1-(4-phenoxyphenoxypropyl)imidazole (KS-175) on larval growth in the silkworm Bombyx mori

1-(4-Phenoxyphenoxypropyl)imidazole (KS-175), which has two types of characteristic moieties of insect growth regulators (IGRs), the phenoxyphenoxyalkyl group of juvenile hormone analogs (JHAs) and imidazole of 1,5-disubstituted imidazole such as KK-42, was tested for its biological activity on the silkworm, Bombyx mori. Penultimate (4th) instar larvae topically treated with KS-175 did not molt for more than 20 days. This activity was different from that reported for any IGRs. After the treatment, ecdysteroid levels in the hemolymph did not increase and the cells of the prothoracic gland had shrunk. When the treated penultimate larvae were fed an artificial diet supplemented with 20 ppm of 20-hydroxyecdysone, the larvae molted to the ultimate (5th) instar with a timing similar to that of control larvae fed a diet with or without 20-hydroxyecdysone. These results suggest that topical application of KS-175 irreversibly damages ecdysone biosynthesis in the prothoracic glands.     

3D-QSAR based optimization of insect neuropeptide allatostatin analogs

Allatostatins (AST) are neuropeptides originally described as inhibitors of juvenile hormone (JH) synthesis in insects. Consequently, they have been considered as potential lead compounds for the discovery of new insect growth regulators (IGRs). In the present work, receptor-based three-dimensional quantitative structure-activity relationship (3D-QSAR) was studied with 48 AST analogs, and a general approach for novel potent bioactive AST analogs is proposed. Hence, six novel AST analogs were designed and synthesized. Bioassays indicated that the majority novel analogs exhibited potent JH inhibitory activity, especially analog A6 (IC₅₀: 3.79?nmol/L), which can be used as lead compound to develop new IGRs.     

Mosquito larvicidal activities of farnesol and farnesyl acetate via regulation of juvenile hormone receptor complex formation in Aedes mosquito

Due to their target specificity and low-toxicity, insect growth regulators (IGRs) are regarded as promising alternatives to chemical insecticides. In this study, farnesol and farnesyl acetate exhibited juvenile hormone (JH)-based IGR activities. While farnesyl acetate showed JH agonist (JHA) activity in concentration-dependent manner, farnesol was identified as JH antagonist (JHAN) by interfering pyriproxyfen-mediated binding JH receptor complex. Both compounds showed mosquito larvicidal activities and caused retardation of ovarian growth of female Aedes albopictus by modulating the formation of JH receptor complex, expression of JH-inducible genes, and thereby disrupting JH-based endocrine regulations. These results suggested that farnesol and farnesyl acetate could be applicable for investigating underlying mechanisms of JH-regulated insect physiologies as well as developing novel eco-friendly insecticides.     

Resistance of the codling moth Cydia pomonella (L.) (Lep., Tortricidae) to pesticides in Israel

Abstract:  Resistance of the codling moth Cydia pomonella (L.) (Lep., Tortricidae) to the organophosphorus compound (OP) azinphosmethyl was observed in apple orchards in Israel. The level of resistance varied with the pest control strategy. Compared with a sensitive laboratory population, the resistance level was highest in insects from the preventative pest control strategy, intermediate in integrated pest management (IPM) orchards, and relatively low in the organic orchards. The level of azinphosmethyl resistance in larvae (but not in adults) exposed for 17 generations in the laboratory to a pesticide-free diet was reduced by 50%. Codling moth larvae resistant to azinphosmethyl were also resistant to various insect growth regulators (IGRs). The IGRs include three chitin synthesis inhibitors (diflubenzuron, novaluron and teflubenzuron), two juvenile hormone mimics (pyriproxyfen and fenoxycarb) and one ecdysone agonist (methoxyfenozide). Codling moth resistant to azinphosmethyl was tolerant to methoxyfenozide and novaluron without previous history of application in apple orchards, indicating the possibility of cross-resistance. According to this study, managing resistance programs in apple orchards should be based on IPM principles with minimum use of conventional neuroactive pesticides.     

Synergism of diacylhydrazine insecticides with metyrapone and diethylmaleate

Abstract:  The two metabolic synergists, metyrapone (2-methyl 1,2-di-3-pyridyl-1-propanone) and diethylmaleate could increase the toxicity of the three most recent diacylhydrazines, representing a novel group of insect growth regulators (IGRs). These components are known as respective inhibitors of oxidative and glutathione S-transferase enzymes. Larvicidal toxicity was tested in the laboratory by oral treatment against last-instar larvae of the Colorado potato beetle Leptinotarsa decemlineata (Say) and of the beet armyworm Spodoptera exigua (Hübner). The obtained results should enable to improve the activity of tebufenozide, methoxyfenozide and halofenozide, and it may be used to suggest potential mechanisms for resistance against this novel group of IGRs, that is important to counteract cross-resistance with other insecticide groups.     

Effect of ecdysone agonist RH-0345 on reproduction of mealworm,Tenebrio molitor

RH-0345 belongs to a new group of insect growth regulators (IGRs) with a benzoylhydrazine structure that mimic the action of the natural insect molting hormone 20-hydroxyecdysone. After topical application on female adult beetles of mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), first oviposition was delayed, the number of eggs per female was reduced by 32%, the follicular epithelium was thinner (-33%) during sexual maturation, the size of deposited eggs was reduced, and egg viability was lost by 68%. Treatment with RH-0345 had also reduced the ovarian protein content and two protein bands were missing in the ovaries. Ultrastructural observations of the ovaries at the end of vitellogenesis in treated females, however, showed no evident differences with the fine structure of both follicular cells and oocytes in controls. In addition, we measured the amount of ecdysteroids in the medium of treated ovary cultures in vitro and in the eggs deposited by treated females. Possible action sites with the reproductive system at different levels in T. molitor are discussed for this novel group of IGRs.     

THE RELATIONSHIP BETWEEN INSECT GROWTH REGULATORS WITH JUVENILE HORMONE ACTIVITY AND INSECT FEEDING BEHAVIOURAL RESPONSE

Abstract  Five insect growth regulators (IGRs) with juvenile hormone (JH) activity including fenoxy-carb, methoprene, NC-170, NC-184 and NC-196 were selected to study on the relationship between IGRs and feeding behaviour of the fourth instar larvae of Calospilos suspecta (Warren) and the fifth instar larvae of Ostrinia furnacalis Guenee, by topical and dietary applications as well as "diet column" methods. The results indicated that the antifeeding indices of methoprene, fenoxycarb, NC-170, NC-184, NC-196 and toosendanin against the fifth instar larvae of Ostrinia furnacalis in no-choice test were -37. 7, 14. 6, -12. 3, 10. 9, 14. 7 and 62. 2% respectively. Methoprene could stimulate the two species of insects to feed, whereas fenoxycarb had some antifeeding activity, and the effects of all the tested chemicals were different. Therefore, disturbances of IGRs with JH activity on insect feeding behavioural response may be one of the mechanisms of action not to be ignored. Moreover, by comparing "diet column" method with "faeces weight" method, it was suggested that the two methods might be applied in bioassay of antifeeding behaviour.     

Stage-specific control of grape berry moth, Endopiza viteana (Clemens) (Lepidoptera: Tortricidae), by selective and broad-spectrum insecticides

The insect growth regulators (IGRs) tebufenozide and methoxyfenozide and the broad-spectrum insecticides azinphosmethyl, carbaryl, and fenpropathrin were compared for their activity against adult, egg, and larval stages of the grape berry moth, Endopiza viteana (Clemens) (Lepidoptera: Tortricidae), under laboratory and vineyard conditions. Adult mortality was not affected by exposure to field-equivalent rates of tebufenozide or methoxyfenozide on grape clusters, whereas all the broad-spectrum compounds significantly reduced adult survival, compared with the untreated controls. Surviving adult moths laid significantly more eggs on berries treated with the IGRs than on berries treated with any of the broad-spectrum insecticides. Survival of these eggs through to late larval and pupal stages was significantly lower on methoxyfenozide-treated grapes than on untreated grapes, and no pupae were found when grapes were treated with azinphosmethyl or fenpropathrin. Neither of the growth regulator insecticides limited egg eclosion or larval development by E. viteana when insecticides were applied before egg laying, whereas broad-spectrum insecticides were effective against both eggs and neonates at this timing. When applied after egg eclosion, all insecticide treatments significantly reduced survival of grape berry moth larvae. Under vineyard conditions, berries with 1-d-old residues of tebufenozide or methoxyfenozide received more E. viteana eggs than berries treated with broad-spectrum compounds. After aging for 7 or 14 d, no significant effects on E. viteana survival were detected among treatments. Whereas broad-spectrum insecticides provide control of multiple life stages of E. viteana, integration of tebufenozide or methoxyfenozide into vineyard management programs for control of this pest will be most successful if applications are timed for egg hatch.     

具保幼激素活性昆虫生长调节剂与昆虫摄食行为反应的关系(英文)

本文以烯虫酯、双氧威、ＮＣ－１７０、ＮＣ－１８４和ＮＣ－１９６等具保幼激素活性的昆虫生长调节剂（ＩＧＲｓ）为药剂,以丝绵木金星尺蠖 Ｃａｌｏｓｐｉｌｏｓ ｓｕｓｐｅｃｔａ４龄幼虫和亚洲玉米螟 Ｏｓｔｒｉｎｉａ　ｆｕｒｎａｃａｌｉｓ５龄幼虫为试材,采用点滴法和混药饲喂法,结合非选择性饲料柱称重法,研究了ＩＧＲｓ与昆虫摄食行为之间的关系。结果表明,烯虫酯、双氧威、ＮＣ－１７０、ＮＣ－１８４、ＮＣ－１９６和川楝素对亚洲玉米螟５龄幼虫的非选择性拒食率依次为－３７．７、１４．６、－１２．３、１０．９、１４．７和６２．２％,烯虫酯刺激两种试虫取食,而双氧威则有一定的拒食作用,不同药剂表现出的影响不尽一致。因此,外源具保幼激素活性的活性物质对昆虫摄食行为反应的干扰破坏,可能是ＩＧＲs作用机理中不可忽视的重要方面之一。对饲料柱称重法和虫粪称重法进行了比较,证实两种方法结果相近,趋势一致,均可用于昆虫摄食行为的生测。