Lymantriidae Research Articles

Two nuclear polyhedrosis viruses of the Douglas-fir tussock moth

Two nuclear polyhedrosis viruses affecting the Douglas-fir tussock moth, Hemerocampa pseudotsugata, are described. One induces formation of polyhedral bodies containing single rod-shaped virus particles, each within its own envelope. The other produces polyhedra with bundles of several rods within a common envelope. The same tissues of the host are affected by both viruses, although not equally. Mean lengths of the rods of the two types differ. One type of virus has been found in only a few geographic locations.

The isolation of cytoplasmic polyhedrosis virus from the white-marked tussock moth, Orgyia leucostigma (Smith).

The procedure for isolating and purifying free and occluded cytoplasmic polyhedrosis virions was improved. The virions are resistant to the enzymes RNase, DNase, trypsin, chymotrypsin, and phospholipase C, and to a detergent, deoxycholate. The use of these enzymes and deoxycholate, in combination with discontinuous and linear sucrose gradients, produced very pure preparations of free virions. Occluded virions were released by dissolving polyhedra in 0.05 M Na2CO3 – 0.04 M NaCl for 60 min at room temperature. The composition of the virion was estimated to be about 28% RNA and 72%protein.

DEVELOPMENT OF SAMPLING METHODS FOR THE DOUGLAS-FIR TUSSOCK MOTH, HEMEROCAMPA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE)

AbstractMethods were developed to standardize sampling of the Douglas-fir tussock moth. Population density was estimated in terms of the number of eggs or larvae per 1,000 sq. in. of branch area of Abies concolor (Gord. and Glend.) Lindl. The density of eggs and larvae varied significantly in different parts of the tree crown. In an outbreak, egg masses were concentrated on inside branches near the bottom of the crown, but in light populations they were most common on outside branches in the top of the crown. Larvae were found over the entire tree, but they were especially concentrated on foliage in the top. Mean density of larvae in the middle crown was representative of the whole tree. Egg density is estimated from whole branches sampled representatively from three crown levels; however, density of larvae is estimated accurately from 17-in. twig samples taken from just the middle crown. Because eggs are clumped in masses and larvae are dispersed over the foliage, larval density can be estimated with much less sampling than can egg density for the same precision.

Laboratory Tests of 55 Insecticides on Douglas-Fir Tussock Moth Larvae1

Fifty-five insecticides were tested for their toxicity to larvae of the Douglas-fir tussock moth, Hemercampa pseudotsugata McDunnough. The 10 most active insecticides in descending order of average toxicity at LD90 were: pyrethrins, Dursban® (O, O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate), Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), dichlorvos, GC-6506 (dimethyl p-(methythio) phenyl phosphate), aminocarb, tetramethrin, allethrin, Bayer 37298 (O-ethyl 0-2,4,5-trichlorophenyl ethylphosphonothioate), and DDT. Four of the 10 insecticides–pyrethrins, Dursban, Zectran. And DDT–have been field-tested recently with varying results. Several insecticides were examined in the laboratory in more detail in different formulations for such characteristics as rate of toxic action and residual activity.

DISTRIBUTION AND PARASITIZATION OF COCOONS OF THE DOUGLAS-FIR TUSSOCK MOTH, HEMEROCAMPA PSEUDOTSUGATA (LEPIDOPTERA: LYMANTRIIDAE), IN AN ISOLATED INFESTATION

AbstractDouglas-fir tussock moth cocoons were collected and their distribution recorded by crown level on white fir, Abies concolor, in northeastern California. Nine trees were sampled in two defoliation classes, light (20–30% defoliated) and moderate to heavy (50–80% defoliated). Cocoons were more abundant in the lower crown levels as defoliation became greater. The proportion of female cocoons increased toward the lower levels of the crown. An overall sex ratio of 1.2♂:1.0♀ was recorded. Significantly more male cocoons were parasitized than female. A list of the natural enemies of the tussock moth from the study area is given.

A nucleopolyhedrosis virus in populations of the Douglas-fir tussock moth, Hemerocampa pseudotsugata, in California

A nuclear-polyhedrosis virus of the Douglas-fir tussock moth, Hemerocampa pseudotsugata, was found in the white fir forests of California for the first time. Tussockmoth populations declined in 1965, and this virus may be one of the important mortality factors. Egg masses were collected in selected study areas and the larvae reared in petri dishes on artificial diet. Larvae were also collected in several instars during the course of the summer and reared individually in petri dishes. An attempt was made to design a survey technique that would indicate the rate of decline, due to virus, of tussock-moth populations in the field. Further refinement will be necessary before egg-mass collections can be used as a survey tool but these studies indicate a good potential for such use. Evidence from this study shows the rate of dying in sample dishes in the laboratory to be related to the rate of larval mortality in the field. The primary use of such a survey would be an indicator to those involved in pest control decisions.

A cytoplasmic polyhedrosis of Hemerocampa pseudotsugata

Histochemical and histological studies of midguts of larvae of the Douglas-fir tussock moth, Hemerocampa pseudotsugata, infected with cytoplasmic-polyhedrosis virus showed that the viral inclusion bodies formed in apicobasally oriented rows in goblet and columnar cells of the epithelium. Electron micrographs of ultrathin sections of infected cells in the late stages of the disease revealed that the cytoplasmic polyhedra, were surrounded by high numbers of virus particles, adjacent to the surface of the inclusion bodies. Biological assay gave an ld 50 estimate of 104 polyhedra/g larval weight. In our samples, the mean volume of the inclusion bodies was 7.7 μ 3 and the mean diameter of the virus particles was 56 mμ.

愛知県におけるドクガの発病調査

愛知県におけるドクガの発病調査

Properties of a cytoplasmic-polyhedrosis virus from the white-marked tussock moth

Properties of a cytoplasmic-polyhedrosis virus from the white-marked tussock moth

Mass purification of polyhedral inclusion bodies by isopycnic banding in zonal rotors

In this paper, we describe the development of a novel field detection system for the identification of Orgyia pseudotsugata nucleopolyhedrovirus (OpNPV) and OpNPV infections in Douglas-fir tussock moth (O. pseudotsugata) (DFTM) larvae, utilizing antibodies in a dipstick immunoassay. The dipstick method is sensitive to a minimum of 10 ng of extracted virus protein, or approximately 1070 virus occlusion bodies, and is sufficiently sensitive to detect OpNPV infections in DFTM prior to mortality. Additionally, the method can be used to unambiguously detect virus in infected larvae without purification of the test sample. This research provides a novel tool for on-site assessment of the incidence of OpNPV in field populations of DFTM, and has the potential to improve the biological control of the DFTM by facilitating on-site pest management decisions.

Rearing Douglas-Fir Tussock Moth Larvae on Synthetic Media for the Production of Nuclear-Polyhedrosis Virus1

A technique for rearing larvae of the Douglas-fir tussock moth, Hemerocampa pseudotsugata McDunnough, in large numbers on a synthetic medium for the production of nuclear polyhedrons virus is described. The insect was reared from the egg stage generally to the 4th and 5th instar before infection. The larvae appeared normal in every way, reaching an average weight of 310 mg. Mortality during the larval stage prior to infection was very low.

DOUGLAS-FIR TUSSOCK MOTH (HEMEROCAMPA PSEUDOTSUGATA) EGG-MASS DISTRIBUTION ON WHITE FIR IN NORTHEASTERN CALIFORNIA

AbstractThe distribution of Douglas-fir tussock moth (Hemerocampa pseudotsugata McD.) egg-masses on white fir (Abies concolor (Gord. and Glend.) Lindl.) was studied in three areas of northern California. In each area 100 trees between 4.5 and 8.4 in. in diameter were stratified into five defoliation classes and four crown classes, giving a total of 20 classes per study area with five trees per class. Trees were divided into four crown levels and samples were taken at each of the cardinal directions at each level. Two branches comprised n sample unit in the top half of the tree (eight branches per level) and one branch the sample unit in the bottom half of the tree (four branches per level). Egg masses were recorded per 10 sq. ft of foliage or branch area. Eighty per cent or more of the egg masses were found in the bottom half of the crown. This percentage in the bottom half of the crown increased on trees with heavy defoliation or with increased exposure of the crown. Of the four possible sources of variation considered in this study, crown level, defoliation class, and crown class were significant while cardinal direction was not. A sampling method is proposed on the basis of the information gathered in this investigation.

Insecticide Tests against Larvae of Hemerocampa, new species, a Tussock Moth that Defoliates Boxelder in New Mexico1

Insecticide Tests against Larvae of Hemerocampa, new species, a Tussock Moth that Defoliates Boxelder in New Mexico1

Rearing Douglas-Fir Tussock Moth Larvae on Synthetic Media

A procedure was developed for rearing larvae of Douglas fir tussock moth, Hemerocampa pseudotsugata McDun-nough, in large numbers on a synthetic medium for use laboratory testing of insecticides. The insect was reared from the egg stage generally to the fourth to seventh in-star, depending on testing needs. The larvae appeared normal in every way, reaching a weight of about 300 mg before pupation. An initial high loss from a nuclear polyhedrosis virus in the third instal was avoided by soaking the eggs in a 10% formaldehyde solution. Mortality during the larval stage on media was about 10%. Three thousand larvae were reared per week at a cost (excluding overhead) of about $15. At least 25,000 larvae could be reared weekly by I person working full time.

Studies on the Bionomics of Notolophus posticus W. a pest on castor in Madras State

The Lymantriids commonly called tussock moths, are well known pests of some cultivated crops and forest trees. Among the oilseed crops, castor (Ricinus communis L.) is a well known host and the damage due to defoliation is often considerable. Observations made in 1962 at the Agricultural College and Research Institute, Coimbatore on the biology of Notolophus posticus W. are reported in this paper.

A note on the relationship between outbreaks of the oriental tussock moth, Euproctis flava and weather conditions

SummaryA relationship between outbreaks of the oriental tussock moth, Euproctis flava, in Akita Prefecture and weather conditions have been analyzed in the present paper. The results obtained are summarized as follows:Outbreaks were, in most cases, observed at intervals of 7–9 years, and the population fluctuation was considered to be regular, when small rises of population density were taken into consideration. The condition of low temperature and decreased percentage of sunny hours in spring and summer has a great influence upon the occurrence of outbreaks, and a big outbreak seems to come when a peak of the intrinsic population fluctuation occurs just simultaneously with such a weather condition.

SUSCEPTIBILITY OF LAMBDINA FISCELLARIA SOMNIARIA (HULST) (GEOMETRIDAE) AND LAMBDINA FISCELLARIA LUGUBROSA (HULST) (GEOMETRIDAE) TO VIRUSES FROM SEVERAL SPECIES OF LEPIDOPTEROUS INSECTS

Fifteen nuclear-polyhedrosis viruses and one granulosis virus were tested against two closely related insects, the oak looper, Lambdina fiscellaria somniaria (Hulst), and the hemlock looper, Lambdina fiscellaria lugubrosa (Hulst). The polyhedrosis viruses from the two insects were highly infectious for each species of host. Viruses from the tussock moth, Orgyia pseudotsugata McD., and the grey forest looper, Caripeta divisata Walker, were, respectively, highly and moderately infectious for the two subspecies. Viruses from five other insects including the California oakworm were poorly infectious for L. f. somniaria.All polyhedra retained their normal shape but nearly all increased in size when passed through the new hosts. All polyhedra (original and transferred) were easily stained with naphthol yellow S and with Buffalo black but only those from C. divisata were stained with Loeffler"s methylene blue. The length of the virus rods of viruses tested was not changed by passage through a new host but the width of three viruses increased.

The Western Tussock Moth, Hemerocampa vetusta (Bdv.), on Citrus in Southern California1

Larvae of the western tussock moth, Hemerocampa vetusta (Bdv.), caused economic losses in 10,000 acres of oranges during the springs of 1956 and 1957 in parts of southern California. Population levels were as high as 1,000 larvae per tree. The larvae may destroy the new spring flush of growth, the newly set fruit, and scar maturing oranges so that the fruit drops or the grade is lowered. This moth has one generation a year. The wingless females lay their eggs on the trees in masses from May to July; the eggs hatch during March and April of the following year. The average length of life cycle is 75 days. A population level of 100 caterpillars per orange tree, or an average of one egg mass per tree, is considered the economic level. Six parasite species, one hyperparasite, and two predator species were collected during the years 1956 and 1957 and were observed to reduce the population approximately 50% in some groves. Chemical control studies showed that parathion, TDE (DDD), DDT, Dilan, Guthion, Sevin ( N -methyl-1-naphthyl carbamate), methyl parathion, and Phosdrin gave excellent control; nine other pesticides did not provide adequate control. Parathion, TDE, and DDT are now registered for use on citrus and are recommended for control of the western tussock moth when applied as complete foliage sprays at the rate of 2, 5, and 5 pounds, respectively, of actual toxicant per acre.

Induction of polyhedral bodies in ovarian tissues of the tussock moth in vitro.

Induction of polyhedral bodies in ovarian tissues of the tussock moth in vitro.

Effects of a C-47 Airplane Application of DDT on Fishfood Organisms in Two Pennsylvania Watersheds

For the control of many defoliators of the forest, DDT dispersed as a spray from airplanes has proved highly effective. The trend has been toward the use of large, fast airplanes to dispense DDT for the control of devastating pests during a susceptible stage of their life cycle, which frequently is of short duration. In widespread spraying operations many streams and ponds become contaminated with insecticides. Although spraying with poisons may be justified on the basis of saving our forests, many people have become concerned regarding its possible detrimental effects to wildlife. Aquatic species appear to be affected more by DDT sprayings than terrestrial animals. To the extent that this is true, it is likely the effects are greater on aquatics because of their intimate and continuous contact with the insecticide. Studies summarized by Surber (1948) have shown that DDT is toxic to fish, and that the damage is usually proportional to the dosage and is especially serious in shallow bodies of water. Forest entomologists at present are interested primarily in single aerial sprayings made at the rate of 1 pound of DDT per acre, since this dosage is effective against several important defoliators. Field studies made in 1945 and in subsequent years on the effects of this dosage on fish and fish-food organisms have been limited to small streams or to 1-mile sections of large streams in the East. Under these conditions fish losses have been negligible, but 70 to 90 percent of the fish-food organisms have been eliminated shortly after the spraying. Further study indicated rapid insect repopulation, and a year later some of the streams contained a variety and abundance as great as before the spraying (Hoffmann and Merkel, 1948). The question arises as to whether similar results would be obtained when thousands of acres, including important streams and their tributaries, are sprayed in a short period of time. In Idaho, where widespread spraying with 1 pound of DDI per acre was undertaken for the control of the Douglas-fir tussock moth (Hemerocan2pa pseudotsugata McD.), most of the aquatic invertebrates were eliminated in heavily treated areas (Adams et al. 1949). A study of one stream showed that annelids were unaffected, and that some reestablishment of other invertebrates occurred about two months after the spraying. Some cottoids, mountain suckers and black bullheads were killed by DDT; whereas rainbow, eastern brook and cutthroat trout, speckled dace and redside shiners were apparently unharmed. Moreover, studies are needed to de-