Wet and dry extremes reduce arthropod biomass independently of leaf phenology in the wet tropics

Newell, Felicity L.; Ausprey, Ian J.; Robinson, Scott K.

doi:10.1111/gcb.16379

Cited by 15 publications

(6 citation statements)

References 109 publications

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“…Similarly, the abundance of top predators in cacao agroforests varies between seasons, and local migrants may contribute to pest control in precise times of the year (Ocampo‐Ariza et al, 2022). Further studies in dry tropical forest areas should account for this variation in trophic interactions during the year, across years and due to climate change, when drought and high temperatures may impact the biomass and abundance of predators and their prey (Karp & Daily, 2014; Newell et al, 2023; Ocampo‐Ariza et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

Birds and bats enhance cacao yield despite suppressing arthropod mesopredation

Ocampo‐Ariza

Vansynghel

Bertleff

et al. 2023

Ecological Applications

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Bird-and bat-mediated biocontrol benefits the productivity of tropical commodity crops such as cacao, but the ecological interactions driving these ecosystem services remain poorly understood. Whereas birds and bats prey on herbivorous arthropods, they may also prey on arthropod mesopredators such as ants, with poorly understood consequences for pest biocontrol. We used a full-factorial experiment excluding birds, bats, and ants to assess their effects on (a) the abundance of multiple arthropod groups; (b) predation pressure on arthropods evaluated through artificial sentinel caterpillars; and (c) cacao yield over 1 year in shaded agroforestry systems of native cacao varieties in Peru. Birds and bats increased cacao yield by 118%, which translates in smallholder benefits of ca.US $959 ha −1 year −1 . Birds and bats decreased predation by ants and other arthropods, but contributed to the control of phytophagous taxa such as aphids and mealybugs. By contrast, ant presence increased the abundance of these sap-sucking insects, with negative impacts for cacao yield.Notably, high abundances of the dominant ant Nylanderia sp., known to attend sap-sucking insects, were associated with lower cacao yield along a distance gradient from the closest forest edge. According to these results, arthropod predation by birds and bats, rather than mesopredation by arthropods, was most responsible for increases in cacao yield. Moving forward, detailed research about their trophic interactions will be necessary to identify the cause of such benefits. Retaining and restoring the large benefits of birds and bats as well as minimizing disservices by other taxa in cacao agroforests can benefit from management schemes that prioritize preservation of shade trees and adjacent forests within agroforestry landscapes.

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Section: Discussionmentioning

confidence: 99%

Birds and bats enhance cacao yield despite suppressing arthropod mesopredation

Ocampo‐Ariza

Vansynghel

Bertleff

et al. 2023

Ecological Applications

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“…Deforestation and removal of large trees leaves the remaining fragments of forest less able to buffer adverse climatic conditions (Betts et al 2018). Many tropical rainforest invertebrates, – the prey of the Alagoas Antwren – are sensitive to extremes of dry or wet conditions (Newell et al 2023). Aerial pesticide applications over sugarcane may have resulted in drift of pesticides into Murici and other forest fragments in past decades, affecting insects and insectivores (Silveira et al 2003; personal communications from local population).…”

Section: Discussionmentioning

confidence: 99%

The Alagoas Antwren Myrmotherula snowi is in imminent danger of extinction

Vilela,

Andrade,

Araujo

et al. 2024

Bird Conservation International

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Summary The “Critically Endangered” Alagoas Antwren Myrmotherula snowi is found only in the Atlantic Rainforest of north-east Brazil. We surveyed all sites where the species has been recorded, as well as 15 other potential sites. We summarise all observations of the species, focusing on the period from 2016 onwards, and including systematic censuses in three breeding seasons (October–March 2018/19, 2019/20, and 2020/21) at the type locality, Murici, where we also searched for nests of the species. We did not locate any individuals at sites other than Murici. The number of apparent individuals detected declined by 67% over seven years (a decline of 50% over the three years in which standardised systematic counts were made), and only six adults were observed in the most recent breeding season. The global population is now likely to be in single-digit figures. Of five nests found, four failed, through predation by snakes and opossums, and abandonment. We installed protective barriers to protect two of these nests from predators, which may have contributed to the single successful fledging. Such methods offer most hope for now of stalling the decline. Efforts to develop captive breeding methods with model species have been underway since 2019 but face many difficulties. Improving habitat protection and restoration is crucial but will only take effect in the long term.

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“…Despite our study being limited to 20 light‐trapping nights during each season, our results were robust enough to detect seasonal and spatial variation in arthropod communities. Insect diversity and abundance are directly related to temporal variation in temperature and resource availability and most tropical insects have their seasonal peak during the wet season (Newell et al., 2023; Richards & Windsor, 2007; Wolda, 1980, 1988). Our results not only detected a greater number of species during the wet season, but we were also able to identify significant differences between sampling locations, and sampling days, further supporting metabarcoding as a cost‐effective strategy to detect fine‐scale differences in arthropod communities.…”

Section: Discussionmentioning

confidence: 99%

Illuminating arthropod diversity in a tropical forest: Assessing biodiversity by automatic light trapping and DNA metabarcoding

Souto‐Vilarós,

Basset,

Blažek

et al. 2024

Environmental DNA

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Although studies of insect decline have recently dominated headlines worldwide, their interpretation requires caution since for most species, we lack long‐term population baselines. In the tropics, where most insect species thrive, our knowledge is even more limited and so reliable insect assessments must originate from well‐established long‐term monitoring efforts. Combining the extensive monitoring data from the Arthropod Program of the Smithsonian Tropical Research Institute (STRI) on Barro Colorado Island (BCI), Panama, we compare whether known arthropod diversity can be detected through metabarcoding of bulk insect samples obtained through automatic light‐trapping. Our study detected 4402 species based on Barcode Index Numbers (BIN) and detected fine‐scale differences between wet and dry seasons and sampling localities. We further refined our analysis to indicate which families and genera explained seasonal turnover. Using samples collected in parallel, but sorted manually as part of the ongoing arthropod monitoring program, we compared these methods. Out of 538 BINs recovered through manual sorting, there was a 70% overlap with the metabarcoding data; however, it represented 30% of the total BINs detected through metabarcoding. Expecting higher detection through metabarcoding, we also compare the results with the 14 years of sampling in BCI to better understand how well the monitoring program has captured the diversity of focal groups. Our results revealed a ~50% overlap between both methods and similar total catch. Barcode Index Numbers manually detected but not recovered by metabarcoding highlight some of the limitations of molecular detection methods such as primer bias. Contrastingly, BINs detected with metabarcoding, but not recovered by the traditional monitoring scheme, highlight the importance of local and regional barcode reference libraries.

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Wet and dry extremes reduce arthropod biomass independently of leaf phenology in the wet tropics

Cited by 15 publications

References 109 publications

Birds and bats enhance cacao yield despite suppressing arthropod mesopredation

Birds and bats enhance cacao yield despite suppressing arthropod mesopredation

The Alagoas Antwren Myrmotherula snowi is in imminent danger of extinction

Illuminating arthropod diversity in a tropical forest: Assessing biodiversity by automatic light trapping and DNA metabarcoding

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