More than you (probably) ever wanted to know about Lygus

Namyatova et al (2022) reviewed five Palearctic Lygus species: L. gemellatus, L. pratensis, L. punctatus, L. rugulipennis,L. wagneri. This document considers four species on the UK Checklist: L. pratensis, L. punctatus, L. rugulipennis, L. wagneri; the fifth UK species, L. maritimus, was not examined by Namyatova et al but is covered by Nau (2004). Namyatova et al conclude that:

1. The currently recognized Lygus species are poorly supported by DNA studies or are non-monophyletic, thus needing reclassification (L. gemellatus, L. pratensis and L. wagneri appear to be synonymous, as do L. punctatusand L. rugulipennis).

2. However, morphometric analysis is generally a reliable way of separating the currently recognized species. 

3. Until a taxonomic revision of this genus is published, the existing species must stand and can be separated (with some difficulty) based on morphology. 

The morphological characters used by Namyatova et al are: 

• punctation on clavus and corium

• vesical spicule shape

• presence or absence of teeth on the right side of the small lobe of the vesica

• colour pattern

Due to the difficulty of examining the vesica, only punctation on clavus and corium and colour patterns are used in this document. (N.B. All Lygus species have antennae light/light+dark; c.f. Orthops, all dark). In general, the species descriptions given by Namyatova et al (2022) agree with those in Nau (2004). 

Lygus pratensis 

Males 5.1-7.0mm, females 5.1-6.6mm. Scutellum usually with single brown mark or stripe or the medial anterior part. Hemelytra with short, dense setae, often appearing shiny. Punctures on middle part of hemelytra evenly spaced, distance between them equal or less than puncture diameter; anterior half of clavus with some punctures at a distance longer than puncture diameter; punctures on posterior half of clavus evenly spaced and close to each other, but distinctly separate from each other. 

Lygus punctatus

Males 5.9-7.2mm, females 5.1-6.7mm. Scutellum either with two stripes or W-shaped mark on the medial anterior part. Hemelytra with short, dense setae, often appearing shiny. Punctures on middle part of hemelytra and on anterior and posterior half of clavus further apart than the puncture diameter. 

Lygus rugulipennis 

Males 4.9-5.9mm, females 4.5-6.4mm. Scutellum either with two stripes or W-shaped mark on the medial anterior part. Hemelytra covered with dense flat setae, its surface appearing dull and matte. Punctures on hemelytra and clavus very small and almost touching each other;

Lygus wagneri

Males 5.7–6.8, females 5.3-6.5mm. Scutellum either with two stripes or W-shaped mark on the medial anterior part. Hemelytra with sparse setae, often appearing shiny. Punctures on middle part of hemelytra evenly spaced, distance between them equal or less than puncture diameter; punctures on anterior half of clavus spaced further apart than the puncture diameter; punctures on posterior half of clavus evenly spaced and close to each other, but distinctly separate.

Lygus maritimus (from Nau, 2004) 

Punctures on apical region of the corium several diameters apart in each direction. 

References: 

Namyatova, A. A., Tyts, V. D., & Bolshakova, D. S. (2022) Identification and delimitation of the trans-Palearctic Lygus species (Insecta: Heteroptera: Miridae) using integrative approach. Insect Systematics & Evolution, 1, 1-47.https://doi.org/10.1163/1876312X-bja10035

and:

Nau, B. (2004) The Lygus situation. Newsletter of the UK Heteroptera Recording Schemes 3, 11.https://www.britishbugs.org.uk/HetNews/Issue%203_Spring%202004_422Kb.pdf

Veterinary flea products in widespread pesticide contamination of English rivers

• The environmental impact of pesticides used in veterinary flea treatments is largely unknown. This is an analysis of potential sources of fiprole and imidacloprid pollution in 20 English rivers. 
• Seven out of 20 sites exceeded the chronic toxicity limit for Imidacloprid. 
• Sewage worksare indicated as a possible route to rivers for fiproles and imidacloprid. 
• Veterinary flea products are a potential source of pollution and ecosystem harm and a reevaluation of the environmental risks is needed. 

Perkins, R., Whitehead, M., Civil, W., & Goulson, D. (2021) Potential role of veterinary flea products in widespread pesticide contamination of English rivers. Science of The Total Environment, 755, 143560. https://doi.org/10.1016/j.scitotenv.2020.143560 

Little is known about the environmental fate or impact of pesticides used to control companion animal parasites. Using data from the Environment Agency, we examined the occurrence of fipronil, fipronil metabolites and imidacloprid in 20 English rivers from 2016 to 2018, as indicators of the potential contamination of waterways from their use as ectoparasiticides on pets. Water samples were collected by the Environment Agency as part of their chemical surveillance programme and analysed using Liquid Chromatography Mass Spectrometry / Quadrupole-Time-of-Flight Mass spectrometry (LC/Q-TOF-MS) methods. A total of 3861 chemical analyses were examined, and the significance and potential sources of this contamination were assessed. Fipronil, fipronil sulfone, fipronil sulfide (collectively known as fiproles) and imidacloprid were detected in 98.6%, 96.5%, 68.7% and 65.9% of samples, respectively. Across the river sites sampled, the mean concentrations of fipronil (17 ng/l, range <0.3–980 ng/l), and fipronil sulfone (6.5 ng/l, range <0.2–39 ng/l) were 5.3 and 38.1 times their chronic toxicity limits of 3.2 and 0.17 ng/l, respectively. Imidacloprid had a mean concentration of 31.7 ng/l (range <1–360 ng/l), which was below its chronic toxicity limit of 35 ng/l, however seven out of 20 sites exceeded that limit. Chronic risk quotients indicate a high environmental risk to aquatic ecosystems from fiproles, and a moderate risk from imidacloprid. Sites immediately downstream of wastewater treatment works had the highest levels of fipronil and imidacloprid, supporting the hypothesis that potentially significant quantities of pesticides from veterinary flea products may be entering waterways via household drains. These findings suggest the need for a reevaluation of the environmental risks associated with the use of companion animal parasiticide products, and the risk assessments that these products undergo prior to regulatory approval.

 

The spiderpocalypse is upon us

Arthropod decline at the local (field) scale is largely influenced by changes at the landscape scale. 

"There is widespread evidence for a worldwide trend of insect decline, but we have much fewer data about recent temporal trends in other arthropod groups, including spiders. Spiders can be hypothesised to similarly decline because of trophic dependence on insects and being equally sensitive to local and global environmental changes. Background trends in arthropod populations can be verified if we decouple large-scale environmental transitions, such as climate change, from local factors. To provide a case study on baseline spider community trends, we observed changes in the spider community of an unsprayed alfalfa field and its margin 23 years apart under largely unchanged local conditions. We aimed to determine whether there are changes in spider abundance, species richness and mean species characteristics. Spider abundance per unit effort decreased dramatically, by 45% in alfalfa and by 59% in the margin, but species richness and most characteristics remained unchanged. Community composition in both habitats shifted and became more similar by the current study period. The population decline was especially marked in certain farmland species. We propose that in the absence of local causative factors, spider abundance decline in our study indicates a reduction of spider populations at landscape and regional scales."

Samu, F., Szita, É., Botos, E. et al. Agricultural spider decline: long-term trends under constant management conditions. Sci Rep 13, 2305 (2023) https://doi.org/10.1038/s41598-023-29003-2 

This is why nature reserves don't work: Cooke, R., Mancini, F., Boyd, R. J., Evans, K. L., Shaw, A., Webb, T. J., & Isaac, N. J. (2023). Protected areas support more species than unprotected areas in Great Britain, but lose them equally rapidly. Biological Conservation, 278, 109884: https://doi.org/10.1016/j.biocon.2022.109884

Not the bee's knees

You may have seen the wildlife documentary "My Garden of a Thousand Bees", wildlife cameraman Martin Dohrn's 2020 Covid lockdown project.  If you haven't seen it, Google it and try and track it down - it's the best wildlife documentary I've seen for years, certainly since before the BBC gave up on anything that is not characteristic megafauna. And if that doesn't give you enough food for thought, read this:

MacInnis G, Normandin E, Ziter CD. 2023. Decline in wild bee species richness associated with honey bee (Apis mellifera L.) abundance in an urban ecosystem. PeerJ 11:e14699 https://doi.org/10.7717/peerj.14699

 

New VC55 Co-ordinators for Bugs (Heteroptera and Auchenorrhyncha)