DNA hybridization assay for detection of gypsy moth nuclear polyhedrosis virus in infected gypsy moth (Lymantria dispar L.) larvae.

Radiolabeled Lymantria dispar nuclear polyhedrosis virus DNA probes were used in a DNA hybridization assay to detect the presence of viral DNA in extracts from infected larvae. Total DNA was extracted from larvae, bound to nitrocellulose filters, and assayed for the presence of viral DNA by two methods: slot-blot vacuum filtration and whole-larval squashes. To test the assays, neonate larvae were fed droplets containing a known concentration of L. dispar nuclear polyhedrosis virus and observed for up to 10 days to determine the percentage of infected larvae. The average percent mortalities were 88.0, 60.7, 26.0, and 5.3% for larvae fed droplets containing 4.0 x 10(4), 1.0 x 10(4), 2.5 x 10(3), and 6.25 x 10(2) polyhedral inclusion bodies (PIBs) per ml, respectively. Other larvae treated with the same virus concentrations were frozen at 2, 4, and 6 days postinoculation and examined by the hybridization techniques. The average percentage of slot blots containing viral DNA equaled 81.0, 58.0, 18.0, and 6.0% for larvae blotted 4 days after treatment with 4.0 x 10(4), 1.0 x 10(4), 2.5 x 10(3), and 6.25 x 10(2) PIBs per ml, respectively, and 89.9, 52.1, 26.6, and 6.0%, respectively at 6 days postinoculation. Thus, the hybridization results were closely correlated with mortality observed in reared larvae. Hybridization of squashes of larvae frozen 4 days after receiving the above virus treatments also produced accurate measures of the incidence of virus infection.     

DNA hybridization assay for detection of gypsy moth nuclear polyhedrosis virus in infected gypsy moth (Lymantria dispar L.) larvae

Radiolabeled Lymantria dispar nuclear polyhedrosis virus DNA probes were used in a DNA hybridization assay to detect the presence of viral DNA in extracts from infected larvae. Total DNA was extracted from larvae, bound to nitrocellulose filters, and assayed for the presence of viral DNA by two methods: slot-blot vacuum filtration and whole-larval squashes. To test the assays, neonate larvae were fed droplets containing a known concentration of L. dispar nuclear polyhedrosis virus and observed for up to 10 days to determine the percentage of infected larvae. The average percent mortalities were 88.0, 60.7, 26.0, and 5.3% for larvae fed droplets containing 4.0 x 10(4), 1.0 x 10(4), 2.5 x 10(3), and 6.25 x 10(2) polyhedral inclusion bodies (PIBs) per ml, respectively. Other larvae treated with the same virus concentrations were frozen at 2, 4, and 6 days postinoculation and examined by the hybridization techniques. The average percentage of slot blots containing viral DNA equaled 81.0, 58.0, 18.0, and 6.0% for larvae blotted 4 days after treatment with 4.0 x 10(4), 1.0 x 10(4), 2.5 x 10(3), and 6.25 x 10(2) PIBs per ml, respectively, and 89.9, 52.1, 26.6, and 6.0%, respectively at 6 days postinoculation. Thus, the hybridization results were closely correlated with mortality observed in reared larvae. Hybridization of squashes of larvae frozen 4 days after receiving the above virus treatments also produced accurate measures of the incidence of virus infection.     

亚洲型舞毒蛾在北美的适生性

采用DYMEX V2.0软件和ArcGIS分析工具相结合的方法,提出亚洲型舞毒蛾Lymantria dispar(L.)的DYMEX参数指标体系和适生性评判标准,分析亚洲型舞毒蛾在北美的适生范围与适生程度。研究表明,加拿大的南部、美国的大部分地区以及墨西哥中南部极少部分区域为该虫的适生区。研究结果将为国家植物保护部门提供有关亚洲型舞毒蛾的植物检疫决策支持。     

Soluble cuticular phenoloxidase in the gypsy moth Lymantria dispar

The soluble enzyme phenoloxidase (tyrosinase) from the larval cuticle of Lymantria dispar has been partially purified using Ultrogel ACA 34, and the activity has been determined using phenolic substrates. The enzyme exhibited more activity toward O-diphenolic substrates and monophenolic substrates. The enzyme is inhibited by diethyl dithiocarbamate, phenylthiourea, and thiourea. The enzyme has been localized in the 7% slab and disc PAGE as an intense band. The enzyme is suggested to be involved in wound healing. © 1992 Wiley-Liss, Inc.     

Development of male-incubated ovaries in the gypsy moth,Lymantria dispar

Ovaries from Lymantria dispar females were transplanted into an environment lacking vitellogenin, the male milieu, in order to determine how the presence of vitellogenin in the hemolymph affects the process of protein uptake by gypsy moth oocytes. When undeveloped ovaries from newly ecdysed last instar females were transplanted into males of the same stage, follicles detached from the germarium and increased in size, but the growth of oocytes proceeded more slowly than those from female controls. Although chorion fromation was delayed in male-grown ovaries, scanning electron microscopy of chorionated eggs recovered from adult males showed that a chorion with normal surface architecture was formed by the adult stage. SDS-PAGE analysis of the male-grown ovaries and hemolymph from males receiving ovaries showed that vitellogenin production was not stimulated by the organ transplant and only male hemolymph proteins were internalized by the male-incubated ovaries. Thus, in the absence of vitellogenin, endocytosis of male hemolymph proteins occurred, but the rate of oocyte growth was slowed.     

Identification of 20-hydroxyecdysone and ecdysone from the pupa of the gypsy moth,Lymantria dispar

Normal and reverse-phase high-performance liquid chromatography in conjunction with radioimmunoassay and mass spectrometry were used to identify the free and conjugated ecdysteroids (after enzymatic hydrolysis) from day-4 pupae of the gypsy moth, Lymantria dispar L. Seven ecdysteroids were searched for, but only 20-hydroxyecdysone (964 ng/g fresh weight) and ecdysone (367 ng/g fresh weight) were detected. Analysis of conjugated ecdysteriods after liberation by hydrolysis also indicated the presence of 20-hydroxyecdysone (21.6 ng/g fresh weight) and ecdysone (2.4 ng/g fresh weight). Neither 26-hydroxyecdysone nor the 3α-epimers of 20-hydroxyecdysone or ecdysone were detected.     

Suitability,digestibility and assimilation of various host plants of the gypsy moth Lymantria dispar L.

Summary The development and survival of gypsy moth (Lymantria dispar) larvae is strongly influenced by the host plant upon which they feed. The most rapid development and largest pupae were produced from grey birch fed larvae. Beech and maple-fed larvae produced the smallest pupae while maple-fed larvae exhibited prolonged development. White and red oak-fed larvae exhibited development and pupal weights intermediate between the above two groups. The approximate digestibility (AD) and efficiencies of conversion of food (ECD and ECI) were generally highest among grey birchfed individuals. The utilization of the relatively closely related oak species, as reflected in AD and ECD values, differed.Leaves were examined for 14 elements. The content of each element varied among host plant species and over time. For example, nitrogen levels were highest in grey-birch and dropped over time in all host plants.Lepidoptera: LymantriidaePaper No. 2277 Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst, MA U.S.A. This research supported (in part) from Experiment Station Project No. 437     

Effects of transferring gypsy moth, Lymantria dispar, larvae between artificial diet and Quercus rubra foliage

Fourth instar gypsy moth larvae, Lymantria dispar, from a laboratory colony were transferred between artificial diet and three ages of leaves from a preferred tree, Quercus rubra. Mortality after transfers was generally minimal (<13.3%) and did not differ from mortality of larvae remaining on the same food. Larvae that were transferred to a new food accepted artificial diet and the early season foliage that is normally eaten by early instars as readily as larvae that were not transferred. Pupal weights from larvae continually fed artificial diet or transferred from artificial diet to early season foliage were not significantly different. For trials beginning during June and later, 12-day weight gain and pupal weight were greater for individuals transferred to or reared continually on artificial diet than for individuals transferred to or reared continually on mature foliage.First instars of wild larvae fed artificial diet gained less weight after 3 weeks than foliage-fed first instars. Pupal weights of wild larvae transferred from June foliage to artificial diet as fourth instars were not significantly different from pupal weights of wild larvae remaining on foliage. Thus, the response of laboratory colony larvae to artificial diet was superior to that of wild larvae.

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Résumé Des chenilles du quatrième stade de L. dispar, élevées au laboratoire sur régime artificiel et sur feuilles de différents stades de leur chêne préféré, Q. rubra, ont été transférées de l'un à l'autre de ces régimes alimentaires. La mortalité après transfert est généralement faible (<13,3%) et de même importance que pour les chenilles maintenues sur le régime artificiel. Les chenilles transférées sur un nouvel aliment ont accepté le régime artificiel ou le feuillage jeune,- normalement consommé par les premiers stades larvaires-, aussi facilement que les chenilles qui n'avaient pas été transférées. Les poids des chrysalides des chenilles élevées continuellement sur régime artificiel ou transférées sur feuillage jeune n'ont pas présenté de différences significatives. Pour des expériences commencées en juin ou ultérieurement, les gains de poids à 12 jours et pour les chrysalides sont plus élevés pour les insectes maintenus ou transférés sur régime artificiel que pour ceux transférés ou maintenus sur feuillage âgé.Le poids des chrysalides, provenant de chenilles de la nature tranférées au quatrième stade, d'un feuillage de juin à un régime artificiel, n'a pas différé significativement du poids des chrysalides provenant de chenilles maintenues sur feuillage. Les premiers stades de chenilles de la nature élevées sur régime artificiel ont pris moins de poids en trois semaines que les premiers stades ayant consommé du feuillage.

     

Vertical transmission and overwintering of microsporidia in the gypsy moth, Lymantria dispar

Vertical transmission and the overwintering success of three different microsporidia infecting Lymantria dispar (Lepidoptera: Lymantriidae) larvae were investigated. Endoreticulatus schubergi, a midgut pathogen, was transmitted to offspring via female and male via the egg chorion (transovum transmission). Between 8% and 29% of the emerging larvae became infected. No spores of E. schubergi were found in surface-washed eggs. Nosema lymantriae, a microsporidium that causes systemic infections, was transovarially transmitted. Between 35% and 72% of the progeny were infected. Vairimorpha disparis, a fat body pathogen, was not vertically transmitted. The infectivity of spores that overwintered in cadavers of infected L. dispar varied by species, placement in the environment, and weather conditions. Spores of E. schubergi were still infective after an eight month exposure period of cadavers on the ground. Spores of N. lymantriae and V. disparis remained highly infective only when cadavers overwintered under a more or less continuous snow cover for four months.     

Ultrastructural studies of male-incubated ovaries of the gypsy moth,Lymantria dispar

Ovaries from Lymantria dispar females were transplanted into an environment lacking the vitellogenin ligand; i.e., the male milieu. Transmission electron micrographs comparing the terminal oocytes of male-grown ovaries and normal ovaries showed that yolk sphere diameters were reduced in the male-grown oocytes. However, there were larger numbers of these small yolk spheres per unit area of cytoplasm, indicating that the coalescence of endosomes into yolk spheres is reduced in the absence of vitellogenin. Although there are larger numbers of yolk spheres in male-grown oocytes, the smaller diameter of yolk spheres resulted in less area being taken up by yolk spheres per unit area of cytoplasm in male-grown oocytes, yielding lowered yolk production. This lowered yolk production is a result at least in part of the lowered number of coated vesicles per unit area of submembrane space and in part of the reduced interfollicular spaces seen in male-grown ovaries.     

Structure-activity studies with pheromone-binding proteins of the gypsy moth,Lymantria dispar

Pheromone olfaction in the gypsy moth, Lymantria dispar, involves accurate distinction of compounds with similar structure and polarity. The identified sex pheromone is (7R,8S)-2-methyl-7,8-epoxyoctadecane, 1a, and a known antagonist is (7Z)-2-methyloctadec-7-ene, 4a. The first step in pheromone olfaction is binding of odorants by small, soluble pheromone-binding proteins (PBPs), found in the pheromone-sensing hairs. We have studied the molecular determinants recognized by the two PBPs found in the gypsy moth, using three pheromone/PBP binding assays. Results indicate that (i) PBPs bind analogs of the pheromone with some discrimination; (ii) PBPs experience enhancement of binding when presented with 1a or its enantiomer and 4a simultaneously; and (iii) the binding enhancement is also seen at high ligand:PBP ratios. We found no evidence of allostery, so the synergistic binding effects and the concentration effect may only be explained by multimerization of PBPs with each other, which leads to more than one population of binding sites. We suggest that the enhanced ligand binding at high ligand:PBP ratios may serve to sequester excess ligand and thereby attenuate very strong signals.     

Deposition and germination of conidia of the entomopathogen Entomophaga maimaiga infecting larvae of gypsy moth,Lymantria dispar

Germination of conidia of Entomophaga maimaiga, an important fungal pathogen of gypsy moth, Lymantria dispar, was investigated on water agar and larval cuticle at varying densities. Percent germination was positively associated with conidial density on water agar but not on larval cuticle. When conidia were showered onto water agar, the rate of germination was much slower than on the cuticle of L. dispar larvae. From the same conidial showers, the resulting conidial densities on water agar were much higher than those on larval cuticle in part because many conidia adhered to setae and did not reach the cuticle. A second factor influencing conidial densities on larval cuticle was the location conidia occurred on larvae. Few conidia were found on the flexible intersegmental membranes in comparison with the areas of more rigid cuticle, presumably because conidia were physically dislodged from intersegmental membranes when larvae moved. Conidia were also exposed to heightened CO(2) to evaluate whether this might influence germination. When conidia on water agar were exposed to heightened CO(2) levels, germinating conidia primarily formed germ tubes while most conidia exposed to ambient CO(2) rapidly formed secondary conidia.     

Sexual dimorphism in life history plasticity in the gypsy moth (Lymantria dispar L.)

Sexual differences in reaction norms of life history traits (larval development time--LDT, pupal weight--PW and adult longevity--L) were investigated in the gypsy moth reared on young or old oak leaves during the first larval instar. Sexual dimorphism was revealed for genetic variation in reaction norms that was expressed only for LDT in males, and PW and L in females. Higher mean plasticity of longevity was found in males compared to females indicating that the sexes are exposed to divergent selective pressures. Greater dependence of males on energy resources (carbohydrates and lipids) may account for the observed differences.     

Detection of alkaloids and carbohydrates by taste receptor cells of the galea of gypsy moth larvae, Lymantria dispar (L.)

Gypsy moth larvae are polyphagous feeders. The electrophysiological responses of the medial and lateral styloconic sensilla to four secondary compounds (e.g., alkaloids), two carbohydrates, and one inorganic salt were examined using an extracellular tip-recording method. In the medial sensillum, one taste receptor cell responded to the alkaloids, strychnine, caffeine, nicotine, and aristolochic acid (i.e., deterrent-sensitive cell), while another, responded to the sugar alcohol and inositol (inositol-sensitive cell). In both medial and lateral sensilla, two taste receptor cells in each sensillum responded minimally and sporadically to 30?mM potassium chloride (KCl) (i.e., KCl-sensitive cells); one cell produced much larger amplitude action potentials than the other. In the medial sensillum, only the large-amplitude KCl-sensitive cell exhibited an increased firing rate with increasing salt concentration. When binary mixture experiments were conducted, it was confirmed that the large-amplitude KCl-sensitive cell and the deterrent-sensitive cell in the medial sensillum were one in the same cell. Only a single cell in the lateral sensillum responded to the sugar, sucrose (sucrose-sensitive cell). The temporal dynamics of responses of the deterrent-sensitive, sucrose-sensitive, and inositol-sensitive cells were compared. Concentration?Cresponse data were obtained for the deterrent-sensitive cell to various alkaloids, as well as to KCl.     

Pheromonotropic activity in the gypsy moth Lymantria dispar: evidence for a neuropeptide

The brain-suboesophageal ganglion complex of the gypsy moth, Lymantria dispar, contains pheromonotropic activity detectable using a Helicoverpa zea in vivo bioassay for pheromone-biosynthesis-activating neuropeptide. Pheromonotropic activity was detected as early as the third larval instar and was present throughout development and through day 6 post-eclosion. Activity in the adult is presumably associated with pheromone production, while it is speculated that larval activity may be related to melanization. Adult pheromonotropic activity is associated with a peptide of approximately 3.500 kDa. It is heat labile and only partially stable when incubated at 35°C or exposed to freeze-thawing. Isolation of L. dispar pheromonotropic factor should facilitate the elucidation of the mechanism of pheromone production in this insect pest.Abbreviations ED₅₀ dose at which one-half maximal response is observal - eq equivalent - MRCH melanization and reddish colorization hormone - MW molecular weight - PBAN pheromone biosynthesis activating neuropeptide - SOG suboesophageal ganglion - TFA trifluoroacetic acid - Z11-16: Ald (Z)-11-hexadecenal     

Male death resulting from hybridization between subspecies of the gypsy moth,Lymantria dispar

We explored the origin of all-female broods resulting from male death in a Hokkaido population of Lymantria dispar through genetic crosses based on the earlier experiments done by Goldschmidt and by testing for the presence of endosymbionts that are known to cause male killing in some insect species. The mitochondrial DNA haplotypes of the all-female broods in Hokkaido were different from those of normal Hokkaido females and were the same as those widely distributed in Asia, including Tokyo (TK). Goldschmidt obtained all-female broods through backcrossing, that is, F1 females obtained by a cross between TK females (L. dispar japonica) and Hokkaido males (L. dispar praeterea) mated with Hokkaido males. He also obtained all-male broods by mating Hokkaido females with TK males. Goldschmidt inferred that female- and male-determining factors were weakest in the Hokkaido subspecies and stronger in the Honshu (TK) subspecies. According to his theory, the females of all-female broods mated with Honshu males should produce normal sex-ratio broods, whereas weaker Hokkaido sexes would be expected to disappear in F1 or F2 generations after crossing with the Honshu subspecies. We confirmed both of Goldschmidt''s results: in the case of all-female broods mated with Honshu males, normal sex-ratio broods were produced, but we obtained only all-female broods in the Goldschmidt backcross and obtained an all-male brood in the F1 generation of a Hokkaido female crossed with a TK male. We found no endosymbionts in all-female broods by 4,′6-diamidino-2-phenylindole (DAPI) staining. Therefore, the all-female broods observed in L. dispar are caused by some incompatibilities between Honshu and Hokkaido subspecies.     

Variation in temperature and dietary nitrogen affect performance of the gypsy moth (Lymantria dispar L.)

Abstract. . The independent and interactive effects of temperature and dietary nitrogen content on performance of the gypsy moth (Lymantria dispar L.) were examined. In long-term feeding trials, larvae were reared from egg hatch to pupation on low (1.5%) and high (3.7% dry weight) nitrogen diets, under three temperature regimes. Short-term feeding trials with fourth instars and the same treatments were conducted in order to calculate nutritional indices.
Higher temperatures did not influence larval survival and marginally increased final pupal weights, but strongly decreased long-term development rates. They also accelerated short-term growth and consumption rates, and tended to improve food processing efficiencies. High concentrations of dietary nitrogen increased survival rates and final pupal weights markedly, but decreased long-term development rates only marginally. A high content of dietary nitrogen also accelerated short-term development and growth rates, reduced consumption rates, and improved food digestibility. Insects responded to low nitrogen-content diets primarily by eating faster, rather than by altering efficiency of nitrogen use. In the short-term feeding trials, thermal regime and dietary nitrogen interacted to influence growth rates, overall food processing efficiencies and nitrogen consumption rates. No interactive effects were observed in long-term studies.
This research demonstrates that small changes in thermal regime and ecologically relevant variation in dietary nitrogen content can strongly affect gypsy moth performance. Moreover, various performance parameters are differentially sensitive to the direct and interactive effects of temperature and diet.     

Behavioural response to an unsuitable host plant in the gypsy moth (Lymantria dispar L.)

To assess local differentiation in host preference, a two-choice test was performed on first-instar gypsy moth larvae originating from an oak and locust-tree forest. More than 40 generations feeding on locust-tree leaves, rich in alkaloids, led to non-efficient discrimination of host leaves in larvae from a locust-tree forest. Possible causes of observed population differences are discussed in the present paper.     

Neurological influences on pheromone release and calling behaviour in the gypsy moth, Lymantria dispar

ABSTRACT. Surgical removal of the brain or disconnection of the last abdominal ganglion from the ventral nerve cord prevented sex pheromone release in female Lymantria dispar (L.) (Lymantriidae), as assayed by the male wing-fanning response. The calling behaviour continued to occur in individuals whose terminal abdominal ganglion had been thus isolated, however, indicating that the neural mechanisms controlling calling function independently in the last abdominal ganglion.