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.     

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.     

Plants protect their roots by alerting the enemies of grubs

Plant roots in the soil are under attack from many soil organisms. Although many ecologists are aware of the presence and importance of natural enemies in the soil that protect the plants from herbivores, the existence and nature of tritrophic interactions are poorly understood. So far, attention has focused on how plants protect their above-ground parts against herbivorous arthropods, either directly or indirectly (i.e. by getting help from the herbivore's enemies). This article is the first in showing that indirect plant defences also operate underground. We show that the roots of a coniferous plant ( Thuja occidentalis ) release chemicals upon attack by weevil larvae ( Otiorhynchus sulcatus ) and that these chemicals thereby attract parasitic nematodes ( Heterorhabditis megidis ).     

广东省新发现一种危害水稻的入侵性瘿螨

最近两年一种新的入侵性瘿螨在中国广东省韶关市危害水稻。这种螨曾经在泰国北部被报道过,推测后来传入中国,目前在韶关严重危害水稻。这种螨被鉴定为具沟掌瘿螨Cheiracus sulcatus Keifer,并进行了重新描述和绘图,对危害症状进行了拍照和描述。文章还分析了其扩散风险性,并提出了控制传播的建议。     

Control of Black Vine Weevil larvae Otiorhynchus sulcatus (Fabricius) (Coleoptera:Curculionidae) in grow bags outdoors with nematodes

Abstract 1 Outdoor trials were carried out during 2001–02 on strawberries grown in commercial growing bags naturally infested with black vine weevil larvae (BVW) Otiorhynchus sulcatus in Co. Wexford, Ireland. 2 The two nematode isolates used in these trials were Heterorhabditis megidis (UK211) and Heterorhabditis downesi (K122), both laboratory cultured. Growing bags received nematodes either once (May 2001), twice (May and October 2001) or three times (May, October 2001 and May 2002). Ten days after each application date, nine blocks (of the total 27) were randomly selected, destructively assessed and discarded. 3 The single application (May 2001) resulted in a mortality of black vine weevil larvae, of 93.4% with H. megidis and 51.3% with H. downesi, compared with the control treatment at that date. Respective figures after the double application (May 2001 and October 2001) were 78.9 and 77.6% and after the triple application (May 2001, October 2001 and May 2002) the figures were 93.7 and 88.1%. 4 Results from these trials clearly indicate that entomopathogenic nematodes are good alternatives to chemical control of the black vine weevil on strawberries grown in growing bags in Ireland.     

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.     

Protected raspberry production accelerates onset of oviposition by vine weevils (Otiorhynchus sulcatus)

• 1 Soft fruit production is increasingly reliant on crops that are grown under the protection of plastic tunnels, which may also affect insect communities as a result of localized climate change and changes to host plant physiology and chemistry. In particular, insect development rates may differ from field populations, making it more difficult to target control measures.
• 2 The present study investigated how protected environments affected adult vine weevil (Otiorhynchus sulcatus) feeding and reproduction on red raspberry (Rubus idaeus). We focused on the period between adult emergence and the onset of oviposition (i.e. the pre‐reproductive period), which represents the optimal period for control.
• 3 Tunnels were up to 4 °C warmer than field plantations in 2008, with plants growing significantly faster (50% increase in height and 16% increase in leaf area) than field grown plants. The carbon/nitrogen ratio in leaves was higher in tunnels (12.07) than the field (10.89) as a result of a significant decrease in nitrogen concentrations (3.40 and 3.90 mg g^?1, respectively).
• 4 Over 4 weeks, weevils consumed significantly more foliage in tunnels (370.89 mg) than weevils in the field (166.68 mg), suggesting compensatory feeding to counteract lower leaf nitrogen concentrations. Weevils in tunnels achieved sexual maturity 8 days earlier than those in the field and produced 20‐fold more eggs by the time they were 5 weeks old.
• 5 Applying a degree‐day model showed good agreement between predicted and observed pre‐reproductive periods for weevils in tunnels (36 and 30 days, respectively) and in field plots (41 and 38 days, respectively).

     

Control of Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae) Larvae on a Range of Hardy Ornamental Nursery Stock Species Using the Entomogenous Fungus Metarhizium anisopliae

The potential of the entomogenous fungus Metarhizium anisopliae as a microbial control agent for vine weevil (Otiorhynchus sulcatus) larvae was examined on a range of outdoor hardy nursery stock species. A curative application of M. anisopliae conidia (5× 10⁸ conidia l^‐1compost) reduced larval numbers by 62% on Skimmia japonica ’Rubella’ and by up to 43% on Viburnum plicatum ’Mariesii’. Four M. anisopliae isolates were examined and all reduced the larval populations on both species. However, the reductions were only significant with strains 159–83 and 100–82 on S. japonica ’Rubella’ and 100–82 on V. plicatum ’Mariesii’. Larval development on two other species (Hydrangea macrophylla ’Blue Wave’ and Thuja plicata ’Zebrina') which had been treated with 0.05% Triton X‐100 (the control treatment) was very poor and therefore it was not possible to determine whether or not the fungal drench had any effect. The experiment was repeated in the following year at two different sites, East Mailing and Littlehampton, using a prophylactic drench of two M. anisopliae isolates on a greater number of plant species. Strain 275–86 was more effective than 159–83 on all species at East Mailing, with the exception of V. davidii. The difference was less pronounced at Littlehampton and the results from the two isolates were similar. Larval control was highly variable and species dependent with a reduction in larval numbers ranging from zero to 96% and zero to 90% at East Mailing and Littlehampton respectively. The larval populations in pots treated with Triton X‐100 were also highly variable, ranging from zero (Chaemaecyparis lawsoniana ’Stardust’ Dianthus ’Maria’ Escallonia ’Crimson Spire’ and Pittosporum tenuifolium ’Gamettii') to 17.8 larvae per pot (Ribes nigrum ’Baldwin ‘). The results indicate the potential of M. anisopliae and demonstrate the complexity of plant‐weevil‐fungus interactions.