Argentine Stem Weevil Research Articles

Effect ofLoliumendophyte fungus infections on survival of larval Argentine stem weevil

Abstract Survival of Argentine stem weevil from eggs to fourth instar larvae was compared in endophyte-infected and endophyte-free ryegrass in the screenhouse. Survival was significantly poorer in endophyte-infected plants. The results are discussed in relation to larval survival and damage in the field.

Effect ofLoliumendophyte fungus infections on behaviour of adult Argentine stem weevil

Abstract The effect of Lolium endophyte on feeding and oviposition by adult Argentine stem weevil (Listionotus bonariensis( (Kuschel)) was studied in the laboratory and screenhouse. The effects of endophyte on weevil behaviour were determined in choice and non-choice experiments. Feeding and oviposition were reduced in weevils confined on endophyte-infected plants compared to those confined on endophyte-free plants.

Effect of Argentine stem weevil on productivity of grasses in the Waikato

Abstract Argentine stem weevil (Listronotus bonariensis (Kuschel)) damage to pasture grasses was studied in relation to life cycle events in the Waikato. For a grazed pasture, numbers of adults at the onset of spring oviposition were low. First generation egg and larval numbers were correspondingly low, and the larvae caused negligible pasture damage. The second generation was considerably larger, and the larvae caused extensive damage. Applications of systemic insecticides increased the yield of grazed Nui ryegrass pasture by 17% over the spring-autumn period. Similarly in autumn-sown plots, Manawa, Ruanui, Nui, and Ellett ryegrasses, browntop, cocksfoot, paspalum, phalaris, and tall fescue, without clover, gave 15–91% higher yields under insecticide protection during the first spring-autumn period. Prairie grass production did not respond to insecticide application. Results show that responses in yield were caused by insecticidal control of stem weevil at a stage when the establishing grasses were parti...

Some protozoan pathogens of the Argentine stem weevil,Listronotus bonariensis(Coleoptera: Curculionidae), in New Zealand

Two microsporidian pathogens, tentatively identified as Orthosoma sp. and Nosema sp., and one unidentified neogregarine pathogen have been found infecting adult Argentine stem weevils, Listronotus bonariensis (Kuschel), from several sites throughout New Zealand. Changes in the incidence of Orthosoma sp. infections of adult weevils from 2 sites near Hamilton have been monitored from November 1982 to August 1983.

Comparison of Argentine stem weevil and slug damage in maize direct-drilled into pasture or following winter oats

Abstract In 2 field trials in the Manawatu, maize was direct-drilled into pasture not treated with insecticide. When wet weather followed sowing, up to 44% of the seedlings were lost before emergence because of slug damage, and when there was dry weather after sowing, up to 57% were lost because of Argentine stem weevil larvae attack. Damage by slugs and stem weevil was reduced when a winter oat forage crop was grown before the summer maize crop, despite oats being a host of both slugs and stem weevil.

Effect of tall fescue and ryegrass endophytes on Argentine stem weevil

Effect of tall fescue and ryegrass endophytes on Argentine stem weevil

Chemical control of Argentine stem weevil in North Island pasture

Chemical control of Argentine stem weevil in North Island pasture

Preliminary results on the biochemical relationship between adult Argentine stem weevil and two endophytes in ryegrass

Preliminary results on the biochemical relationship between adult Argentine stem weevil and two endophytes in ryegrass

WHAT IS THE MAKE-UP OF A DRYLAND PASTURE?

Summer grazing managements, spelling, set-stocking, fast or slow rotations and topping or no topping, did not influence herbage growth in autumn of Nui ryegrass pasture. The cause of pasture deterioration on dryland, previously suggested to be through summer overgrazing, now seems more likely to be an effect of autumn overgrazing, particularly if pastures have been attacked by Argentine stem weevil and drought is continuing from summer. Low nitrogen fertility through often low fixation of nitrogen by clover, uncertainty of response of pasture to nitrogen fertiliser in cool season, and the effects from overgrazing, cause an extreme limitation in autumn-winter feed supply for stock in drought years. Feeding of silage in summer-autumn is advocated as a positive approach to this situation. On sunny aspects of dry hill country, buildup of dead herbage through summer considerably reduces the quality of the subsequent cool season growth of grass in the herbage mass. Several attempts to establish oversown grasses for improved cool season yield have not been successful. Dry hill grassland thus provides a considerable challenge to effect much improvement beyond manipulating the quality of the existing vegetation by grazing management. Keywords: Dryland pasture, grazing management, fertility, herbage quality

THE RELATIONSHIP BETWEEN NITROGEN SUPPLY, ENDOPHYTIC FUNGUS, AND ARGENTINE STEM WEEVIL RESISTANCE IN RYEGRASSES

Experiments are described which indicate that the degree to which ryegrasses, Loburn SPP., are damaged by Argentine stem weevil, Listronotusbonariensis (Kuschel), is affected bv three major factors. Ryegrasses with high levels of infection with andophytic fungi carry fewer stem weevil eggs and larvae and consequently suffer less damage. Some ryegrasses with low levels of endophyte infection, such as 'Grasslands Ruanui', suffer more damage when grown with high inputs of nitrogen, while others with the genotype Lolium multiflorum x perenne L., such as 'Grasslands Manawa' are more susceptible than those with the genotype Lolium perenne L. Keywords: Lolium spp., Listronotus bonariensis, endophvtic fungus, nitrogen, plant resistance, stem weevil

A COMPARISON OF PERENNIAL GRASSES UNDER SHEEP GRAZING ON THE CENTRAL PLATEAU

Details are given on the production and survival over four years of five perennial grasses under rotational sheep-grazing on a pumice soil. The comparison involved three perennial ryegrasses ('Grasslands Nui and Ruanui', and Yates Ellett), and mixtures of Ellett with 'Grasslands Roa' tall fescue and Ellett with 'Grasslands Maru' phalaris. All pastures were sown with white and red clovers. Annual dry matter yields from Nui and Ellett pastures were similar, at about 6,500 kg/ha. Ruanui pastures were on average 600 kg/ha lower. The pastures containing tall fescue and phalaris were similar to Ellett. The major seasonal yield effects were in autumn and winter, when Ruanui pastures were substantially poorer than those with Nui and Ellett. Ryegrass yield of Ellett pasture was greater than Nui, and Nui was greater than Ruanui at all seasons. Ellett ryagrass was a higher proportion of the total yield at all times, and had higher tiller populations than Nui and Ruanui. Neither tall fescue or phalaris were, able to compete with Ellett ryegrass. It is suggested that neither of these be sown with ryegrass. Clover yields were higher in Ruanui than Ellett pastures, with Nui intermediate. The use of Nui, Ellett and Ruanui ryegrasses is related to the problems of seasonal distribution and total annual yields of pastures on the Central Plateau. It is suggested using Nui or Ellett as the base for perennial pastures will give substantial increases in production. Ellett ryegrass had higher survival than Nui which was considered an advantage, though this was achieved at the expense of a small reduction in clover vields. Keywords: Perennial ryegrass, Ellett, Nui, Ruanui, Roa tall fescue, Maru phalaris, canary grass, sheep grazing, central North Island, Central Plateau, grass grub, Argentine stem weevil, Lolium endophyte.

Implications of oöcyte resorption bodies in the ovarioles of Argentine stem weevil,Listronotus bonariensis(Coleoptera: Curculionidae)

Abstract Yellow-orange inclusions were occasionally found in the ovariolar constrictions of Listronotus bonariensis (Kuschel). Investigation established that they were probably crystals of β-carotene, for which a liquid precursor was present in very high concentrations. Such inclusions are often found in the ovarioles of acridids, and can arise from the resorption of terminal oöcytes. Caging, which suppresses egg production, increased the proportion of weevils with resorption crystals. In a naturally occurring reproductive population the crystals became prevalent at the onset of diapause, and were demonstrable in 30% of the total population throughout the winter. The incidence of crystals indicates that the female population was of mixed sexual maturity, which may have been due to differences in age. Almost invariably only fertilised females contained resorption crystals, indicating that advanced vitellogenesis and egg production take place after mating rather than before.

Argentine stem weevil effects on Nui and Ruanui ryegrasses grown with two levels of nitrogen/water nutrition

Abstract Monoculture plots of ‘Grasslands Ruanui’ and ‘Grasslands Nui’ perennial ryegrasses were established with high and low nitrogen/water treatments. Twice-weekly examinations of tagged rye grass tillers showed Ruanui with high N/water (RH) to be more severely damaged by Argentine stem weevil larvae than Ruanui with low N/water (RL) or Nui with either treatment (NL and NH). More stem weevil larvae were found in Ruanui plots, and in plots with high N/water. Peak larval densities in RH plots were 1500 larvae/m2 or one per 4.8 tillers. Although RH plots sustained higher rates of stem weevil damage, no similar cultivar × nutrition interaction was detected for larval density. Net growth rates for RH plots were reduced because of high rates of herbage and tiller death during January and February when stem weevil damage was greatest. High rates of tillering in RH plots during April were associated with a recovery of both tiller density and growth rate. It is suggested that studies concerning stem weevil susceptibility should allow for nutritional effects.

Influence of cultivation, sowing date and the life cycle of Argentine Stem weevil relative to seedling survival in maize

Influence of cultivation, sowing date and the life cycle of Argentine Stem weevil relative to seedling survival in maize

An examination of the relationship between Argentine stem weevilListronotus bonariensis(Kuschel)) and several of its host grasses

Abstract The susceptibilities of several New Zealand pasture grasses to Argentine stem weevil oviposition and larval attack were investigated. Short rotation cultivars of ryegrass showed higher susceptibility to both forms of attack than perennial ryegrass cultivars. It is possible that the latter are resistant to weevil attack because of their comparatively high cellulose levels and consequent toughness. Of the other grasses, tall fescue was found to be highly resistant to egg-laying whereas Timothy was found to be tolerant to larval mining. Larval survival of 30%–40% was estimated to occur between the egg and first instar stage in most grasses compared with the more variable and lower survival levels of 7%–23% between the first and second instars. These levels of survival were again proportional to relative cellulose levels. From the second instar onwards there was little or no larval mortality. The resistance to adult weevil feeding in the young seedlings of‘low cellulose’ (‘L.C.’) selection of ‘Grasslands Arikï’ (N889) ryegrass is not expressed as ovipositional or larval resistance in mature plants. It is hypothesised that the seedling ‘L.C.’ Ariki plants initially have high levels of the alkaloid perloline which confer resistance but this rapidly dissipates as the plants develop.

Argentine stem weevil(hyperodes bonariensiskuschel) resistance in perennial and hybrid ryegrasses

Abstract A high level of host plant resistance to Argentine stem weevil (ASW) (Hyperodes bonariensis Kuschei) has been recorded under field conditions in a line of perennial ryegrass (Lolium perenne L.) collected from the Takapau district in Central Hawkes Bay. When compared with the commonly sown cultivars of perennial ryegrass, ‘Grasslands Ruanui‘ and #x2018;Grasslands Nui‘, this ryegrass suffered minimal adult ASW damage, harboured low number of eggs and larvae, and hence suffered low levels of larval damage. Another ryegrass cultivar, Ellett, was also found to be more ASW resistant than Nui but its superiority over this cultivar was less marked than that recorded for ‘Takapau‘. The production and persistence of Ruanui and Nui swards was severely affected by ASW damage and as a result these became white clover (Trifolium repens L.) dominant whereas swards of ‘Takapau‘ ryegrass persisted as well balanced grass–clover mixtures. The production of Nui and Ruanui ryegrass was similar but was approximately 6...

Computer modelling of Argentine stem weevil (Coleoptera: Curculionidae) phenological events

Preliminary results of a simple phenological modelling system for the Argentine stem weevil are presented.

Non‐reproductive determination of ‘migratory’ flight in Argentine stem weevils, Listronotus bonariensis

ABSTRACT. The seasonal flight activity of Listronotus bonariensis (Kuschel) between 1976 and 1978 in Canterbury, New Zealand, is described and, in the light of current thinking, interpreted as migratory. Flight intensity appeared to be closely linked to prevailing weather conditions and unrelated to sexual activity. Furthermore, during the summer months a large proportion of flying weevils were gravid, and at the onset of hibernatory diapause flight continued unabated until the occurrence of cold winter conditions. These results indicate none of the energy partitioning often observed in other insect species where reproductive and migratory effort are mutually exclusive.

A comparison of controlled droplet application and hydraulic nozzles to control blue-green lucerne aphid and Argentine stem weevil

A comparison of controlled droplet application and hydraulic nozzles to control blue-green lucerne aphid and Argentine stem weevil

Seasonal changes in the fatty acid composition of Argentine stem weevil,Hyperodes bonariensis(Coleoptera: Curculionidae)

Abstract The fatty acids of the Argentine stem weevil were examined by gas-liquid chromatography. Peaks were attributed to myristic (14:0), palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2), linolenic (18:3), and small amounts of 20-carbon fatty acids. During diapause the major fatty acids were oleic (42%) and palmitic (29%), and it is suggested that the majority of oleic acid originated from bacterial (Enterobacter sp.) biohydrogenation of linoleic acid, which constituted 72% of the fatty acids in the ryegrass diet. Relative to the diapausing weevils, the reproductive population showed a marked increase (12%) in palmitic acid and 32% less oleic acid. Furthermore, only 43% of the fatty acids from reproductive weevils were unsaturated, as against 63% in diapausing weevils. The reasons for these dramatic differences are unclear. However, preferential oxidation of oleic acid during periods of high metabolic activity may account for much of the change in fatty acid composition.