A wheat germ medium for rearing of the gypsy mothLymantria dispar L.

Procedures for mass-rearing ofLymantria dispar L. in a simple and effective manner were described byLeonard & Doane (1966),Odell & Rollinson (1966), andZlotin & Lymareva (1966). During the past three years several attempts were made to develop an artificial medium for rearing the gypsy moth in this Station. The wheat germ diets formulated by the American authors were also tested, but with contrasting results. The present paper reports the composition of a meridic diet that supports growth and development of the moth.

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Résumé Un milieu semi-synthétique a été mis au point pour l’élevage des chenilles deLymantria dispar L. De la comparaison des résultats obtenus il ressort que le milieu à base de germes de blé permet d’obtenir une production permanente et abondante d’insectes normaux. A 23 °C la durée moyenne du développement larvaire et nymphal a été de 51 jours avec un rendement en adultes de 97 p. 100. Les papillons obtenus ont présenté une fécondité très satisfaisante, ayant déposé en moyenne 865 œufs fertiles.

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Presented at the 1st meeting of the “Working Group onLymantria dispar, O.I.L.B.”, Tempio Pausania, Italy, October 16–17, 1969.     

A new egg-parasite of gipsy mothLymantria dispar (L.)

Summary Species ofScelionidae, parasiting in eggs ofLymantria dispar (L.) are mentioned and the results of use of these parasites are added. A new egg-parasite of gipsy moth —Hadronotus lymantriae n.sp. — is described. A key to Scelionid egg-parasites living inLymantria dispar (L.) is given. Attention is drawn to the fact thatH. bernardi Manev. is a nomen nudum. Finally, the author discusses the phylogenetical and taxonomical internal relations inHadronotus Foerst.

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Résumé L'auteur mentionne les différentes espèces de Scélionides parasites des œufs deLymantria dispar (L.) et rappelle les résultats obtenus par l'utilisation de ces parasites. Un nouveau parasite des œufs de ce Bombyx,Hadronotus lymantriae n. sp., est décrit. Il est montré en outre queH. bernardi Manev. doit être considérénomen nudum. Enfin l'auteur discute les relations phylogéniques et taxonomiques des espèces du genreHadronotus Foerst.

     

L'applicazione di un virus poliedrico nucleare nella lotta control larve diLymantria dispar L.

Summary Small scale field tests with a nuclear-polyhedrosis virus were conducted, for the first time in Sardinia during 1965–1966, on the larvae of the gypsy moth (Lymantria dispar L.). Promising results were obtained by spraying the pathogen at several dosage levels on the cork-oak trees (Quercus suber L.). Mortality varied with the concentration of virus used and with the age of the larvae at the time of spraying. In 1965 a suspension containing 1,2×10⁹ purified polyhedra per milliliter gave 100% mortality of the second-instar larvae in 16 days. Lower polyhedra counts gave mortality ranging between 84 and 99 per cent. In 1966 the treatments with a raw suspension containing 10⁸ polyhedra per milliliter brought about the death, in 20 days, of 100 per cent and 93 per cent respectively of the second- and third-instar larvae. Even lower concentrations caused considerable larval mortality. The lower temperatures occurring in 1966 account for the delay in the appearance of elevated mortality rates. Application of the virus to third-instar larvae carrying microsporidian infections (Nosema lymantriae Weiser) led to an accelerated mortality. On the basis of the frass collected it is obvious that the insects fed poorly on the treated trees as compared to the controls. It is not possible to make direct comparisons of dosages between the 1965 and the 1966 treatments. The different feeding activity, however, of second-instar larvae treated with similar concentrations of purified or unpurified polyhedra suggest that further research is necessary in order to ascertain if the frass reduction obtained using the raw virus suspension is not due to a greater efficacy of the unpurified as compared to the purified virus. Field results indicate that a virus suspension containing 10 million polyhedral inclusion bodies per milliliter of water will prevent excessive defoliation of trees by the larvae.      

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     

Exploration into a mechanism of transgenerational transmission of nucleopolyhedrovirus in Lymantria dispar L. in Western Siberia

The mechanisms of nucleopolyhedrovirus (NPV)transmission through gypsy moth (Lymantriadispar L., Lepidoptera: Lymantriidae)populations in Western Siberia wereinvestigated. Field and laboratory studies werecarried out during 1992–1998 in a gypsy mothoutbreak in the Novosibirsk Area (WesternSiberia), Russia. The damaged trees were primarilytwo species of birch, Betula pendula Roth. and B. pubescensEhrh. Investigations were performed at threestages of the outbreak: population increase(1992–1993), population peak (1994–1995) andpopulation decline (1996–1998). Experiments onactivation of occult virus by different stressfactors were carried out in order to clarifythe mechanism of transgenerational transmissionof NPV. In both laboratory and fieldexperiments NPV-caused mortality levels werelow; most insects did not acquire a lethal doseof virus. Occult virus can provide an importantroute of transgenerational NPV transmission,particularly in Western Siberia where gypsymoths migrate by female flight and can moveaway from trees contaminated by virus fromprevious larval infections.     

Impact of predators on artificially augmented populations of Lymantria dispar L. pupae (Lep., Lymantriidae)

The impact of predators on artificially augmented populations of Lymantria dispar pupae (Lep., Lymantriidae) and the species composition of the predator community were investigated in two oak stands in eastern Austria. The population density of L. dispar has been at innocuous levels for several years at both sites. From mid-June to mid-July, we created artificial prey populations by mounting gypsy moth pupae with beeswax on burlap bands placed at the base, 25, 50 and 100 cm height on 25 trees at each site. A total of 6600 pupae were exposed at each site. A total of 92% of exposed pupae were destroyed by predators, at site I (with dense understorey vegetation) whereas 67% were destroyed on site II (with sparse understorey vegetation). Initially, pupal mortality was highest at the base of trees, but differences in mortality among the four locations where pupae were exposed decreased during the course of the study period. Spatial differences in predation were ascertained, suggesting that the aggregation of small mammals, for example, is related to patches of dense shrub vegetation. Pupal mortality was primarily caused by mice (46.3% at site I and 36.4% at site II). Many exposed pupae simply disappeared (40.4% at site I and 22.8% at site II). Calosoma spp. and other invertebrate predators caused very little mortality among L. dispar pupae (5.5% at site I and 7.8% at site II). Trap catches on separate study plots at both sites revealed that Apodemus flavicollis (Rodentia, Muridae) was the most important predator species present, whereas Apodemus sylvaticus (Rodentia, Muridae) and Clethrionomys glareolus (Rodentia, Arvicolidae) were captured in low numbers.     

Introns of Entamoeba histolytica and Entamoeba dispar.

The genome of Entamoeba histolytica is considered to possess very few intervening sequences (introns), as only 5 intron-containing genes from this protozoan parasite have been reported so far. However, while sequencing a number of genomic contigs as well as three independent genes coding for ribosomal protein L27a, we have identified 9 additional intron-containing genes of E. histolytica and the closely related species Entamoeba dispar, indicating that introns are more common in these organisms than previously suggested. The various amoeba introns are relatively short comprising between 46 and 115 nucleotides only and have a higher AT-content compared to the corresponding exon sequences. In contrast to higher eukaryotes, amoeba introns do not contain a well-conserved branch point consensus, and have extended donor and acceptor splice sites of the sequences G     

Larvicidal and antifeedant activity of some plant-derived compounds to Lymantria dispar L. (Lepidoptera: Limantriidae)

Ethanol solutions of essential oil of Ocimum basilicum and its main component, linalool (both isomer forms), all in three concentrations, as well as botanical standard Bioneem (0.5%), were tested for their toxicity and antifeedant activity against the second instar gypsy moth larvae in the laboratory bioassay. The essential oil of O. basilicum was subjected to gas chromatography analysis, and totally 37 compounds were detected, of which linalool was predominantly present. All tested solutions showed low to moderate larvicidal effect in both residual toxicity test and in chronic larval mortality bioassay. Chronic mortality tests showed that obtained mortality was a consequence of starving rather than ingestion of treated leaves. However, antifeedant index achieved by application of tested solutions in feeding choice assay was remarkable. Foliar application of all tested compounds deterred feeding by L2 in the same percent as Bioneem. Antifeedant index was relatively high at all tested treatments (85-94%); moreover, the larval desensitization to repelling volatiles has not occurred after five days of observation. Low toxic and high antifeedant properties make these plant-derived compounds suitable for incorporation in integrated pest management programs, especially in urban environments.     

Ghrelin effect on nutritional indices, midgut and fat body of Lymantria dispar L. (Lymantriidae)

Ghrelin is a 28-amino acid peptide that has significant effects on appetite and growth in humans and animals. The aim of this study was to examine 4th instar larvae of the pest insect Lymantria dispar L. after ghrelin treatment. Parameters included changes in nutritional indices (efficiency of conversion of ingested food, efficiency of conversion of digested food, approximate digestibility); midgut and fat body mass; total proteases, trypsin and leucine aminopeptidase activities in the midgut; number, height and width of columnar and goblet cells and their nuclei in the midgut epithelium and detection of ghrelin-like immunoreactivity in the midgut tissue. Four subpicomolar injections of ghrelin (0.3pmol) or physiological saline (control) were applied every 24h. The nutritional indices were higher in the ghrelin treated than in the control group. Ghrelin treatment was also associated with elevation of midgut mass, induced digestive enzyme activities, increased fat body mass and morphometric changes in columnar and goblet cells. This is the first report of the presence of ghrelin-like hormone in endocrine cells of an insect midgut. Such information provides additional evidence for application of this relatively simple model system in the future studies of the mechanisms underlying of digestion and energy balance in more complex organisms.     

Laboratory and field experiments on the effectiveness of purified and non-purified nuclear polyhedral virus ofLymantria dispar L.

Résumé Des expériences de laboratoire et en plein champ ont révélé que le virus de la polyédrose nucléaire deLymantria dispar L. est plus efficace quand on l'emploie sous forme de suspension non purifiée. La virulence plus élevée des préparations non purifiées par rapport aux préparations purifiées, s'est manifestée, suivant l'age des chenilles, par l'augmentation des différences de mortalité avec la diminution de la concentration des suspensions employées. Tandis qu'en laboratoire on a pu observer une différence maximum de la mortalité égale à 43,3%, en plein champ, il n'y a pas eu de différence supérieure à 19%. Avec les doses les plus concentrées, la plus grande eflicacité de la préparation non purifiée a eu l'unique effet d'abréger la période d'incubation de la polyédrie. Bien qu'on ait démontré que, dans des forêts de chênes-lièges, il convient de se servir de préparations non purifiées, au lieu de préparations purifiées, il est nécessaire d'effectuer des recherches ultérieures, afin de distinguer les facteurs responsables de cette activité différente.      

Variabilité de la sensibilité deLymantria dispar L., aBacillus thuringiensis Berliner

Summary Seven strains ofBacillus thuringiensis (berliner, anduze, sotto, dendrolimus, galleriae, subtoxicus, entomocidus) that belong to five different serotypes, have been studied in the laboratory as to their comparative activity againstLymantria dispar L. Thesubtoxicus preparation revealed being the most active. Apartsubtoxicus, the precise activity range of the other strains is difficult to evaluate, because of the heterogenous results of the different repetitions. The later larval instars were less sensible than the younger ones for each of the seven strains. A higher mortality was observed with starved caterpillars.      

Host range factor 1 from Lymantria dispar Nucleopolyhedrovirus (NPV) is an essential viral factor required for productive infection of NPVs in IPLB-Ld652Y cells derived from L. dispar

Host range factor 1 (HRF-1) of Lymantria dispar multinucleocapsid nucleopolyhedrovirus promotes Autographa californica MNPV replication in nonpermissive Ld652Y cells derived from L. dispar. Here we demonstrate that restricted Hyphantria cunea NPV replication in Ld652Y cells was not due to apoptosis but was likely due to global protein synthesis arrest that could be restored by HRF-1. Our data also showed that HRF-1 promoted the production of progeny virions for two other baculoviruses, Bombyx mori NPV and Spodoptera exigua MNPV, whose replication in Ld652Y cells is limited to replication of viral DNA without successful production of infectious progeny virions. Thus, HRF-1 is an essential viral factor required for productive infection of NPVs in Ld652Y cells.     

Eine mutante mit abnormer flügelform beiLymantria dispar L. und ihre temperaturabhängigkeit in der manifestation

The mutantIncisiva (Ic) found in a German population ofLymaniria dispar L. is characterized by a semicircular to parabolic incision on the tips of the hind-wings (occasionally on the forewing also). The inheritance of this character is dominant, autosomal, and presumably monofactorial. Penetrance and expressivity of theIncisiva-allele are strongly temperature dependent. As a rule the penetrance increases with decreasing temperatures from 0% in 27°C-cultures to 100% in 16°C-cultures. Modifying genes which are partly sex-linked can considerably decrease the penetrance of the gene in cold-cultured individuals. At low temperatures incisions are often observed even on the tips of the fore-wings. In this case the hind-wings are split up to the base, thus displacing or even suppressing the radial and median veins. The size of incisions and their occurrence in fore-wings are influenced by the genetic background. The temperature sensitive period forIc mutant manifestation was determined to be lying in the last but two instar before pupation i.e. in the 4th in ♂♂, and in the 5th in ♀♀. This temperature sensitive phase coincides with the initial stages of development of the presumptive wing-blade in the imaginal disc. The wing incision is recognizable as a split already before the main growth period of the wing-blade at the beginning of the last larval instar.