Differences in colour preference among pollen beetle species (Coleoptera: Nitidulidae)

AbstractThe predator-predator naïveté hypothesis suggests that non-native predators benefit from being unknown to native predators, resulting in reduced intraguild interference with native predators. This novelty advantage should depend on the ability of native predators to recognize cues of non-native predators. Here, we compared ant aggression and lady beetle reaction in four native and the invasive lady beetle species Harmonia axyridis. In addition, we tested whether lady beetle cuticular hydrocarbons (CHCs) are involved in species recognition, which might explain naïveté if the invasive species has a specific CHC profile. To this end, we conducted behavioral assays confronting two native ant species with both living lady beetles and lady beetle elytra bearing or lacking CHCs of different lady beetle species. Finally, we characterized CHC profiles of the lady beetles using GC–MS. In general, the aggression of Lasius niger was more frequent than that of Myrmica rubra and L. niger aggression was more frequent towards most native lady beetle species compared to H. axyridis. The removal of CHCs from lady beetle elytra reduced aggression of both ant species. If CHCs of respective lady beetle species were added on cue-free elytra, natural strength of L. niger aggression could be restored. CHC analyses revealed a distinct cue composition for each lady beetle species. Our experiments demonstrate that the presence of chemical cues on the surface of lady beetles contribute to the strength of ant aggression against lady beetles. Reduced aggression of L. niger towards H. axyridis and reduced avoidance behavior in H. axyridis compared to the equally voracious C. septempunctata might improve the invasive lady beetle’s access to ant-tended aphids.

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RNAi efficacy is enhanced by chronic dsRNA feeding in pollen beetle

Communications Biology ◽

10.1038/s42003-021-01975-9 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Jonathan Willow ◽

Liina Soonvald ◽

Silva Sulg ◽

Riina Kaasik ◽

Ana Isabel Silva ◽

...

Keyword(s):

Rna Interference ◽

Pest Management ◽

Oilseed Rape ◽

Growth Stages ◽

Short Term ◽

Pollen Beetle ◽

Brassicogethes Aeneus ◽

Crop Growth Stages ◽

Insecticidal Compounds ◽

Significant Mortality

AbstractDouble-stranded RNAs (dsRNAs) represent a promising class of biosafe insecticidal compounds. We examined the ability to induce RNA interference (RNAi) in the pollen beetle Brassicogethes aeneus via anther feeding, and compared short-term (3 d) to chronic (17 d) feeding of various concentrations of dsRNA targeting αCOP (dsαCOP). In short-term dsαCOP feeding, only the highest concentration resulted in significant reductions in B. aeneus survival; whereas in chronic dsαCOP feeding, all three concentrations resulted in significant mortality. Chronic dsαCOP feeding also resulted in significantly greater mortality compared to short-term feeding of equivalent dsαCOP concentrations. Our results have implications for the economics and development of dsRNA spray approaches for managing crop pests, in that multiple lower-concentration dsRNA spray treatments across crop growth stages may result in greater pest management efficacy, compared to single treatments using higher dsRNA concentrations. Furthermore, our results highlight the need for research into the development of RNAi cultivars for oilseed rape protection, given the enhanced RNAi efficacy resulting from chronic, compared to short-term, dsRNA feeding in B. aeneus.

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3-Methylcyclohex-2-en-1-one and the Douglas-fir beetle (Coleoptera: Curculionidae): history of successful bark beetle pheromone treatments

The Canadian Entomologist ◽

10.4039/tce.2020.62 ◽

2020 ◽

Vol 153 (1) ◽

pp. 62-78

Author(s):

Darrell W. Ross

Keyword(s):

Bark Beetle ◽

Douglas Fir ◽

Future Research ◽

Beetle Species ◽

Successful Management ◽

Dendroctonus Pseudotsugae ◽

Successful Development ◽

History Of ◽

Antiaggregation Pheromone

AbstractThis paper reviews the literature on the identification of 3-methylcyclohex-2-en-1-one (MCH) as the antiaggregation pheromone of the Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) and the development of successful management applications using the pheromone. Previously unpublished data from two studies on novel uses of MCH are included. The successful development of antiaggregation pheromone-based treatments for the Douglas-fir beetle is discussed in relation to efforts to develop similar treatments for other bark beetle species, and opportunities for future research on MCH and the Douglas-fir beetle are suggested.

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