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.     

Systemic insecticides reduce feeding, survival, and fecundity of adult black vine weevils (Coleoptera: Curculionidae) on a variety of ornamental nursery crops

Systemic activity of the neonicotinoids clothianidin, dinotefuran, and thiamethoxam and the anthranilic diamide chlorantraniliprole was tested against adult black vine weevils, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), on Astilbe, Euonymus, Heuchera, Rhododendron, Sedum, and Taxus. Insecticide treatments were applied to the soilless substrate of containerized plants. Bioassays were conducted 12 or 13, 26, and 42 d after treatment (DAT) and ran for 7 d; and feeding, mortality, and weight gain or loss by weevils were evaluated. Foliage was removed from test plants and then placed in arenas with adult black vine weevils. The neonicotinoids reduced feeding and weight gain by adult black vine weevils on most plant species with residual activity 42 DAT on some plant species. At 12 DAT, mortality was caused by the three neonicotinoids on Astilbe and by thiamethoxam on Sedum; and at 26 DAT dinotefuran caused mortality on Astilbe. Chlorantraniliprole reduced feeding on Taxus at 12 DAT, with no activity detected in other bioassays. Another set of bioassays was conducted to examine survival and fecundity of adult black vine weevils during prolonged feeding on Heuchera and Taxus systemically treated with dinotefuran or thiamethoxam. Bioassay procedures were similar to those described above, except they ran continuously for 56 d. Prolonged feeding on dinotefuran and thiamethoxam treated Heuchera and Taxus resulted in high mortality of adult black vine weevils and reduced fecundity. These studies show that the systemic activity of neonicotinoids is influenced by plant species and that systemic neonicotinoids have the potential to suppress black vine weevil populations in containerized nursery crops.     

Chemical control of vine weevil larvae on container-grown hardy ornamental nursery stock 1986–1989

In a search for alternatives to the former standard aldrin compost incorporation treatment for control of vine weevil (Otiorhynchus sulcatus) larvae on container-grown hardy ornamental nursery stock, a series of 87 tests of insecticides were done at four experimental centres of the ADAS (Leeds, Reading, Wolverhampton and Wye) from 1986 to 1989. Insecticidally-treated plants and untreated controls were artificially infested with vine weevil eggs at varying intervals before and after treatment, and the survival of the pest was assessed. Aldrin treatment gave consistent and excellent preventive control of vine weevil larvae for over 2 years. Of the candidate materials tested, a slow-release granular formulation of chlorpyrifos incorporated into compost at a dose rate of 100 g a.i. m^-3 of compost gave good control for up to 34 wk after treatment (the longest period evaluated) and a micro-encapsulated slow release formulation of fonofos incorporated at a dose rate of 43.3 g a.i. m^-3 usually gave good control for up to two years (the longest period evaluated). Surface applications of these two organophosphates or of carbofuran granules, though sometimes effective, were unreliable as either preventive or remedial treatments even for short term control.     

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.     

Otiorhynchus sulcatus, an autopolyploid general-purpose genotype species?

The weevil Otiorhynchus sulcatus is a pest species that has spread rapidly to large parts of the world due to human activities. O. sulcatus is extremely polyphagous and found to attack a large number of agricultural and horticultural plant species despite that all individuals are clonal triploid females. I here compare the genetical variation in specimens from various parts of the distribution using both mtDNA and nuclear DNA. The genetical markers employed indicate O. sulcatus to be an evolutionary young clonal species of non-hybrid origin. The extreme polyphagy and ecological success indicate that these weevils may well be a prime example of general purpose genotypes.     

Potential of a Dried Rice/Mycelium Formulation of Entomopathogenic Fungi to Suppress Subterranean Pests in Small Fruits

The potential of a dried rice/mycelium formulation of three species of entomopathogenic fungi ( Metarhizium anisopliae, Beauveria bassiana and Paecilomyces farinosus ) was assessed according to five criteria: storage life, field efficacy against two subterranean pests of cranberry, persistence and efficacy against first-instar black vine weevil larvae in potted strawberry and field persistence in a cranberry bog. The number of conidia sporulated from the formulation did not decline between 4 and 20 days. In small plot field trials, the numbers of black vine weevil, Otiorhynchus sulcatus (F.), were significantly lower in plots treated with 1000 gm - 2 of formulated M. anisopliae than in untreated plots. In similar trials, the numbers of adult cranberry girdler, Chrysoteuchia topiaria (Zeller), inside emergence cages were significantly lower on plots treated with the formulated M. anisopliae than on untreated plots. The formulation suppressed first-instar black vine weevil larvae in potted strawberry regardless of the species of entomopathogenic fungus or the post-inoculation interval. M. anisopliae was periodically isolated for up to 637 days from plots in cranberry bogs treated with the formulation. In general, the dried rice/mycelium formulation may be a useful fungal mycopesticide for the management of subterranean pests of small fruits, especially if applied at high rates to areas of serious pest infestation.     

Behavioural responses of the vine weevil, Otiorhynchus sulcatus, to semiochemicals from conspecifics, Otiorhynchus salicicola, and host plants

The vine weevil Otiorhynchus sulcatus is a parthenogenetic reproducing species which forages for suitable host plants at night, but is found congregated in dark places during the day. Frass of this weevil species is suspected to contain attractive compounds that are host‐plant related. Using a still‐air olfactometer, we tested adult vine weevils at night for their behavioural response to odours from conspecifics, feeding on a mixture of spindle tree (Euonymus fortunei) and yew (Taxus baccata), and to a sexually reproducing related species (Otiorhynchus salicicola), feeding on a mixture of ivy (Hedera helix) and cherry laurel (Prunus laurocerasus). Their attraction to conspecifics and O. salicicola appeared to be related to frass production. Freshly collected frass from O. sulcatus and from O. salicicola males and females was attractive. Prunus laurocerasus and H. helix have not been observed to be hosts of the vine weevil in the field. However, our tests showed that the vine weevil was attracted to mechanically damaged leaves of both plant species, whereas undamaged leaves were not attractive. Only undamaged young unfolding leaves of H. helix were also attractive. The attraction to odours from mechanically damaged host and non‐host plants suggested the involvement of compounds that are commonly found in many plant species. The involvement of plant compounds and/or aggregation pheromones in attraction to frass of the vine weevil and frass of the related weevil species O. salicicola is discussed.     

The bacterial community associated with adult vine weevil (Otiorhynchus sulcatus) in UK populations growing on strawberry is dominated by Candidatus Nardonella

Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), commonly known as black vine weevil or simply vine weevil, is an important pest of soft fruit and ornamental crops. This species is endemic to temperate areas of Europe but has spread to many other areas over the last century, including North America and Australasia. The ability of vine weevils to adapt to such different environments is difficult to reconcile with the parthenogenetic reproduction strategy, which is likely to underpin a low genetic diversity. It is therefore tempting to hypothesize that weevil adaptation to different environments is mediated, at least partly, by the microbial communities inhabiting these insects. As a first step towards testing this hypothesis we characterized the composition of the bacterial microbiota in weevils from populations feeding on strawberry plants across four geographically separate locations in the UK. We performed 16S rRNA gene Illumina amplicon sequencing, generating 2 882 853 high‐quality reads. Ecological indices, namely Chao1 and Shannon, revealed that the populations used for this study harboured a low diversity and an uneven bacterial microbiota. Furthermore, β‐diversity analysis failed to identify a clear association between microbiota composition and location. Notably, a single operational taxonomic unit phylogenetically related to Candidatus Nardonella accounted for 81% of the total sequencing reads for all tested insects. Our results indicate that vine weevil bacterial microbiota resembles that of other insects as it has low diversity and it is dominated by few taxa. A prediction of this observation is that location per se may not be a determinant of the microbiota inhabiting weevil populations. Rather, other or additional selective pressures, such as the plant species used as a food source, ultimately shape the weevil bacterial microbiota. Our results will serve as a reference framework to investigate other or additional hypotheses aimed at elucidating vine weevil adaptation to its environment.     

Olfactory antennal responses of the vine weevil Otiorhynchus sulcatus to plant volatiles

Electroantennograms (EAGs) were recorded from the vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae) to a broad range of volatile plant compounds. The response profile is restricted to a small number of volatiles that evoke substantial EAGs. Large EAG responses were particularly found among green leaf volatiles (GLV) such as (E)-2-hexenol-1, (Z)-3-hexenol-1, hexanol-1, hexanal, and heptanal. Other plant volatiles eliciting responses in the weevils' antenna are 2,5-dimethylpyrazine, hexylamine, benzylalcohol, 1,2-dimethoxybenzene, o-cresol, myrtenol, 3-methylcyclohexanol, -hexalactone, and -heptalactone. EAG responses to terpenes were generally weak. Many of the monoterpenes are characteristic for the odour of conifers, a group of plants which tend to be avoided by adult vine weevils. The EAG response to several GLV and benzene derivatives in three geographically distinct populations of the vine weevil differed, suggesting between-population variation in receptor sensitivities for several compounds under test. The GLV-composition of the odour profile of potential food plants may be an important criterion for a polyphagous insect like the vine weevil to be used in host-plant selection, since compounds in this odour group dominate so strongly the EAG response profile. In multiple food-choice situations the weevils are known to prefer certain plant species and we hypothesize that they combine GLV information with that of more specific plant volatiles, thereby promoting attraction or avoidance.     

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.     

Behavioural and electrophysiological responses of Pantomorus cervinus (Boheman) (Coleoptera: Curculionidae) to host plant volatiles

Abstract  Fuller's rose weevil (FRW; Pantomorus cervinus ) (Coleoptera: Curculionidae), a polyphagous pest of citrus and other horticultural plants, was studied in laboratory assays designed to identify potential semiochemicals from host plants that might be exploited for weevil pest management. Using still-air bioassays, weevils were found to be most attracted to fresh whole lemon leaves compared with cut and/or dried lemon leaves. White clover, an understorey plant in kiwifruit orchards, was also found to be attractive to weevils in the dual-choice tests. Coupled gas chromatography-electrophysiological recording of weevil antennal responses to commercial extracts of lemon leaves indicated that weevils detected at least eight monoterpene components of the oil, i.e. linalool, terpinen-4-ol, nerol, neral, geraniol, geranial, neryl acetate and geranyl acetate. Significant antennal dose–responses were evident to lemon leaf oil, lemon constituent odours and two major green leaf volatiles detected from clover ( Z )-3-hexenol and ( Z )-3-hexenyl acetate. Still-air dual-choice tests on individual chemicals showed significant repellency from seven of the lemon leaf compounds at 500 µg/100 µL (all except geranyl acetate). Weevils were attracted to a synthetic blend consisting of the green leaf volatiles over a range of concentrations (1, 10 and 100 mg/100 µL), as well as to clover leaves. These plant kairomone components may be potentially useful as repellents or attractants for FRW control and management programme.     

Effects and implications of antibiotic treatment on Wolbachia-infected vine weevil (Coleoptera: Curculionidae)

1 The parthenogenetic weevil Otiorhynchus sulcatus was collected from five geographical locations in the U.S.A. All weevils from each location were infected by Wolbachia belonging to supergroup B. 2 We hypothesized that treatment with tetracycline, which has been used to clear Wolbachia infection, would influence the reproduction of Wolbachia‐infected parthenogenetic O. sulcatus females. Tetracycline treatment of preovipositional O. sulcatus females specifically inhibited egg hatching but had no effect relative to controls on any other physiological trait. 3 Treatment with gentamicin, which reportedly has no effect on Wolbachia infection but is indistinguishable from tetracycline in inhibiting protein synthesis of other bacterial genera, did not influence egg hatching. 4 These findings strongly suggest that the inhibition of egg development results from the antibiotic effect on Wolbachia rather than by direct toxic effects on O. sulcatus physiology. 5 We speculate that Wolbachia may be necessary for normal development of O. sulcatus eggs and discuss the implications of these findings for O. sulcatus ecology.     

Impact of azadirachtin on vine weevil (Coleoptera: Curculionidae) reproduction

Abstract 1 The dose–response of azadirachtin on vine weevil, Otiorhynchus sulcatus (Fabricius), reproduction is investigated by confining adults to feed on treated Taxus × media leaves, and by counting and evaluating development in the resulting eggs. 2 A dosage‐dependent reduction in oviposition is discovered for foliar surface residues of azadirachtin, with an EC₅₀ of 25–50 parts per million (p.p.m) and 99.2% inhibition of viable egg production with 100 p.p.m. 3 Switching weevils from treated to untreated foliage allows reproductive capability to be restored for weevils that cease egg laying after azadirachtin exposure of 50 p.p.m. Weevils that had already started laying eggs in untreated groups soon cease oviposition once switched to azadirachtin‐treated foliage. 4 A transovarial effect results in a decrease in the percentage of viable eggs as the azadirachtin concentration increases. 5 The amount of feeding on foliage does not appreciably decrease at these hormonally effective concentrations, and adult weevil mortality is only slightly greater in the azadirachtin‐treated groups. Therefore, the overall effect of azadirachtin on weevil populations in the field is difficult to assess, except by collecting weevils to determine whether they are able to lay viable eggs.     

Susceptibility of strawberry cultivars to the vine weevil Otiorhynchus sulcatus (Coleoptera: Curculionidae)

Abstract 1 The feeding preference of vine weevil, Otiorhynchus sulcatus (Fabricius), adults for foliage from 21 commercial cultivars of strawberries is investigated using binary choice tests with leaf disks, using ‘Honeoye’ as a standard against which all other cultivars are compared. ‘Delmarvel’, ‘Idea’, ‘Lester’, ‘Primetime’ and ‘Seneca’ are not preferred. 2 Variation in leaf nitrogen content is correlated with feeding preference, but does not explain all the variation, because outliers exist for both preferred and nonpreferred cultivars. 3 Removal of leaf hairs with adhesive tape permits their role in deterrence to be evaluated. Eight of the 21 cultivars have deterrent leaf hairs. Paradoxically, some highly preferred cultivars (e.g. ‘Latestar’ and ‘Tristar’) have deterrent leaf hairs, and four of the five nonpreferred cultivars lack significantly deterrent leaf hairs. 4 The 21 tested cultivars do not differ in their suitability for vine weevil larval development. 5 Differences in cultivar susceptibility to vine weevil in the field may involve interactions between the palatability and nutritional value of foliage, which influence fecundity and egg placement, and the tolerance of strawberry plants to larval feeding, determined by root biomass. The nonpreference traits found in the foliage of commercial cultivars of strawberry are present by chance. Accordingly, further selective breeding to enhance strawberry varietal tolerance to vine weevils may be possible.     

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.     

Association of Beauveria bassiana with grapevine plants deters adult black vine weevils,Otiorhynchus sulcatus

Fungal entomopathogens are known as microbial pathogens of insects, colonising multiple habitats and ecosystems. Besides being an entomopathogen, the fungus Beauveria bassiana can also establish as an endophyte in plants. Limited knowledge is so far available on the ability of plant-associated B. bassiana to influence plant-feeding insects. Here, we assessed the capability of adult black vine weevils Otiorhynchus sulcatus to select grapevine as a host plant in the presence of plant-associated B. bassiana after foliar application of a commercially available mycoinsecticide (product Naturalis®) on young potted grapevine plants. Three pairwise comparisons of weevil behaviour were conducted when weevils were released in a two-choice olfactometer and were given the choice between (i) control plants and plants treated with Naturalis®, (ii) control plants and plants treated with the formulation of Naturalis® without fungal propagules, and (iii) plants treated with Naturalis® and plants treated with the formulation. Adult O. sulcatus were significantly deterred by plants treated with Naturalis® or the formulation in comparison to control plants. In a direct comparison between plants treated either with Naturalis® or the formulation weevils significantly preferred plants treated with the formulation and avoided Naturalis® treated plants, where B. bassiana putatively had established as an endophyte. These results suggest that adult black vine weevils are able to detect and subsequently avoid plants treated with B. bassiana and indicate a new mode of action of plant-associated entomopathogenic fungi when integrated in pest management programmes.     

Host plant preference and performance of the vine weevil Otiorhynchus sulcatus

Abstract 1 The relationship between reproductive performance and preference for potential host plants of the vine weevil is investigated, as shown in tests on contact (or feeding) preference, presented herein, and tests on olfactory preference, published elsewhere. 2 Assessment of reproductive performance shows that the host‐plant range of the adult vine weevil Otiorhynchus sulcatus in Europe is limited to one gymnosperm genus (Taxus sp.) and a broad range of angiosperm plants in two subclasses of the Dicotyledonae, namely Dilleniidae and Rosidae. The successful reproduction on very distantly related plant taxa suggests that the original weevil‐ and plant‐habitat has mediated the current host‐plant range of the vine weevil. 3 Contact‐preference tests with equally suitable hosts, such as Aronia, Fragaria, Euonymus and Taxus, and one less suitable host, Humulus, indicate a mismatch between contact preference and performance and, as far as olfactory preferences are known, these match neither the contact preferences nor the performance. This mismatch may arise because (i) host plant species offered do not occur in weevil habitat in Europe (e.g. Aronia and the cultivated Fragaria come from North America) and (ii) predation (or disease) risks differ among host plants, thereby altering effective reproductive performance. 4 With respect to performance on novel hosts (Thuja, Prunus) and bad hosts (Rhododendron), some between‐individual variation is found within a single population, suggesting that local populations harbour (possibly genetic) variation for adaptation to new hosts. How this variation is maintained in the face of strong selection pressures on local populations of flightless and thelytokous weevils, is an important question for understanding the broad host plant range in the vine weevil.     

Evaluation of extended-life pheromone formulations used with and without dichlorvos for boll weevil (Coleoptera: Curculionidae) trapping

Boll weevil traps baited with a ComboLure (25 of mg grandlure + 30 mg of eugenol + 90 of mg dichlorvos [DDVP]), an extended-release lure (25 mg of grandlure + 30 mg of eugenol + 60 of mg DDVP kill-strip), and extended-release lure with no DDVP were evaluated for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captures in South Texas cotton, Gossypium hirsutum L., fields during February-March 2005 and March-April 2006. The traps were serviced once a week for five consecutive weeks by using the same methodology as active boll weevil eradication programs. Mean captured boll weevils from extended-release lures with no DDVP were significantly higher in five of 10 trapping weeks compared with captures of the ComboLure and extended lure. Weekly mortality of boll weevils captured was similar for the ComboLure (72.6 +/- 4.7%) and extended lure + DDVP (73.5 +/- 4.0%), and both were significantly higher than the extended lure (32.8 +/- 5.0%) with no DDVP. The presence or absence of DDVP did not significantly affect the sex ratio of field-captured boll weevils. We found no functional reasoning for using DDVP in large scale trapping of boll weevils regardless of the formulation or presentation in the trap. We conducted two additional trapping evaluations after the 2005 and 2006 studies, but the numbers of boll weevils captured were too low for statistical comparisons, indicating that boll weevil eradication is reducing populations in the Rio Grande Valley of Texas.     

Potential of a Dried Mycelium Formulation of an Indigenous Strain of Metarhizium anisopliae Against Subterranean Pests of Cranberry

We demonstrated that a dried mycelium formulation of an indigenous strain of Metarhizium anisopliae has good potential as an effective biopesticide against the black vine weevil (BVW), Otiorhynchus sulcatus (F.), and the cranberry girdler (CG), Chrysoteuchia topiaria (Zeller). The formulation was produced at moderate sized batches scales (~ 100g product per batch) using inexpensive and easily obtainable equipment (< US$1000). Levels of conidiation were consistent among production batches and storage intervals with the product remaining viable for long time periods at 4&#176;C, in one case for more than a year. Levels of contamination by yeasts and other benign fungi were also consistent. Fewer BVW and CG were found in small plots treated with the dried mycelium formulation than in untreated plots, but differences were not always significant. A waxmoth ( Galleria mellonella ) bait bioassay demonstrated the formulation remained viable in the soil over long time periods (> 7 months). Percentage of M. anisopliae infected waxmoth larvae was significantly affected by rate.     

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.