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One of the most significant pests of white clover (Trifolium repens L.) is the clover root weevil (Sitona lepidus L. Coleoptera; Curculionidae). The adult of this species feeds on the leaves of the plant. However, root feeding by the larvae is more insidious. An experiment is described that was designed to test the hypothesis that root nodule herbivory by early instar larvae of S. lepidus reduces the assimilation of C by plants of white clover. White clover plants were grown (± larvae) in individual growth chambers and the net carbon (C) assimilation by each plant was estimated by monitoring CO2 flux in the chambers. White clover plants which had been infested with larvae had a significantly (P

Plots of two cultivars of white clover (Trifolium repens) Grasslands Prestige (smallleaved early flowering) and Grasslands Kopu (largeleaved later flowering) were established in coldframe beds Clover root weevil (Sitona lepidus) larval numbers were manipulated to obtain winter larval densities ranging from 0 to over 1000/m2 Increasing winter larval densities increased Prestige seed production (g/m2) when harvested on 28 December and 10 January and the trend was still evident on 24 January No such relationships were found in Kopu for the early and middle harvests but at the late harvest increasing winter larval densities had a negative impact on seed production The results indicate that the effect of clover root weevil larvae on second year clover seed crops may vary substantially between cultivars and may even be positive rather than negative

Several candidate biological control agents of Sitona lepidus have been identified since a search commenced in 1997. Interestingly, Microctonus aethiopoides from Europe is a much more effective parasitoid of S. lepidus than the M. aethiopoides ecotype already established in New Zealand. To assess further the suitability of the European M. aethiopoides for biological control of S. lepidus, 1599 infected S. lepidus were shipped to New Zealand quarantine during late 2000. These yielded 267 parasitoid pupae from which 204 adult parasitoids were reared. This material was obtained from a wide geographical range in Europe and has been used to establish cultures in New Zealand quarantine based on genetic material from France, England, Norway, Finland, Romania, Ireland, Scotland, Italy and Wales. This contribution presents an overview of the work associated with the importation of the parasitoids and the effort now being made to maintain genetic diversity. Planned research is also discussed.

The decimation of white clover in Waikato and Bay of Plenty pastures owing to the invasion clover root weevil (CRW) initiated an extensive screening of legume germplasm to identify plant material that could survive and remain productive under high CRW pressure. A total of 50 000 plants from 275 lines and six species, were planted on seven commercial farms and evaluated for tolerance/ resistance to CRW under conventional farming practices. Plant productivity and level of CRW damage were both highest on white clover. Significant CRW damage was also observed on red clover and caucasian clover, but not on birdsfoot trefoil, lotus major or lucerne. However, the productivity under stock grazing of the latter three species was not sufficient to consider them suitable alternatives to white clover. Within the white clover lines there was encouraging variability in the level of CRW damage, and in the ratio of damage to shoot production. While root damage is of greater importance than shoot damage, the latter reflects CRW activity and egg deposition and is a good indicator of likely larval development and root damage. Factors such as farm type (dairy farms versus dry stock farms) had some influence on shoot production, but very little influence on CRW damage. Climatic conditions appeared to have strong influences on clover shoot production and CRW damage, with dry conditions from late spring to early autumn having a particularly suppressive effect on CRW damage and CRW population growth. Top performing lines have been selected from this screening and are currently being evaluated in more detail under high CRW pressure. Keywords: clover, clover root weevil, plant screening, Sitona lepidus, tolerance, Trifolium repens

Clover root weevil, Sitona lepidus (syn. flavescens) (Coleoptera: Curculionidae), has recently arrived in New Zealand. It has emerged as a pest of white clover (Trifolium repens) in the central North Island and appears likely to spread throughout the country. This contribution describes efforts made in 1998 to source biological control agents of S. lepidus from Europe and North America. Six species of parasitoids (one nearctic, five palaearctic) have been recorded in the literature as attacking S. lepidus. Three species which warrant investigation as candidate biological control agents were identified in this study. These were the palaearctic species Microsoma exiguum (Diptera: Tachinidae), Microctonus aethiopoides (Hymen‐optera: Braconidae), and Pygostolus falcatus (Hymenoptera: Braconidae). Also, a preliminary description is provided of a disease which was observed to infect S. lepidus adults collected in California.

Individual adult Sitona lepidus were given the choice between damaged or undamaged seedlings mature plants of white clover damp soil or a blank in laboratory experiments carried out in a simple olfactometer Adult weevils displayed five different behavioural responses two of which head lifting and antennal movement appeared to be associated with host location In choice tests 7484 of adults chose a white clover plant over the blank or damp soil When given a choice 72 of adults selected white clover seedlings over mature plants Root and leaf damage did not affect response of S lepidus to white clover seedlings

A slant board experiment investigated the effect of four white clover (Trifolium repens L) root types on tolerance of root feeding by larvae of clover root weevil (Sitona lepidus Gyllenhål) Root damage was determined by image analysis and larval weight gains were measured Differences in root type did not have a major impact on initial damage by clover root weevil However different root types were affected differently by the clover root weevil A clover genotype with long fine roots had more functional root length after larval feeding than genotypes with different root types

The efficacy of the entomopathogenic nematodes Heterorhabditis zealandica, H. bacteriophora, Steinernema carpocapsae and S. feltiae against clover root weevil (CRW) larvae and pupae was determined in petri dish and pot experiments. Field collected third instar (L3)‐pupal CRW immature stages were used, and experiments were conducted in a controlled environment room at 18 °C. Weevil survival and development was assessed 7 and 10 days after nematode inoculation for petri and pot experiments respectively. All nematodes significantly reduced CRW survival, and all except S. feltiae prevented adult development. Under the conditions used in this study, Heterorhabditis spp. were generally more effective than Steinernema spp. Results are discussed in terms of the potential use of entomopathogenic nematodes as biocontrol agents for this clover pest.

Microctonous aethiopoides Loan has been introduced into New Zealand to control the lucerne pest Sitona discoideus Gyllenhal (Coleoptera: Curculionidae). Sitona lepidus Gyllenhal (Coleoptera: Curculionidae) a pest of clover ( Trifolium spp.), has recently established in New Zealand. Laboratory experiments to test the potential of M. aethiopoides to parasitize S. lepidus has resulted in very low levels of parasitism. To investigate whether there were behavioural or physiological barriers to successful parasitism, two experiments were conducted using the insect pathogenic bacterium. Serratia marcescens Bizio as a marker for parasitoid ovipositor penetration. Firstly, M. aethiopoides 'treated' with S. marcescens were exposed to weevils and rapid weevil mortality was used to indicate ovipositor penetration. Up to 50% mortality of S. lepidus occurred, which was comparable with mortality observed in the permissive host Listronotus bonariensis . Dissection of S. lepidus exposed to parasitoids treated with distill...

A small plot trial was undertaken in the Waikato to determine the potential impact of Sitona lepidus adults on white clover seed production. Five densities of adult weevil were caged on 1 m2 plots from the time of peak adult emergence in November 1998 until harvest in late January 1999. In the laboratory, weevil adults were found to severely damage clover inflorescences when no leaves were present. Although feeding damage on leaves was highly visible in the field plots, with over 80% of the leaflets damaged at the highest density of 600 adults/m2, weevil adults were found to have no effect on flowering or seed production.

Populations of adult Sitona lepidus were sampled from five irrigated and five non-irrigated dairy pastures in the Waikato from November 1998 to April 1999. Under irrigated conditions, the presence of a second peak of adults with significantly more tenerals present provides evidence of a second generation over the summer months. The importance of the role of moisture in the development of S. lepidus was further demonstrated by the differences in the development of eggs in the calyces of sexually mature females. Egg development was significantly greater in females in irrigated pastures. Onset of rain after a dry period resulted in rapid egg development in females in non-irrigated pastures. These findings explain why the summer dry La Nina weather conditions in the Waikato led to farmer observations of a reduced impact of S. lepidus on clovers in Waikato pastures in 1998 and 1999.

Three clover root weevil (Sitona lepidus) adults infected with the entomopathogenic fungus, Beauveria bassiana, were collected from pastures in the Waikato in 1997. Genotyping using rDNA comparisons showed the strain from weevils to be a cosmopolitan type. Application of fungal conidia topically and by contaminating leaf, soil and root surfaces showed that both B. bassiana isolated from S. lepidus in New Zealand and commercial preparations of this species were pathogenic to adult and larval clover root weevil, with up to 100% mortality within two to four weeks of inoculation. Isolates varied in their effectiveness against larvae and adults, with two isolates effective against adults found to be less pathogenic to larvae than a third isolate.

Measurements of feeding damage by adult clover root weevil (Sitona lepidus) on both seedlings and excised leaf material from thirteen pasture legume species were made in four laboratory experiments. Clover root weevil showed no feeding preferences in the choice and non-choice feeding experiments using seedlings. However, in both choice and non-choice experiments using excised leaf material from mature plants, food intake was higher on perennial Trifolium spp. compared to annual Trifolium spp. Feeding on leaf material from mature Medicago spp. and Lotus spp. was very limited in both choice and non-choice experiments.

In a year of spring–summer drought on a sandy volcanic ash soil, ryegrass/caucasian clover (RG/ CC) and RG/white clover (RG/WC) pastures had similar rapid increases in pasture growth rates during September. Growth rates peaked around 25 October (65–70 kg DM/ha/day) for RG/CC and around 14 October (50–60 kg DM/ha/day) for RG/ WC. As drought intensified the declines in pasture growth rates were similar, but delayed by up to 3 weeks for RG/CC. Both pastures reached minimum summer growth rates of

Laboratory experiments were carried out to determine whether either of the two braconid parasitoids Microctonus aethiopoides Loan or Microctonus hyperodae Loan, already established in New Zealand, would parasitise the recently introduced clover root weevil, Sitona lepidus Gyllenhal. No parasitism by either parasitoid was recorded in two no-choice experiments. In a third experiment, M. aethiopoides was exposed to S. lepidus and S. discoideus in either choice or no-choice cages. In this case, a very low level of parasitism of S. lepidus (1%) occurred in no-choice cages, but this was increased to about 6% in cages where both weevil species were present. It was concluded that neither parasitoid was likely to be a suitable biological control agent for

Laboratory host specificity of 2 biological control agents, already introduced in New Zealand, was compared with actual field parasitism. The parasitoids were Microctonus aethiopoides Loan and Microctonus hyperodae Loan, braconids imported to control the curculionid forage pests Sitona discoideus Gyllenhal and Listronotus bonariensis (Kuschel), respectively. The nontarget weevil species tested included native, introduced, and beneficial species. M. aethiopoides oviposited in 11 of the 12 species to which it was exposed and successfully parasitized 9 species. M. hyperodae oviposited in 5 of the 11 species to which it was exposed and developed successfully in 4 species. Higher percentage parasitism was recorded with M. aethiopoides than with M. hyperodae . Field collections of weevils from Otago, Canterbury, and Waikato indicated that 10 New Zealand native species and 3 other nontarget species, including the weed biological control agent Rhinocyllus conicus (Froehlich), were parasitized by M. aethiopoides . M. hyperodae has been found parasitizing 1 native species, as well as Sitona lepidus Gyllenhal, which was accidentally introduced to New Zealand recently. In nontarget species, parasitism levels in the field of >70% have been recorded for M. aethiopoides and

Clover root weevil (Sitona lepidus) is established in Auckland, Waikato and Bay of Plenty provinces. A pasture survey in 1997 estimated that the rate of its spread at about 35 km annually. Adults feed on the foliage and larvae on roots and nodules of white clover. Pasture populations appear to be 10 times higher in New Zealand than in the UK. New Zealand's temperate climate and high clover content in pastures may offer a very favourable environment for S. lepidus, with serious implications for New Zealand's pastoral farming. Keywords: clover root weevil, pasture pests, Sitona lepidus, Trifolium repens, white clover

Antennal olfactory receptor neurons (ORNs) for pheromone and plant volatile compounds were identified and characterized in male and female clover root weevil, Sitona lepidus (Gyllenhal), using the single sensillum recording technique with five pheromone-related compounds, and 40 host and non-host plant volatile compounds. Overall, seven different types of olfactory sensilla containing specialized ORNs were identified in each sex of S. lepidus. Among them, three different types of sensilla in the males and two types in the females housed ORNs specialized for pheromone-related compounds. The ORNs in males were specialized for 4-methyl-3,5-heptanedione or one or more of four stereoisomers of 5-hydroxy-4-methyl-3-heptanone. In contrast, female sensilla did not contain ORNs sensitive to 4-methyl-3,5-heptanedione while they contained ORNs sensitive to and specialized for the stereoisomers of (4S,5S)-5-hydroxy-4-methyl-3-heptanone. In addition to the pheromone-related ORNs, four types of olfactory sensilla contained ORNs responsive to plant volatile compounds in male S. lepidus, and five types in females. Most of the ORNs identified in S. lepidus showed a high degree of specificity to specific volatile compounds although some of the active compounds showed overlapping response spectra in the ORNs across different types of sensilla. The most active plant volatile compounds were the four green leaf volatile compounds, (E)-2-hexenol, (Z)-2-hexenol, (Z)-3-hexenol and (E)-2-hexenal, and isomers of two monoterpenols, (±)-linalool and (±)-α-terpineol, all eliciting strong responses from relatively large numbers of ORNs in male and female S. lepidus. Our study indicates that S. lepidus has a set of highly sensitive and selective ORNs for pheromone and plant volatile compounds. Further work is needed to elucidate the behavioral implications of these findings.

The phenology and some aspects of the biology of the clover weevil Sitona lepidus Gyll. were studied in the field and the laboratory. Oviposition and hatching were temperature dependent. Most eggs were laid in September and October, although there was also an oviposition period in early summer. Hatching was largely confined to late spring and early summer. The relevance of this to control strategies is discussed. Most eggs were laid on the plant but(were very easily dislodged and probably usually hatch on the ground. In no-choice tests, there were as many eggs laid on more cyanogenic as on less cyanogenic plants and cultivars. There was no evidence that the cyanogenic ability or any other cultivar characteristic would be useful in control strategies.

Sitona lepidus has recently established in New Zealand, being first recognised in pastures in the vicinity of Hamilton (Waikato) in March 1996. The distribution of this species in the North Island was ascertained from retrospective examination of curculionid samples collected from pastures during the period February 1995 to March 1996, and from a contemporary field survey of curculionids from pastures during MarchApril 1996. Collectively, these surveys provided coverage of the North Island from Te Hana, Northland to Masterton, Wairarapa. S. lepidus was confirmed as being widespread in the Auckland, north Waikato and coastal Bay of Plenty regions, but was not found south of these regions.

Sitona lepidus Gyllenhal (syn. S. flavescens (Marsham)) (Coleoptera: Curculionidae), a potential legume pest species new to New Zealand, is reported from near Hamilton. A key is provided to distinguish S. lepidus from S. discoideus Gyllenhal, a lucerne pest already established in New Zealand. Information is given on the distribution of S. lepidus in New Zealand and overseas, the biology and life cycle, mostly derived from the literature, and potential pest status and control.

North American species of Sitona Germar are reviewed. Eleven species, five introduced from Europe, are recognized. Sitona lineellus (Bonsdorff) is established as the correct name for the widely recognized S. scissifrons Say. Three new species are described: S. desertus and S. tanneri from southern California and S. aquilonius from northern Canada. New synonymies are S. ordinarius Fahraeus, S. occidentalis Casey, S. bryanti Tanner (= S. californius Fahraeus); S. procerus Casey (= S. cylindricollis Fahraeus); and S. margaritosus Casey, S. eximius Casey, S. montanus Casey, S. alternans Casey, S. osculans Casey, S. sparsus Casey (= S. vittatus LeConte). Lectotypes are designated for S. extrusus Casey, S. hispidiceps Casey, S. margaritosus Casey, S. eximius Casey, S. montanus Casey, and S. osculans Casey. All species are described and keyed. Distribution maps are given for more common, widely distributed species. Photographs of elytral vestiture and drawings of the female 8th sternite and the apex of the aedeagus are given for each species. Habitus illustrations are given for S. flavescens, S. hispidulus , and S. californius .

Bacillus thuringiensis subsp. tenebrionis produces a 65 kilodalton polypeptide toxin which is lethal to various coleopteran insect larvae. The gene encoding this toxin was cloned in E. coli in the broad host range vector pKT230 and subsequently transferred to Rhizobium leguminosarum by conjugation. Western blot analysis showed that the toxin gene was expressed in the free living state of Rhizobium producing two major polypeptides of 73 and 68 kilodalton in size. The level of expression of the toxin gene in Rhizobium varied from strain to strain. Cell extracts from toxin-producing rhizobia were toxic to larvae of Gasterophysa viridula. Bioassays also showed that the δ-endotoxin was toxic to larvae of the clover weevil Sitona lepidus. Furthermore, pea (Pisum sativum) and white clover (Trifolium repens) plants suffered less root and nodule damage by Sitona larvae when they were inoculated with Rhizobium strains containing the toxin gene. This suggests that such rhizobia could be useful in the biological control of this important legume pest.

Red clover (Trifolium pratense L.) is becoming increasingly important in grassland systems because of its high productivity, protein content and nitrogen-fixing ability, but its use has been constrained by losses due to pests and diseases, and this contributed to the decline of red clover usage allowing white clover (T. repens L.) to become the dominant legume of UK grasslands. One of the major pests of red clover is the clover root weevil (Sitona lepidus Gyllenhal, Coleoptera, Curculionidae) which attacks both the shoots and roots, particularly the N-fixing root nodules, of clover plants. This current work investigates the feeding preferences of S. lepidus with respect to 11 varieties (Pawera, Kuhn, Astra, Norseman, Norseman low, Norseman high, Marcom, Merviot, Milvus, Britta, Sabtoron) and 5 lines (AA30, AA31, AA4493, AA4494 and AA4495) of red clover in order to identify relationships between the variation in attractiveness of different red clover varieties for both adult and larval stages of the weevil. Of those tested Norseman high showed potential resistance, being less favoured by both adults and larvae of the weevil. This may be attributed to the potentially high phyto-oestrogen levels in this variety.

Virus-like particles (MaVLP) have been discovered in the ovarial epithelial cells of the solitary, koinobiont, endoparasitoid, Microctonus aethiopoides Loan (Hymenoptera: Braconidae) introduced to New Zealand originally from Morocco to control the lucerne pest Sitona discoideus Gyllenhal (Coleoptera: Curculionidae). MaVLP have been found in all females examined. It has been suggested, although not demonstrated, that like many other such VLP found in parasitoids, MaVLP might play a role in host immunosuppression. Since another biotype of M. aethiopoides from Ireland has been proposed for introduction to control the white clover pest, Sitona lepidus Gyllenhal, in New Zealand, it was considered that females from this biotype warranted transmission electron microscope examination for VLP. No VLP were observed in ovarian tissues of specimens collected from three different locations in Ireland. Similarly, none were found in M. aethiopoides sourced from France, Wales, and Norway. These observations are discussed in relation to quarantine host specificity tests with the Irish biotype, which found that the host range of the Irish biotype is likely to be less extensive than that of the Moroccan biotype already in New Zealand.

Since the discovery of the clover pest Sitona lepidus (Coleoptera: Curculionidae) in New Zealand in 1996, substantial effort has been made to find suitable biological control agents. In the summer of 2000 about 8600 Sitona lepidus were collected from 15 locations in 11 European countries. The most common parasitoid recovered was Microctonus aethiopoides (Hymenoptera: Braconidae). These parasitoids were used to infect S. lepidus populations that were then forwarded to a quarantine facility in New Zealand. All European‐derived populations of this parasitoid were found to develop readily in both British and New Zealand populations of S. lepidus. This contrasted with the New Zealand ecotype of M. aethiopoides which was unable to develop in S. lepidus. The S. lepidus population obtained from Caen, France was also parasitised by a Perilitus sp. (Hymenoptera: Braconidae) along with Microsoma exiguum (Diptera: Tachinidae). Microsoma exiguum was also reared from weevils collected in Devon along with a sin...

A laboratory study of aspects of parasitoid host acceptance, suitability and physiological regulation in natural and novel host species was carried out to investigate the degree of variability encountered with different hosts and to determine the value of such observations in host range determination. The parasitoid Microctonus aethiopoides Loan was exposed to a natural host, Sitona discoideus Gyllenhal (Coleoptera: Curculionidae) and three novel hosts, the New Zealand native Nicaeana cervina Broun, the introduced weed biological control agent Rhinocyllus conicus (Froehlich), and a congeneric pest species, Sitona lepidus Gyllenhal (all Coleoptera: Curculionidae). Per cent parasitism of these species was 54%, 43%, 39% and 0%, respectively. The results indicated that for both S. discoideus and R. conicus more males than females were parasitized (69% cf. 45%, and 49% cf. 32% respectively) but host size was not a significant factor. Overall, superparasitism was recorded in about 29% of parasitized weevils and there was evidence that host discrimination to avoid superparasitism occurred in the natural host. Conversely, superparasitism occurred more frequently than would be expected in N. cervina (42%) coupled with higher survival of larvae in superparasitized hosts in this species. The frequency distribution of attack of R. conicus by M. aethiopoides was not different from random. Parasitoid development was more rapid in the natural host, S. discoideus, and parasitoid size was positively correlated with host size. There was a strong positive relationship between parasitoid larval survival and the presence of teratocytes in all hosts. Host fecundity and fertility were reduced by parasitism for most species, and in some cases, by exposure to parasitoids in the absence of detectable parasitism. It was concluded that laboratory observations can provide useful information on the compatibility between host and parasitoid which can complement traditional host range tests to predict field host range.

The extent to which larvae of the root feeding insect, Sitona lepidus , affects the transfer of N from clover to associated wheat plants in soil systems is assessed in this paper. White clover ( Trifolium repens ) plants were grown from seed in a nutrient solution containing 99.99 atom % 14 NH 3 14 NO 3 as the N-source. Individual clover plants were transferred to pots containing sieved field soil. A single wheat ( Triticum arvense ) seed was planted with the clover plant and allowed to develop for 47 d. The pots were either infested with insect larvae or uninfested. The presence of the insect larvae in the pots significantly reduced clover dry matter and it was calculated that 7 % of the N in the wheat plants originated from clover.

Many insects inhabit concealed locations, such as within timber, but leave outward signs of their presence, such as frass. Deposits of fresh frass on the outside of infested material would indicate a high probability of live insects being present within. A method for estimating the age of frass could therefore be useful for assessing treatment efficacy. For example, the success of termite eradication could be monitored by regularly checking for the presence of fresh frass near old colonies. Similarly, the presence of fresh frass in borer holes in fumigated timber would raise concerns that the fumigation had been ineffective. This study examined whether the age of frass could be estimated from levels of esterase enzyme activity in frass of four species; the termites Stolotermes inopinus and Kalotermes brouni, and the weevils Sitona lepidus and Listronotus bonariensis. With the termites, active esterases were found in 1-day-old frass, but not in 1-month-old frass, indicating clear potential for development of a test. With the weevils, esterase activity occurred both in 1-day-old frass and in 1-month-old frass, so development of a method for these species requires a faster degrading enzyme.

A series of laboratory and field studies were done to evaluate a range of leguminous plant species for their feeding potential by adult weevils of the genus Sitona Germar. (Coleoptera: Curculionidae). Three species of Sitona, S. lineatus L., S. flavescens Marsh. and S. hispidulus F. all of which are found commonly on white clover (Trifolium repens L.) in the UK were offered a range of 11 legume species, T. repens (white clover, cv. Olwen), T. pratense L. (red clover, cv. Marcom), T. fragiferum L. (strawberry clover, cv. Palestine), T. hybridum L. (hybrid clover, cv. Tetra), T. incarnatum L (crimson clover), T. dubium Sibth. (lesser yellow trefoil), Lotus corniculatus L. (birdsfoot-trefoil, cv. Leo), L. uliginosus Schkuhr. (large birdsfoot-trefoil), Melilotus alba Desr. (white melilot), Medicago sativa L. (lucerne, cv. Europe) and M. lupulina L. (black medick) in two laboratory experiments. The weevils were offered a choice of these legumes in one experiment whilst in the other they did not have a choice of food material. These legumes were also sown in the field and a number of measurements of damage, together with counts of Sitona spp., were made. In the laboratory S. lineatus and S. hispidulus favoured some of the legumes to a greater or lesser extent than white clover. S. flavescens was more restricted in its feeding than the other two weevil species. In the field study S. lineatus invaded the experimental area quickly and tended to favour Medicago spp. and Melilotus spp. Later in the year S. flavescens dominated the sitona fauna on the experiment, with the exception of aggregations of S. lineatus on M. sativa and M. alba. In a separate screen of 5 varieties of white clover (cvs Donna, Menna, Kersey, Olwen and Grasslands Huia), cv. Olwen appeared to be the most susceptible to sitona attack.

Parasitoid host discrimination and the effect of superparasitism on weevil survival and emergence of parasitoids were investigated for the braconid parasitoid Microctonus aethiopoides introduced for control of Sitona lepidus Gyllenhal (Coleoptera Curculionidae) The quarantinebased study compared Irish Welsh Norwegian and French strains of the parasitoid All strains were similar in their ability to parasitise S lepidus but Welsh Norwegian and French strains did not discriminate between parasitised and unparasitised hosts In comparison oviposition in the Irish strain was biased towards parasitised weevils Furthermore in the Irish strain where more than one egg was laid in a host supernumerary larvae were able to survive and emerge from the weevil The gregarious oviposition behaviour displayed by the Irish strain has not been observed in other M aethiopoides biotypes parasitising Sitona or Hypera species

In plots of perennial ryegrass and white clover, regular treatment with chlorpyrifos and methiocarb more than trebled the clover content of the sward, compared with untreated plots, in just over 2 years from sowing. Chlorpyrifos alone accounted for most of the effect, which was attributed mainly to the control of Sitona lepidus. Combined treatment increased total herbage dry matter yield by 4·24 t ha−1 during this period but had little effect on grass-only plots. Methiocarb appeared to have contributed by assisting earlier establishment of clover, but otherwise had little effect until slugs, which were initially uncommon, became more abundant in the later stages of the experiment. The effect of slug control was most noticeable in a cultivar of low cyanogenic potential. This factor did not influence the effect of chlorpyrifos.

In laboratory experiments to clarify earlier field observations, Sitona lepidus larvae caused significant damage to established clover plants at infestations of approximately 1–2 per plant. When eggs were placed on the soil, cultivars of differing cyanogenic capacity were damaged equally. The plants did not recover when larval feeding ended. Leatherjackets, slugs and ‘lucerne flea’ fed most on the least cyanogenic cultivars, even where no choice was offered. Plants ultimately recovered from damage by leatherjackets. Deroceras reticulatum caused more damage than did Arion fasciatus. The proportion of leaves damaged by lucerne fiea was highest in the least cyanogenic eultivar but also tended to increase in the most cyanogenic cultivar, confirming a field observation. At high population densities lucerne flea was capable of killing some seedlings but was not tested against established plants.

From 1975 to 1979, biotypes of the braconid wasp Microctonus aethiopoides were forwarded from the Mediterranean region to be reared and released in south-eastern Australia for control of the weevil Sitona discoideus. The origins of the various biotypes of the parasitoid are indicated. M. aethiopoides was recovered from most of the liberation sites. At sites where early releases were made, parasitisation rates of up to 62% per parasitoid generation, and initial dispersal of about 10 km per annum were recorded. The conditions influencing establishment and spread of the parasitoid are discussed.

The feasibility of locating resistance to Sitona spp. larvae and effects of root nodules on growth and survival of larvae was studied by using a slant board plant culture technique. No resistance to larvae of S. hispidulus (F.) was found in diverse genotypes of alfalfa, Medicago sativa L., red clover, Trifolium pratense L., and white clover, T. repens L. No resistance to S. flavescens (Marsham) was found in red or white clover; however, three cultivars of birdsfoot trefoil, Lotus corniculatus L., two cultivars of crownvetch, Coronilla varia L., and bigflower vetch, Vicia grandiflora var. kitaibeliana W. Koch, were resistant to S. hispidulus larvae. S. flavescens did not survive on alfalfa or crownvetch roots. Growth but not survival of larvae of S. hispidulus was less on red clover plants without root nodules than on those with nodules. Growth and survival of larvae was less on alfalfa roots without nodules than on roots with nodules. The slant board culture system should be useful to evaluate plant germplasm for antibiosis to Sitona spp. larvae.

Adult clover root weevil (Sitona lepidus CRW) catches on sticky traps of different colours design and height were evaluated in two field experiments carried out on the outskirts of Hamilton in the summer of 19992000 In Experiment 1 yellow cylinder traps placed at a height of 1200 mm caught the most CRW In Experiment 2 both white and yellow cylinder traps placed at a height of 1200 mm were equally attractive to CRW adults In both experiments fewer CRW adults were caught on cylinder traps of all colours set 400 mm above the ground Cylinder traps painted red green and blue and set 1200 mm above the ground caught similar numbers of insects to traps of all colours set at 400 mm In Experiment 2 flat traps with a sticky surface that was parallel to the ground caught very few weevils irrespective of their colour and height

Non‐indigenous, invasive invertebrate pests have a detrimental effect on the New Zealand economy through impacts on pasture and forage production. Estimates of the economic impact have varied from $800 million to $2 billion. This paper reviews the literature on plant biosecurity concerns in New Zealand, and examines five of the major invasive pests in pastoral agriculture: clover root weevil (Sitona lepidus Gyllenhal), Argentine stem weevil (Listronotus bonariensis Kuschel), lucerne weevil (Sitona discoideus Gyllenhal), and the lucerne aphids (Acyrthosiphon kondoi Shinji and Mac‐rosiphum pisi Shinji). The difficulties in assessing risk impact, and the limited value of extrapolation from results from other countries are discussed, as is the potential for using computer models in assessing potential impact. Recommendations for research approaches for the future are made.

The impact of a range of simulated pasture management options on damage to white clover resulting from the presence of the clover root weevil was evaluated in a glasshouse experiment. Pasture management options included were irrigation, cutting regime, cultivar, soil fertility (Olsen P) level, and nitrogen application. Two different soil types were used. White clover growth was significantly enhanced by moist soil conditions, as were clover root weevil (CRW) larval numbers recovered per plot. Few (

Self-reporting cameras have the potential to revolutionise the trapping networks utilised in pest management and biosecurity. A study was carried out to determine whether commercially available self-reporting camera systems that use Wi-Fi™ and GSM to transmit images to secure websites could be incorporated into trapping networks. Of 45 systems initially examined, one, the RedEye security camera, was laboratory tested. Tests showed that the standard optics package was incapable of distinguishing between clover root weevil (Sitona lepidus) and Argentine stem weevil (Listronotus bonariensis). An upgrade of the camera's optics enabled it be used to successfully monitor porina (Wiseana spp.) flight activity. While this result was encouraging, more research is needed before the technology can be incorporated into trapping networks. In particular, further thought is needed as to the level of image resolution that is required to ensure that the system is relevant to all pest management and biosecurity practitioners.

A biochemical viability assay was recently developed to quickly and easily assess the viability of small immobile arthropods including eggs intercepted on plant products On finding a viable specimen species identification often becomes the next hurdle This paper demonstrates that amplifiable DNA is present in a used biochemical viability assay solution and can be used for making taxonomic identifications Cryptically labelled heattreated and untreated eggs of three weevil species (Listronotus bonariensis Sitona lepidus and S discoideus) were first tested for viability then a 1135 bp fragment of the cytochrome c oxidase I gene was amplified from each viability assay solution in the presence of a fluorescent dye SYBR Green Melt curve analysis of the amplicons (n36) revealed three distinct melt profiles that correctly corresponded to each of the three weevil species This shows that the biochemical viability assay is compatible with the application of subsequent molecular identification methods which will facilitate the appropriate management response

The effect of clover root weevil (Sitona lepidus) (CRW) larval feeding on subterranean, suckling, striated and clustered clovers was compared with white clover in a glasshouse experiment. Growth of suckling, striated, and clustered clover was significantly reduced by CRW, approaching the levels of damage recorded in white clover. N fixation in suckling and clustered clovers was also reduced. Growth and nitrogen fixation of two subterranean clovers (cv. Denmark, cv. Leura) were changed relatively little by CRW larval feeding. The relatively high level of the isoflavonoid biochaninA that was present in subterranean clover roots may explain the species' tolerance of CRW. These results suggest that CRW may not pose a major threat to dryland farming systems based on subterranean clover. Keywords: annual clover, clover root weevil, roots, Trifolium dubium, Trifolium glomeratum, Trifolium striatum, Trifolium subterraneum