This literature review concerns insect responses to fire, compared to other feasible and appropriate conservation managements of open habitats. Many insect groups decline markedly immediately after fire, with the magnitude of reduction related to the degree of exposure to the flames and mobility of the insect. Niche diversity is lower in recently burned habitat, and the rate of insect increase following fire also relates to the species' ability to gain access to the regrowing vegetation. Postburn flora can be quite attractive to some recolonizing insects, possibly to some degree a result of fire-caused insect mortality which provides plants with short-term release from insect herbivory. Insect declines may follow immediately after mowing, but usually of lesser degree and shorter duration than after a fire of comparable timing and size. Season and scale of cutting may affect how much and which species showed positive or negative responses. Cut areas offer the vegetational structure and composition preferred by some insects, but cutting – or cutting at certain scales, seasons, or frequencies – may also be unfavorable for some species. Heavy grazing results in niche and assemblage simplification. Nonetheless, some invertebrates prefer the short turfs and bare ground resulting from heavier grazing. Other species vary in whether they peak in abundance and diversity in intermediate, light, or no grazing. In comparisons of mowing/haying and grazing regimes of similar compatibility with maintenance of the same habitat types, responses of particular species and species groups varied as to whether they had a preference for one or the other. Characteristics associated with insect responses to fire related to the degree of exposure to lethal temperature and stress experienced in the post-fire environment, suitability of post-treatment vegetation as habitat, and ability to rebuild numbers in the site (from survivors and/or colonizers). These factors appear equally useful for explicating insect responses to other managements such as haying, mowing, and grazing. By contrast, the assumption that the most habitat-restricted species will be most adapted to ecological forces believed to be prevalent in that ecosystem appears less efficacious for predicting insect management preferences.

A literature review of insect responses to fire, compared to other conservation managements of open habitat

Most extinctions estimated to have occurred in the historical past, or predicted to occur in the future, are of insects. Despite this, the study of insect extinctions has been neglected. Only 70 modern insect extinctions have been documented, although thousands are estimated to have occurred. By focusing on some of the 70 documented extinctions as case studies, I considered ways in which insect extinctions may differ from those of other taxa. These case studies suggested that two types of extinction might be common for insects but rare for other taxa: extinction of narrow habitat specialists and coextinctions of affiliates with the extinctions of their hosts. Importantly, both of these forms of extinction are often ignored by conservation programs focused on vertebrates and plants. Anecdotal evidence and recent simulations suggest that many insect extinctions may have already occurred because of loss of narrow habitat specialists from restricted habitats and the loss of hosts. If we are serious about insect conservation, we need to spend more time and money documenting such extinctions. To neglect such extinctions is to ignore the majority of species that are or were in need of conservation.

Modern Insect Extinctions, the Neglected Majority

Ecological restoration enjoys widespread use as a technique to mitigate for environmental damage. Success of a restoration project often is evaluated on the basis of plant cover only. Recovery of a native arthropod fauna is also important to achieve conservation goals. I sampled arthropod communities by pitfall trapping in undisturbed, disturbed, and restored coastal sage scrub habitats in southern California. I evaluated arthropod community composition, diversity, and abundance using summary statistics, cluster analysis, and detrended correspondence analysis (DCA) and investigated influence of vegetation on arthropod communities with multiple regression analysis. Arthropod diversity at undisturbed and disturbed sites was greater than at sites that were 5 and 15 years following restoration ( p � 0.05). Number of arthropod species was not significantly different among undisturbed, disturbed, and restored sites, and two restoration sites had significantly more individuals than other sites. Vegetation at disturbed and undisturbed sites differed significantly; older restorations did not differ significantly from undisturbed sites in diversity, percent cover, or structural complexity. In multiple regression models, arthropod species richness and diversity was negatively related to vegetation height but positively related to structural complexity at intermediate heights. Exotic arthropod species were negatively associated with overall arthropod diversity, with abundance of the earwig Forficula auricularia best predicting diversity at comparison (not restored) sites ( r 2 � 0.29), and abundance of the spider Dysdera crocata and the ant Linepithema humile predicting diversity at all sites combined ( r 2 � 0.48). Native scavengers were less abundant at restored sites than all other sites and, with a notable exception, native predators were less abundant as well. DCA of all species separated restored sites from all other sites on the first axis, which was highly correlated with arthropod diversity and exotic arthropod species abundance. Lower taxonomic levels showed similar but weaker patterns, with example families not discriminating between site histories. Vegetation characteristics did not differ significantly between the newly restored site and disturbed sites, or between mature restoration sites and undisturbed sites. In contrast, arthropod communities at all restored sites were, as a group, significantly different from both disturbed and undisturbed sites. As found in other studies of other restoration sites, arthropod communities are less diverse and have altered guild structure. If restoration is to be successful as compensatory mitigation, restoration success standards must be expanded to include arthropods.

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Terrestrial Arthropods as Indicators of Ecological Restoration Success in Coastal Sage Scrub (California, U.S.A.)

Colour is an important attractant for many flower-visiting insects (anthophiles). Consequently, coloured pan trapping is an efficient technique that can be easily and cost-effectively used to quantitatively sample assemblages of anthophiles. However, colour preferences of anthophiles is an important source of bias that needs to be considered in pan trap surveys. By drawing sub samples comprised of different colour combinations from a database of pan trap surveys in the lowlands of the Cape Floristic Region, we examine the effects of colour on pan trap catches and determine which combinations of colours might provide better estimates of diversity when sampling with multi-colour sets of pan traps. Pan trap catches included the major groups of anthophiles in the region (Coleoptera, Diptera and Hymenoptera), but butterflies (Lepidoptera) were strongly under-represented. Colour played an important role in determining the species richness and composition of pan trap catches, with colour sets that included high reflectance yellow and white generally having catches with the highest species richness. While all colour combinations provided reasonable estimates of proportional species richness, proportional abundance of taxa varied among different colour sets, and did not accurately reflect actual proportions of different taxa in the entire dataset. For comparative biodiversity surveys and assessments we recommend the use of high reflectance colours such as white and yellow traps, while for full inventory surveys, it may be necessary to include other colours to catch rarer species that are excluded by the high reflectance colours alone.

Optimising coloured pan traps to survey flower visiting insects

Assessment of changing agricultural land use: response of vegetation, ground-dwelling spiders and beetles to the conversion of arable land into grassland

Arthropod communities from several habitats on and adjacent to the El Segundo dunes (Los Angeles County, CA) were sampled using pitfall and yellow pan traps to evaluate their possible use as indicators of restoration success. Communities were ordinated and clustered using correspondence analysis, detrended correspondence analysis, two-way indicator species analysis, and Ward's method of agglomerative clustering. The results showed high repeatability among replicates within any sampling arena that permits discrimination of (1) degraded and rela- tively undisturbed habitat, (2) different dune habitat types, and (3) annual change. Canonical correspondence analysis showed a significant effect of disturbance history on com- munity composition that explained 5-20% of the variation. Replicates of pitfall and yellow pan traps on single sites clus- tered together reliably when species abundance was con- sidered, whereas clusters using only species incidence did not group replicates as consistently. The broad taxonomic approach seems appropriate for habitat evaluation and monitoring of restoration projects as an alternative to assess- ments geared to single species or even single families.

ENVIRONMENTAL AUDITING: Arthropod Monitoring for Fine-Scale Habitat Analysis: A Case Study of the El Segundo Sand Dunes.

Before, during and after habitat restoration from 1984 to 1994, we monitored population size of the federally listed endangered El Segundo blue butterfly, Euphilotes bernardino allyni (Shields). In the subsequent formalization of a recovery plan for the species, the U.S. Fish and Wildlife Service established several recovery criteria, including a requirement of ‘a scientifically credible monitoring plan’ to track population size annually. To avoid detrimental effects of the extensively used mark-release-recapture method on the delicate El Segundo blue butterfly, which would conflict with protection afforded by the Endangered Species Act, we chose instead to perform transect counts to estimate relative population size. Herein, we analyze the results of our transect counts by three different methods, developed by or modified from Pollard, Watt et al. and Zonneveld. Qualitatively, the three methods, which have different assumptions, produced similar results when applied to the same data. Zonneveld's model estimates death rate in addition to an index of population size, thus providing more information than the other two methods. The El Segundo blue butterfly's sedentary nature and the close relationship of its adult and early stages to one foodplant permits extrapolation of the index of population size based on transect counts, to an estimate of actual population size. Our data document butterfly numbers increasing from 1984 to 1989, but then declining until the end of our observations in 1994. Based on analysis of our El Segundo blue butterfly data, we propose an implementation of a scientifically credible monitoring plan.

Analysis of Transect Counts to Monitor Population Size in Endangered Insects The Case of the El Segundo Blue Butterfly, Euphilotes Bernardino Allyni

With the listing of the quino checkerspot butterfly, Euphydryas editha quino, as a federally endangered species, research into its ecology and conservation is necessary to allow for recovery planning and manage- ment. We review systematics, distribution, natural history, and conserva- tion prospects, with reference to pertinent literature about other E. editha subspecies. Additional information is presented from museum specimens and ongoing research on the species.

The endangered quino checkerspot butterfly, Euphydryas editha quino (Lepidoptera: Nymphalidae)

Mass rearing of the endangered lycaenid Glaucopsyche lygdamus palosverdesensis (Palos Verdes blue butterfly) is described Numerous problems were encountered in our attempts to predictably produce a large stock population both as insurance against extinction and for re-introduction to sites where the species has been extirpated We describe our approaches to mass rearing with discussion of all aspects of life history, difficulties with parasitoids and predators, cage design, and artificial diet use Both cylindrical cages placed over individual potted plants and outdoor tent cages were successful in providing conditions where captive individuals would mate without intervention, transcending previous limits posed by hand pairing From a small initial stock, we produced between 168 and 968 pupae each season Highest losses were experienced in first instar, with later losses from microsporidian infection Predation during pupation was also significant in semi-natural confined conditions The effort has been in progress for eight years and is continuing

Mass rearing the endangered Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis: Lycaenidae)

ECOLOGICAL RESTORATION 21:1 n MARCH 2003 43 Tree-Species Preferences of Foraging Insectivorous Birds: Implications for Floodplain Forest Restoration. 2002. Gabbe, A., Dept. of Environmental Studies, University of California, Santa Cruz, CA 95064, gabbe@cats.ucsc.edu; S.K. Robinson and J.D. Brawn. Conservation Biology 16(2):462-470. The authors examined the foraging behavior of 13 bird species in floodplain forests in southern Illinois. They found that 12 of the species foraged selectively with regards to tree species. Most favored the kingnut hickory (Carya laciniosa), bitternut hickory (C. cordiformis), and silver maple (Acer saccharinum). The yellow-throated warbler (Dendroica dominica) and cerulean warbler (D. cerulea) were the most selective, and the yellow-throated vireo (Vireo flavifrons), red-eyed vireo (V. olivaceus), and eastern tufted titmouse (Baeolophus bicolor) were the least. In general, the more selective foragers were less common. Because heavy-seeded hickories do not quickly recolonize forests restored with common oak species (Quercus spp.), the authors conclude that restoring floristically diverse floodplain forests with heavy-seeded and uncommon trees preferred by these birds will enhance their habitat quality.

Rudi Mattoni

Papers

ENVIRONMENTAL AUDITING: Arthropod Monitoring for Fine-Scale Habitat Analysis: A Case Study of the El Segundo Sand Dunes.

Analysis of Transect Counts to Monitor Population Size in Endangered Insects The Case of the El Segundo Blue Butterfly, Euphilotes Bernardino Allyni

The endangered quino checkerspot butterfly, Euphydryas editha quino (Lepidoptera: Nymphalidae)

Mass rearing the endangered Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis: Lycaenidae)

Insect count analyzer: A tool to assess responses of butterflies to habitat restoration.