Bivittatus Say Research Articles

A Survey of the Arthropod Fauna Associated with Hemp (Cannabis sativa L.) Grown in Eastern Colorado

Industrial hemp was found to support a diverse complex of arthropods in surveys of fields in eastern Colorado. In 2016-2018, surveys of industrial hemp in eight eastern Colorado counties, eighty families of arthropods were collected, primary taxa in the orders Diptera, Coleoptera, and Hemiptera. The arthropods collected from hemp included herbivores, natural enemies, pollen feeders, and incidental species. Hemp cultivars grown for seed and fiber had higher insect species richness compared to hemp grown for cannabidiol (CBD). Species that were observed to cause economic damage included: corn earworm, (Helicoverpa zea Boddie), hemp russet mite (Aculops cannibicola Farkas), cannabis aphid (Phorodon cannabis Passerini), and Eurasian hemp borer (Grapholita delineana Walker). In addition, serious damage to hemp plants was observed by grasshoppers, particularly the twostriped grasshopper, Melanoplus bivittatus Say, and the differential grasshopper, M. differentialis Thomas. This survey serves as the first checklist of arthropods associated with industrial hemp in any area of North America.

Grasshopper (Orthoptera: Acrididae) damage to flowers and pods of lentil ( Lens culinaris L.)

A study was initiated in response to concerns that grasshoppers were becoming an economic issue in lentil crops. The study characterized the type and extent of damage and determined the relationship between grasshopper numbers ( Melanoplus bivittatus Say) in lentil ( Lens culinaris L.) during flowering and yield loss. In commercial fields, grasshopper damage was found on sepals, flowers and both immature and mature pods. Grasshoppers at relatively low population density levels have a major impact on yield of lentil. Populations of 2–3/m 2 damaged up to 23% of the viable pods and 47% of the flowers and immature pods. Field-cage trials along with recent estimates of crop yields, crop price and control costs were used to estimate an economic threshold. The relationship was linear ( F=42.98; P=0.0001). The fitted linear relationship ( y=247.5−5.2 x; R 2=0.71) estimates an average yield loss of approximately 2% for every one grasshopper/m 2. This information is pertinent to an economic evaluation of management strategies against grasshoppers in lentil.

THE EGGS AND LARVAE OF PACHYBRACHIS PECCANS AND P. BIVITTATUS, WITH A KEY TO THE KNOWN IMMATURE STAGES OF THE NEARCTIC GENERA OF CRYPTOCEPHALINAE (COLEOPTERA: CHRYSOMELIDAE)

AbstractThe egg and larval instars of Pachybrachis peccans Suffrian and P. bivittatus Say are described and illustrated. Adults of both species appear in late May, feed on willow leaves, mate and oviposit in June–July. The larvae, unable to climb the host plants, feed in the leaf litter of dead leaves of willow; they reach the second-last or last instar by the end of the fall; then they seal their case and overwinter. Pupation occurs the following spring, probably in early May.Larval instars can be distinguished as follows: first instar with egg bursters on meso- and metathorax, with typical head chaetotaxy consisting of flattened-papillate setae and 1 pair of very long simple setae, and tibiae with 2 pairs of spiniform setae; older instars without egg bursters, and showing differences in size, in head and pronotal chaetotaxy, and in the number of spiniform setae on the tibiae.In the larvae, the premental sclerites of the head seem to be present throughout the Campsomata, a group with case-bearing larvae and not only in the Lamprosomatinae as previously reported.

Observation and Interpretation of Nuclear Reductions During Maturation and Germination of Entomophthoralean Resting Spores

tory ofthe pathogen. It is important to determine if karyogamy and meiosis occur in the life cycle of this fungus, and if so, at what site and time, before any strain improvement through genetic manipulation might be attempted. Conflicting data about the nuclear events associated with resting spore pro? duction and germination in the Entomophthorales have presented difficulty in the correct interpretation of entomophthoralean life cycles. Sawyer (1931) believed the resting spores of E. radicans {=Entomophthora sphaerosperma Fres.) re? mained multinucleate at maturity; Perry et al. (1982) studied the germination of resting spores of this species but did not note the nuclear condition at any time in mature, activated, or germinating spores. Latge (1976) reported a reduction in the number of nuclei to one during resting spore maturation in Conidiobolus thromboides Drechsler {=Entomophthora virulenta Hall & Dunn). Resting spores of E. radicans (strain RS-141, Insect Pathology Research Unit) were harvested from 3% yeast extract agar at various stages of development and stained with haematoxylin following the procedures of Lu and Raja (1970). Resting spores of Entomophaga grylli (Fres.) Batko were recovered from field-collected cadavers of Melanoplus bivittatus Say after several months of storage at 4 C in a sealed container. Confirmatory studies on the nuclear condition of resting spores of C thromboides (strain RS-40) were done with spores produced on egg yolk/ Sabouraud maltose agar (Soper et al, 1975). Nuclear conditions of germinating resting spores in this species were studied from spores stored over silica gel in a sealed container at 4 C for 3 yr; approximately 25% of these spores would ger? minate after being wetted. These 3-yr-old spores were used to determine nuclear events during the germination process. In the early formation of E. radicans resting spores, the prespores may contain as many as 25 nuclei (Fig. 1). The young resting spore forms in less than 24 h inside the parental prespore. During the deposition of the spore wall some nuclei may be trapped between the prespore (parental) wall and newly formed inner (sporangial) wall (Fig. 2). The excluded nuclei rapidly disintegrate leaving a more or less empty space between the two thickened wall layers. As the resting spore matures, many ofthe nuclei degenerate until, after two wk, only two nuclei remain in each spore (Fig. 3). No further reduction in the number of nuclei was observed,

Comparison of gravimetric and chromic oxide methods for measuring percentage utilization and consumption of food by phytophagous insects

An indirect method using chromic oxide (Cr 2O 3) for measuring percentage utilization and consumption of dry matter in diets by two species of phytophagous insects is described and results are compared with those of the classical gravimetric method. Fifth-instar larvae of the two-striped grasshopper, Melanoplus bivittatus Say, and fifth-instar larvae of the pale western cutworm, Agrotis orthogonia Morr., were fed individually. Diets were prepared from lyophilized tissues of the wheat plant to which about 4 per cent of the inert index compound, chromic oxide, was added. Three diets varying widely in nutritive value were compared for both utilization and consumption. When residual food and excreta could be quantitatively recovered, measurements by the two methods generally agreed. However, the chromic oxide procedure for measuring utilization gives more reliable results than did the gravimetric method, is convenient, and can be used even when quantitative recovery of excreta is not possible.

The Fungous Disease Caused by Entomophthora grylli Fres., and its Effects on Grasshopper Populations in Saskatchewan in 1963

AbstractA widespread epizootic of the fungous disease caused by Entomophthora grylli Fres. occurred among grasshoppers in Saskatchewan in 1963. Camnula pellucida (Scudder), in particular, suffered high mortality and was nearly wiped out in those areas of central and east-central Saskatchewan where heavy infestations had been present. Weather was warm and humid during the outbreak with above normal rainfall in the seriously affected areas.Field-cage studies showed that proper timing of rainfall was essential for continuation and spread of the disease. Rainfall shortly after death of the diseased grasshopper induced profuse growth of conidiophores along with intense discharge of conidia. When death occurred during hot, dry weather, no sporulation was noted and the insects rapidly dried up. The interval from infection to death of the grasshopper was about 13 days.The fungous disease also developed in natural field populations of Melanoplus bivittatus Say, but none was noted in field cages where this grasshopper was being reared alongside of or together with C. pellucida that were dying continuously from the disease; this suggests that different strains of E. grylli were involved.

SOME OBSERVATIONS ON AN OUTBREAK OF THE TWO-STRIPED GRASSHOPPER (MELANOPLUS BIVITTATUS SAY) IN NOVA SCOTIA

During the summer of 1931 an outbreak of the two-striped grasshopper (Melanoplus bivittatusSay) occurred in localized areas in Nova Scotia on the dyked lands along the Avon River in Hants County and on the Grand Pré dyke lands in Kings County. Reports were also sent in of localized outbreaks in Cumberland and Antigonish Counties, but so far as the writer is aware these terminated in that year. The writer investigated the two first mentioned outbreaks and made careful observations during that season and the subsequent two years when the outbreak finally terminated and feels that certain data should be recorded.