Quercus Emoryi Research Articles

Ecology and description of a new species of Ophiognomonia endophytic in the leaves of Quercus emoryi

In a study to examine plant-insect-fungal endophyte interactions, we surveyed the fungal endophyte populations in over 4600 leaves of an evergreen oak over three growing seasons. Three of the most frequently isolated endophytes were undescribed species. We describe one of these endophytes as a new taxon, Ophiognomonia cryptica, and present details of its ecology in leaves studied from 1993–1995. Ophiognomonia cryptica was not isolated from leaves during the 6 months following bud burst (May-Nov) but rapidly increases in isolation frequency from December until leaf abscission in April. The first appearance of O. cryptica coincides with a drop in temperature and increase in cumulative precipitation. Infection levels (infections/cm2) were negatively correlated with leaf area on 6 of 7 dates. However, infection frequencies (total number of infections per leaf) were negatively correlated with leaf area on only 3 of 8 sampling dates and not correlated on the other 5. We found no within-leaf pattern of infection, exterior sun leaves were more heavily infected relative to interior shaded leaves, and infection levels varied among trees. We discuss the ecology of this endophyte in relation to the theory of island biogeography. In addition, we discuss our results with respect to the prediction that each plant species may harbor 2–4 endophytes species specific to that plant species and its implications to fungal biodiversity.

Fungal Endophytes in Oak Trees: Long-Term Patterns of Abundance and Associations with Leafminers

Endophytic fungi inhabiting foliage of woody plants are diverse and abundant, yet little is known of their temporal and spatial variation or their interactions with more commonly studied invertebrate and vertebrate macroherbivores. We studied seasonal and yearly variation in endophyte infections in five Emory oak trees over a 4-yr period from 1989 to 1993. In the 1992–1993 growing season, we documented seasonal patterns of abundance of the three most common fungal endophyte species, an ascomycete, Ophiognomonia cryptica, and two coelomycete species, Plectophomella sp. and Asteromella sp. To determine the association of fungal endophytes with macroherbivores, we compared infection frequencies of endophytes in unmined leaves and leaves harboring living and dead larval leafminers of Cameraria sp. nov., the dominant macroherbivore on Emory oak, over the 4-yr period. In the 1992–1993 growing season, we monitored survival and mortality of leafmining larvae on the five study trees. We then determined the association of total infections and infections by individual endophyte species with seasonal survival and sources of mortality of leafminers. Infection levels of endophytes varied over the 4-yr period, but seasonal patterns within years were consistent. The three dominant species of endophytes varied differently in frequencies over the growing season. Leafminers were positively associated with endophytic infections in all years. In two of the four years, leaves with living leafmining larvae had greater total infection frequencies than unmined leaves. In one of these years, infection frequencies were greater in leaves with dead larvae than in those with living larvae, suggesting that endophytes may increase mortality of leafminers. However, when infection levels of individual species were compared among leaf types, only levels of Asteromella were greater in mined leaves relative to unmined ones. This difference was explained largely by higher infection levels in leaves with living larvae than in leaves with dead larvae. Furthermore, seasonal changes in endophyte levels varied independently from seasonal changes in leafminer mortality from unexplained causes or natural enemies. We conclude that leafmining activity is associated with higher endophyte infections, but increased infections are not associated with increased leafminer mortality. Higher infections on mined leaves are likely caused by leafmining damage that enhances fungal colonization and penetration into oak leaves. Although endophytes of Emory oak are diverse and abundant and their presence is associated with leafmining activity, we do not find strong correlative evidence that endophytes interact mutualistically with Emory oak by increasing resistance to a dominant herbivore, the leafminer Cameraria. A companion paper (Faeth and Hammon 1997) corroborates experimentally the lack of antagonistic interaction between endophytes and the leafminer.

FUNGAL ENDOPHYTES IN OAK TREES: LONG-TERM PATTERNS OF ABUNDANCE AND ASSOCIATIONS WITH LEAFMINERS

Endophytic fungi inhabiting foliage of woody plants are diverse and abundant, yet little is known of their temporal and spatial variation or their interactions with more commonly studied invertebrate and vertebrate macroherbivores. We studied seasonal and yearly variation in endophyte infections in five Emory oak trees over a 4-yr period from 1989 to 1993. In the 1992–1993 growing season, we documented seasonal patterns of abundance of the three most common fungal endophyte species, an ascomycete, Ophiognomonia cryptica, and two coelomycete species, Plectophomella sp. and Asteromella sp. To determine the association of fungal endophytes with macroherbivores, we compared infection frequencies of endophytes in unmined leaves and leaves harboring living and dead larval leafminers of Cameraria sp. nov., the dominant macroherbivore on Emory oak, over the 4-yr period. In the 1992–1993 growing season, we monitored survival and mortality of leafmining larvae on the five study trees. We then determined the association of total infections and infections by individual endophyte species with seasonal survival and sources of mortality of leafminers. Infection levels of endophytes varied over the 4-yr period, but seasonal patterns within years were consistent. The three dominant species of endophytes varied differently in frequencies over the growing season. Leafminers were positively associated with endophytic infections in all years. In two of the four years, leaves with living leafmining larvae had greater total infection frequencies than unmined leaves. In one of these years, infection frequencies were greater in leaves with dead larvae than in those with living larvae, suggesting that endophytes may increase mortality of leafminers. However, when infection levels of individual species were compared among leaf types, only levels of Asteromella were greater in mined leaves relative to unmined ones. This difference was explained largely by higher infection levels in leaves with living larvae than in leaves with dead larvae. Furthermore, seasonal changes in endophyte levels varied independently from seasonal changes in leafminer mortality from unexplained causes or natural enemies. We conclude that leafmining activity is associated with higher endophyte infections, but increased infections are not associated with increased leafminer mortality. Higher infections on mined leaves are likely caused by leafmining damage that enhances fungal colonization and penetration into oak leaves. Although endophytes of Emory oak are diverse and abundant and their presence is associated with leafmining activity, we do not find strong correlative evidence that endophytes interact mutualistically with Emory oak by increasing resistance to a dominant herbivore, the leafminer Cameraria. A companion paper (Faeth and Hammon 1997) corroborates experimentally the lack of antagonistic interaction between endophytes and the leafminer.

Acorn selection by Mexican jays: a test of a tri-trophic symbiotic relationship hypothesis.

By caching acorns, jays serve as important dispersal agents for oak (Quercus) species. Yet little is known about which acorn characteristics affect selection by jays. In the traditional model of jay/oak symbiosis, large, brown, ripe acorns free of invertebrate parasites (e.g., Curculio acorn weevils) are selected by jays. Recently, it has been suggested that a tri-trophic relationship between oaks, jays, and weevils may have evolved to counter the negative dietary effects of acorn tannins. Under the tri-trophic model, jays would preferentially select acorns containing weevil larvae. We tested the assumptions that (1) acorns containing curculionid larvae exist in sufficient quantities to support jay populations and (2) jays can detect, and preferentially select, acorns containing weevil larvae, and investigated the cues by which jays select acorns. Captive Mexican jays (Aphelocomaultramarina) were presented Emory oak (Quercusemoryi) acorns in aviary feeding trials. Large, dense, viable acorns free of curculionid larvae were preferentially selected. Contrary to results of previous research, color did not affect selection. Acorn viability increased and curculionid larval occupancy decreased in adjacent savannas and isolated stands relative to existing oak woodland, perhaps favoring oak recruitment into adjacent lower-elevation grasslands. Our results compel us to reject the tri-trophic model for this system, and are consistent with the traditional jay/oak symbiosis model. Relatively long-distance dispersal of viable acorns favors Emory oak replacement, and spatial patterns of acorn viability and curculionid parasitism suggest expansion of Emory oak into adjacent low-elevation semi-arid grasslands.

Fungal endophytes and phytochemistry of oak foliage: determinants of oviposition preference of leafminers?

Sedentary insect herbivores, such as gallformers and leafminers, are usually non-randomly distributed among and within host plants. Dispersion of these insects is largely a function of female oviposition choice. In field experiments and observations spanning two growing seasons, we tested the hypothesis that selective oviposition on individual leaves within trees by the dominant herbivore of Emory oak, the monophagous leaf-miner Cameraria sp. nov., is determined by the probability of colonization by endophytic fungi. These fungi are alleged to act as plant mutualists by deterring, killing, or inhibiting the growth of insect herbivores. We found that leaves selected by females for oviposition and paired, unmined leaves were equally likely to be colonized by fungal endophytes. Furthermore, condensed and hydrolyzable tannin levels, purported inhibitors of fungal infection, and protein content did not vary between leaves selected by females and unmined leaves, or between leaves with and without endophyte infections. We conclude that female Cameraria do not choose leaves within trees for oviposition on the basis of propensity for endophytic fungal infection or on phytochemical parameters that might indicate probability of future infections. At this spatial scale at least, fungal endophytes do not explain the highly aggregated distribution of Cameraria among leaves and associated costs in terms of increased larval mortality. Fungal endophytes may, nevertheless, affect leafminer dispersion and abundance at larger spatial scales, such as host plant populations or species. We did find, however, that the amount of mining activity on leaves is positively associated with increased colonization by fungal endophytes. We suggest that mining activity increases endophyte fungal infections by facilitating spore germination and hyphal penetration into the leaf or by altering leaf phytochemistry. The facilitation of endophyte colonization by leafmining activity coupled with the lack of predictability of endophyte infections based on leaf phytochemistry and almost 100% infectivity of all oak leaves during sporadic wet years may prevent female leafminers from discriminating leaves for oviposition on the basis of current or future levels of endophytes in leaves.

Effects of Quercus emoryi on herbaceous vegetation in a semi-arid savanna

Ten trees (5–70 m2 canopy area) were selected to determine effects of tree size (crown area) on herbaceous species composition and biomass in a Quercus emoryi savanna in southeastern Arizona. Consistent with most studies in temperate savannas, herbaceous biomass was reduced beneath the canopy relative to grassland areas. However, tree size appeared to exert no influence over herbaceous biomass. In contrast to most temperate savannas, Q. emoryi trees did not affect distribution of herbaceous species.

Stable carbon isotope analysis of soil organic matter illustrates vegetation change at the grassland/woodland boundary in southeastern Arizona, USA.

In southeastern Arizona, Prosopis juliflora (Swartz) DC. and Quercus emoryi Torr. are the dominant woody species at grassland/woodland boundaries. The stability of the grassland/woodland boundary in this region has been questioned, although there is no direct evidence to confirm that woodland is encroaching into grassland or vice versa. We used stable carbon isotope analysis of soil organic matter to investigate the direction and magnitude of vegetation change along this ecotone. δ13C values of soil organic matter and roots along the ecotone indicated that both dominant woody species (C3) are recent components of former grasslands (C4), consistent with other reports of recent increases in woody plant abundance in grasslands and savannas throughout the world. Data on root biomass and soil organic matter suggest that this increase in woody plant abundance in grasslands and savannas may increase carbon storage in these ecosystems, with implications for the global carbon cycle.

Kluyveromyces bacillisporus sp. nov., a Yeast from Emory Oak Exudate

Three strains of a new diploid species of the genus Kluyveromyces van der Walt emend. van der Walt were isolated from exudates of Emory oak (Quercus emoryi) trees in Arizona. In physiological characteristics and nuclear DNA base composition (38 mol% G+C) these isolates most closely resemble Kluyveromyces africanus and Kluyveromyces delphensis, but the three taxa are genetically unrelated, as shown by DNA reassociation and ribosomal DNA restriction mapping. The morphology of these organisms is typical of the genus Kluyveromyces, except that the mature ascospores (four and occasionally more spores per ascus) are characteristically bacilliform rather than spheroidal, ellipsoidal, or reniform. Mitochondrial DNA (21 mol% G+C) is present in unusually large proportions (ca. one-half of the total DNA). The type strain of Kluyveromyces bacillisporus sp. nov. is strain UWO(PS) 85-349.2 (= ATCC 90019 = CBS 7720).

Germination of two warm-temperate oaks, Quercusemoryi and Quercusarizonica

Quercusemoryi Torr. (emory oak) and Quercusarizonica Sarg. (Arizona white oak) are the dominant trees in many of the oak savannas and woodlands of Arizona and northern Mexico. The objectives of this study were (i) to evaluate germination on two media as influenced by storage and stratification and (ii) to determine the effects of oak canopy and depth of burial on acorn viability and germination. Germination was higher (P < 0.05) on filter paper than in mineral soil in laboratory trials. Maximum germination of Q. emoryi in the field was observed at a depth of 7.5 cm (29%), with only 5% germination at the soil surface. Germination of Q. arizonica at 7.5 and 15 cm (73%) was not different (P > 0.10) but exceeded germination at the surface (17%). These results represent the first reported germination of either species and indicate that recruitment into mature oak woodlands is not limited by germination.

Cultural studies of four North American species of Perenniporia (Aphyllophorales: Polyporaceae)

Perenniporia phloiophila colonizes the dead, outer bark of live oak ( Quercus virginiana ) and is known in the southeastern United States on this host only. On 2% malt extract agar, P. phloiophila has an average growth rate of 5–6 mm day −1 at its optimum temperature range of 30–35 °C. P. phloiophila gives strong oxidase reactions on gallic and tannic acid agar media and does not produce chlamydospores in cultures of single dikaryons or homokaryons. P. medulla-panis has an average growth rate of 6–8 mm day −1 at its optimum temperature range of 30–35°. It has strong reactions on gallic and tannic acid agar media and produces chlamydospores in culture. Vegetative incompatibility between different dikaryotic isolates of P. phloiophila resulted in antagonistic hyphal interactions and dark pigmented zones between opposing isolates. Chlamydospores developed in the interaction zones of incompatible dikaryotic isolates. Self crosses of dikaryons resulted in complete intermingling of isolates with no interaction zone or pigmentation. Incompatible matings of homokaryotic isolates of P. phloiophila have abundant chlamydospores in the interaction zone while chlamydospores are absent in compatible matings of single spore isolates. Chlamydospores occur in all homokaryotic isolates of P. medulla-panis . Both species are heterothallic and tetrapolar. In vitro wood decay abilities of P. phloiophila, P. medulla-panis, P. ohiensis and P. fraxinophila were studied using wood of silverleaf oak, white fir and velvet ash. Percent weight loss (PWL) was greatest on silverleaf oak wood for three of the four species tested. P. medulla-panis caused the greatest PWL on white fir while P. fraxinophila caused the greatest PWL on silverleaf oak and velvet ash wood. Significant ( P = 0·05) differences in PWL occurred with P. phloiophila isolates tested at 25 and 30°. Mycelium of P. phloiophila readily colonized Emory oak bark blocks but only one isolate caused significant PWL.

Effect of Oak Leaf Size on Abundance, Dispersion, and Survival of the Leafminer Cameraria sp. (Lepidoptera: Gracillariidae)

Patterns of relative densities of a dominant leafmining species, Cameraria sp. ( agrifoliella Braun group), on eight trees of Quercus emoryi Torrey were documented over five growing seasons. Relative abundances tended to remain constant among trees throughout the five growing seasons, and densities were consistently greater in the shaded regions of trees than in the sunny regions. To test the hypothesis that variation in leaf size affects colonization, dispersion, and survival of Cameraria sp., equal numbers of leafminers were introduced into field enclosures and allowed to colonize branches varying in mean leaf size. Densities of leafminers were lower and dispersion was more aggregated on small-leaved branches than on large-leaved ones. Mortality of larval leafminers was either inversely density-dependent or density-independent at the spatial scale of the branch. However, log linear analysis showed that survival of leafminers was a negative function of clumping of leafminers among and within leaves. Small-leaved branches and trees appear to be less susceptible to leafminer attack because adult females deposit fewer eggs overall, and eggs are more frequently laid singly on leaves of inadequate size for development or are more frequently clumped on leaves with competing conspecifics. It is suggested that variation in leaf size, coupled with variation in other morphological and phenological traits, acts as a ceiling on densities of Cameraria sp. on Emory oak at the study site by altering dispersion such that interference and exploitative competition increase.

Abundance and mortality of leaf miners on artificially shaded Emory oak

ABSTRACT. We measured solar radiation reaching ten Quercus emoryi Torr. trees and recorded densities of four leaf‐mining insect species on these trees from June until September 1982. The measurements showed that densities of two leaf miner species were negatively correlated with solar radiation. In a field experiment, polypropylene shade fabric was suspended 1.3 m above four experimental trees to test for effects of reduced sunlight. Leaves of experimentally‐shaded trees were heavier and contained lower percentages of proteins and gallotannins than leaves of control, sun trees, while per cent foliar monomeric, polymeric, and total phenols, and water content did not differ between sun and shaded trees. Two of four leaf miner species had greater densities on experimentally‐shaded trees than sun trees. One of these two species experienced lower survivorship on sun trees owing to high levels of death from unknown causes on sun trees. Two leaf miner species had greater densities on sun trees. One of these species had higher survivorship on shaded trees owing to high levels of parasitism on sun trees. We conclude that even subtle differences in shading influences leaf miner density and mortality; however, the effects of shading vary from positive to negative among leaf miner species.

Impact of Irrigation and Experimental Drought Stress on Leaf-Mining Insects of Emory Oak

The hypothesis that drought-stressed trees suffer higher levels of herbivory than unstressed trees was tested experimentally with two as yet undescribed species of Cameraria leaf miners. Densities and site selection of the species differ within a common host plant. Several roots of four trees in a wash were severed and four trees at a more xeric site were irrigated. Densities of leaf miners on the experimental trees and also on four control trees were monitored at each of the two sites.

Yeast communities from host plants and associated Drosophila in southern arizona: new isolations and analysis of the relative importance of hosts and vectors on comunity composition.

The yeast communities from slime fluxes of three deciduous trees (Prosopis juliflora, Populus fremontii and Quercus emoryi) and the necroses of two cacti (Opuntia phaeacantha and Carnegiea gigantea) were surveyed in the region of Tucson, Arizona. In addition, the yeasts carried by dipterans associated with the fluxes or necroses (Drosophila carbonaria, D. brooksae, D. nigrospiracula, D. mettleri, and Aulacigaster leucopeza) were sampled. The results indicate that each host sampled had a distinct community of yeasts associated with it. The dipterans, which can act as vectors of the yeasts, deposited yeasts from other sources in addition to those found on their associated hosts. It is argued that host plant physiology is relatively more important than the activity of the vector in determining yeast community composition. Furthermore, the average number of yeast species per flux or necrosis is not different from the average number of yeast species per fly. It is hypothesized that the vector may affect the number of species per individual flux or not, and that the number is lower than the rot or necrosis could potentially support.

Leaf Size Selection by Leaf-Mining Insects on Quercus emoryi (Fagaceae)

Leaf size selection by four species of leaf-mining insects on their host plant, Quercus emoryi, was studied in central Arizona, USA. Two species (Stigmella sp. and Tischeria sp.) that produced small mines also selected small leaves. One species, Stilbosis juvantis, which has an intermediate-sized mine, did not select larger or smaller leaves than the average leaf size available. Only one species, Cameraria sp. nov., showed a relationship between its survivorship and leaf size; it selected large leaves and experienced greater survivorship on large leaves. Survivorship of the other species was not related to leaf size.

Indirect Interactions Between Temporally Separated Herbivores Mediated by the Host Plant

I tested the hypothesis that early season herbivory by leaf—chewing insects affects distribution, densities, and survivorship of late—feeding, leaf—mining insects; early chewing may physically and chemically alter quality of leaf miners on the shared host plant, Quercus emoryi. Proportions of intact leaves and leaves damaged by native leaf chewers on six control and six experimental trees were determined over two growing seasons. I manually damaged °50% of leaves on experimental trees to increase the total fraction of damaged leaves to °75%. Leaf—miner densities, distribution, survivorship, and mortality were monitored on control and experimental trees and in intact and damaged leaves within trees. Leaf miners occurred more frequently than expected by chance on intact than damaged leaves for both control and experimental trees. Leaf—miner densities did not differ between control and experimental trees. This result suggests ovipositing leaf miners did not discriminate between damaged and undamaged trees, but selected leaves within trees. More leaf miners survived intact than damaged leaves in both growing seasons. Survivorship was less in damaged leaves because of significantly increased rates of parasitism on these leaves. However, death from other causes (including bacterial and fungal death) was significantly less for leaf miners on damaged leaves. This positive effect did not compensate for overall lower survivorship of leaf miners in damaged leaves due to increased parasitism. Survivorship and mortality did not differ between control and experiment trees when damaged and intact leaves were pooled within treatments. However, in 1982—1983, survival was lower and parasitism greater for leaf miners in control—damaged leaves than experimental—damaged leaves. Survival and parasitism were not different between control—intact and experimental—intact leaves. These result suggest that (1) the effect of early season herbivory on leaf miners was inversely density dependent and, (2) occurrence of leaf miners on intact leaves may be caused by avoidance of damaged leaves rather than preference for intact leaves. Early season herbivory caused localized changes in phytochemistry within trees, and these chemical alterations were consistent with observed distributions and survivorship of leaf miners. Both early season herbivory and experimental damage resulted in higher levels of condensed tannins and lower protein content in damaged leaves within trees, but herbivory had no effect on between—tree chemistry differences. Leaf miner distributions correspond to these localized chemical changes: leaf miners avoided damaged leaves within trees but showed no between—tree preferences. Parasitism of miners on damaged leaves was higher, possibly because parasitoids used physical and chemical changes as cues to locate leaf—miner hosts, or because exposure of leaf miners to parasitoids was prolonged. However, when many leaves were damaged (experimental trees), the negative effect of parasites was mitigated because physical and chemical cues associated with damaged leaves were less effective. Lower leaf—miner mortality from other causes may be related to the bactericidal of fungicidal properties of increased tannins in damaged leaves. This study demonstrates that temporally separated guilds can interact subtly at low levels of herbivory through changes in the host plant. Current theories of within— and between—guild organization of phytophagous insects may need to be re—evaluated if such interactions are common.

Selective oviposition by a leaf miner in response to temporal variation in abscission.

We studied within-tree variaton in density and mortality of the leaf miner, Cameraria sp. nov., on Emory oak. Miner densities were lower in the peripheral than the central parts of trees. Following tagged mined and unmined leaves revealed that peripheral leaves fall sooner than central leaves and that more Cameraria mining peripheral leaves die due to abscission than those mining central leaves. We discuss factors that might influence interactions between leaf miners and abscission of the host-leaves they attack.

Experimental Evidence for Intraspecific Competition in a Lepidopteran Leaf Miner

We manipulated field densities of the leaf—mining insect Cameraria sp. nov. (Lepidoptera: Gracillariidae) by caging them on branches of Quercus emoryi in central Arizona to test for intraspecific competition. High density cages (n = 7 replicates) had mean larval densities about 3 times those of low—density cages (n = 3 replicates). Our results demonstrate intraspecific competition in the form of density—dependent larval mortality. While mortality for leaf miners co—occurring on leaves was higher than for those occurring singly on leaves, larval mortality on leaves with multiple mines was just as high in low— as in high—density cages. That is, high mortality in high—density treatments was not related to interactions of larvae co—occurring on leaves. Rather, greater mortality in high density treatments resulted from increased mortality of miners on singly mined leaves in high—density treatments compared to those on singly mined leaves in low—density treatments. We suggest that ovipositing Cameraria compete with one another via interference when searching for leaves of superior quality. Natural field densities of Cameraria were highly variable. We conclude that natural high—density aggregations of Cameraria may result in some intraspecific competition, but, for the most part, Cameraria remains at low levels such that the competitive effect we found would not usually operate. However, intraspecific competition may act as a ceiling that prevents Cameraria aggregation on branches of Emory oak from exceeding the levels we observed in the field. Phytophagous insects that are commonly aggregated may compete to some degree even at relatively low densities, such as those of many leaf miners, if leaf quality (chemical/physical) is variable and leaves superior for insect growth and survival are rare.

Quantitative defense theory and patterns of feeding by oak insects.

Patterns of herbivory over a two year period on Quercus emoryi (Fagaceae) were correlated with seasonal and yearly changes in tannin and protein content. Quantitative defense theory predicts that tannin and protein content in apparent plants should be negatively and positively correlated, respectively, with degree of herbivory. Most herbivory occurred early in the growing season, but the pattern varied between the two years. Tannin and protein content sometimes varied negatively and sometimes positively with degree of herbivory; they did not consistently covary with herbivory. Protein content was positively correlated with herbivory in 1981-1982 but not in 1982-1983. Condensed tannin content was negatively correlated with herbivory in 1981-1982 but not in 1982-1983. Hydrolysable tannin content was positively correlated with herbivory activity. Multiple regression analyses indicated these phytochemical variables explained either no significant variation in herbivory (1982-1983) or did so in a fashion opposite (1981-1982) to the predictions of the theory of quantitative defense.Feeding by oak insects was not solely a function of seasonal changes in quantitative defenses and nutrients. Obviously, population dynamics of the insects are sensitive to factors other than phytochemistry of the trees and I discuss other factors that can influence patterns of herbivory.

Observations on Torvothrips kosztarabi (Thysanoptera: Phlaeothripidae) Inhabiting Coccoid Galls

Observations are given on the biology and protective behavior of Torvothrips kosztarabi Johansen, which inhabits galls of the coccoid Olliffiella cristicola Cockerell on Emory oak, Quercus emoryi Torrey in southeastern Arizona. The galls and their inhabitants are described, including the immature stages of the thrips. The mean frequency of infested galls over several sampling dates in different years was 25%. Twelve other species of arthropods were found in the galls.