Miscanthus x giganteus (Miscanthus) grass shelterbelts can deliver multiple ecosystem services on New Zealand commercial dairy farms. However, there has been little investigation into how these shelterbelts contribute to insect pest management. Here, on a Canterbury dairy farm, we investigated what generalist surface-dwelling invertebrate natural enemies of insect pests inhabit three separate Miscanthus shelterbelts compared to three unmanipulated field margin plots. The potential contribution of these natural enemy assemblages to future biological control was also investigated. To measure this, live moth egg baits with associated pitfall trapping were deployed in autumn, winter and spring of 2015. Miscanthus and the field margin plots were found to have similar potential natural enemy richness but differed in their community composition. The potential predation rate of pests in Miscanthus was 85% higher than in the field margin. Infrared video and Sanger sequencing confirmed that the harvestman Phalangium opilio and the slug Deroceras reticulatum consumed the egg baits in Miscanthus. Conversely, no bait-consuming invertebrates were identified in the field margin. These preliminary results indicate potential natural enemies inhabit Miscanthus and may consume insect pest eggs on the soil-surface. However, to achieve anyinsect pest suppression, further habitat manipulation would be required.

Importation biological control can create new host-natural enemy responses that are different from those behaviours elicited in native ranges of the agent, and/or the pest. This possibility was investigated with the Argentine stem weevil (Listronotus bonariensis) in the presence of three endoparasitoid species with different levels of affinity to the weevil in New Zealand pasture. The question posed was whether the weevil exhibits species-specific or generic responses to the three parasitoids. The first parasitoid was Microctonus hyperodae which has a coevolutionary history with L. bonariensis. The second, was Microctonus aethiopoides, which has similar ecological and behavioural characteristics to M. hyperodae. The third parasitoid was Aphidius colemani, which attacks pasture aphids and is phylogenetically remote from the Microctonus spp. Microcosms were used to examine and compare the L. bonariensis responses when confronted by each of these parasitoids. L. bonariensis showed strong behavioural responses when confronted by M. hyperodae and similar, but very much reduced responses when exposed to M. aethiopoides. The weevil exhibited no measured reaction to A. colmani. Therefore, L. bonariensis showed a species-specific response to M. hyperodae rather than a generic response. The implications of the L. bonariensis behavioural responses to all three parasitoids are discussed in terms of the species' phenotypic closeness and centres of origin.

The tomato-potato psyllid (TPP) Bactericera cockerelli is an important pest of several solanaceous crops. The current pest management strategy based on synthetic insecticides is being challenged through the development of pesticide resistance and environmental concerns. This contribution investigates the biological control potential of the mirid bug Engytatus nicotianae, either alone, or in combination with the parasitic wasp T. triozae, for combating the TPP on infested greenhouse tomato plants. In doing so we measured (a) the efficacy of E. nicotianae in reducing TPP numbers on lightly infested plants and (b) the potential for E. nicotianae and T. triozae in combination for effective biological control. In the E. nicotianae only treatment, the predator reduced the number of TPP-infested leaves, but the TPP population reduction was not significant. Conversely, the combined E. nicotianae + T. triozae treatment did show a consistent and significant reduction of TPP-infested leaves as well as TPP populations. These findings suggest that using a combination of the two species might deliver a biological control of TPP under glasshouse conditions. Further research is needed to determine the optimum ratio of E. nicotianae and T. triozae release-densities under different levels of TPP infestation and how this may translate from caged conditions to greenhouse performance.

Pasture and improved grasslands are commonly managed by a combination of artificial fertilisation and biomass removal, but a deeper understanding of how management options interact over the long-term are required to improve sustainability. Studies of multi-trophic responses to these options can provide important insights for biodiversity and soil management, particularly when they cover long time periods. In this study, we provide a novel perspective on long-term experimental field studies of grassland management by examining the direct and indirect effects of N fertilisation and mowing (with biomass retention and removal) on above-ground biodiversity, below-ground soil chemistry and their interactions. Our experimental treatments were applied annually from 1994 in medium to high soil fertility conditions on a non-native pastoral farm in New Zealand, and analysis of data to 2013 show that in general, plants and soil properties did not respond to N fertiliser treatments. In response to mowing regimes, soil properties exhibited subtle, but annually varying changes mostly related to biomass retention or removal, and plant richness was consistently higher under all mowing treatments. The management regime with the greatest gains in diversity also depended on year of study. We further analysed the indirect effects of mowing treatments on plant and arthropod richness via soil properties using structural equation modelling, and found that the impact of mowing is likely to be mediated by soil chemistry changes. In particular, the direct positive impact of mowing on plant richness may be offset by changes to soil properties, depending on whether biomass is retained or removed. We suggest that management regime effects on soil chemistry may limit plant composition changes to those species able to take advantage of altered conditions. These findings suggest that management to improve grassland diversity and soil conditions should consider the abiotic history and conditions of the site.

An insect’s fitness varies on different host plant species, and can be affected by previous host feeding experience. In New Zealand, Bactericera cockerelli (the tomato potato psyllid (TPP)) overwinter on various host species, and later migrate to annually grown crop host plants. How changing host plant species affects the insect’s fitness is unknown. This study evaluated if transferring adult TPP from non-crop to crop host species impacts the development and survival of their progeny. TPP were reared on non-crop host species, boxthorn, poroporo, and crop host species, potato and tomato. Adults were transferred from non-crop to the crop host species and allowed to oviposit for 48 hours before being removed. The eggs and nymphs were monitored every 24 hours for the development and survival of each life stage. The incubation period of eggs from adults transferred from poroporo to tomato was 6.9 days, and for boxthorn to tomato was 7.2 days, and was less than for eggs of adults moved from tomato to tomato (9.0 days) and potato to potato (9.2 days) (P < 0.05). Nymph developmental time was similar for all treatments. Total development time (egg to adult) was shorter for the progeny of adults from poroporo transferred to tomato (20.5 days) than those from tomato to tomato (23.2). The survival of eggs did not differ across treatments. Fewer nymphs survived when adults were transferred from tomato to tomato (50.4%) than those from poroporo to tomato (92.1%) (P < 0.05). Total survival (egg to adult) was higher for progeny of adults transferred from poroporo to tomato (80.0%) compared to boxthorn to potato (35.3%), boxthorn to boxthorn (40.7%), poroporo to potato (33.9%) and tomato to tomato (37.6%) (P < 0.05). The implications of this shift in fitness are discussed in relation to TPP management.

The tomato-potato psyllid (TPP), Bactericera cockerelli, is a serious pest of solanaceous crops. As an alternative to the use of insecticides, we tested the potential of the mirid bug Engytatus nicotianae (adults) as a biocontrol agent of TPP on greenhouse tomato plants. The experiment comprised: a) a laboratory choice feeding assay to investigate the preferences of E. nicotianae when offered TPP eggs and nymphs and b) a greenhouse experiment to assess the potential of E. nicotianae as a biocontrol agent under close to commercial conditions. The laboratory choice experiment highlighted a preference by E. nicotianae for the first two TPP instars, followed by the third instar and then the eggs. Consumption of fourth instars occurred only when all other life-stages had been consumed. In the cage experiment, the E. nicotianae-only treatment produced the same numbers of fruits and flowers as the control (no insects), even though TPP feeds on tomato leaves and stems. In contrast, the TPP-only treatment resulted in fewer fruits and flowers. The simultaneous introduction of E. nicotianae and TPP markedly reduced TPP build up compared to the TPP-only treatment and prevented the pest from establishing at all in four of the seven replicates of the experiment. These findings suggest that E. nicotianae should be considered as a potential biocontrol tool against TPP and further research is needed to determine an optimum release configuration.

New Zealand pastures largely comprising Lolium ryegrass species (Poales: Poaceae) are worth $19.6B and are subject to major pest impacts. A very severe pest is the Argentine stem weevil Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). This has been previously suppressed by the importation biological control agent, Microctonus hyperodae Loan (Hymenoptera: Braconidae). However, this suppression has recently declined and is subject to investigation. It has been hypothesised that grass type influences the parasitism avoidance behaviour by the weevil and thus parasitism rates. This study explored the hypothesis using three common pasture grasses: a diploid Lolium perenne x Lolium multiflorum hybrid ryegrass (cv. Manawa), a tetraploid Italian ryegrass L. multiflorum Lam. (cv. Tama), and a diploid perennial ryegrass L. perenne L. (cv. Samson). The described laboratory-based microcosm methodology determined the extent of weevil avoidance behaviour on each of these three grasses when subjected to the parasitoid. Such reaction was gauged by the extent of reduced weevil on-plant presence and feeding compared to the control populations. In the absence of the parasitoid, the hybrid cv. Manawa ryegrass is as highly favoured by the weevil as the tetraploid cv. Tama. On diploid cv. Samson, feeding is considerably less. In the presence of the parasitoid, weevils on the tetraploid cv. Tama plants showed little avoidance activity in response to the parasitoid and it can be argued that the benefits of staying on this plant outweighed the possibility of parasitism. Conversely and surprisingly, in the parasitoid’s presence, weevils on diploid cv. Manawa showed very strong avoidance behaviour leading to levels of exposure similar to those found on the less-preferred diploid cv. Samson. These findings reflect how weevil parasitism rates have declined in most Lolium grasses, particularly diploids, since the 1990s, but not in the tetraploid L. multiflorum. This contribution supports the hypothesis that the decline in weevil parasitism rates has been the result of rapid evolution arising from parasitoid-induced selection pressure and the countervailing effect of the nutritional quality of the host plants.

Biological control of pests continues to become more important in agriculture as pesticides are being withdrawn. However, successful control can be compromised by contemporary evolution. Recent work in New Zealand has shown that the once-successful biological control programme of the sexually reproducing grassland weevil pest Listronotus bonariensis by the asexual parasitoid Microctonus hyperodae has now failed. To explain the mechanisms associated with this, weevil parasitism rates were intensively monitored between 1994 and 2019. Frequent sampling took place at widely dispersed New Zealand sites spanning the warmer northern regions to the cooler south. Based on elapsed heat accumulation above the parasitoid’s development temperature threshold of 10.2°C degree-day (DD), the results over c. 25 years indicated that the extent of parasitism decline at a given location was directly related to the accumulated DD. The latter, in turn, was taken to be indicative of parasitoid activity and selection pressure. Accordingly, laboratory microcosm experiments measuring the response of weevils collected from the North–South distribution to a common population of parasitoids showed that the weevils from the warmer northern region showed higher rates of avoidance of the searching parasitoids than those from the cooler south. This strongly supported the hypothesis that the weevil resistance mechanism is related to levels of parasitoid avoidance behaviour arising from long-term parasitoid selection pressure. This study of the behaviourally based acquisition of resistance to a biological control agent illustrates a general need to consider the potential capability of an exotic target host to develop resistance to imported biological control agents. This includes identifying existing host adaptations that selection pressure could potentially act upon that may compromise otherwise successful biological control programmes. Such a requirement points to the need for long-term monitoring of biological control systems and understanding of parasitoid/host dynamics.

Sodium (Na) concentrations are low in plant tissues, and its metabolic function in plants is minor; however, Na is a key nutrient for plant consumers. Previous studies have thus far focused on Na concentration. Nevertheless, a balanced potassium (K) to Na ratio (K:Na) is more important than Na concentration alone since food with high K:Na has detrimental effects on consumers irrespective of Na concentration. Therefore, plants may actively regulate K:Na in their tissues and products, shaping plant-insect interactions. Studies considering nutritional aspects of plant-insect interactions have focused on nonreproductive tissues and nectar. In this study, we consider pollen as serving a primary reproductive function for plants as well as a food of pollinivores. Plants might regulate K:Na in pollen to affect their interactions with pollinivorous pollinators. To investigate whether such a mechanism exists, we manipulated Na concentrations in soil and measured the proportion of K, Na, and 13 other nutrient elements in the pollen of two sunflower (Helianthus annuus) cultivars. This approach allowed us to account for the overall nutritional quality of pollen by investigating the proportions of many elements that could correlate with the concentrations of K and Na. Of the elements studied, only the concentrations of Na and K were highly correlated. Pollen K:Na was high in both cultivars irrespective of Na fertilization, and it remained high regardless of pollen Na concentration. Interestingly, pollen K:Na did not decrease as pollen increased the Na concentration. We hypothesize that high K:Na in pollen might benefit plant fertilization and embryonic development; therefore, a tradeoff might occur between producing low K:Na pollen as a reward for pollinators and high K:Na pollen to optimize the plant fertilization process. This is the first study to provide data on pollen K:Na regulation by plants. Our findings broaden the understanding of plant-bee interactions and provide a foundation for a better understanding of the role of the soil-plant-pollen-pollinator pathway in nutrient cycling in ecosystems. Specifically, unexplored costs and tradeoffs related to balancing the K:Na by plants and pollinivores might play a role in past and current shaping of pollination ecology.

1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink ‘dirty water’ from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments. 2. Six minerals (NaCl, KCl, CaCl 2 , MgCl 2 , NH 4 Cl, and KH 2 PO 4 ) were used in mixtures to simulate different mineral stoichiometries, which may occur in ‘dirty water’, such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees ( Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h. 3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral ‘dirty water’ should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets.

The tomato–potato psyllid (TPP) Bactericera cockerelli, is a serious pest of solanaceous crops. Some populations are becoming pesticide-resistant, increasing the need for alternatives such as biological control (BC). This approach may be improved by combining different species of BC agents. We conducted three separate experiments to test four BC agents, either alone or combined with others: (1) A laboratory assay to test the effect of buckwheat (Fagopyrum esculentum) and alyssum (Lobularia maritima) flowers on the longevity of females of the parasitic wasp Tamarixia triozae; (2) A no-choice laboratory assay to investigate the consumption of B. cockerelli life stages by the predatory bug Engytatus nicotianae; (3) A cage experiment in a greenhouse to assess four natural enemy species against B. cockerelli on tomatoes: these were the predators Cleobora mellyi, Amblydromalus limonicus, E. nicotianae, and T. triozae. Access to buckwheat flowers allowed female T. triozae to live for an average of 10.9 days compared to 2.1 days with alyssum and 1.4 day with water but did not improve the BC of B. cockerelli. Adult E. nicotianae preyed on all offered B. cockerelli stages. In experiment 3, combinations of T. triozae with A. limonicus or E. nicotianae were not significantly better than single natural enemy species, except for the reduction of nymphal populations when A. limonicus and T. triozae were combined. Although there were few significant reductions in numbers of TPP when using natural enemy species combinations, some species showed good potential when used alone. We suggest testing earlier release of combinations of natural enemy for evaluate its impact on TPP.

Wheat bug, Nysius huttoni, is considered as an economic pest of forage Brassicas and many other cultivated crops, such as wheat, kale, and vegetables in New Zealand. Insecticides- as seed coatings and sprays are frequently used to manage this pest, but a high proportion of these insecticidal compounds enter the soil and leads to pesticide resistance, and they may impact beneficial arthropods and soil microorganisms, creating an adverse effect on ecosystem services (ES). In this paper, we discuss a technology, that we have developed to trap , for example, wheat bug away from kale seedlings, and integrating these in less susceptible kale cultivars that can potentially reduce over-reliance on orthodox pesticides on brassicas. Laboratory studies were conducted to screen the suitable trap crop among nine other plants (alyssum, wheat, phacelia, buckwheat, coriander, white clover, alfalfa, and kale) mainly by considering growth stages (vegetative and flowering), and select less susceptible kale cultivars among six other (Kestrel, Gruner, Sovereign, Regal, Corka and Colear). Alyssum (Lobularia maritima) and wheat (Triticum aestivum) were the most favoured potential trap plants for the wheat bug in a laboraotry study. Flowering stage of alyssum is the most susceptible growth stage by the bug damage. Kestrel and Coleor are the most popular kale cultivars used as forage brassicas in New Zealand, but they are the most susceptible to the wheat bug. Corka and Regal were the least susceptible cultivars. The integration of trap cropping technology by using alyssum as the trap crop, preferably depolying flowering stage, along with sowing less susceptible kale cultivars such as Corka and Regal in main fields have been suggested to protect brassica seedlings from bug damage.

The main contemporary challenge for agriculture is to meet the food demands of the increasing world population while becoming more environmentally sustainable. One way to achieve this is through the promotion of functional biodiversity and the ecosystem (nature's) services (ES) that it can provide. The Syrphinae subfamily is a widespread group of hoverflies with a high potential for that service. Hence, the present review aims to synthesize the existing literature on this group. This review is divided in three main sections. First, we focus on those aspects of the ecology of hoverflies that are relevant to their role in biological control. These are divided into nutrition, feeding preferences and prey detection of the different developmental stages, overwintering and the effect of landscape on their dispersal and efficacy. Second, we review the ES that predatory hoverflies can provide, particularly pollination and biological control. Finally, we discuss those farming practices that can affect the effectiveness of these Diptera as providers of ES. Overall, this review highlights the potential, as well as limitations and current gaps in knowledge, for enhancing the efficacy of hoverflies as ecosystem-service providers in agricultural systems.

Radish, Raphanus sativus is an important vegetable crop worldwide. It is the second most important vegetable after cabbage and cauliflower in winter (January to March) in Nepal. This crop is damaged by various herbivores such as the green peach aphid, Myzus persicae, the soybean hairy caterpillar, Spilarctia casigneta and the flea beetle, Monolepta signata. Prophylactic pesticide use is a part of the common pest management practice in Nepal. The candidate floral plant, alyssum, Lobularia maritima, was deployed in a radish field to improve pest biological control. Beneficial arthropods trapped such as Syrphidae, Coccinellidae, Carabidae, Staphylinidae, Formicidae, Lycosidae, Apidae and Ichneumonidae were significantly more abundant in flowering alyssum plots than the control (non-flowering) plots. Flowering alyssum in radish fields significantly increases the population of observed syrphids (larva and adult). Similarly observed ladybirds was slightly higher in flowering plot compared with control plot however that was not significant. These beneficial predators potentially increase the biological control of M. persicae. These results provide evidence of the alyssum's ability to increase the abundance of predators and support the suppression of M. persicae in radishes. This study is useful in developing an integrated pest management protocol by integrating flowering strips in radish fields. Habitat manipulation in radish fields by maintaining flower strips can improve pest biological control and support the provision of multiple ecosystem services that restore diminished ecosystem functions in agriculture.

The adoption of agro-ecological practices in agricultural systems worldwide can contribute to increased food production without compromising future food security, especially under the current biodiversity loss and climate change scenarios. Despite the increase in publications on agro-ecological research and practices during the last 35 years, a weak link between that knowledge and changed farmer practices has led to few examples of agroecological protocols and effective delivery systems to agriculturalists. In an attempt to reduce this gap, we synthesised the main concepts related to biodiversity and its functions by creating a web-based interactive spiral (www. biodiversity function.com). This tool explains and describes a pathway for achieving agro-ecological outcomes, starting from the basic principle of biodiversity and its functions to enhanced biodiversity on farms. Within this pathway, 11 key steps are identified and sequentially presented on a web platform through which key players (farmers, farmer networks, policy makers, scientists and other stakeholders) can navigate and learn. Because in many areas of the world the necessary knowledge needed for achieving the adoption of particular agro-ecological techniques is not available, the spiral approach can provide the necessary conceptual steps needed for obtaining and understanding such knowledge by navigating through the interactive pathway. This novel approach aims to improve our understanding of the sequence from the concept of biodiversity to harnessing its power to improve prospects for 'sustainable intensification' of agricultural systems worldwide.

The wheat bug Nysius huttoni is a major pest of brassica seedlings. Management of this insect currently relies on seed treatment with neonicotinoids and spraying with chlorpyrifos and pyrethroid insecticides. These practices can generate severe external costs, including human health, the environment and biodiversity. Trap cropping is one alternative option to protect brassica seedlings from N. huttoni. Trap crop species evaluated in field cage experiments were: alyssum (Lobularia maritima L. Desvauxcv. Benthamii White), wheat (Triticum aestivum L. cv. Morph), coriander (Coriandrum sativum L. cv. Santo) and clover (Trifolium repens L. cv. Nomad). These were compared with kale (Brassica oleracea L. cv. Kestrel). In open-field experiments, alyssum (L maritima), wheat (T. aestivum) and a mixture of alyssum (L. maritima) and wheat (T. aestivum) were used. All of these were compared to kale (B. oleracea). Alyssum and wheat were the most favoured potential trap plants for N. huttoni. Results indicated that two treatments: alyssum (used as a single trap crop) or 'alyssum plus wheat' (a multiple trap crop), may be useful in brassica fields to protect the seedlings from N. huttoni damage. Such a trap cropping protocol potentially reduces pesticide use in forage brassicas and can also deliver multiple ecosystem services such as biological control of insect pests.

In Central and North America, Australia and New Zealand, potato (Solanum tuberosum) crops are attacked by Bactericera cockerelli, the tomato potato psyllid (TPP). ‘Mesh crop covers’ which are used in Europe and Israel to protect crops from insect pests, have been used experimentally in New Zealand for TPP control. While the covers have been effective for TPP management, the green peach aphid (GPA, Myzus persicae) has been found in large numbers under the mesh crop covers. This study investigated the ability of the GPA to penetrate different mesh hole sizes. Experiments using four sizes (0.15 × 0.15, 0.15 × 0.35, 0.3 × 0.3 and 0.6 × 0.6 mm) were carried out under laboratory conditions to investigate: (i) which mesh hole size provided the most effective barrier to GPA; (ii) which morph of adult aphids (apterous or alate) and/or their progeny could breach the mesh crop cover; (iii) would leaves touching the underside of the cover, as opposed to having a gap between leaf and the mesh, increase the number of aphids breaching the mesh; and (iv) could adults feed on leaves touching the cover by putting only their heads and/or stylets through it? No adult aphids, either alate or apterous, penetrated the mesh crop cover; only nymphs did this, the majority being the progeny of alate adults. Nymphs of the smaller alatae aphids penetrated the three coarsest mesh sizes; nymphs of the larger apterae penetrated the two coarsest sizes, but no nymphs penetrated the smallest mesh size. There was no statistical difference in the number of aphids breaching the mesh crop cover when the leaflets touched its underside compared to when there was a gap between leaf and mesh crop cover. Adults did not feed through the mesh crop cover, though they may have been able to sense the potato leaflet using visual and/or olfactory cues and produce nymphs as a result. As these covers are highly effective for managing TPP on field potatoes, modifications of this protocol are required to make it effective against aphids as well as TPP.

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.

The potato psyllid Bactericera cockerelli (Hemiptera: Triozidae) has recently emerged as a serious pest of potatoes and other solanaceous crops. It causes direct feeding damage and also vectors Candidatus Liberibacter solanaceaerum (Lso), a pathogen that causes zebra chip disease in potatoes and which potentially costs growers millions of dollars each year. Such producers rely on frequent sprays of pesticides for psyllid control but the results are unsatisfactory and there are negative side effects. The psyllid has spread beyond its native range in southwest US and northern Mexico to Canada, El Salvador, Honduras, Guatemala and Nicaragua via medium to long range dispersal flights perhaps aided by wind currents, and through anthropogenic means. It was accidentally introduced into New Zealand in 2006 and most recently Australia, most likely through the importation of infested plant material. This review summarizes information from studies on the biology, impact and management of B. cockerelli, and highlights the imminent risk of this insect and its associated pathogen invading China, the world's largest producer of fresh potatoes. Development of risk maps leading to increased surveillance, could prevent or delay an incursion and facilitate early detection or eradication should this occur. Long-term management with Lso-tolerant potato cultivars and psyllid control using the parasitic wasp Tamarixia triozae and other natural enemies should be pursued, rather than depending on synthetic pesticides.

This paper provides evidence that an endangered monophagous weevil overexploits its host plant and can cause its local extinction. Over three consecutive summers a mark-recapture study was carried out on a geographically isolated weevil population on Mangere Island (New Zealand) to obtain population estimates and recruitment and survival rates. The host plants in the study area were mapped each summer. A release experiment was carried out to assess the host finding ability of the weevils and to simulate a local extinction of their host plants. At least 68% of the released weevils reached the host plants 100m away from the release site. During the three summers the weevil population more than quadrupled, while the area covered by the host plants halved. We predict the local extinction of the host plant population in the study area for the next summer and the migration of the weevils to other host plant patches.