Zealand Grass Grub Research Articles

Adhesion of bacteria (Serratiaspp.) to the foregut of grass grub (Costelytra zealandica(white)) larvae and its relationship to the development of amber disease

Adhesion of pathogenic strains of Serratia spp. to the foregut tissue of the New Zealand grass grub (Costelytra zealandica) was shown to be associated with the development of amber disease. Bacteria were always found adhering to the crop in the region of the cardiac valve in larvae showing disease symptoms after in vivo treatment with pathogenic bacteria while no significant colonization was observed in larvae treated with wild‐type, non‐pathogenic strains. The in vitro inoculation of excised crops with pathogenic and non‐pathogenic strains resulted in a similar pattern of adhesion. It is suggested that adhesion is an early step in pathogenesis and that farther bacterial mediated factors could be required for fall expression of amber disease.

Hirsutella stylophoraMains, a pathogen ofCostelytra zealandica(Coleoptera: Scarabaeidae) in New Zealand

The entomopathogenic fungus, Hirsutella stylophora, is described as a pathogen of larvae of the New Zealand grass grub, Costelytra zealandica, for the first time. This species is the anamorph of Cordyceps stylophora. Infected grass grub larvae were dull brown in colour, usually with a distinctive stromatal growth extending from the head capsule. Despite the frequent production of stromata on diseased larvae, no ascospores (sexual stage) were found. Collections of diseased C. zealandica were made from several sites in the southern half of the South Island.

Serological identification of Serratia entomophila, a bacterial pathogen of the New Zealand grass grub ( Costelytra zealandica)

A competitive inhibition enzyme-linked immunosorbent assay was used to examine the antigenic relationships between strains of the bacterium Serratia entomophila and other members of the genus. S. entomophila causes amber disease of the New Zealand grass grub ( Costelytra zealandica) and is currently being developed as a biological agent to control this pasture pest. The assay distinguished S. entomophila from other Serratia species and indicated variability in the antigenic structure of the species, suggesting the existence of several serotypes. The method is potentially useful as an identification method as an alternative to biochemical testing.

Serratia entomophila sp. nov. Associated with Amber Disease in the New Zealand Grass Grub Costelytra zealandica

Serratia entomophila sp. nov. is a homogeneous deoxyribonucleic acid relatedness group most closely related to Serratia ficaria and Serratia marcescens. All 19 strains studied resembled S. marcescens (the phenotypically closest species) by their inability to ferment or utilize l-rhamnose, l-rhamnose, d-melibiose, dulcitol, and d-raffinose but differed from S. marcescens by their inability to ferment or utilize sorbitol and their lack of lysine and ornithine decarboxylases. All strains utilized itaconate, a unique characteristic among Serratia species. Two biotypes could be distinguished. Strains of biotype 1 utilized d-arabitol but not l-arabitol or d-xylose. Strains of biotype 2 utilized l-arabitol and d-xylose but not d-arabitol. S. entomophila has been isolated from insect larvae and water. Most strains were isolated in New Zealand from the grass grub Costelytra zealandica infected with amber disease. None of the strains were isolated from infected humans, animals (other than insects), or plants. The type strain is strain A1T (ATCC 43705T).

Glutathione [formula omitted] from the New Zealand grass grub, Costelytra zealandica Their isolation and characterization and the effect on their activity of endogenous factors

Isolation of glutathione S- transferase from the New Zealand grass grub, is complicated by the marked loss of activity from crude homogenates. This loss may be due to proteolysis or to modification by endogenous chemicals. The effect may be minimized by immediate fractionation with ammonium sulphate and by inclusion of 5mM glutathione in homogenates. Two enzymes species, isoelectric at pH 8.7 and 5.9 respectively, could be isolated by ammonium sulphate fractionation, affinity chromatography, anion exchange chromatography and chromatography on hydroxyl apatite. They had different substrate specificities and had differing subunit structure. The pI 8.7 enzyme appeared to be a homodimer of subunits of M r 23,700 and the pI 5.9 enzyme one of subunit M r 22,500. A third major enzyme species, isoelectric at pH 4.3 differed from the other two enzymes in having low affinity for the affinity matrix. This preparation was heterogeneous. The enzymically active species in this preparation had the same molecular weight as that of the pI 8.7 enzyme, had a very similar substrate specificity to the basic enzyme species and was characterized by kinetic parameters almost identical to those of the pI 8.7 enzyme.

Kinetic studies on a glutathione S-transferase from the larvae of Costelytra zealandica.

Of the glutathione S-transferases from the New Zealand grass grub (Costelytra zealandica) active in conjugating the model substrate 1-chloro-2,4-dinitrobenzene, the most active was isolated in a functionally homogeneous form. This had an isoelectric point of 8.7. Preliminary evidence suggests that it is a homodimer with subunits of Mr 23 500. The dependence of the enzyme-catalysed reaction on substrate concentration was analysed in terms of the rate equation characteristic of Ordered Bi Bi or Rapid-Equilibrium Random mechanisms. Evidence was found for a critical ionizing event at pH 9.3 at 37 degrees C. This event appears to involve a twofold change in charge on the enzyme, which may be the result of co-operative ionizations rather than independent ionizations. This appears to affect neither the binding of the aromatic substrate to the enzyme, nor the maximum catalytic velocity of the enzyme-catalysed reaction. The variation of the kinetics with temperature was studied. Apparent thermodynamic parameters characteristic of the reaction were derived. The possible relevance of the temperature-dependence of the enzyme-catalysed reaction in vivo is discussed.

Studies on the Insect Attractant Resin Durez 12687: Presence of an Odor Synergist1

Males of the New Zealand grass grub beetle, Costelytra zealandica (White), are more strongly attracted to the phenol/formaldehyde resin Durez 12687 than to phenol or aqueous phenol. The activity of the resin is thus not explicable in terms of phenol content alone. An odor synergist is present in the resin.

Electroantennogram responses of maleCostelytra zealandica(Coleoptera: Scarabaeidae) to phenol and related compounds

Electroantennograms recorded from male New Zealand grass grub beetles, Costelytra zealandica (White), were used to compare the activity of phenol with that of closely related phenolics. These compounds had no masking effect on the antennal response. A comparison of activity between phenol and a crude female extract indicated that phenol is the sole pheromone.