Host range ofPachycerus cordiger (=P. Scabrosus) (Col.: Curculionidae)

The univoltine weevilPachycerus cordiger Germar (=P. scabrosus Brullé) completes its life cycle on species of Boraginaceae, it is found from western Europe to the Middle East. In southern France, adultP. cordiger were collected feeding on the leaves ofHeliotropium europaeum L.,Echium vulgare L. andCynoglossum creticum Miller, whereas larvae were found feeding externally on the roots of the three plant species from within an earthen cell. BecauseP. cordiger is considered too much of a generalist to be released in Australia, work on the weevil as a potential biological control agent ofH. europaeum has been stopped.     

Laboratory rearing ofAnaphes sordidatus [Hym.: Mymaridae] on carrot weevil eggs [Col.: Curculionidae]

A technique for rearingAnaphes sordidatus (Girault) on eggs of laboratory-reared carrot weevil,Listronotus oregonensis (Le Conte), is described. Individual rearing was possible by using polyethylene embedding capsules that enabled easy manipulation of parasitized carrot weevil eggs for use in subsequent experimental procedures. The technique described resulted in 65% parasitization of carrot weevil eggs and 90 mn per day were sufficient to obtainca. 200 parasites daily.      

Life cycle and host specificity of Amblyomma triste (Acari: Ixodidae) under laboratory conditions

We report biological data of two generations of Amblyomma triste in laboratory and compared the suitability of different host species. Infestations by larval and nymphal stages were performed on guinea pigs (Cavia porcellus), chickens (Gallus gallus), rats (Rattus norvegicus), rabbits (Oryctolagus cuniculus), wild mice (Calomys callosus), dogs (Canis familiaris) and capybaras (Hydrochaeris hydrochaeris). Infestations by adult ticks were performed on dogs, capybaras and rabbits. Tick developmental periods were observed in an incubator at 27 °C and RH 90%. Guinea pigs were the most suitable hosts for larvae and nymphs, followed by chickens. The remaining host species were less suitable for immature ticks as fewer engorged ticks were recovered from them. Mean larval feeding periods varied from 3.8 to 4.7 d between different host species. Mean larval premolt periods ranged from 8.9 to 10.4 d. Nymphal mean feeding periods varied from 4.2 to 6.2 d for ticks fed on different host species. Premolt period of male nymphs (mean: 15.4 d) was significantly longer than that of female nymphs (14.7 d). Female nymphs were significantly heavier than male nymphs. The overall sex ratio of the adult ticks emerged from nymphs was 0.9:1 (M:F). Capybaras were the most suitable host for the tick adult stage as significantly more engorged females were recovered from them and these females were significantly heavier than those recovered from dogs or rabbits. The life cycle of A. triste in laboratory could be completed in an average period of 155 d. The potential role of guinea pigs, birds and capybaras, as hosts for A. triste in nature, is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

The biology and host specificity of the stem-boring weevilListronotus setosipennis [Col.: Curculionidae] A potential biocontrol agent forParthenium hysterophorus [Asteraceae]

The stem-boring weevilListronotus setosipennis (Hustache) is widespread and damaging to its hostParthenium hysterophorus L. in northern Argentina and southern Brazil. In detailed host-testing it was shown to have a restricted host-range and, despite some feeding and development on sunflower in tests, to be a safe biological control agent againstP. hysterophorus. Field releases in Queensland, Australia took place from 1982 to 1986 and the weevil has established over several thousand hectares at numerous sites. Spread is however slow and the effect on the plant still negligible.      

Life history of the Onopordum capitulum weevil Larinus latus (Coleoptera: Curculionidae)

The population structure and stage-specific survival of the capitulum weevil, Larinus latus, a potential control agent for weedy Onopordum thistles in Australia, was studied in its native range in Greece. Although fecundity of this univoltine insect was low (35.4 eggs/female), survival was relatively high, with 45% of eggs reaching adulthood when protected from predators and parasitoids, and 23% surviving when exposed to these natural enemies. Other mortality factors of importance for immature stages were a failure to establish, due largely to oviposition by females on inappropriate sites on the thistle capitula, and inter- and intraspecific competition for larval resources. Once emerged, adult losses due to overwintering mortality and net migration were estimated at a further 48%. Despite these losses there was a net doubling of the population at the study site between Onopordum flowering seasons. The data suggest that movement of adults occurs both within and between patches and that variability in population size relative to the resource base is low. Overall, L. latus may be considered a K-strategist which forms relatively stable populations over a fragmented habitat and which maintains its population integrity through a certain degree of annual redistribution. The implications of these data for the potential effectiveness of L. latus as a biological control agent of weedy Onopordum spp. are discussed.     

Competition betweenBracon mellitor [Hym.: Braconidae] andCatolaccus grandis [Hym.: Pteromalidae] for their hostAnthonomus grandis [Col.: Curculionidae]

BioControl - Laboratory studies of competition between populations of 2 parasitoids of the cotton boll weevil,Anthonomus grandis Boheman, showed that populations ofCatolaccus grandis (Burks)...     

Life cycle and abundance oflongitarsus jacobaeae [Col.: Chrysomelidae], biocontrol agent ofSenecio jacobaea

The life cycle and abundance of the tansy ragwort flea beetle,Longitarsus jacobaeae (Waterhouse), were investigated in a dune area in the Netherlands. The beetle overwinters in the egg stage, which is parasitised by a Mymarid wasp. No larvae were found until spring. Three larval instars can be separated by head capsule size and coloration. Initial larval numbers are high (up to 214 larvae per plant), but drop to very low levels by late spring. Adults appear during June or July, the numbers are high until October, the adults can be found until the end of December. This life cycle differs remarkably from those described for the species in Switzerland, Italy and Britain. Possible causes for these differences are discussed, as well as implications for the use ofLongitarsus in biological control.      

Zur Wirksamkeit vonBeauveria bassiana (Bals.) Vuill. gegenHylobius abietis L. [Col.: Curculionidae]

Zusammenfassung Um die Wirksamkeit einesBeauveria bassiana-Pr?parates gegenHylobius abietis zu überprüfen, wurden die Versuchstiere mit Sporenstaub und Sporensuspension behandelt und bei 13°, 23° und 33°C (bei Futterangebot bzw. Hunger) gehalten. 33°C erwies sich in allen Versuchen für die K?fer als zu hoch (100% Mortalit?t nach 2 Wochen) bei gleichzeitiger Reduktion von Pilzsporenkeimung und Hyphenwachstum. Bei 23 °C wurden dagegen bei mittlerer Lebensdauer (bei Sporenstaub 8,2 Tage und bei Sporensuspension 21,5 Tage) h?chste Infektionsraten erzielt (86,9 bzw. 100 %). Obwohl die kontaminierten K?fer bei 13 °C am langsamsten starben (ohne Futter: nach Sporenstaub 12,9 und 18,9 Tage nach Sporensuspension, mit Futter: 72,3 bzw. 86,6 Tage mittlere Lebensdauer) erkrankte auch hier ein sehr hoher Prozentsatz (55 % nach Sporenstaub, mit Futter und 91,4 % nach Sporensuspension, ohne Futter). Die Verwendung von verdünnten Sporenst?uben brachte eine deutliche Abstufung der Mortalit?tsgeschwindigkeit in Abh?ngigkeit von der applizierten Sporenmenge. Sporendosen unter 3×10⁴ Konidien/K?fer erwiesen sich auch nach 8 Wochen als wenig wirksam, solche von etwa 4×10⁷ Konidien/K?fer dagegen erzielten schon nach 2 Wochen h?chste Sterberaten bei gleichzeitig 100 % Infektion mitb. bassiana. Mit Sporenstaub kontaminiertes Futter (1,17×10⁸ Konidien/cm² Rinde) führte bei niedrigen Infektionsraten etwa gleich schnell zu 100 % Mortalit?t wie direkte Kontamination der K?fer. Das Angebot st?rker kontaminierten Futters (5,83×10⁸ Konidien/cm² Rinde) über nur 3 Tage führte trotz anschlie?ender Versorgung mit unbehandeltem Frischfutter, bei langsamer Sterblichkeit zu einer 100 prozentigen Infektion der Versuchstiere. Fangrinden die in einem Freilandexperiment mitB. bassiana behandelt worden waren, zeigten eine ungeminderte Lockwirkung, bewirkten jedoch nur geringe, unmittelbare Sterblichkeit. Die hohenB. bassiana-Infektionsraten in den Laborexperimenten k?nnten bei einer praktischen Anwendung unter günstigen Bedingungen auch im Freiland langfristig zu Erfolgen führen.      

Predation of eggs ofSitona hispidulus [Col.: Curculionidae] in alfalfa

The predation on egg populations ofSitona hispidus (Fabricius) [Col.: Curculionidae] in a stand of alfalfa was evaluated in 1982 and 1983. By using pitfall traps, catches of reproductive adults ofS. hispidulus were correlated with catches of carabid species, and potential egg predators were identified for further evaluation. Results indicated that predators removed 28 % of eggs under field conditions.Amara aenea DeGeer was found to be particularly efficient on eggs ofS. hispidulus under caged-field conditions.      

Investigations on the parasitism ofOtiorrhynchus salicicola andO. Sulcatus [Col.: Curculionidae] byHeterorhabditis sp. [Nematoda]

Experiments were conducted to study the efficacy of the insect parasitic nematodeHeterorhabditis sp. (HW79) as a biological control agent ofOtiorrhynchus salicicola. This weevil species is reported as a pest of ornamental plants in Switzerland and Italy. Dipping plastic boxes containing heavily infested cuttings of laurel (Prunus laurocerasus) in a nematode suspension resulted in approximately 100% parasitisation of full-grown larvae, pupae and non-emerged young adults. The average dose resulting from dipping varied between 56,000 and 62,000 nematodes per liter soil. This experiment was run under natural outdoor conditions. In a further outdoor experiment, pottedLigustrum plants were inoculated with eggs ofO. salicicola and later 20,000 infective juvenile nematodes per liter soil were added to the soil surface. The resulting weevil mortality in the treated pots was 78%. In seven greenhouse tests using the same nematode dose in pots with horticultural soil to which weevil larvae had been added, weevil mortality varied between 76% and 100%, the arithmetic average being 90%. These results indicate that Heterorhabditid nematodes may provide an effective means of controllingO. salicicola. In an other experiment usingO. sulcatus larvae, the influence of application time on nematode efficacy was investigated. When nematodes were added a few days before weevil larvae had hatched from the eggs, no parasitic effect was obtained. Nematode applications done shortly after larval hatching however, resulted in complete weevil control. These results are of significance in timing nematode applications in practice.      

Insects associated with the Sitka spruce weevil,Pissodes Strobi [Col.: Curculionidae] on Sitka spruce,Picea sitchensis in British Columbia,Canada

BioControl - Insects associated with the Sitka spruce weevil,Pissodes strobi (Peck), on Sitka spruce,Picea sitchensis (Bong.) Carr. were sampled at 9 locations in British Columbia. Fourteen species...     

Host-specificity of fiveAnacassis species [Col.: Chrysomelidae] introduced into australia for the biological control ofBaccharis halimifolia [Compositae]

Foliage-feeding beetles of the genusAnacassis [A. phaeopoda Buzzi,A. fuscata (Klug),A. fuscata var.unicolor (Burmeister),A. cribrum (Klug) andA. dubia (Boheman)] were collected fromBaccharis spp. andBaccharidastrum spp. in South America. Specificity studies showed that they were restricted to these 2 host genera. Between 1974 and 1976 these species were introduced into Australia for the control ofBaccharis halimifolia. A. phaeopoda andA. fuscata were first released in 1976. One field colony ofA. fuscata persisted for up to 3 years but no recoveries ofA. phaeopoda were made after the 1st field generation. The other species died out in quarantine and were not released.      

Host-specificity and biology ofMetallactus patagonicus [Col.: Chrysomelidae] introduced into Australia for the biological control ofBaccharis halimifolia [Compositae]

Biology and host-specificity of the foliage-feeding chrysomelidMetallactus patagonicus Suffrian were studied in Brazil to determine its suitability for introduction into Australia to control the shrubBaccharis halimifolia L. Multiple-choice host preference testing of plants related toBaccharis and of desirable plants from a range of plant families, showed thatM. patagonicus was restricted toBaccharis spp. It was released in Australia in 1975, but did not establish.      

Host specificity and biology of the weevilNeohydronomus affinis [Coleoptera: Curculionidae] a biological control agent ofPistia stratiotes

Waterlettuce,Pistia stratiotes L., has been successfully controlled in Australia with the weevil,Neohydronomus affinis Hustache. In this study, the weevil was tested in quarantine against 34 plant species in 27 families. In non-replicated no-choice tests, it fed and oviposited on 3 species of duckweeds [(Lemna minor L.,Spirodela punctata (Meyer) Thomps.,S. polyrhiza (L.) Schleid.], frogbit [(Limnobium spongia (Bosc.) Steud.], mosquitofern (Azolla caroliniana Willd) and waterfern (Salvinia mimima Baker). Feeding also occurred on golden club (Orontium aquaticum L.) and one egg was laid on the terrestrial panda plant (Kalanchoe tomentosa Baker). Plants oviposited and fed upon were retested in choice tests. The weevils then fed and oviposited exclusively on waterlettuce. Various aspects of weevil biology, including larval feeding and mining, plant response to weevil attack, and adult behavior are discussed. Florida Agric. Expt. J. series No 8580.     

Biological control of water lettuce,Pistia stratiotes [Araceae] byNeohydronomus affinis [Coleoptera: Curculionidae]

Neohydronomus affinis was imported into Australia as a potential biological control agent for the floating aquatic weedPistia stratiotes. Quarantine studies demonstrated that this weevil was host specific toP. stratiotes and it was released into the field in 1982. Subsequently it was released as a control agent for this weed in several other countries. In AustraliaN. affinis reduced infestations ofP. stratiotes by 40% or more within 12–18 months. The results are discussed in relation to its effectiveness in other parts of the world. We concluded thatN. affinis effectively controlsP. stratiotes in tropical regions (to lat. 22°), but in cooler regions its effectiveness fluctuates with seasonal conditions.      

Occurrence and pathogenicity ofBeauveria bassiana infesting larvalSitona discoideus [Col.: Curculionidae] in the Mediterranean region

Field survey showed that the fungusBeauveria bassiana Vuillemin was the predominant natural enemy ofSitona discoideus Gyllenhal larvae and pupae in the Mediterranean region. The present area of distribution of the disease does not, however, include the parts of North Africa, Cyprus, Syria and Iraq with a Mediterranean climate. At localities regularly investigated in southern France over the period 1973–79, the population dynamics of larvalSitona on volunteerMedicato species appeared to be correlated to some extent with the impact of the fungal disese, which could produce up to 100% mortality on its host larval populations. Several isolates of the pathogen were tested in laboratory bioassays to determine their potential activity. One accession from southern France proved particularly virulent toS. discoideus larvae and pupae at the relatively low concentration of 10⁵ conidia/g of soil. This accession seemed worth considering for further quarantine testing and introduction into Australia. Differences between isolates were however confounded by varying ages of the cultures involved.

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Résumé Les recherches entreprises de 1973 à 1984 ont montré que le champignon entomophatogèneBeauveria bassiana Vuillemin était largement répandu sur larves deSitona spp. en rǵeion méditerranéenne. Il y fait toutefois défaut (tableau 2) dans les zones pastorales d'Afrique du Nord, de Chypre, de Syrie et d'Irak. La mortalité larvaire due à cette mycose parait en mesure d'influencer l'évolution dynamique des populations deSitona discoideus Gyllenhal (tableau 3). En effet,B. bassiana est susceptible d'affecteur jusqu'à 100% des larves deS. discoiduus s'attaquant aux dieverses espèces deMedicago, suivant les sites considérés en France méditerranéenne. Lors de tests en laboratoire une souche méridionale deB. bassiana s'est révélée paritculièrement infectieuse à des doses relativement faibles, de l'ordre de 10⁵ conidies par gramme de terre (tableau 4). Une telle virulence perment d'envisager d'éventuelles applications de plein champ contreS. discoideus en Australie méridionale. Une expérimentation plus détaillée est`a prévoir, qui devra cependant tenir compte d'un affaiblissement graduel du pouvoir infectieux des isolats au cours de leur conservation en mycothéque.

     

Observations on the biology and host specificity ofEpiblema strenuana [Lepidoptera,Tortricidae], a potential biocontrol agent forParthenium hysterophorus [Compositae]

The tortricid mothEpiblema strenuana (Walker), which attacksAmbrosia spp. over most of North America, is shown to have the annual weedParthenium hysterophorus L. [Compositae] as its main host in northern Mexico. The larvae produce galls in the stems and growing-points which can considerably stunt growth when young plants are attacked. In tests it was shown to have a restricted host-range and not to damage any composite of economic importance. Its release in Australia for trial as a biological control agent againstP. hysterophorus has been approved.      

The introduction and recovery in the United States ofAnaphes diana [Hym.: Mymaridae], an egg parasite ofSitona weevils [Col.: Curculionidae]

Anaphes diana (Girault) (=Patasson lameerei Debauche), a mymarid egg parasite ofSitona spp., was introduced from Europe beginning in 1976 and is now tentatively established in the United States. Techniques are described for the separation of eggs ofSitona spp. from soil, using a series of fine-mesh sieves, water, and a saturated salt solution. Data from 9 years of sampling in an alfalfa field at Newark, Del. (>19,300 host eggs extracted), showed that the mean peak density of viable overwintering eggs ofSitona hispidulus (F.) was 14.6 per 100 cm³ of 1 cm deep surface soil. At the study site,Sitona egg densities consistently increased during the fall as a result of oviposition, peaked during January and February and decreased during the spring as a result of egg hatch. Although the incidence of parasitism byA. diana remained surprisingly low (0.29%), the fact that the species was recovered during 3 years and up to 7 years after the last release, indicates that it has colonized at the Delaware release site.      

Evaluation ofHadena perplexa [Lepidoptera: Phalaenidae] as a biocontrol agent of bladder campionSilene vulgaris [Caryophyllaceae] in Canada: Rearing and host specificity

Rearing techniques and results of preliminary host range tests are reported forHadena perplexa (Denis & Schiffermuller) (Lep.: Phalaenidae) a candidate biocontrol agent against the weed bladder campion,Silene vulgaris (Moench) Garcke, in Manitoba, Canada. In the laboratory, it was necessary to pipette a 15% honey solution in water into the flowers as food for the adult moths. When reared singly to avoid cannibalism, 56% of the 1^st instar larvae developed to pupae. Larvae fed on a natural diet for 10 days can then be reared on either one of 2 artificial diets. Choice oviposition tests and no-choice larval feeding tests were conducted with plant species closely related toS. vulgaris in the generaSilene, Dianthus, Gypsophila, Lychnis, Saponaria. Species in 4 of 5 of these genera were accepted for oviposition, and species in all 5 genera supported the development of 1^st instar larvae to the pupal stage.H. perplexa should not be introduced into Canada.      

Observations on the heliotrope flea beetle,Longitarsus albineus [Col.:Chrysomelidae] with tests of its host specificity

Longitarsus albineus (Foudras) is a potential agent for the biological control ofHeliotropium europaeum L. in Australia. The adults feed on the leaves and the larvae on the rootlets of the weed. Large populations of the beetle reduce plant vigour but rarely cause death of well established plants in the Mediterranean region. There are 3 beetle generations per year in southern France. Third generation adults overwinter and, at the first appearance of the weed in spring, start to feed and reproduce. Feeding trials of adults and larvae against a range of economically important plants and severalBoraginaceae demonstrated specificity to the genusHeliotropium.

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Résumé Longitarsus albineus Foudras est un auxiliaire possible de lutte biologique contre l'adventiceHeliotropium europaeum Linnaeus en Australie. Les adultes se nourrissent des feuilles et les larves des radicelles d'héliotrope. Par forte infestation, le longitarse affecte la vigueur de la mauvaise herbe, dont il détermine rarement le dépérissement en région méditerranéenne. Le longitarse a 3 générations annuelles dans le midi de la France. Les adultes de la 3^e génération hivernent, s'attaquant aux premières pousses d'héliotrope et se reproduisant dès le printemps. Des essais d'alimentation portant sur une série de plantes cultivées et plusieurs boraginées ont montré que larves et adultes sont spécifiques au genreHeliotropium.