Moths are the most taxonomically and ecologically diverse insect taxon for which there exist considerable time-series abundance data. There is an alarming record of decreases in moth abundance and diversity from across Europe, with rates varying markedly among and within regions. Recent reports from Costa Rica reveal steep cross-lineage declines of caterpillars, while other sites (Ecuador and Arizona, reported here) show no or only modest long-term decreases over the past two decades. Rates of decline for dietary and ecological specialists are steeper than those for ecologically generalized taxa. Additional traits commonly associated with elevated risks include large wingspans, small geographic ranges, low dispersal ability, and univoltinism; taxa associated with grasslands, aridlands, and nutrient-poor habitats also appear to be at higher risk. In temperate areas, many moth taxa limited historically by abiotic factors are increasing in abundance and range. We regard the most important continental-scale stressors to include reductions in habitat quality and quantity resulting from land-use change and climate change and, to a lesser extent, atmospheric nitrification and introduced species. Site-specific stressors include pesticide use and light pollution. Our assessment of global macrolepidopteran population trends includes numerous cases of both region-wide and local losses and studies that report no declines. Spatial variation of reported losses suggests that multiple stressors are in play. With the exception of recent reports from Costa Rica, the most severe examples of moth declines are from Northern Hemisphere regions of high human-population density and intensive agriculture.

Reports of biodiversity loss have increasingly focused on declines in abundance and diversity of insects, but it is still unclear if substantive insect diversity losses are occurring in intact low-latitude forests. We collected 22 years of plant-caterpillar-parasitoid data in a protected tropical forest and found reductions in the diversity and density of insects that appear to be partly driven by a changing climate and weather anomalies. Results also point to the potential influence of variables not directly measured in this study, including changes in land-use in nearby areas. We report a decline in parasitism that represents a reduction in an important ecosystem service: enemy control of primary consumers. The consequences of these changes are in many cases irreversible and are likely to be mirrored in nearby forests; overall declines in the region will have negative consequences for surrounding agriculture. The decline of important tropical taxa and associated ecosystem function illuminates the consequences of numerous threats to global insect diversity and provides additional impetus for research on tropical diversity.

Article Information: Abstract: 142 words, Main text: 3525 words, 64 references, 4 figures 23 (main text) 15 figures (including main text and supplemental information), 6 tables 24 (supplemental information only) 25 26 27 2 ABSTRACT 28Abstract: Reports of biodiversity loss have increasingly focused on the abundance and diversity 29 of insects, but it is still unclear if substantive insect diversity losses are occurring in intact low-30 latitude forests. We collected 22 years of plant-caterpillar-parasitoid data in a protected tropical 31 forest and found reductions in diversity and density of these insects that appear to be partly 32 driven by a changing climate and weather anomalies. The decline in parasitism represents a 33 reduction in an important ecosystem service: enemy control of primary consumers. The 34 consequences of these changes are in many cases irreversible and are likely to be mirrored in 35 nearby forests; overall declines in the region will have negative consequences for surrounding 36 agriculture. The decline of important tropical taxa and associated ecosystem function illuminates 37 the consequences of numerous threats to global insect diversity and provides additional impetus 38 for research on tropical diversity. 39 40 41 42 43 44 45 46 47 63 Documenting long term population trends and fluctuations in diversity in tropical insect 64communities is especially important because of an unjustified assumption that tropical 65 communities are more stable (13,14) and therefore more resilient to multiple global change 66 disruptions. Threats to insect diversity include climate change, habitat loss, fragmentation, 67 invasive species, pesticides, and pollutants (15)(16)(17)(18)(19)(20), and the magnitude of these effects and 68 associated levels of ecosystem resilience do indeed vary considerably across biogeographic 69 regions. For example, changes in some climate parameters, such as mean annual temperature are 70 4 most severe at the poles, and some of the most dramatic examples of biotic change have been 71 observed at high latitudes, such as increased overwintering survival and voltinism in pest insects 72 (21, 22). In contrast, increases in extreme weather events will have complex and large effects on 73 lowland tropical communities, where plant-insect food webs may be particularly sensitive 74 because of highly-specialized trophic relationships relative to interactions at higher latitudes 75 (23). Furthermore, vulnerability of tropical communities to global change is exacerbated by the 76 thermal constraints of tropical ectotherms (24-26) high degrees of endemism and high rates of 77 tropical habitat loss (27)(28)(29)(30). 78 79In general, reports on insect declines have mostly included cases where the causes are 80 unspecified or unclear (12, 31), or the consequences to ecosystem services have not been 81 explored (12, 16, 32). Here we contribute to understanding species declines and losses of 82 biological interactions in a protected and well-studied tropical wet forest and examine potential 8...

Insect herbivores are relatively specialized. Why this is so is not clear. We examine assumptions about associations between local abundance and dietary specialization using an 18‐year data set of caterpillar–plant interactions in Ecuador. Our data consist of caterpillar–plant associations and include standardized plot‐based samples and general collections of caterpillars, allowing for diet breadth and abundance estimates across spatial scales for 1917 morphospecies. We find that more specialized caterpillars are locally more abundant than generalists, consistent with a key component of the ‘jack of all trades, master of none’ hypothesis. As the diet breadth of species increased, generalists were not as abundant in any one location, but they had broader occupancy across the landscape, which is a pattern that could reflect high plant beta diversity and is consistent with an alternative neutral hypothesis. Our finding that more specialized species can be both rare and common highlights the ecological complexity of specialization.

Frequently disturbed ecosystems are characterized by resilience to ecological disturbances. Longleaf pine ecosystems are not only resilient to frequent fire disturbance, but this feature sustains biodiversity. We examined how fire frequency maintains beta diversity of multi-trophic interactions in longleaf pine ecosystems, as this community property provides a measure of functional redundancy of an ecosystem. We found that beta interaction diversity at small local scales is highest in the most frequently burned stands, conferring immediate resiliency to disturbance by fire. Interactions become more specialized and less resilient as fire frequency decreases. Local scale patterns of interaction diversity contribute to broader scale patterns and confer long-term ecosystem resiliency. Such natural disturbances are likely to be important for maintaining regional diversity of interactions for a broad range of ecosystems.