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Gonipterus species are pests of Eucalyptus plantations worldwide. The egg parasitoid wasp Anaphes nitens is used in many countries for the biological control of Gonipterus spp. Recent taxonomic studies have shown that the three invasive Gonipterus spp., which were previously considered as G. scutellatus, form part of a cryptic species complex. These taxonomic changes have implications for the biological control of Gonipterus spp. The aims of this study were to understand the species composition and distribution of Gonipterus spp. and their egg parasitoids in Australia. Gonipterus spp. adults and egg capsules were collected in south-eastern Australia and Tasmania. Adult Gonipterus were identified using morphology and DNA barcoding. Parasitoids were reared from Gonipterus egg capsules and identified. Thirteen Gonipterus species were collected: twelve species were found on the Australian mainland and one species in Tasmania. These included three described species, four previously recognized but undescribed species, two undescribed species and four unidentified species. Five egg parasitoid species that attack Gonipterus spp. were identified. Anaphes nitens, Centrodora damoni and Euderus sp. were identified on the Australian mainland and A. tasmaniae and A. inexpectatus were identified in Tasmania. The results from this study will contribute to the improvement of Gonipterus biological control in the future.

Gonipterus scutellatus (Coleoptera: Curculionidae), once thought to be a single species, is now known to reside in a complex of at least eight cryptic species. Two of these species (G. platensis and G. pulverulentus) and an undescribed species (Gonipterus sp. n. 2) are invasive pests on five continents. A single population of Anaphes nitens, an egg parasitoid, has been used to control all three species of Gonipterus throughout the invaded range. Limited knowledge regarding the different cryptic species and their diversity significantly impedes efforts to manage the pest complex outside the native range. In this review, we consider the invasion and taxonomic history of the G. scutellatus cryptic species complex and the implications that the cryptic species diversity could have on management strategies. The ecological and biological aspects of these pests that require further research are identified. Strategies that could be used to develop an ecological approach towards managing the G. scutellatus species complex are also suggested.

The study was initiated by the relative failure of the parasitoid Anaphes nitens in controlling the eucalypt weevil Gonipterus platensis on the Iberian Peninsula. Our aim was to gain insight into the community of Gonipterus egg parasitoids occurring in Tasmania. During surveys in 2016 and 2017, adult weevils and egg pods were collected from Eucalyptus trees in Tasmania. The weevils were identified using male genital structure and DNA extracted from hatched larvae. Parasitoids that emerged from the egg pods were identified, and trophic associations of egg parasitoids, weevils and host plants were analyzed. Five species of the Gonipterus scutellatus complex, to which G. platensis belongs, were found, including Gonipterus sp. 2, which is reported for the first time from Tasmania. Molecular analysis corroborated previous phylogenetic studies of this group of species. A sixth species, G. notographus, was also collected. Most species were found to overlap in distribution in Tasmania and, despite being oligophagous, to display selectivity among Eucalyptus species used as hosts: G. platensis and G. pulverulentus were mainly found on E. ovata, Gonipterus sp. 1 on E. nitens and E. globulus and G. notographus on ‘peppermint’ species (E. amygdalina and E. pulchella). Five egg parasitoid species were found associated with these Gonipterus species: Anaphes inexpectatus, A. nitens, A. tasmaniae, Cirrospilus sp. and Euderus sp., with no apparent host specialization. Anaphes nitens, Cirrospilus sp. and Euderus sp. were more frequently found on E. ovata, possibly associated with G. platensis and G. pulverulentus, which were dominant on this host species. Conversely, A. inexpectatus was dominantly found on peppermints (43%), suggesting a main association with G. notographus. Anaphes nitens was found at 23 locations out of 117 and in 2017 was the most abundant parasitoid obtained, with an average 20% parasitism rate, indicating that this species is undergoing a geographical and population expansion since its first report from Tasmania in 2012. These findings contribute to the understanding of the parasitoid-Gonipterus-Eucalyptus trophic relationship and stand to improve future classical biological control programs against G. platensis and other invasive Gonipterus species.

The efficiency of local augmentation releases of the egg parasitoid Anaphes nitens to control the Eucalyptus snout‐beetle Gonipterus platensis was tested in Eucalyptus globulus plantations in Galicia (NW Spain). On May–June 2006, at two localities of Pontevedra province, the release of host egg capsules parasitized by A. nitens at a potential rate of 300 adults/ha was compared with a release density of 900 adults/ha, and a control group of eucalypts not subjected to augmentation. Parasitism rate after 1–2 weeks did not significantly increase over the control plots at both localities. The high release rate did not ensure a higher crop protection and therefore could be not economically justified. On March–April 2017, at four localities of Pontevedra province, the test was replicated by releasing 300 parasitoids/ha. Parasitism level did significantly increase over the control just in one locality. Augmentation of A. nitens at small scale generally failed to achieve a higher protection from the pest, possibly due to the large extension of the E. globulus plantations, the magnitude of the G. platensis population and the fluctuations of the established parasitoid population, whose density is in turn affected by host egg availability and density‐dependent dispersal.

The Eucalyptus snout beetle, Gonipterus platensis (Marelli), is an important pest of Eucalyptus globulus Labill. This insect is partially controlled by the egg parasitoid Anaphes nitens (Girault) in many regions, but the introduction of additional natural enemies can potentially increase pest control. In this study, we evaluate intra- and interspecific competitive interactions between the incumbent A. nitens and the new egg parasitoid Anaphes inexpectatus Huber and Prinsloo. The effects of temperature, order of parasitism, number of parasitoid ovipositions, time interval between ovipositions, and host egg age were analysed. Distinct outcomes of competition were found at different temperatures, with benefit to A. inexpectatus at 20 °C. The first species to parasitise generally prevailed over the second, indicating exploitation competition. However, interference competition was also apparent, namely when A. inexpectatus laid multiple eggs, outcompeting A. nitens, and when the first parasitism occurred six days before. In this case, the second species was able to eliminate the first. Anaphes nitens tended to reject eggs parasitised by A. inexpectatus, whereas A. inexpectatus showed no interspecific host discrimination behaviour towards eggs parasitised by A. nitens. Overall, A. nitens parasitised more hosts and is expected to contribute more to pest control, but it was found to be more susceptible to intraspecific competition. Results suggest that A. inexpectatus and A. nitens should be able to coexist, as asymmetric competition was found to depend on temperature. However, A. inexpectatus establishment in the field in areas where A. nitens is already present may be delayed or even prevented due to interspecific competition. As such, the introduction of A. inexpectatus in a classical biological control programme against G. platensis is advised to be carried out by releasing large numbers of parasitoids in consecutive occasions.

Anaphes (Patasson) nitens (Girault, 1928) Anaphoidea nitens Girault, 1928 [420]: 262. Lectotype ♀ (MVMA), designated by Huber & Prinsloo, 1990: 336. TL: Australia, Victoria, Ferntree Gully. Huber & Prinsloo, 1990: 334 (key); Millar et al., 1996: 508 (biological control); Hanks et al., 2000: 476 (biological control); Paine et al., 2000: 12 (biological control); Paine & Millar, 2002: 149 (biological control); Paine & Millar, 2003: 68 (biological control); Jetter & Paine, 2004: 314 (biological control); Riddick, 2005a: 63 (egg load); Boivin, 2010a: 459 (phenotypic plasticity); Mills, 2010: 394 (biological control success); Mapondera et al., 2012: 186 (host, biological control); Paine et al., 2015: 2498 (biological control success); Boivin & Ellers, 2016: 164 (ovigeny index); Paine, 2016: 717 (biological control); Schröder et al., 2017: 99 (biological control); Jeger et al., 2018: 21 (biological control); Van Driesche et al., 2018: 13 (biological control). Anaphes (Patasson) nitens: Viggiani, 1994: 479 (male genitalia, key); Huber & Thuróczy, 2018: 28 (catalogue). Anaphoidea gonipteri Ferrière, 1930: 38. Lectotype ♀ (NHMUK), designated by Huber & Prinsloo, 1990: 336. TL: Australia, South Australia, Penola. Synonymy by Girault, 1930 [433]: 4. Nearctic hosts. Curculionidae: Gonipterus platensis Marelli. The host was misidentified as G. scutellatus Gyllenhal in the publications listed above, other than in Mapondera et al. (2012). Over 100 extralimital publications treat A. nitens. Distribution. USA: CA (introduced and established)., Published as part of Huber, John T., Read, Jennifer D. & Triapitsyn, Serguei V., 2020, Illustrated key to genera and catalogue of Mymaridae (Hymenoptera) in America north of Mexico, pp. 1-411 in Zootaxa 4773 (3) on page 73, DOI: 10.11646/zootaxa.4773.1.1, http://zenodo.org/record/3821373, {"references":["Girault, A. A. (1928 [420]) Australian chalcid-wasps. Victorian Naturalist, 44, 261 - 263.","Huber, J. T. & Prinsloo, G. L. (1990) Redescription of Anaphes niten s (Girault) and description of two new species of Anaphe s (Hymenoptera: Mymaridae), parasites of Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) in Tasmania. Journal of the Australian Entomological Society, 29, 333 - 341. https: // doi. org / 10.1111 / j. 1440 - 6055.1990. tb 00373. x","Millar, J. G., Hanks, L. M. & Paine, T. D. (1996) Control of the eucalyptus snout beetle Gonipterus scutellatus Gyllenhal in California by the egg parasitoid Anaphes nitens (Girault) (Coleoptera: Curculionidae-Hymenoptera: Mymaridae). Abstract 16 - 017. In: Proceedings, XX International Congress of Entomology, Firenze, Italy, 25 - 31 August 1996, pp. 508.","Hanks, L. M., Millar, J. G., Paine, T. D. & Campbell, C. D. (2000) Classical biological control of the Australian weevil Gonipterus scutellatus (Coleoptera: Curculionidae) in California. 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(2004) Consumer preferences and willingness to pay for biolgical control in the urban landscape. Biological Control, 30, 312 - 322. https: // doi. org / 10.1016 / j. biocontrol. 2003.08.004","Riddick, E. W. (2005 a) Egg load of lab-cultured Anaphes iole and effects of mate presence and exposure time on load depletion. BioControl, 50, 53 - 67. https: // doi. org / 10.1007 / s 10526 - 004 - 1071 - 2","Boivin, G. (2010 a) Phenotypic plasticity and fitness in egg parasitoids. Neotropical Entomology, 39 (4), 457 - 463. https: // doi. org / 10.1590 / S 1519 - 566 X 2010000400001","Mills, N. (2010) Egg parasitoids in biological control and integrated pest management. In: Consoli, F. L., Parra, J. R. P. & Zucchi, R. A. (Eds.), Egg parasitoids in agroecosystems with emphasis on Trichogramma. Progress in Biological Control 9, Springer, Dordrecht, pp. 389 - 411. https: // doi. org / 10.1007 / 978 - 1 - 4020 - 9110 - 0 _ 15","Mapondera, T. S., Burgess, T., Matsuki, M. & Oberprieler, R. G. (2012) Identification and molecular phylogenetics of the cryptic species of the Gonipterus scutellatus complex (Coleoptera: Curculionidae: Gonipterini). Australian Journal of Entomology, 51, 175 - 188. https: // doi. org / 10.1111 / j. 1440 - 6055.2011.00853. x","Paine, T. D., Millar, J. G., Hanks, L. M., Gould, J., Wang, Q., Daane, K., Dahlsten, D. L. & McPherson, E. G. (2015) Cost-benefit analysis for biological control programs that targeted insect pests of eucalypts in urban landscapes of California. Journal of Economic Entomology, 108 (6), 2497 - 2504. https: // doi. org / 10.1093 / jee / tov 224","Boivin, G. & Ellers, J. (2016) Replacing qualitative life-history traits by quantitative indices in parasitoid evolutionary ecology. Entomologia Experimentalis et Applicata, 159, 163 - 171. https: // doi. org / 10.1111 / eea. 12425","Paine, T. D. (2016) Chapter 24. Insects colonizing eucalypts in California. I n: Paine, T. & Lieutier, F. (Eds), Insects and Diseases of Mediterranean Forest Systems. Springer, Cham, pp. 711 - 730. https: // doi. org / 10.1007 / 978 - 3 - 319 - 24744 - 1 _ 24","Schroder, M. L. Nahrung, H. F., Lawson, S. A., Slippers, B., Wingfield, M. J. & Hurley, B. P. (2017) 6.3 Biological control of the Gonipterus scutellatus species complex: testing the species, climatic or phenological mismatch hypotheses. In: Mason, P. G., Gillespie, D. R. & Vincent, C. (Eds.), Proceedings of the 5 th International Symposium on Biological Control of Arthro- pods. Langwaki, Malaysia, September 11 - 15 2017. CAB International, Wallingford, pp. 99 - 101. https: // doi. org / 10.1079 / 9781786394118.0099","Jeger, M., Bragard, C., Caffier, D., Candresse, T., Chatzivassiliou, E., Dehnen-Schmutz, K., Gilioli, G., Miret, J. A. J., MacLeod, A., Navarro, M. N., Niere, B., Parnell, S., Potting, R., Rafoss, T., Rossi, V., Urek, G., Van Bruggen, A. Van der Werf, W., West, J., Winter, S., Santolamazza-Carbone, S., Kertesz, V., Aukhojee, M. & Gregoire, J. - C. (2018) Pest categorization of the Gonipterus scutellatus species complex. EFSA Journal, 16 (1), 1 - 34. https: // doi. org / 10.2903 / j. efsa. 2018.5107","Van Driesche, R., Cock, M. J. W., Winston, R. L., Reardon, R. & Weeks, R. D. Jr. (2018) Catalog of species introduced into Canada, Mexico, the USA, or the USA overseas territories for classical biological control of arthropods, 1985 - 2018. Forest Health Assessment and Applied SciencesTeam (FHAAST). United States Department of Agriculture, Morgantown, West Virginia, 190 pp.","Huber, J. T. & Thuroczy, C. (2018) Review of Anaphes Haliday (Hymenoptera: Mymaridae) with keys to species in Europe and a world catalogue. Zootaxa, 4376 (1), 1 - 104. https: // doi. org / 10.11646 / zootaxa. 4376.1.1","Ferriere, C. (1930) On some egg-parasites from Africa. 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Despite the importance of invasive pests, few studies address the costs and benefits of the strategies used to control them. The present work assesses the economic impact of the Eucalyptus snout beetle, Gonipterus platensis, and the benefits resulting from its biological control with Anaphes nitens in Portugal, over a 20-year period. Comparisons were made between the real situation (with A. nitens) and three scenarios without biological control: 1) replacement of Eucalyptus globulus by resistant eucalypts; 2) insecticide use; and 3) offset of yield losses by imported wood. A cost-benefit analysis was performed to evaluate a programme that aimed to accelerate A. nitens establishment. Although A. nitens provides adequate pest control in several regions, 46% of the area planted with eucalypts is affected by the beetle, causing wood losses of 648 M euros over 20 years. Losses in the three hypothetical scenarios were estimated at 2451 M-7164 M euros, resulting in benefits from biological control of 1803 M–6516 M euros, despite the fact that only partial success was achieved. Anticipating biological control by just one, two, or three years resulted in benefit-cost ratios of 67, 190, and 347, respectively. Because nonmarket values were not accounted for, these figures are likely underestimated.

The weevil Gonipterus platensis is among the most important eucalypt (Eucalyptus spp.) pest species worldwide. In Portugal, weevil-induced damage has great economic significance and efforts are being taken to find adequate alternatives to the biological control of this defoliator by its parasitoid Anaphes nitens, which is ineffective at altitudes above 400 m. With the aim of improving current knowledge on the ecology of G. platensis, we evaluated its interactions with local and landscape factors through the application of generalized linear mixed models for (1) the probability of weevil occurrence in sampling points, and (2) the relative abundance of each of its two annual generations on eucalypt trees. Our models confirmed the significant positive effect of elevation, here found to come off just above 360 m a.s.l., on both the occurrence and the abundance of G. platensis. Moreover, our results denoted that stand-level variables can likewise affect this pest. Points located more than 400 m inside the stands and, to a lesser extent, those comprising smaller (yet mature) eucalypt trees and where trees of other species were absent, showed an increased probability of G. platensis occurrence. Concordantly, significantly higher abundances of both weevil generations were observed on 3–8 years-old eucalypt trees. In addition, there was a negative effect of coppiced stands on G. platensis abundance which was only significant for the first annual generation and probably was related with weevil’s recent colonization of stands ravaged by wildfires two years before our field surveys. Weevil populations were not influenced by the density of stand canopy, neither by understory structure and composition, nor by bare soil cover, hence it is not expected that thinning, shrub removal and soil scarification practices can affect G. platensis attacks in eucalypt stands. Overall, our study provides key knowledge on the ecology of G. platensis and its response to local and landscape features, paving the way for enhanced management of eucalypt plantations.

The Eucalyptus snout beetle, Gonipterus platensis (Marelli), causes severe damage to eucalypt plantations in several countries, despite the presence of the parasitoid Anaphes nitens (Girault). Climate and/or host–parasitoid mismatch may explain A. nitens shortcomings in some areas in Portugal, Spain, Chile, South Africa, or Australia. Because additional parasitoids may be needed to achieve reliable control of this pest, Anaphes inexpectatus Huber and Prinsloo, retrieved from field surveys conducted in Tasmania (the pest’s native habitat), was selected for pre-release studies in Portugal. Life history traits of A. inexpectatus and A. nitens were compared at six temperatures (5, 10, 15, 20, 25, and 30 °C), including development times, thermal constants, viability, parasitism, and behaviour. Temperatures ranging from 10 to 20 °C were adequate for development, while at 25 and 30 °C, deleterious effects of temperature were detected, particularly in A. nitens. Development thresholds were similar for A. inexpectatus and A. nitens (6.0 and 5.4 °C, respectively), but A. nitens needed 313 degree-days to complete development, while A. inexpectatus needed 263 degree-days. Globally, A. nitens produced more progeny, parasitised more eggs, and lived longer than A. inexpectatus. Net reproductive rates were higher for A. inexpectatus at lower temperatures (10 and 15 °C), and higher for A. nitens at moderate temperatures (20 and 25 °C). In addition, A. inexpectatus evidenced higher tolerance to the highest temperature tested (30 °C). Anaphes inexpectatus is likely to establish under field conditions and may enhance parasitism of G. platensis.

Summary Native to Australia Gonipterus platensis Marelli (Coleoptera: Curculionidae) is the main beetle defoliator of eucalyptus worldwide, causing damage in various regions in which it was introduced, where its management relies mostly on biological control with the parasitoid Anaphes nitens (Girault) (Hymenoptera: Mymaridae). In this report, we present the first laboratory evidence of efficient predation by Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) on G. platensis larvae. This predatory species is native to Brazil and a promising biological control agent for use in the integrated pest management of G. platensis.

Curculionidae are a large mainly herbivorous family of beetles, some of which have become crop pests. Classical biological control has been attempted for about 38 species in 19 genera, and at least moderate success has been achieved in 31 % of cases. Only two weevil species have been considered to be completely controlled by a biological control agent. Success depends upon accurately matching natural enemies with their hosts, and hence taxonomy and phylogeny play a critical role. These factors are discussed and illustrated with two case studies: the introduction of the braconid parasitoid Mictroctonus aethiopoides into New Zealand for biological control of the lucerne pest Sitona discoideus, a case of complex phylogenetic relationships that challenged the prediction of potential non-target hosts, and the use of a mymarid egg parasitoid, Anaphes nitens, to control species of the eucalypt weevil genus Gonipterus, which involves failure to match up parasitoids with the right target amongst a complex of very closely related species. We discuss the increasing importance of molecular methods to support biological control programmes and the essential role of these emerging technologies for improving our understanding of this very large and complex family.

The Panel on Plant health performed a pest categorisation of the Australian Eucalyptus snout-beetle Gonipterus scutellatus (Coleoptera: Curculionidae), for the EU. G. scutellatus should be referred as the G. scutellatus species complex because it includes several cryptic species. A complete nomenclature of the species present in the EU is still pending. It is a quarantine pest listed in Annex IIB of Council Directive 2000/29/EC. Protected zones are in place in Greece and Portugal (Azores). In the EU, it has been found in Italy, France, Spain and Portugal. It only consumes Eucalyptus species leaves. The main pathways of spread are the trade of Eucalyptus timber, hitchhiking in various commodities, trade of apple fruit as well as of plants for planting or plant parts. Spread by fl ight is also possible. The climate of the EU protected zones is similar to that of the Member States (MS) where the G. scutellatus complex is established, and the pest ’ s main host plants are present. The damaged trees suffer die-back and the development of epicormics shoots. Severe attacks may provoke massive amounts of tree death. Biological control by using the egg parasitoid wasp Anaphes nitens is the most effective control measure. Some species within the G. scutellatus complex are not yet present in the EU (including G. scutellatus sensu stricto) and might therefore be considered as potential union quarantine pests for the EU territory. At least two species within the G. scutellatus complex (most likely G. platensis and Gonipterus species no. 2) meet the criteria assessed by EFSA for consideration as potential protected zone quarantine pests for the territory of the protected zones: Greece and Portugal (Azores). The criteria for considering the G. scutellatus complex as a potential regulated non- quarantine pest for the EU are not met since plants for planting are not the main pathway.

Available at SciVerse ScienceDirect Sustainable management of forest plantations and cost-effective control strategies depend on previous estimations of the economic level of damage caused by the pests. The eucalyptus weevil, a key pest of Eucalyptus plantations worldwide, is mainly controlled using classical biological control, using the mymarid egg-parasitoid Anaphes nitens (Girault). Nevertheless, in several temperate regions, the parasitoid fails to reduce the weevil populations to economically sustainable levels. This study attempts to (i) relate the efficiency of the parasitoid with climate variables, (ii) relate the level of damage caused by the weevil with the rate of parasitism, (iii) estimate the implications of weevil damage on wood production. Weevil density, damage caused by defoliation on the upper crown and parasitism rates were monitored in 2007, in 34 Eucalyptus globulus stands. Elevation, temperature and precipitation were assessed by using the Worldclim database. Using historic inventory data, wood production was projected to an age of 10 years, prior to the arrival of the weevil, and compared with current data for the same stands. Parasitism rate by A. nitens was a key element explaining weevil density and tree defoliation, r2 = 0.37 and 0.41 (p < 0.001), respectively. Significant relationships between parasitism rates and maximum temperature of the winter months (MaxTw), r2 = 0.55 and elevation r2 = 0.59 (p < 0.001) were found. Other climatic variables, such as temperatures of the warmest months and precipitation, were not significantly related to parasitism rates. An upper threshold limit for the efficiency of the parasitoid appears for MaxTw of 10–11 C. The mean percentage of parasitism was low 10.1% (±4.9) for MaxTw below 10 C, increasing to 70.9% (±3.8) above 11.5 C. A reduction of the efficiency of A. nitens due to differences in the climatic niches of both the host and the parasitoid is hypothesised. The lower temperature threshold in particular, is of paramount importance for this host-parasitoid system. In consequence, in colder areas MaxTw < 10 C, a defoliation of 74.1% was attained. Wood volume (projected to the age of 10 years) was estimated to decrease to 51% in the affected areas in 2004–2006, compared to the previous period of 1995–1998. Estimated loss in wood volume increased exponentially reaching 43% and 86%, for 75% and 100% of tree defoliation, respectively. Therefore, considering the increase in the economic costs calculated for these regions, due to the high defoliation caused by the weevil, research into alternative control strategies is urgently needed.

The Eucalyptus Weevil, generally referred to as Gonipterus scutellatus Gyllenhal, 1833 is a significant pest of Eucalyptus species in Africa, America, Europe and New Zealand. It has recently become a pest of Eucalyptus globulus plantations in Western Australia, despite the presence there of the mymarid egg-parasitoid Anaphes nitens (Girault). Recent taxonomic study has indicated G. scutellatus to comprise a complex of cryptic species, obscuring the identity of the various pest populations of the weevil in the world. We examined (1) whether the apparent cryptic species identifiable on genital differences have a genetic basis; (2) the distribution of these species; and (3) the origin of the population in Western Australia. We studied specimens from across the distribution range of Eucalyptus Weevil in Australia and obtained sequences of three genes from them: cytochrome oxidase I mtDNA, elongation-factor 1-a nuclear DNA and 18s rDNA. The cladogram of COI haplotypes resolved 10 well supported clades fully corresponding with genital-morphologically distinct species, eight of them constituting a monophyletic G. scutellatus complex. Only four of these species proved to be described, as G. balteatus Lea, 1897 G. platensis (Marelli, 1926), G. pulverulentus Lea, 1897 and G. scutellatus Gyllenhal, 1833. The pest species in the world were found to be G. platensis (New Zealand, America, western Europe), G. pul- verulentus (eastern South America) and an undescribed species (Africa, France, Italy). The population of G. platensis in Western Australia showed little genetic variation and is indicated to be a recent introduction from Tasmania. The discrimination of the cryptic species of the G. scutellatus complex enables improvements in the management of the pest species in terms of biological control and plantation practices. Our study highlights the critical importance of proper taxonomic studies under- pinning biocontrol programs.

In this work we explored the female mating frequency of the quasi-gregarious egg parasitoid Anaphes nitens and its consequences on offspring sex-ratio. In a previous study we have shown that sex-ratio (proportion of males) increases with maternal age, suggesting that sperm depletion could occur if females mate only once. Here, we tested: (1) whether A. nitens females are polyandrous; (2) whether polyandry increases daughter production; and (3) the relationship between polyandry, fecundity and longevity. Virgin females were mated and provided with host egg-capsules and drops of honey as food. Afterward, they had the opportunity to re-mate daily during the rest of their life. About 55% of females were polyandrous, but multiple mating significantly increased the proportion of males in the offspring. In particular, daughter production of multi-mated females crashed at the 9th day of life, despite having obtained 2–3 matings. Hence, this suggests that females did not replenish their spermatheca by additional m...

The Eucalyptus weevil, Gonipterus scutellatus Gyllenhal, is the most serious pest of established Eucalyptus globulus plantations in southwestern Australia where it may have been introduced from its endemic origin in southeastern Australia. This species has been introduced to many countries but has been brought under successful biological control by the introduction of the egg parasitoid, Anaphes nitens Girault, from southeastern Australia. I investigated whether the elevated pest status of G. scutellatus in southwestern Australia is a result of inadequate biological control by quantifying parasitism rates of the pest. Parasitism rates of G. scutellatus egg masses by A. nitens were very low between late winter and mid spring when most oviposition occurs, and a high percentage of parasitised egg masses at these times were incompletely parasitised. Parasitism rates from late spring onwards approached 100%, but fewer egg masses were laid at these times. Low parasitism rates up to mid spring are likely to be due to low numbers of A. nitens at these times because hosts are not available for half the year. In southwestern Australia G. scutellatus has one principal oviposition period in early spring and a second lesser oviposition period in early summer. This short reproductive period appears to be caused by a scarcity of suitable new flushing foliage after spring that is essential for G. scutellatus reproduction. A. nitens did not emerge from eggs of the closely related weevil Oxyops despite eggs of this species being available at a time when G. scutellatus hosts were largely unavailable. Taxonomic difficulties with Gonipterus and possibly Anaphes may also explain the breakdown of biological control in southwestern Australia, and taxonomic revision of these insect groups must be a future research priority.

We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments (n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber at 20°C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother’s diet and size affected development time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host.

We investigated under outdoor conditions and inside a climate chamber: (i) whether Anaphes nitens Girault (Hymenoptera: Mymaridae), an egg parasitoid of the Eucalyptus snout beetle, Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae), experienced egg resorption, and (ii) how various treatments (location, food, and/or host supply) and body size influenced egg load, egg resorption, fecundity, and longevity. One-day-old females were mated and randomly assigned to five groups: (A) honey + hosts, (B) water + hosts, (C) only honey, (D) only water, and (E) control females killed at emergence. We compared the egg load of the newly emerged females, which represent the control group (egg load = ovarian eggs present at emergence), with the lifetime egg load (i.e., ovarian eggs + emerged offspring + not emerged offspring) of the females with various host and diet treatments, by dissection of the ovaries to find evidence of egg resorption. All groups reared outdoors had fewer eggs than the control, while indoors there was no significant difference. Outdoors, starved but hostprovided wasps (B) experienced the highest reduction of the lifetime egg load (51%). Groups without access to food (B + D) resorbed more eggs than groups provided with honey (A + C). Females with honey and hosts (A) had the highest lifetime fecundity, but those with water and hosts (B) showed a higher daily realized fecundity. Host-deprived females with access to food (C) attained the longest lifespan. Our results suggest that under stress conditions, such as low temperature and food shortage, A. nitens females practice egg resorption, probably to save energy.

In this study, the effects of maternal age, diet, and size on offspring sex ratio were investigated for the solitary egg parasitoid, Anaphes nitens Girault (Hymenoptera: Mymaridae), both outdoors, during the winter, and inside a climatic chamber under favourable constant conditions. During the winter of 2005-2006, each of seven groups containing 40 1-day-old females was mated and randomly distributed among two treatments: (treatment 1) a droplet of undiluted honey ad libitum + one fresh egg capsule of the snout beetle Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae) as host; (treatment 2) drops of water + one fresh egg capsule of G. scutellatus. We recorded the lifetime fecundity, the daily sex allocation, and the lifetime offspring sex ratio to study the existence of a relationship with maternal characteristics. Moreover, we assessed the effect of location (outdoors vs. indoors) and group (groups are representative of early, mid, and late winter) on sex ratio. The most important factor that biased the sex ratio was maternal body size: larger females of both treatments produced more female offspring. As females of A. nitens could gain more advantage than males from body size, larger mothers have a higher fitness return if they produce more daughters. The effect of the treatment was significant: starved females produced more females. Location and group were not significant. Fecundity and sex ratio were age dependent. Old mothers that received honey (treatment 1) had fewer offspring and a more male-biased offspring sex ratio, probably due to reproductive senescence and sperm depletion. Starved females (treatment 2) experienced reproductive decline earlier, perhaps because they invested more energy in maintenance rather than in reproduction.

Laboratory experiments and field surveys were carried out to study the thermal requirements and phenology of the Eucalyptus snout beetle Gonipterus scutellatus (Curculionidae) and its parasitoid, Anaphes nitens (Mymaridae). Developmental times were recorded for G. scutellatus life stages: egg to first instar larva, first instar to pre-pupal larva, prepupae to adults and the complete life cycle. Experiments were performed in temperature-controlled chambers maintained at 10, 15, 20, 25 and 30°C with a photoperiod of 11 : 13 h of light : darkness and 50–60% RH. To calculate the minimum threshold temperature of the parasitoid, parasitized egg capsules were kept under similar conditions. During 1998 and 1999 we studied the phenology and the day-degree (DD) accumulation of G. scutellatus and its parasitoid in plots of Eucalyptus globulus at six different sites in NW Spain. Every 2 weeks, the numbers of snout beetle adults and egg capsules were counted in each plot. The rate of parasitism was estimated by collecting 90 egg capsules from each plot on each sampling date. We recorded the temperatures in each plot to test whether differences in temperature alone could account for the phenology of this snout beetle. To complete a full life cycle from egg to adult, the weevil required a mean of 1119.83 ± 20.59 DD above a base temperature of 6.11°C. The parasitoid had a base temperature of 5.09°C and needed 318.16 DD to complete a life cycle. Our model indicated that three generations of snout beetle could develop each year, corresponding to peaks of snout beetle numbers in the field in March–April, June–July and November. In some years only one generation of G. scutellatus was recorded due probably to the effectiveness of the parasitoid. Differences in numbers of adults and egg capsule were recorded between neighbouring ‘coastal plots’ and between neighbouring ‘inland plots’. Hence, climate alone does not appear to explain the phenology of G. scutellatus.

Alpha-cypermethrin is widely used in Australian forestry to control defoliating beetle pests but no information exists on its efficacy against beetle pests or impacts on non-target arthropods. To address this deficiency I quantified the short-term impacts of single commercial applications of the insecticide alpha-cypermethrin on populations of both defoliating beetle pests and beneficial arthropods over 12 months in two southwestern Australian eucalypt plantations. A single application of alpha-cypermethrin (24 g a.i./ha) in October or November reduced beetle pest populations to near zero levels. Beetle recovery began immediately after spraying but high populations of eucalyptus weevil and chrysomelid beetles, and high defoliation levels did not eventuate until 10–12 months later. Despite the success of alpha-cypermethrin in controlling defoliating beetle pests, the broad-spectrum nature of the insecticide led to nearly complete mortality of all beneficial arthropods immediately after spraying. Spiders were the main group of beneficial arthropods present after spraying probably because some individuals occupy a concealed and protected habitat. Populations of Anaphes nitens (Girault), the important eucalyptus weevil egg parasitoid, also partly survived the spray because they were protected within weevil egg masses. Post-spray recovery of both beetle pests and beneficial arthropods occurred gradually in the following 12 months, presumably through immigration from outside the plantation.

The egg parasitoid Anaphes nitens (Girault) was successfully introduced into South Africa in 1926 to control the Eucalyptus snout beetle, Gonipterus scutellatus Gyllenhal. However, outbreaks of the beetle on the Highveld in the 1980s questioned the efficacy of the parasitoid as a biological control agent and a programme was instituted to determine its present status. This study represents the Western Cape programme where 20 host egg-capsules were collected at fortnightly intervals for five years from three localities and the percentage parasitism was recorded. The mean parasitism rate varied between Cape Town (76%), George (82%), and Grabouw (89%). The highest parasitism occurred in spring (October) at Cape Town (96%) and (September) Grabouw (92%); and in autumn (May) at George (78%), coinciding with that of maximum host egg production, which in turn was dependent on the availability of fresh foliage. More host eggs were present in Cape Town (42%) than at either George (30%) or Grabouw (28%). Parasitism o...

We investigated, by means of topical, residual and field assays, the toxicity of four insecticides (Bacillus thuringiensis, azadirachtin, flufenoxuron and ethofenprox) to adult, larvae and eggs of the Eucalyptus snout-beetle Gonipterus scutellatus and their side-effects on the adults of the solitary egg parasitoid Anaphes nitens, its natural enemy. In the topical toxicity experiment, both flufenoxuron and ethofenprox severely affected G. scutellatus, causing 100% adult mortality after 7 days, and 75 and 100% larval mortality, respectively. Ethofenprox also caused 93% larval pre-eclosion mortality and 100% parasitoid mortality. In the residual experiment, azadirachtin acted as an effective larvicide when ingested (73% mortality after 7 days). Ethofenprox showed the highest toxicity, with 100% mortality of adults and larvae of G. scutellatus after 24 h. On the day 7 of observation, flufenoxuron resulted in 93% adult mortality and 100% larval mortality. After contact with residuals, only ethofenprox and flufenoxuron had adversely affected A. nitens (98% mortality after 48 h). Bacillus thuringiensis exhibited only a slight activity against the pest or the parasitoid. The field experiment was carried out on three localities, with a preliminary sampling, and three samplings after the applications of the products, on days 7, 14 and 30. We evaluated the parasitism rate, parasitoid sex ratio, parasitoid pre-eclosion mortality, the abundance of G. scutellatus adults, larvae and egg capsules, the pre-eclosion mortality rate of weevil eggs and larvae and the foliar damage. Only fluenoxuron and ethofenprox reduced the pest population and the foliar damages, but ethofenprox also significantly decreased the rate of parasitism (17%) after 7 days. Given our experimental results, we suggest that flufenoxuron and azadirachtin could be used in association with the natural enemy.

We investigated host finding and host discrimination ability in Anaphes nitens, a solitary egg parasitoid that attacks a gregarious host, the egg capsules of the Eucalyptus snout-beetle, Gonipterus scutellatus. In a first experiment, females were assigned to three treatments: no experience, one experience on an unparasitized egg capsule or one experience on a parasitized egg capsule. We combined this variable with three types of hosts: unparasitized, previously parasitized by the experimental female, or parasitized by conspecifics. Females were observed in a no-choice test, and results indicate that: (1) naive females can discriminate but do not refrain from superparasitism, (2) previous experience and the type of egg capsule affect host acceptance and visit duration, and (3) there is no evidence of self-discrimination. The acceptance of parasitized hosts decreased from 90% for the inexperienced females at their first encounter with the host, to 45% for the experienced females, and visit duration from 17.2 to 9.2 min. In a second experiment, a choice test was performed to assess A. nitens preference towards hosts of different age. Females oviposited preferentially in very young hosts. A field experiment tested the ability to find new hosts within the window of vulnerability of the egg capsules, by manipulation of the time that hosts were exposed to parasitism. Results showed that parasitoids need one day to discover the hosts and that parasitism does not increase after three days. We conclude that A. nitens biocontrol success is due to its ability to find fresh hosts, and to its discrimination ability, even if the female is inexperienced. 2003 Elsevier Inc. All rights reserved.

We studied egg production and the occurrence of adaptive superparasitism in Anaphes nitens , an egg parasitoid of the Eucalyptus snout beetle Gonipterus scutellatus . First, we determined whether A. nitens females were synovigenic or pro-ovigenic. Newly emerged females were allowed to lay eggs alone during 3 days on six fresh egg capsules. A first group of females (n = 25) were killed by freezing and the remaining females (n = 21) were maintained during two extra days with food, but without hosts. Their fecundity was measured by dissection of host eggs and females’ ovarioles. We found that the second group of females increased their fecundity by about 20%, suggesting they were weakly synovigenic. To test for the occurrence of adaptive superparasitism in relation to competitors’ density, we compared the oviposition behaviour of females kept alone, in pairs, or in groups of four during patch visit. Results indicated that the females superparasited significantly more often in this last treatment. Synovigeny and the ability to modulate the use of superparasitism could be mentioned as important attributes that allow A. nitens to efficiently control the pest population.

In March 1994, Gonipterus scutellatus Gyllenhal, an Australian weevil that feeds on foliage of eucalypts, was discovered in Ventura County, CA. By the time of its discovery, the weevil was defoliating eucalypt trees in citrus orchard windrows. We imported, reared, and released a parasitoid of the weevil’s eggs, Anaphes nitens Siscaro (Hymenoptera: Mymaridae). A. nitens was firmly established in several southern California counties by mid-1997 and was spreading in tandem with its host. The wasp has proven to be effective in suppressing weevil populations, killing >95% of weevil eggs, except possibly in areas where insecticides are applied to manage pests of field crops. A. nitens appears to be a promising biological control agent for G. scutellatus in California.

Gonipterus scutellatus is a weevil that has become a pest in most Eucalyptus plantations in Africa, America and Europe. The egg parasitoid Anaphes nitens has been introduced into many countries as a biological control agent. Even if control has been successful in most countries no detailed study of the interactions between both species has been published. 2 Gonipterus scutellatus was detected in 1991 in north-west Spain and A. nitens was introduced in early 1994. Here we report on the results of a 2-year study of parasitism in a field plot and a survey of 16 localities in North-west Spain. In 1996, parasitism was so intense (80-100% of eggs) that G. scutellatus became lo- cally extinct, and as a consequence A. nitens disappeared. In 1997, G. scutellatus recolonized the area and was followed by its parasitoid, but parasitism was low in spring, probably because the parasitoid population needed 3 weeks to achieve a similar size as in 1996. Consequently, damage to the trees was extreme in 1997. We interpret these results as population fluctuations due to parasitoid-host inter- actions and suggest that parasitoids should not to be so effective as to locally ex- tinguish their host to be useful for biological control. 3 The analysis of parasitism level in 16 localities indicates that A. nitens is highly efficient in finding G. scutellatus egg-masses. At a small spatial scale (single trees) positive density dependence was detected where parasitism was low and in- verse density dependence where parasitism was high.

O presente trabalho tem como objectivo a compilação e revisão dos resultados até agora obtidos relativos ao desenvolvimento de modelos matemáticos que permitam descrever a interacção entre a espécie Gonipterus scutellatus e o seu parasitóide Anaphes nitens. Estes modelos, para além de permitirem compreender melhor os mecanismos que regulam a dinâmica populacional de ambos os insectos, poderão ainda ser utilizados na previsão da gravidade dos ataques, possibilitando decidir atempadamente sobre a necessidade de intervenção contra a praga.

Anaphes nitens (Girault), the most important biological control agent of the eucalyptus snout beetle Gonipterus scutellatus, is redescribed, from specimens from South Africa. Two new species of Anaphes Haliday from Tasmania, A. tasmaniae and A. inexpectatus, also from egg pods of G. scutellatus, are described and compared with A. nitens. A key is given to separate these species. Lectotypes are designated for Anaphoidea nitens Girault and its junior synonym A. gonipteri Ferriere.

[EN] We have combined the results of experiments done in the laboratory and in the field to evaluate the toxicity of four insecticides: flufenoxuron, ethofenprox, azadirachtin and Bacillus thuringiensis subsp. kurstaki on the eucalyptus snout-beetle Gonipterus scutellatus and its natural enemy Anaphes nitens. Adults and larvae of G. scutellatus and adults of A. nitens were exposed to treated leaves of Eucalyptus globulus in the laboratory. The weevil egg-capsules were treated topically applying 1 ul droplets of each insecticide on the surface. B. thuringiensis showed no activity against the different stages of the pest, or the adult parasitoids. Azadirachtin acted as a larvicide by ingestión (72.5% of mortality after 7 days). Ethofenprox showed the highest toxicity in all the experimental groups. It determined 100% of mortality of adults and larvae of G. scutellatus after 24 h and 93.1% of mortality rate of the egg-capsules. On the last day of observation, flufenoxuron provoked 92.5% of adult mortality and 100% of larval mortality. In the laboratory, only ethofenprox and flufenoxuron have adversely affected A. nitens (97.5% mortality after 48 h.). The field experiment was done on three localities, with a preliminary sampling, and three samplings after the applications of the products, on the 7th, 14th and 30th day. In each sampling we evaluated parasitism rate and the abundance of adults, larvae and egg-capsules. Only fluenoxuron and ethofenprox reduced the pest population, but ethofenprox also significantly decreased parasitism rate after seven days. Considering the possible development of an integrated pest management plan, we suggest that flufenoxuron is the most appropriate product to be used in association with the natural enemy. [ES] Se han integrado los resultado de experimentos realizados en el laboratorio y en el monte para averiguar la toxicidad de cuatro insecticidas: flufenoxuron, etofenprox, azadiractina y Bacillus thuringiensis var. kurstaki, sobre adultos, larvas y puestas del defoliador del eucalipto Gonipterus scutellatus y sobre los adultos de su agente de control biológico Anaphes nitens. En el laboratorio se midió el efecto mediante la exposición de los sujetos experimentales a hojas de Eucalyptus globulus previamente tratadas y la aplicación tópica de 1 ul de cada insecticida sobre las puestas. Los resultados indican que B. thuringiensis no ha tenido ningún efecto sobre la plaga ni sobre los parasitoides adultos. Azadiractina ha mostrado un efecto larvicida por ingestión y contacto (72.5% de mortalidad después de 7 días). El resultado más contundente lo ha provocado etofenprox, con el 100% de mortalidad de adultos y larvas de G. scutellatus a las 24 horas y el 93.1% de tasa de mortalidad de las puestas. A los 7 días, flufenoxuron ha producido una tasa de mortalidad de los adultos del 92.5% y del 100% de las larvas. En el laboratorio sólo etofenprox y flufenoxuron han incrementado la tasa de mortalidad de A. nitens (en ambos casos 97.5% a las 48 horas). En el monte se han aplicado los cuatro insecticidas en tres localidades, efectuándose un muestreo preliminar antes del tratamiento y al 7.°, 14." y 30.° día. En cada muestreo se evaluó la tasa de parasitismo de las puestas de G. scutellatus y la abundancia de adultos, larvas y puestas. De los cuatro insecticidas sólo flufenoxuron y etofenprox han conseguido contener la población de la plaga, aunque etofenprox ha sido el único que también ha disminuido de manera significativa la tasa de parasitismo de las puestas a los siete días del tratamiento. En vista del desarrollo de un plan de lucha integrada contra G. scutellatus, flufenoxuron parece ser el producto más apropiado. Este estudio ha sido financiado por Agrodan S.A, Agrichem S.A., BASF, ENCE, y Reboreda S.L.

[EN] We have combined the results of experiments done in the laboratory and in the field to evaluate the toxicity of four insecticides: flufenoxuron, ethofenprox, azadirachtin and Bacillus thuringiensis subsp. kurstaki on the eucalyptus snout-beetle Gonipterus scutellatus and its natural enemy Anaphes nitens. Adults and larvae of G. scutellatus and adults of A. nitens were exposed to treated leaves of Eucalyptus globulus in the laboratory. The weevil egg-capsules were treated topically applying 1 ul droplets of each insecticide on the surface. B. thuringiensis showed no activity against the different stages of the pest, or the adult parasitoids. Azadirachtin acted as a larvicide by ingestión (72.5% of mortality after 7 days). Ethofenprox showed the highest toxicity in all the experimental groups. It determined 100% of mortality of adults and larvae of G. scutellatus after 24 h and 93.1% of mortality rate of the egg-capsules. On the last day of observation, flufenoxuron provoked 92.5% of adult mortality and 100% of larval mortality. In the laboratory, only ethofenprox and flufenoxuron have adversely affected A. nitens (97.5% mortality after 48 h.). The field experiment was done on three localities, with a preliminary sampling, and three samplings after the applications of the products, on the 7th, 14th and 30th day. In each sampling we evaluated parasitism rate and the abundance of adults, larvae and egg-capsules. Only fluenoxuron and ethofenprox reduced the pest population, but ethofenprox also significantly decreased parasitism rate after seven days. Considering the possible development of an integrated pest management plan, we suggest that flufenoxuron is the most appropriate product to be used in association with the natural enemy., [ES] Se han integrado los resultado de experimentos realizados en el laboratorio y en el monte para averiguar la toxicidad de cuatro insecticidas: flufenoxuron, etofenprox, azadiractina y Bacillus thuringiensis var. kurstaki, sobre adultos, larvas y puestas del defoliador del eucalipto Gonipterus scutellatus y sobre los adultos de su agente de control biológico Anaphes nitens. En el laboratorio se midió el efecto mediante la exposición de los sujetos experimentales a hojas de Eucalyptus globulus previamente tratadas y la aplicación tópica de 1 ul de cada insecticida sobre las puestas. Los resultados indican que B. thuringiensis no ha tenido ningún efecto sobre la plaga ni sobre los parasitoides adultos. Azadiractina ha mostrado un efecto larvicida por ingestión y contacto (72.5% de mortalidad después de 7 días). El resultado más contundente lo ha provocado etofenprox, con el 100% de mortalidad de adultos y larvas de G. scutellatus a las 24 horas y el 93.1% de tasa de mortalidad de las puestas. A los 7 días, flufenoxuron ha producido una tasa de mortalidad de los adultos del 92.5% y del 100% de las larvas. En el laboratorio sólo etofenprox y flufenoxuron han incrementado la tasa de mortalidad de A. nitens (en ambos casos 97.5% a las 48 horas). En el monte se han aplicado los cuatro insecticidas en tres localidades, efectuándose un muestreo preliminar antes del tratamiento y al 7.°, 14." y 30.° día. En cada muestreo se evaluó la tasa de parasitismo de las puestas de G. scutellatus y la abundancia de adultos, larvas y puestas. De los cuatro insecticidas sólo flufenoxuron y etofenprox han conseguido contener la población de la plaga, aunque etofenprox ha sido el único que también ha disminuido de manera significativa la tasa de parasitismo de las puestas a los siete días del tratamiento. En vista del desarrollo de un plan de lucha integrada contra G. scutellatus, flufenoxuron parece ser el producto más apropiado., Este estudio ha sido financiado por Agrodan S.A, Agrichem S.A., BASF, ENCE, y Reboreda S.L.

Anaphes nitens is a solitary parasitoid of the egg capsules of the Eucalyptus snout beetle, Gonipterus scutellatus. Some traits of its natural history suggest that Local Mate Competition (LMC) could account for sex ratio adjustment in this species. We tested whether males emerged early, a prerequisite for fully local mating, and investigated the occurrence and effect of superparasitism on adult size and pre-emergence mortality, factors that might influence sex ratio adjustment. We found in field-collected egg capsules that males emerged first. To investigate the effects of superparasitism on adult size, we compared the sizes of parasitoids that emerged early and late from egg capsules collected in the field, and from egg capsules parasitized and superparasitized in the laboratory. Superparasitism reduced parasitoid size, affecting females more strongly than males, and increased pre-emergence mortality. We estimated A. nitens sex ratio and parasitism rate in the field during 2 years in five localities and during 4 years in a sixth. Following LMC we expected an increase in sex ratio (proportion of males) with increasing parasitism rate (assumed to reflect parasitoid density). We found that sex ratio decreased from 0.38 when the parasitism rate was low (0-20%) to 0.21 when parasitism was high (80-100%). In contrast with field results, a laboratory experiment showed that: (1) at a low parasitism level sex ratio was clearly female biased (0.28+/-0.04), (2) at a high parasitism level sex ratio increased (0.40+/-0.07), (3) male larval survivorship was not lower than female survivorship, and (4) low-quality hosts (i.e. superparasitized) were allocated more males. We conclude that LMC cannot explain the sex ratio adjustment observed in the field, even at low parasitism rates, and alternative explications for highly female-biased sex ratios must be found. One such alternative is female-biased dispersal.

This work identified semiochemicals that might mediate host selection by the eucalyptus weevil Gonipterus platensis (Coleoptera, Curculionidae) and by its egg parasitoid Anaphes nitens (Hymenoptera, Mymaridae), as well as pheromones emitted by the weevil. Characterization of Eucalyptus globulus and G. platensis volatile organic compounds was conducted using one and two-dimensional gas chromatographic techniques, coupled to different detectors. Antennal active compounds for the weevil and for the parasitoid, were detected by gas chromatography-mass spectrometry/electroantenography. Bioassays were performed in an olfactometer and Petri dish arenas, respectively. For G. platensis, 51 compounds emitted by E. globulus elicited antennal responses, eight of which showed kairomonal activity and two allomonal property. Behavioural responses depended both on sex and physiological condition (mated or virgin) of the insects. Neste trabalho identificaram-se semioquímicos potencialmente utilizados pelo gorgulho do eucalipto, Gonipterus platensis (Coleoptera, Curculionidae) e pelo seu parasitóide oófago, Anaphes nitens (Hymenoptera, Mymaridae), no processo de selecção de hospedeiro, bem como feromonas emitidas pelo gorgulho. As fracções voláteis de Eucalyptus globulus e G. platensis foram caracterizadas utilizando técnicas de cromatografia gasosa uni- e bidimensional abrangente, acopladas a diferentes detectores. Os compostos percepcionados pelas antenas do gorgulho e do seu parasitoide foram detectados por cromatografia gasosa acoplada a espectrometria de massa e electroantenografia. Realizaram-se bioensaios comportamentais num olfactómetro e em arenas. Foi registada resposta das antenas de G. platensis a 51 compostos voláteis emitidos pelo eucalipto, oito dos quais se revelaram atractivos e dois repelentes, dependendo as respostas comportamentais tanto do sexo como do estado fisiológico (virgem ou acasalado) dos gorgulhos.

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia The Australian weevil Gonipterus platensis (Marelli) (Coleoptera: Curculionidae), commonly known as the Eucalyptus snout-beetle, is one of the main pests of eucalypts. Because this is a non-native species, classical biological control with natural enemies from its region of origin should be a viable control strategy. The introduction of the Australian parasitoid Anaphes nitens (Girault) (Hymenoptera: Mymaridae) has been the main method to control the pest worldwide. However, this natural enemy is not completely effective in reducing G. platensis populations and does not avoid the occurrence of damage in several regions. Therefore, it is important to identify effective control alternatives for these areas. In this work, the economic impact of the pest and the benefit of biological control with A. nitens over the last 20 years were assessed, using Portugal as a case study. The results of the economic analysis showed that, without biological control, the losses caused by G. platensis would be at least four times higher than those occurring with partial control by A. nitens. Given the insufficient efficacy of A. nitens, the existence of other natural enemies in Australia that could be used in a classical biological control programme was evaluated. From a set of eight natural enemies identified in Tasmania, the egg parasitoid Anaphes inexpectatus Huber and Prinsloo (Hymenoptera: Mymaridae) was selected for further studies. Laboratory studies comparing the biology of A. inexpectatus and A. nitens at different temperatures, a competition study between these two species, and a risk analysis for the introduction of A. inexpectatus in the Iberian Peninsula were carried out. Overall results suggest that A. inexpectatus might complement parasitism by A. nitens under field conditions without non-target effects on native fauna N/A