Sustainable control of black vine weevil larvae,Otiorhynchus sulcatus (Coleoptera: Curculionidae) with Heterorhabditis bacteriophora in strawberry

Efficacy, persistence and recovery of the nematode Heterorhabditis bacteriophora was tested in the laboratory after application of the nematode to strawberry roots by dipping. To mitigate nematode sedimentation and improve attachment to strawberry roots, carboxy-methyl-cellulose was added to the nematode solution. Mortality of black vine weevil Otiorhynchus sulcatus varied between 90 and 96% in the pot trials.     

Field attraction of the vine weevil Otiorhynchus sulcatus to kairomones

Root weevils in the genus Otiorhynchus are cited as one of the most important pests in the major nursery and small fruit production areas throughout the United States, western Canada, and northern Europe. A major problem in combating weevil attack is monitoring and timing of control measures. Because of the night-activity of the adult weevils growers do not observe the emerging weevils in a timely manner and oviposition often starts before effective control measures are taken. Several vine weevil electroantennogram-active plant volatiles were identified from a preferred host plant, Euonymus fortunei. Main compounds evoking antennal responses on the weevils' antennae were (Z)-2-pentenol, (E)-2-hexenol, (Z)-3-hexenol, methyl benzoate, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, methyl eugenol, and (E, E)-alpha-farnesene. Several of these compounds were tested alone and in mixtures on attractiveness for the vine weevil Otiorhynchus sulcatus (F.) in field-grown strawberry in Oregon. O. sulcatus were attracted to (Z)-2-pentenol (approximately 3 x more than control) and a 1:1 ratio mixture of (Z)-2-pentenol and methyl eugenol (4.5 x more than control). This is the first report of field-active attractants for O. sulcatus which holds promise for the development of new monitoring strategies for growers in the near future.     

Olfactory responses of the vine weevil, Otiorhynchus sulcatus, to tree odours

Abstract A Y-tube olfactometer and a still-air olfactometer were developed to determine the attractiveness of several host plants for the vine weevil ( Otiorhynchus sulcatus (F.); Coleoptera: Curculionidae). Odours of weevil-damaged yew ( Taxus baccata ) and spindle trees ( Euonymus fortunei ) are attractive to the vine weevil, but Rhododendron and strawberry ( Fragaria  ×  ananassa ) are not. Undamaged Euonymus is attractive to the weevils in springtime but not in late summer. When clean air or undamaged Euonymus is the alternative, weevils strongly prefer weevil-damaged Euonymus foliage, and this preference is retained throughout the year. Hence, plant damage plays a role in attraction of the vine weevil. In contrast to the permanent attractiveness of weevil-damaged Euonymus , mechanically damaged plants gradually lose the attractiveness that they have early in the growing season. This suggests that emission of volatiles, produced by the plants in response to weevil damage, is important for attraction of the weevils because the weevils may use these plant odours to find suitable food plants throughout the season. Apart from weevil-damage-related plant volatiles, green leaf volatiles must also play a significant role, as indicated by the fact that weevils prefer: early season, undamaged Euonymus over clean air; early season, mechanically damaged Euonymus over undamaged Euonymus ; and, throughout the season, had no preference when mechanically damaged Euonymus is tested against weevil-damaged Euonymus . Thus, monitoring traps may be developed by the use of green leaf volatiles and/or herbivore-induced volatiles, as attractants.     

The entomopathogenic nematode Steinernema kraussei and Metarhizium anisopliae work synergistically in controlling overwintering larvae of the black vine weevil,Otiorhynchus sulcatus,in strawberry growbags

Previously, the combination of reduced rate of entomopathogenic nematodes (EPN) and fungus caused additive or synergistic mortality to third-instar black vine weevil (BVW), Otiorhynchus sulcatus. In this study, we examined this interaction in unheated glasshouses during winter and compared a combination of commercial formulation of a cold-tolerant EPN, S. kraussei (Nemasys L?) and fungus Metarhizium anisopliae strain V275 against overwintering third-instar BVW. The combination of M. anisopliae with S. kraussei at a rate of 1×10¹⁰ conidia+250,000 nematodes/growbag resulted in additive or synergistic effects, providing 100% control of overwintering larvae.     

Persistence of Metarhizium anisopliae incorporated into soilless potting media for control of the black vine weevil, Otiorhynchus sulcatus in container-grown ornamentals

The objective of this study was to determine the persistence of Metarhizium anisopliae (F52), measured as infectivity against black vine weevil larvae, in a soilless potting medium at six wholesale nursery locations across the Willamette Valley, Oregon. A granule formulation (0.30 and 0.60 kg/m(3)) was incorporated into media at planting and fungal persistence determined over two growing seasons. The fungus persisted in the potting media over the duration of the experiment with 50-60% of the larvae exposed to treated media becoming infected at the end of the experiment. The percentage of infected larvae gradually declined from > or = 90% on week 3 to 40-60% by week 19. Larval infection rebounded over the fall and winter months of 2004 to 75-80% followed again by a slow decline over the course of the second growing season.     

Effects of a novel microsporidium on the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae)

A newly discovered microsporidium infecting the black vine weevil, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), provisionally placed in the genus Canningia, was studied to determine its impact on O. sulcatus. O. sulcatus populations from several locations were sampled and evaluated for microsporidiosis. A very low prevalence of the disease was observed in all locations surveyed (<3.0%). Laboratory studies were conducted by orally exposing both larvae and adults of O. sulcatus to varying concentrations of Canningia sp. spores. Larval bioassays at a variety of dosages (0, 10, etc.) were performed to evaluate pathogen infectivity, larval survival and growth. Adult bioassays (dosages: 0, 10, etc.) were performed to evaluate longevity, fecundity and mechanisms of vertical pathogen transmission. Larvae and adults were infected in all spore treatments. Larval growth was significantly reduced at dosages above 10 spores/larva. Adults infected at all dosages experienced high levels of mortality and fecundity was reduced to zero. Greenhouse trials were performed to determine if larvae feeding in soil acquired infections when spores were topically applied as a drench application (0, 10⁵, 10⁶, 10⁷ spores/pot). Established larvae feeding on plant roots in pots developed infections when exposed to drench treatments of 10⁶ and 10⁷ spores/pot after 14-21 days. Canningia sp. is an acute pathogen of O. sulcatus infective to both larvae and adults. Topically applied spores also infected larvae feeding on roots in soilless potting media, suggesting the possibility of using this pathogen in a microbial control program.     

Biological control of the black vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae) with entomopathogenic nematodes (Nematoda: Rhabditida)

Trials conducted under glasshouse conditions showed that control of Otiorhynchus sulcatus larvae in strawberry plants can be effective using Steinernema carpocapsae and Heterorhabditis megidis, given that temperature and moisture extremes are avoided. In field experiments, the double line T-Tape® drip irrigation system performed better than the single line T-Tape® system, effectively distributing the nematodes along and across strawberry raised beds, and placing them close to the root zone where O. sulcatus larvae feed. As soil temperatures are satisfactory for nematode infectivity from late spring to early autumn, nematode applications were aimed at late instar larvae during spring, and early instar larvae during summer. Late summer field treatment with S. carpocapsae induced 49.5% reduction of the early instar larvae, and field application of the same nematode species in late spring resulted in 65% control of late instar larvae. In the same trial, spring application of H. megidis caused 26% mortality of late instar larvae of O. sulcatus.     

A review of the biology and control of the vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae)

At the turn of the century, damage by Otiorhynchus sulcatus was sporadic and limited to small areas. Increasing horticultural intensification and the adoption of husbandry techniques favourable to the weevil, such as the use of polythene mulches, increased its pest status. The development of the early inorganic pesticides reduced the number of serious outbreaks of this pest and weevil control was further improved by the development of the persistent organochlorine insecticides in the 1940's. The banning of a number of the more persistent insecticides over recent years has now left the horticultural industry in a very vulnerable position. O. sulcatus is now a pest on a range of horticultural crops throughout the temperate regions of the world. Infestations are most common in Europe (where it originated) and the USA, and nearly 150 plants species have been identified as potential hosts to O. sulcatus. Damage is most frequently caused by the root feeding larval stage. Populations as low as one larva plant can kill sensitive species such as Cyclamen. Severe damage by the leaf feeding adults is less common, although low levels of damage or contamination by adults may be unacceptable in certain situations. There is one generation a year. Oviposition by the flightless parthenogenetic females occurs over the summer months with oviposition rates of c. 500 and 1200 eggs adult^-1for outdoor and laboratory populations, respectively. O. sulcatus mainly overwinters as larvae, although significant numbers of adults may survive in areas where winter temperatures are not too severe. A number of natural enemies, such as hedgehogs, frogs and predatory beetles, help to maintain O. sulcatus populations at a low level in natural environments, but they are less successful in intensive horticultural systems where persistent chemicals have been heavily relied on to maintain the population below the economic threshold level. Increasing environmental concern is now forcing growers to consider new pest control strategies. Controlled release formulations of non-persistent products, such as fonofos and chlorpyrifos, have shown potential as control agents for O. sulcatus larvae. Biological control agents, such as insect parasitic nematodes, have been developed commercially and new microbial control agents are in the process of development. Most of the new control products are directed towards control of O. sulcatus larvae. Adult vine weevils are nocturnal and a much more difficult target for the new control agents. It is likely that an integrated approach to pest control will be required to maintain O. sulcatus populations below their economic threshold level.     

Influence of the application methods and doses on the susceptibility of black vine weevil larvae Otiorhynchus sulcatus to Metarhizium anisopliae in field-grown strawberries

Entomopathogenic fungi are commercially available for the control of insect pests, including the black vine weevil (BVW) Otiorhynchus sulcatus Fabricius (Coleoptera:Curculionidae). However, Metarhizium anisopliae (Metsch.) Sorokin (Clavicipitaceae) has not been used to control BVW in field-grown strawberries. Field trials were conducted in different locations in the UK during 2009–2010 to evaluate the different formulations (granular vs. drench) and application methods (premixed, drench, bare root treatment) of commercial strain of M. anisopliae Met52^® (=F52), the entomopathogenic nematodes and the organophosphate insecticide Cyren^® against BVW. The highest dose (10¹⁴ cfu ha^?1) tested provided significantly better control than the intermediate (10¹³ cfu ha^?1) or low (10¹² cfu ha^?1) doses. BVW larval control at the high, intermediate and low doses was 71–96, 40–75 and 6–11 %, respectively. Premixing, drench or bare root treatment with Met52^® gave similar levels of BVW control. Irrespective of the application methods or soil types, the high dose rate of Met52^® provided the best control. Significantly high larval control was achieved (78–97 %) when chlorpyrifos was applied at planting than eight weeks post planting (53 %). There were significant differences in BVW control between Met52^® (88 %) and reduced doses of Heterorhabditis bacteriophora Poinar (20–29 %) or Steinernema kraussei Steiner (39–75 %) when applied alone. However, when used together, low dose of S. kraussei and Met52^® provided 100 % control of BVW larvae. This study shows that Met52^® has considerable potential for the control of BVW larvae in commercial field-grown strawberry, thereby offering an environmentally benign alternative to chemical insecticides.     

Influence of fungicides and insecticides on the entomogenous fungus Metarhizium anisopliae a pathogen of the vine weevil,Otiorhynchus sulcatus

In the laboratory, the fungicides chlorothalonil and zineb prevented germination of Metarhizium anisopliae conidia when incorporated into Sabouraud dextrose agar (SDA) at the commercial concentration (based on the manufacturers’ recommended rates for horticultural crops). Twelve other fungicides and six insecticides had no effect on spore germination when applied at the same rate. Mycelial growth of M. anisopliae on SDA plates containing the recommended rate of all the pesticides (except propamocarb) was reduced compared with SDA alone. Two fungicides, benomyl and carbendazim, totally inhibited growth at 0.1 times the recommended rate. Growth was also completely prevented by the fungicides etridiazole, triforine and zineb, and the insecticides dichlorvos and hostathion, at 10 times the recommended rate. In a glasshouse experiment, a prophylactic drench of M. anisopliae conidia reduced vine weevil (Otiorhynchus sulcatus) populations on Impatiens plants by 88%. This level of control was not significantly reduced by subsequent application (7 days after egg infestation) of any of the pesticides at the recommended concentration. Larval control in pots treated with M. anisopliae plus any one of the 12 fungicides and four insecticides examined, ranged from 82% to 98%. The insecticide diazinon applied alone reduced larval numbers by 100%. Two other insecticides, dichlorvos and cypermethrin, and the fungicide pyrazaphos, also reduced weevil populations by over 50%. These experiments demonstrate the limitations of laboratory based in vitro screening programmes for assessing the chemical compatibility of M. anisopliae.     

Investigating preference-performance relationships in aboveground-belowground life cycles: a laboratory and field study with the vine weevil (Otiorhynchus sulcatus)

The preference-performance hypothesis has principally considered insect herbivores with aboveground lifecycles, although the hypothesis could be equally relevant to insects with life stages occurring both aboveground and belowground. Moreover, most studies have focussed on either laboratory or field experiments, with little attempt to relate the two. In this study, the preference-performance hypothesis was examined in an aboveground-belowground context in the laboratory using the vine weevil (Otiorhynchus sulcatus (F.)) (Coleoptera: Curculionidae) and two cultivars of red raspberry (Rubus idaeus), Glen Rosa and Glen Ample. A two-year field study (2008-2009) was also undertaken to characterise the population dynamics of adult weevils on the two raspberry cultivars. Larval performance (abundance and mass) differed significantly between Glen Rosa and Glen Ample, with Glen Rosa resulting in 26% larger but 56% fewer larvae compared to Glen Ample. Larval abundances were significantly and positively correlated with root nitrogen and magnesium concentrations, but negatively correlated with root iron. However, concentrations of these minerals were not significantly different in the two cultivars. Adult weevils did not preferentially select either of the two cultivars for egg laying (laying 3.08 and 2.80 eggs per day on Glen Ample and Glen Rosa, respectively), suggesting that there was no strong preference-performance relationship between adult vine weevils and their belowground offspring. Field populations of adult vine weevils were significantly higher on Glen Ample than Glen Rosa, which may reflect the higher larval survival on Glen Ample observed in laboratory experiments.     

The effect of the CpTi gene in strawberry against attack by vine weevil (Otiorhynchus sulcatus F. Coleoptera: Curculionidae)

The degree of protection against insect feeding conferred upon transgenic strawberry lines expressing the Cowpea trypsin inhibitor was evaluated under glasshouse conditions. Insect bioassays were carried out using vine weevil (Otiorhynchus sulcatus) in two experiments and in both experiments there was a highly significant reduction in damage by weevil larvae on the transgenic lines.     

The influence of temperature on the susceptibility of vine weevil, Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), larvae to Metarhizium anisopliae (Deuteromycotina: Hyphomycetes)

Mortality of Otiorhynchus sulcatus (Fabricius) larvae at 10^oC, 15^oC, 20^oC and 25^oC following treatment with 10⁷conidia ml“¹suspensions of six Metarhizium anisopliae (Metschnikoff) Sorokin isolates was temperature dependent. In all cases, the LT₅₀s were inversely related to temperature, but the nature of this response varied between isolates. Strain 101-82 was the most virulent isolate at 25^oC with an LT₅₀ of 3.7 days, but it was the least virulent isolate at 15^oC and it failed to kill any O. sulcatus larvae at 10^oC. In contrast, strain 159-83 had the lowest virulence at both 20^oC and 25^oC, whereas it was the most virulent isolate at 10^oC with an LT₅₀ of 20.0 days. The mortality rates followed a similar pattern and were positively related to temperature in all cases with the exception of strain 159-83 at 25^oC. Mycosis development was examined on larvae treated with strain 275-86 and significant differences were obtained between all four temperatures. Sporulation commenced after approximately 2.75 days at 25^oC, but took nearly 11 days at 10^oC. The infection rates also varied between temperatures; sporulation occurred on 98% of the treated larvae at 25^oC, but only on 93%, 87% and 49% of the larvae at 20^oC, 15^oC and 10^oC, respectively. The results of these bioassays demonstrate that temperature has a significant effect on the virulence of M. anisopliae. The differences between fungal strains also emphasises the importance of selecting isolates for specific situations on the basis of their temperature profiles.     

Entomopathogenic nematodes to control black vine weevil (Coleoptera: Curculionidae) on strawberry.

We investigated the potential of heterorhabditid nematodes to control larvae of the black vine weevil, Otiorhynchus sulcatus (F.), in 2 field experiments in commercial strawberry plantings. In both experiments, nematodes were applied directly onto the straw mulch, or onto the soil after temporary removal of the mulch. Heterorhabditis marelatus Lui & Berry (Rhabditida: Heterorhabditidae) reduced numbers of weevil larvae and the percentage of plants infested in both experiments, irrespective of straw removal. In the 1st field experiment, a sponge-packed H. marelatus formulation produced lower numbers of O. sulcatus larvae per strawberry plant (mean O. sulcatus larvae per plant = 0.7) and proportion of infested plants (42%) compared with a vermiculite formulation (mean O. sulcatus larvae per plant = 1.8, proportion infested plants 67%) and an untreated control (mean O. sulcatus larvae per plant = 1.9, proportion infested plants 75%). In the first 2 wk after application, more H. marelatus were found in soil samples collected from plots treated with sponge-packed nematodes, than from plots treated with vermiculite-formulated nematodes. In the 2nd field experiment, sponge-packed formulations of H. bacteriophora Poinar (Rhabditida: Heterorhabditidae) and H. marelatus were tested. H. marelatus caused a reduction in both numbers of weevil larvae (mean O. sulcatus larvae per plant = 0.1) and proportion of infested plants (9%) but H. bacteriophora did not (mean O. sulcatus larvae per plant = 0.45, proportion infested plants 34%). More H. bacteriophora were recovered from soil samples than H. marelatus during the first 7 d of this experiment. However, laboratory studies revealed no difference in the persistence of these 2 nematodes in sand.     

Evaluation of application technologies of entomopathogenic nematodes for control of the black vine weevil

Black vine weevil, Otiorhynchus sulcatus (F.), is a severe pest of small fruit and nursery crops around the world. These studies were conducted to determine the efficacy of three species of entomopathogenic nematodes (Heterorhabditis marelatus, Heterorhabditis bacteriophora, and Steinernema riobrave) applied in infected host cadavers or as aqueous applications for black vine weevil larval control. Experiments were conducted in the greenhouse and outdoors. Application of three infected host cadavers or 40 infective juvenile nematodes (IJs) /cm2 were made to pots of Impatiens walleriana 5-7 d after larval infestation. Efficacy was assessed at 14 d in the greenhouse and at 14 and 28 d after nematode application in outdoor trials. In the greenhouse, all treatments with the exception the S. riobrave (cadaver and aqueous applications) provided nearly 100% efficacy after 14 d. The S. riobrave applications, although significantly better than the control, only provided 40-70% control and were not included in the outdoor trials. Nematode efficacy was slowed in the outdoor trials particularly in the cadaver applications. In the initial outdoor trial (soil temperatures < 12 degrees C), there were no significant differences between any nematode treatment and the control after 14 d. The nematode efficacy in the initial outdoor trial after 28 d was improved from the 14-d evaluation but not to the level seen in the second trial. In the second outdoor trial, in which soil temperatures were higher (> 12 degrees C), the aqueous applications of H. marelatus and H. bacteriophora provided nearly complete control after 14 d. The cadaver applications also provided nearly complete control in the second outdoor trial after 28 d. Even though the potential total number of IJs estimated per pot was higher in the cadaver-applied treatments, cool soil temperatures apparently delayed or potentially reduced IJ emergence from cadavers resulting in delayed control.     

Biological control of black vine weevil Otiorhynchus sulcatus in Ireland using Heterorhabditis megidis

Heterorhabditis megidis (UK211) was applied against black vine weevil (BVW, Otiorhynchus sulcatus) in potted plants in a polyethylene (2002) or glasshouse (2003) and in field planted strawberries (2003). Both potted and field strawberries were artificially infested with BVW larvae. In a 2002 pot planting in the polyethylene house, a single drench application of 25,000 H. megidis infective juveniles per plant in 50 ml of water in mid September, reduced the number of BVW larvae to 1.8/20 plants. A second application in early October gave a reduction of 0.2/20 plants and in the third application, the following March no live weevils were recovered, compared to the control which had 8.2 larvae/20 plants. In a 2003 pot planting in a glasshouse, similar treatments gave a reduction of 5.2, 5.4 and 0.8 larvae/20 plants, respectively, compared to the control where 26.2 larvae/20 plants were recovered. In an artificially, BVW infested field trial, similar treatments gave a reduction to 2.2 larvae/20 plants in the single September treatment, and 2 larvae/20 plants in the single October treatment. The double (September and October) application reduced BVW larvae further to 1.6/20 plants and the triple (September, October and April) application to 0.4 larvae/20 plants, compared to the control where four larvae corresponded to every 20 plants. There was, therefore, little difference between the single and double autumn treatments indoors or in the field, and it mattered little whether the single application in the field was made in September or October under the conditions of 2003. Early spring application gave a significant reduction in BVW in each of the three experiments.     

Response of digestive cysteine proteinases from the colorado potato beetle (Leptinotarsa decemlineata) and the black vine weevil (Otiorynchus sulcatus) to a recombinant form of human stefin A

The effects of the cystatins, human stefin A (HSA) and oryzacystatin I (OCI) on digestive cysteine proteinases of the Colorado potato beetle (CPB), Leptinotarsa decemlineata, and the black vine weevil (BVW), Otiorynchus sulcatus, were assessed using complementary inhibition assays, cystatin-affinity chromatography, and recombinant forms of the two inhibitors. For both insects, either HSA and OCI used in excess (10 or 20 μM) caused partial and stable inhibition of total proteolytic (azocaseinase) activity, but unlike for OCI the HSA-mediated inhibitions were significantly increased when the inhibitor was used in large excess (100 μM). As demonstrated by complementary inhibition assays, this two-step inhibition of the insect proteases by HSA was due to the differential inactivation of two distinct cysteine proteinase populations in either insect extracts, the rapidly (strongly) inhibited population corresponding to the OCI-sensitive fraction. After removing the cystatin-sensitive proteinases from CPB and BVW midgut extracts using OCI- (or HSA-) affinity chromatography, the effects of the insect “non-target” proteases on the structural integrity of the two cystatins were assessed. While OCI remained essentially stable, HSA was subjected to hydrolysis without the accumulation of detectable stable intermediates, suggesting the presence of multiple exposed cleavage sites sensitive to the action of the insect proteases on this cystatin. This apparent susceptibility of HSA to proteolytic cleavage may partially explain its low efficiency to inactivate the insect OCI-insensitive cysteine proteinases when not used in large excess. It could also have major implications when planning the use of cystatin-expressing transgenic plants for the control of coleopteran pests. © 1996 Wiley-Liss, Inc.     

Application of Metarhizium anisopliae (Metsch.) Sor. conidia to control Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae) larvae on glasshouse pot plants

The efficacy of the entomogenous fungus Metarhizium anisopliae was assessed against vine weevil (Otiorhynchus sulcatus) larvae in the glasshouse. Prophylactic application of M. anisopliae conidia to begonia resulted in total larval control, but curative applications were less effective with only 65% control when conidial application was delayed until 8 weeks after egg infestation. Prophylactic applications also provided effective larval control on begonia plants which received multiple egg applications over a six week period. Larval mortality was monitored on cyclamen plants which had received a prophylactic drench of M. anisopliae conidia. The population was reduced by 78% within 5 weeks of egg application and control rose to 90% after 17 weeks, although the increase was not significant. Prophylactic conidial drenches were compared with a similar number of compost incorporated conidia on cyclamen, but there was no significant difference between the two spore application strategies. Application of M. anisopliae conidia to impatiens modules before potting-on resulted in over 89% larval control compared to over 97% control when a similar number of conidia were applied to the plants after potting. Larval control was further reduced to 79% when the module drenches were reduced to one quarter of the highest dose (5 × 10⁷ compared to 2 × 10⁸ conidia per module). The persistence of three M. anisopliae strains was examined over a 20 week period on impatiens. There was no overall decline in efficacy over this period, although there was variability in the performance of the different strains and it was suggested that this was linked to temperature. The results of these experiments suggest that M. anisopliae has considerable potential as a microbial control agent for O. sulcatus on glasshouse ornamentals.     

Contribution to the knowledge of the weevil genus Otiorhynchus (Coleoptera, Curculionidae) from northeastern Turkey and Transcaucasia

Otiorhynchus (Podonebistus) korotyaevi sp. n., (Proremus) karsavurani sp. n., and O. (Proremus) temeli sp. n. from northeastern Turkey are described. O. kirschi is transferred from the genus Simo (= Homorhythmus) to the genus Otiorhynchus (subgenus Proremus); O. madari, from the genus Cirrorhynchus to the genus Otiorhynchus (subgenus Motilacanus); and O. kataevi, from the subgenus Nilepolemis to the subgenus Otismotilus. New data on the morphology and distribution of O. cataphractus, O. latinasus, O. terrifer, O. pipitzi, O. angustifrons, O. jarpachlinus, and O. sculptirostris are given. Lectotypes of O. lederi, O. erivanensis, O. diotus, O. terrifer, O. kirschi, and O. madari are designated.     

Susceptibility of the Carrot Weevil (Coleoptera: Curculionidae) to Steinernema feltiae,S. bibionis,and Heterorhabditis heliothidis

Larvae, pupae, and adults of the carrot weevil (Listronotus oregonensis) were infected and killed by the three entomophagous nematodes (Steinernema feltiae, S. bibionis, and Heterorhabditis heliothidis) under controlled conditions. Third-stage larvae were more susceptible than pupae or adults. S. feltiae and S. bibionis were the most aggressive nematode species, causing larval mortality after 24-48 hours in both continuous and 2-hour contact with nematode suspension. The nematodes multiplied sufficiently in all insects at all stages of development; however, production of infective-stage larvae per host cadaver was variable.