Effects of a juvenile hormone analogue, pyriproxyfen, on the apterous form of soybean aphid (Aphis glycines)

The soybean aphid, Aphis glycines Matsamura, is an eastern Asian soybean [Glycine max (L.) Merr.] pest which can reduce soybean yield. We determined the effects of pyriproxyfen, a juvenile hormone analogue, on development, mortality, longevity and fecundity of A. glycines under laboratory conditions. Distance Insect Growth Regulator, containing ∼11.2% pyriproxyfen, was applied at two concentrations, 50 and 150 mg/l, to first and fourth instar nymphs. When first or fourth instar A. glycines were treated with pyriproxyfen, some nymphs became supernumerary‐molted nymphs with 1–3 extra molts or were sterilized. Mortality of treated first instar nymphs was >68% greater than the control group and longevity was reduced by >40%. The higher concentration of pyriproxyfen reduced fecundity of first instar nymphs when they reached adulthood by ∼79%. Pyriproxyfen similarly affected fourth instar nymphs. Mortality of treated fourth instar nymphs was ≥15% greater than the control group and longevity was reduced by >24%. Both concentrations of pyriproxyfen lowered the fecundity of fourth instar nymphs by >27%. Pyriproxyfen also had other sublethal effects on fourth instar nymphs which became apparent when they molted to adulthood. In a few instances they developed wing pads and many produced dead, deformed or abnormal neonates that lacked appendages.     

Effects of juvenile hormone analogue treatment in adult females of the ovoviviparous cockroach,Blaptica dubia (Dictyoptera,Blaberidae)

Adult females of the ovoviviparous Argentinian cockroach, Blaptica dubia, were repeatedly treated with either 100?μg methoprene or 100?μg pyriproxyfen in 5?μL acetone either during the first vitellogenic cycle or during the period of gestation. Treatment during the first vitellogenic cycle (days 2–20 of adult life) did not inhibit vitellogenesis and oocyte growth, but prevented the formation of an ootheca. This was accompanied with a significant reduction of the titer of juvenile hormone (JH) III and an increased amount of ecdysone (E) and 20-hydroxyecdysone (20E) in the haemolymph of the animals. Treatment of adult females during the period of gestation (days 30–70) resulted in a complete degradation and resorption of the ootheca and induced another vitellogenic cycle. Again, this was associated with a decrease in haemolymph JH III titer, but an increase in the concentrations of free ecdysteroids.     

Effects of pyriproxyfen on ovarian development and fecundity ofRhagoletis pomonella flies

Three-day old female apple maggot flies,Rhagoletis pomonella (Walsh), were topically exposed to different doses (0.1, 1, 10, and 100 μg per fly) of a juvenile hormone mimic, pyriproxyfen, in the laboratory. Pyriproxyfen had little lethal effect on females except at the extremely high dose of 100 μg. It also had no significant effect on egg viability of treated females. A non-lethal dose of 1 μg per fly did, however, enhance significantly the fecundity (egg production) as well as the ovarian development (number of eggs in ovaries and length of egg folicles) of treated flies. We conclude that pyriproxyfen could be a useful aid in exploring endocrine regulation of feeding and reproductive physiology behavior inR. pomonella, about which current knowledge is scant.     

Degradation of a radiolabeled juvenile hormone analog using two insect species

A synthetic insect juvenile hormone analog (a juvenoid), ethylN-[2-[4-[[2,2-(ethylenedioxy)cyclohexyl]methyl]phenox]ethyl]carbamate, which has displayed high biological activity against different insect species and high stability under field conditions, was selected as a biologically active model compound for a study of a juvenile hormone analog degradation. The biologically active compound itself and its three diversely radiolabeled derivatives were applied to the flesh fly (Sarcophaga bullata) or the tsetse fly (Glossina palpalis), respectively. Monitoring of a fate of the applied juvenile hormone analog was carried out using a detection method of the radioactivity microdistribution within the whole insect body in combination with a radio high performance liquid chromatography (radio-HPLC), both of whole-body extracts made in different, but in advance scheduled, time intervals, and of extracts of insect excreta accumulated over an eight-day experiment.     

Formulation of pyriproxyfen, a juvenile hormone mimic, for tsetse control

A topical dose, in 1 microliter acetone, of 0.02 microgram-2-[1-methyl-2-(4-phenoxyphenoxy) ethoxy] pyridine, the juvenile hormone mimic pyriproxyfen (S-31183, Sumitomo Chemical Co.), caused an adult female tsetse, Glossina morsitans morsitans Westwood, to produce non-viable offspring for the whole of her life. Using 14C labelled pyriproxyfen it was determined that as little as 0.001 microgram transferred to the in utero larva was sufficient to arrest development in the pupal stage. A formulation in vegetable oil was prepared for treating black cotton cloth targets which caused females to pick up 0.1 microgram active ingredient (a.i.) by tarsal contact during 1 min of exposure. Males exposed similarly for between 1 and 5 min transferred up to 0.016 microgram a.i. to females if they mated immediately after treatment. Doses as low as 0.01 micrograms in 10 microliters oil cm-2 on black cotton cloth targets caused females to produce non-viable offspring for at least two reproductive cycles following exposure. However, a dose of 0.1 microgram in 10 microliters oil cm-2 was necessary for an exposed male to cause disruption of the reproductive potential of his mate. This juvenile hormone mimic has potential to induce sterility via both sexes of tsetse using treated targets or traps under field conditions.     

Effects of the juvenile hormone analog pyriproxyfen on German cockroach, Blattella germanica (L.), tergal gland development and production of tergal gland secretion proteins

Male German cockroaches possess secretory glands that secrete fluid into a pair of transverse depressions on the seventh and eighth abdominal tergites. We investigated the effects of altered juvenoid titer during the first part of the last instar on tergal gland secretory tissue development and the production of tergal gland secretion proteins. Male fifth (last) instar nymphs (1-3 days post-emergent) were topically treated with the JH analog pyriproxyfen. Light and transmission electron microscopy demonstrated that treatment with pyriproxyfen produced a visible decrease in the amount of tergal gland tissue present, a deformation of the overall shape of the gland located on tergite seven, and a less orderly arrangement of the secretory cells in the tissue. The protein fraction of tergal gland secretion was examined in pyriproxyfen-treated and control insects 1, 5, and 15 days after the insects molted to the adult stage. Amounts of all tergal secretion proteins were reduced in treated insects.     

Physiological effects of a juvenile hormone analog on larvae of Spodoptera littoralis

Topical application of JHA to Spodoptera littoralis larvae extends the duration and increases the final weight of the last larval instar. No supernumary moults occur. Respiration decreases to very low levels and glycogen and lipid stores increase. Respiration remains lower in JHA-treated pharate pupae and more polyunsaturated C₁₈ fatty acids accumulate than in normal pharate pupae. These physiological parameters are similar to those occurring during diapause but are not definitive. Diapause has not been reported in field populations of S. littoralis, nor it's artificial induction by photoperiodic manipulation.

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Résumé Le dernier stade des chenilles de Spodoptera littoralis, traitées avec JHA, est nettement prolongé par rapport aux témoins. Bien que le poids final des chenilles traitées soit plus élevé que celui des témoins, il n'y a pas de mue surnuméraire. Ces chenilles géantes s'alimentent rarement et leur respiration est sérieusement réduite. Les réserves de glycogène s'accumulent chez les chenilles traitées à la même date chronologique que chez les prénymphes non traitées. Bien que les prénymphes traitées à la JHA conservent leur profil biochimique juvénile — tout au moins dans la mesure où on considère la teneur en glycogène et en lipides totales — leur composition en acides gras saturés et non saturés diffère de celle normalement rencontrée à la fin du développement larvaire, et beaucoup plus d'acide oléique monosaturé s'accumule finalement chez les insectes traités par JHA. Ces résultats suggèrent que la JHA fournie peut avoir provoqué un état de développement de diapause naissante semblable par quelques traits fondamentaux à celle induite par la JH endogène chez les insectes enclins à la diapause. Il est cependant prématuré de définir cet état physiologique comme indiquant une vraie diapause chez Spodoptera littoralis.

     

Effects of the juvenile hormone mimic pyriproxyfen on female reproduction and longevity in the butterfly Bicyclus anynana

Female Bicyclus anynana butterflies given pyriproxyfen, a mimic of juvenile hormone, exhibited increased egg‐laying rates and early fecundity, but reduced longevity compared with control animals. Thus, pyriproxyfen application yielded antagonistic effects on different components of fitness, possibly demonstrating a juvenile hormone‐mediated trade‐off between present and future reproduction. Lifetime fecundity and egg size, however, showed no consistent response to pyriproxyfen, with lifetime fecundity being increased or decreased and egg size being reduced in one out of four experiments only. Females were most sensitive to pyriproxyfen around the onset of oviposition, coinciding with naturally increasing juvenile hormone titers in other Lepidoptera. Amounts between 1 and 10 µg pyriproxyfen were found to be effective, with, however, pronounced differences among experiments. This is attributed to differences in assay conditions. High pyriproxyfen concentrations (100 µg) as well as repeated applications of smaller amounts did not affect reproductive traits, but tended to reduce longevity.     

Effects of the ecdysteroid agonists RH 5849 an RH 5992, alone and in combination with a juvenile hormone analogue, pyriproxyfen, on larvae ofSpodoptera exigua

Biological activity assays with RH 5849 and RH 5992 indicated that both compounds affected growth and development of last-instar larvae ofSpodoptera exigua (Hübner) (Lepidoptera: Noctuidae) in a dose-dependent manner. Within the first 24 h after treatment by continuously offering leaves dipped in a water solution of ≥50 mg/l RH 5849 and ≥0.5 mg/l RH 5992, symptoms of a prematurely induced larval moult and head capsule apolysis were visible. Intoxicated larvae died shortly afterwards, showing signs of unsuccessful ecdysis. LC₅₀-values of RH 5849 and RH 5992 for fifth-instarS. exigua larvae were 110 and 2.5 mg/l, respectively. Pyriproxyfen alone affected the larval stage and disturbed normal metamorphosis. One supernumerary larval instar occurred occasionally. LC₅₀-value for pyriproxyfen was 1.7 mg/l. Larvae simultaneously treated with RH 5849 or RH 5992 and pyriproxyfen, continued to grow until they attained a size and weight about 2–3 times that of the controls. This growth was accompanied by at least one and sometimes two supernumerary moults. Concerning thein vivo imaginal wing disc growth and development, only in larvae treated with 10 and 50 mg/l RH 5849 or 0.5 mg/l RH 5992, tracheole migration was observed earlier than in the controls. When applying 300 mg/l RH 5849 or 3–7 mg/l RH 5992, the discs remained small and no signs of tracheole migration were observed. In larvae simultaneously treated with RH 5849 or RH 5992 and pyriproxyfen, tracheole migration was not prematurely induced and a pupal cuticle was produced in the discs of larvae, undergoing a supernumerary moult. No clear signs of evagination were observed.     

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.     

Juvenile hormone effects on polymorphism in the pea aphid, Acyrthosiphon pisum

When reared in short days (LD 12:12) at 15°C, apterous Acyrthosiphon pisum gave birth to sexual females (oviparae) exclusively for the first eight days of larviposition. After this time they switched to the production of parthenogenetic females (viviparae). Topical application of juvenile hormones I, II and III to fourth instar or adult ovipara-producers induced the precocious appearance of parthenogenetic females in the progeny sequence. Various forms intermediate between oviparae and viviparae were also produced and repetitive JH-I treatments resulted in a few alatiform progeny. However, many of the JH induced apterous, parthenogenetic females appeared to be normal viviparae and were capble of reproduction. Thus, prenatal treatment of oviparous embryos with JH diverts development towards the viviparous form. JH-I treatment of long-day reared A. pisum had no effect on the type of progeny produced.

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Effets de l'hormone juvénile sur le polymorphisme d'Acythosiphon pisum

Résumé Quand il est élevé sous jours courts (LN 12/12) à 15°C, le type anglais vert d'Acyrthosiphon pisum ne donne naissance qu'à des femelles sexuées (ovipares) pendant la première partie de sa période de reproduction. Ensuite quelques types intermédiaires ovipares/vivipares peuvent apparaitre avant que les pucerons ne bifurquent spontanément vers la production de femelles parthénogénétiques (vivipares). L'application cutanée d'hormones juvéniles (JH I, II, et III) aux larves de quatrième stade ou à des adultes producteurs d'ovipares provoque l'apparition prématurée d'intermédiaires et de vivipares dans la descendance. Les différentes formes intermédiaires produites par des applications répétées de J.H. comprenaient des types ailés ou partiellement ailés. Cependant, les vivipares aptères induits par J.H. étaient morphologiquement normaux et beaucoup étaient capables de se reproduire. Des traitements semblables aux J.H. de vivipares élevées en jours longs (LN 16/8) n'ont pas eu d'effets sur le type de la descendance.On ne sait pas si l'action de JH exogène sur l'induction des vivipares est direct ou indirect. La reprogrammation des embryons, autrement destinés à se développer comme ovipares, est examinée en relation avec notre connaissance du contrôle endocrine du polymorphisme des pucerons.

     

Mispatterning in the ommatidia of Apis mellifera pupae treated with a juvenile hormone analogue

To further understand the function of morphogenetic hormones in honeybee eye differentiation, the alterations in ommatidial patterning induced by pyriproxyfen, a juvenile hormone (JH) analogue, were studied by scanning and transmission electron microscopy. Prepupae of prospective honeybee workers were treated with pyriproxyfen and the effects on ommatidial differentiation were described at the end of the pupal development. The results show that the entire ommatidia, i.e., the dioptric as well as the receptor systems, were affected by the JH analogue. The wave of ommatidial differentiation, which progresses from the posterior to the anterior region of the pupal eyes, was arrested. In treated pupae, the rhabdomeres only differentiated at the apical axis of the retinula, the secondary and tertiary pigment cells did not develop their cytoplasm protrusions, and the cone cell quartet did not pattern correctly. Simultaneously, an intense vacuolization was observed in cells forming ommatidia. In a previous study we showed that pyriproxyfen exerts an inhibition on pupal ecdysteroid secretion. In this sense, the arrested ommatidial differentiation in pyriproxyfen-treated pupae could be due to a secondary effect resulting from an alteration in pupal ecdysteroid titers.     

Transport and kinetics of diflubenzuron and pyriproxyfen in the beet armywormSpodoptera exigua and its predatorPodisus maculiventris

Transport and retention of the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen in larvae of the beet armywormSpodoptera exigua (Hübner) and in nymphs of the predatory bugPodisus maculiventris (Say) were investigated. In a first experiment, the retention of orally administered [¹⁴C]radiolabeled isotopes of both compounds in fifth-instar larvae of the beet armyworm was studied. Rate of excretion of both IGRs inS. exigua caterpillars was high, with a 50% excretion time of approximately 6 h after intake. In a second experiment, the transport of the compounds from prey to predator and their retention inside the predator were studied. Fifthinstar nymphs ofP. maculiventris were allowed to feed on caterpillars that had been given contaminated food. For both diflubenzuron and pyriproxyfen, more than 80% of the amount of radiolabel applied was recovered in consumed prey. Low levels of radioactivity (c. 3% of the applied amount of radiolabel) were also found in the fluid regurgitated by the prey larvae when attacked by the predatory bugs. Relatively small amounts of radiolabel (c. 8 and 15% of the amount orally applied to the prey for diflubenzuron and pyriproxyfen, respectively) were ingested byP. maculiventris nymphs when feeding on beet armyworm caterpillars. The data suggest that the predators did not use gut content as food. The pattern of excretion in nymphs ofP. maculiventris differed between compounds. For diflubenzuron, there was a drastic decrease of radioactivity inside the predator body of around 40% within the first 6 h and then the level of retained radiolabel remained stable at 3–4% up to 72 h. For pyriproxyfen, a slow decrease of radioactivity inside the body was observed and at 72 h only 2% of the applied quantity was detected. Results of this study are discussed in relation to the findings from previous studies on the toxicity of both IGRs toP. maculiventris.     

Effects of aluminum mulch on fecundity of apterous Myzus persicae on head lettuce in a field planting

Head lettuce field plantings were artificially infested with apterous adults of the green peach aphid, Myzus persicae (Sulzer). Significantly greater aphid fecundity was demonstrated on plants grown through aluminum-coated construction paper than on plants grown on bare soil. Higher temperatures and host-plant physiology were factors modified by the mulch, and could have resulted in larger aphid populations on plants grown over a reflective surface as the season progressed. Faster plant growth and a significantly larger yield per head of lettuce also resulted from the use of the aluminum mulch. The incidence of a leafhopper-borne plant disease, aster yellows, was significantly reduced on head lettuce in the aluminum mulch plots.

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Résumé Des cultures de laitue ont été artificiellement contaminées avec des adultes aptères de Myzus persicae. La fécondité a été significativement augmentée sur les plantes poussant sur un sol recouvert par un voile d'aluminium, comparées à celles poussant sur un sol nu. Cette augmentation pourrait entrainer des populations de pucerons de plus en plus importantes, au fur et à mesure de l'avancement de la saison, sur les plantes poussant au dessus d'une surface fortement réfléchissante. L'utilisation du voile d'aluminium a provoqué simultanément une accélération de la croissance et une augmentation des rendements de laitue. Ces résultats semblent dus à une augmentation de la température diurne, à une meilleure conservation de l'humidité et à une plus forte réflexion de la lumière lorsqu'il y a présence de voile d'aluminium. Par aulleurs, les dégâts provoqués sur feuilles par les germes pathogénes transmis par les Cicadelles delles sont significativement plus rares sur sol couvert de voile d'aluminium.

     

保幼激素类似物苯氧威对异色瓢虫不同发育阶段的影响

【目的】本研究旨在明确保幼激素类似物苯氧威对天敌异色瓢虫Harmonia axyridis的影响, 并探讨其作用机理, 以便进行安全性评价并为科学使用提供理论依据。【方法】应用连叶浸渍法、浸渍法、点滴法和药膜法分别处理异色瓢虫卵、2龄幼虫、蛹和成虫, 观察苯氧威对4个虫态的影响。【结果】用浓度为0.0001 μg/mL的药液处理初产卵, 能抑制胚胎的发育; 但用高达20 000 μg/mL的药液处理发育2 d的卵, 幼虫仍可正常孵化; 用浓度高达4 000 μg/mL的药液浸渍2龄幼虫, 对幼虫的致死作用极小; 用浓度为0.0001 μg/头的药液处理当天蛹, 形成蛹 成虫中间体, 羽化的成虫畸形; 用浓度为0.0125 μg/mL的药液处理成虫, 24 h后成虫的生命力受到明显影响。【结论】苯氧威对异色瓢虫初产卵有明显的毒杀作用, 严重阻碍蛹到成虫的变态和影响成虫的存活。在田间使用该杀虫剂时, 要避开异色瓢虫的敏感期。     

Effect of juvenile hormone on the embryogenesis of a polyembryonic wasp,copidosoma floridanum,in vitro

Summary Single two-cell-stage embryos of a polyembryonic waspCopidosoma floridanum cultured in 20 μl droplets of culture medium developed to morulae at the same developmental rate as those in host eggs, but the subsequent development into polymorulae was inferior. This inferior development was markedly improved by addition of juvenile hormone (I, II, or III) or its analogues to the culture medium in a concentration-dependent manner.     

The effect of C18 juvenile hormone and Altosid on the efficiency of egg production in Rhodnius prolixus

The product (R) of the weight of the blood meal and the initial weight of the insect is shown to be a reliable predictor of egg production. The egg production efficiency (E), defined as the number of eggs produced per R, has a value characteristic of virgin females, and another, higher, value characteristic of mated females. Topical applications of C18 JH or Altosid to virgin females increase the value of E to the mated level in a fashion which suggests that these compounds act via a trigger mechanism. These compounds do not affect the rate at which oviposition occurs.     

The effect of farnesyl methyl ether, a mimic of insect juvenile hormone, on Hymenolepis Diminuta in vitro

The effect of farnesyl methyl ether, a mimic of insect juvenile hormone, on Hymenolepis diminuta in vitro. International journal for Parasitology4: 211–218. The inhibition of weight gain of Hymenolepis diminuta in vitro by farnesyl methyl ether (FME) was not dose-dependent, so that there were no differences produced by FME in concentrations from 10^?5 to 10^?13m. At all concentrations of FME used the weight gain over a 6-day culture period was half of that of controls. The FME-treated and control worms were identical to each other in proglottid number and the degree of maturity. Neither the dry to wet weight ratios of worms nor the carbohydrate, protein or lipid ratios were altered by FME. The release of neurosecretory material from the neurosecretory cells in the rostellum (as measured by the degree of their fuchsinophilia) was more advanced in time in the FME-treated worms than in the controls, and it is suggested that this premature release of neurosecretion, triggered either directly or indirectly by traces of FME in the medium, upset a control mechanism in the germinative tissue of the neck region, which determines the mass, but not the number, of the proglottids in the strobila.     

Effects on German cockroach nymphs of contact exposure to IGRs, singly and in combination

Late instar German cockroach male and female nymphs were exposed continuously for two weeks to surfaces treated with fenoxycarb, diflubenzuron, and pyriproxyfen, singly and in combination. Concentrations were determined that eliminated or nearly eliminated reproduction in matings with untreated mates, either through mortality, effects on reproduction, or a combination of mortality and sterility (no hatch). The major effect of fenoxycarb, pyriproxyfen, and pyriproxyfen plus fenoxycarb was on reproduction. The major effect of diflubenzuron was mortality. No hatch occurred in matings of females that were exposed to low concentrations of pyriproxyfen and fenoxycarb (2 ng/cm² and 6 ng/cm², respectively); sterility was incomplete when females were exposed to 600 ng/cm² of diflubenzuron. Mortality and sterility acted together to eliminate productive matings (matings that produced nymphs) when relatively high concentrations of diflubenzuron were combined with one or both of the other insect growth regulators (IGRs). In the triple combination, very small amounts of fenoxycarb and pyriproxyfen (total 1.1 ng/cm²) combined with 200 ng/cm² of diflubenzuron eliminated productive matings of treated females, but similar results with treated males were found only at higher concentrations of each IGR.