Management of strawberry blossom weevil and European tarnished plant bug in organic strawberry and raspberry using semiochemical traps

The strawberry blossom weevil (Anthonomus rubi) and the European tarnished plant bug (Lygus rugulipennis) cause large (10 - >80%) losses in yield and quality in organically grown berries. A consortium with 6 European countries has been created to work on the management of those pests. The pheromones of A. rubi and L. rugulipennis have been characterized in England by NRI/EMR. For the attraction of A. rubi the importance of host plant volatiles in combination with the pheromones has also been documented. The natural semiochemical mechanisms of sexual attraction and host plant finding of A. rubi and L. rugulipennis will be further studied and exploited to develop effective semiochemical traps for their management through mass trapping. Attractive lures for these two species will then be combined into a single multitrap with the aim of managing two pests simultaneously in each crop. This will be one of the first approaches to pest management of non-lepidopteran insect pests of horticultural crops using semiochemicals in the EU, and probably the first to target multiple species from different insect orders. The project will be organized in the following work packages; 1) Chemical analysis of plant volatiles, 2) Pest insects in strawberry, 3) Pest insects in raspberry and 4) Trap design and lure development. The authors gratefully acknowledge the financial support for this project provided by the CORE Organic II Funding Bodies, being partners of the FP7 ERA-Net project, CORE Organic II (Coordination of European Transnational Research in Organic Food and Farming systems, project no. 249667)

Investigations of a Possible Chemical Effect of Salvadora persica

Salvadora persica is commonly used chewing sticks in many parts of the world as an oral hygiene tool. This study measured the amount of benzyl isothiocyanate (BITC) released into the mouth and assessed its retention time in saliva. The study also tested if the released amount of BITC could potentially be antibacterial or cytotoxic. Twelve subjects brushed their teeth with fresh Miswak once, twice, and four times. The amount of BITC in the saliva and in the used brushes was quantified using gas chromatography-mass spectrometry. The antibacterial effect of BITC and Miswak essential oil (MEO) was tested against Haemophilus influenzae, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. The cytotoxic effect on gingival fibroblasts and keratinocytes was tested using MTT. The highest amount of the active compounds was detected in saliva after using the Miswak tip for once and immediately. It significantly decreased when the Miswak tip was used more than once and thus after 10 min. The growth of the tested bacteria was inhibited by MEO and BITC in a dose dependent manner, P. gingivalis being the most sensitive. MTT assay showed that BITC and MEO were cytotoxic towards gingival fibroblasts while oral keratinocytes showed resistance. This study suggests that the Miswak tip should be cut before each use to ensure the maximum effect

Gravid Anopheles gambiae sensu stricto avoid ovipositing in Bermuda grass hay infusion and it's volatiles in two choice egg-count bioassays.

BACKGROUND: A number of mosquito species in the Culex and Aedes genera prefer to lay eggs in Bermuda grass (Cynodon dactylon) hay infusions compared to water alone. These mosquitoes are attracted to volatile compounds from the hay infusions making the infusions effective baits in gravid traps used for monitoring vectors of arboviral and filarial pathogens. Since Bermuda grass is abundant and widespread, it is plausible to explore infusions made from it as a potential low cost bait for outdoor monitoring of the elusive malaria vector Anopheles gambiae s.s. METHODS: This study investigated preferential egg laying of individual An. gambiae s.s. in hay infusion or in tap water treated with volatiles detected in hay infusion headspace compared to tap water alone, using two-choice egg-count bioassays. Infusions were prepared by mixing 90 g of dried Bermuda grass (hay) with 24 L of unchlorinated tap water in a bucket, and leaving it for 3 days at ambient temperature and humidity. The volatiles in the headspace of the hay infusion were sampled with Tenax TA traps for 20 h and analysed using gas chromatography coupled to mass spectrometry. RESULTS: In total, 18 volatiles were detected in the infusion headspace. Nine of the detected compounds and nonanal were selected for bioassays. Eight of the selected compounds have previously been suggested to attract/stimulate egg laying in An. gambiae s.s. Gravid females were significantly (p < 0.05) less likely to lay eggs in hay infusion dilutions of 25, 50 and 100 % and in tap water containing any of six compounds (3-methylbutanol, phenol, 4-methylphenol, nonanal, indole, and 3-methylindole) compared to tap water alone. The oviposition response to 10 % hay infusion or any one of the remaining four volatiles (4-hepten-1-ol, phenylmethanol, 2-phenylethanol, or 4-ethylphenol) did not differ from that in tap water. CONCLUSIONS: Anopheles gambiae s.s. prefers to lay eggs in tap water rather than Bermuda grass hay infusion. This avoidance of the hay infusion appears to be mediated by volatile organic compounds from the infusion. It is, therefore, unlikely that Bermuda grass hay infusion as formulated and used in gravid traps for Culex and Aedes mosquitoes will be suitable baits for monitoring gravid An. gambiae s.s

Combining 1,4-dimethoxybenzene, the major flower volatile of wild strawberry Fragaria vesca, with the aggregation pheromone of the strawberry blossom weevil Anthonomus rubi improves attraction

The aggregation pheromone of strawberry blossom weevil [Anthonomus rubi Herbst (Col.: Curculionidae)], a 1:4:1 blend of Grandlure I, II and racemic lavadulol, has been available for pest monitoring for several years but shows low attractancy. Attempts to control A. rubi using the pheromone alone were also unsuccessful. This paper reports the finding that addition of the major flower volatile from wild strawberry flowers [Fragaria vesca L. (Rosaceae)], 1,4-dimethoxybenzene (comprising 98% of the volatiles emitted from wild strawberry flowers), to the aggregation pheromone increased trap catches by over two fold compared to the pheromone alone. There was no significant difference between the response of overwintered or summer emerged adults. Field trials in 2007-2008 in central and southern Norway, Denmark and southern England used green funnel traps with white cross vanes for the evaluations. (-)-Germacrene D, previously shown to be emitted by plants in increased amounts in the presence of pheromone producing weevils, did not improve trap catches. Thus, the combined use of the aggregation pheromone and 1,4-dimethoxybenzene is promising for improved monitoring and possibly control of this important pest of strawberry

MANAGEMENT OF STRAWBERRY BLOSSOM WEEVIL AND EUROPEAN TARNISHED PLANT BUG IN ORGANIC STRAWBERRY AND RASPBERRY USING SEMIOCHEMICAL TRAPS “Softpest Multitrap”

Many European growers of organic strawberry and raspberry have large losses in yield (sometimes >80%) and reduced quality of their products because of insect damage. Among the major threats are the strawberry blossom weevil (Anthonomus rubi Herbst), the European tarnished plant bug (Lygus rugulipennis Popp.) and the raspberry beetle (Byturus tomentosus De Geer). In organic soft fruit production there are no effective control measures for these pest insects. For many insects species pheromones and host plant volatiles are of major importance in mate finding and location of host plants for mating, feeding and oviposition. Thus, there is potential for using these insect-insect and/or insect-host plant interactions to develop new strategies and effective control measures for pest insects. In this project we want to extend our knowledge of these systems to develop effective control measures to control these pests in organic crops

Trapping of Lygus rugulipennis in Norwegian strawberry crops

European tarnished plant bug (ETB) sex pheromone traps in Norwegian strawberry must be deployed very early in the season to maximize catches. To trap females or the new generation, other attractants must be added. The strawberry blossom weevil attractant PV2 may act as a slight antagonist in ETB trapping, especially early in the season

Softpest Multitrap. Management of strawberry blossom weevil and European tarnished plant bug in organic strawberry and raspberry using semiochemical traps

The strawberry blossom weevil (Anthonomus rubi) and the European tarnished plant bug (Lygus rugulipennis) cause large (10 - >80%) losses in yield and quality in organically grown strawberry. A consortium with 6 European countries has been created to work on the management of those pests. The pheromones of A. rubi and L. rugulipennis have been characterized in England by NRI/EMR. For the attraction of A. rubi the importance of host plant volatiles in combination with the pheromones has also been documented. The natural semiochemical mechanisms of sexual attraction and host plant finding of A. rubi and L. rugulipennis will be further studied and exploited to develop effective semiochemical traps for their management through mass trapping. Attractive lures for these two species will then be combined into a single multitrap with the aim of managing two pests simultaneously in each crop. This will be one of the first approaches to pest management of non-lepidopteran insect pests of horticultural crops using semiochemicals in the EU, and probably the first to target multiple species from different insect orders. The full project also includes pest management in raspberry. The project will be organized in the following work packages; 1) Chemical analysis of plant volatiles, 2) Pest insects in strawberry, 3) Pest insects in raspberry and 4) Trap design and lure development. The project period is 2012-2014 and the project is funded by the ERA-net CORE Organic II

Traps for Lygus rugulipennis and Anthonomus rubi: preliminary results from Softpest Multitrap activities in Latvia

There is a lack of appropriate plant protection methods against strawberry blossom weevil (SBW) not only in organic plantations, but also in plantations, where IPM is used. European tarnished plant bug (ETPB) is not currently recognized as a pest in Latvian strawberry plantations, because the visual defects made by bugs are not important for Latvian consumers. Cross vane bucket traps and sticky stake traps were the most effective for trapping SBW in Latvia. These traps, where the lure was positioned at the top of cross vanes, were also the most effective for capturing ETPB

Mass trapping Anthonomus rubi and Lygus rugulipennis in strawberries

The strawberry blossom weevil, Anthonomus rubi, and the European tarnished plant bug,Lygus rugulipennis, can cause substantial damage in organic strawberries in Northern and Central Europe. In conventional production it is also desirable to find alternatives to current pesticide controls, which negatively affects beneficials and also creates a risk of building pesticide resistance. Anthonomus rubi lays an egg in a developing flower bud and then partially bites off the flower stem, resulting in a loss of yield. Lygus rugulipennis nymphs and adults feed on flowers and developing fruitlets, causing a fruit distortion which makes the damaged fruit unmarketable. In the ERA-NET CORE Organic project “Softpest Multitrap”, we studied how pheromone and plant volatiles can be combined to improve trapping of the two pests. Our studies also included trap design and placement of traps in the field (grid size, perimeter versus field centre), investigations of the phenology of A. rubi and L. rugulipennis. In 2014 we assessed a ‘multi’-trap for both species. Results will be presented and discussed

Induced Terpene Accumulation in Norway Spruce Inhibits Bark Beetle Colonization in a Dose-Dependent Manner

Background: Tree-killing bark beetles (Coleoptera, Scolytinae) are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleoresin has long been considered important in conifer defense against bark beetles, but it has been difficult to demonstrate a direct correlation between terpene levels and resistance to bark beetle colonization. Methods: To test for inhibitory effects of induced terpenes on colonization by the spruce bark beetle Ips typographus (L.) we inoculated 20 mature Norway spruce Picea abies (L.) Karsten trees with a virulent fungus associated with the beetle, Ceratocystis polonica (Siem.) C. Moreau, and investigated induced terpene levels and beetle colonization in the bark. Results: Fungal inoculation induced very strong and highly variable terpene accumulation 35 days after inoculation. Trees with high induced terpene levels (n = 7) had only 4.9% as many beetle attacks (5.1 vs. 103.5 attacks m22) and 2.6% as much gallery length (0.029 m m22 vs. 1.11 m m22) as trees with low terpene levels (n = 6). There was a highly significant rank correlation between terpene levels at day 35 and beetle colonization in individual trees. The relationship between induced terpene levels and beetle colonization was not linear but thresholded: above a low threshold concentration of ,100 mg terpene g21 dry phloem trees suffered only moderate beetle colonization, and above a high threshold of ,200 mg terpene g21 dry phloem trees were virtually unattacked. Conclusion/Significance: This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance. This knowledge could be useful for developing management strategies that decrease the impact of tree-killing bark beetles