Foliage Insect Research Articles

Elevational Distribution of Insect Pollinators

-Based on data from a wide range of locations, including two elevationally distinct sites in Utah, a generalized distribution pattern in the relative importance of various insect taxa as pollinators along elevational gradients emerged. In terms of relative species richness, hymenopterans are generally the dominant pollinators in lowland communities, but yield dominance at higher elevations to lepidopterans or, more often, to dipterans, which usually dominate the pollinator fauna at the highest elevations. Coleopterans are seldom of major significance as pollinators and generally decline in relative species richness as elevation increases. The observed trends for hymenopterans, dipterans and coleopterans have analogous counterparts among foliage insects, suggesting that the distributional patterns are a consequence of life history and thermoregulatory factors rather than selective pressures exerted by changes in flower structure along an elevational gradient. A lack of a generalized distribution pattern among lepidopteran pollinators may indicate that the thermoregulatory factors are less important in determining the elevational distribution of that taxon.

Abundance of Nontarget Foliage-Dwelling Insects After Insecticide Treatment for Adult European Corn Borer (Lepidoptera: Pyralidae)1

Species composition and seasonal abundance of the insect fauna were identified from the foliage of mating and resting sites of European corn borer (ECB), Ostrinia nubilalis (Hubner). A total of 99,519 foliage-dwelling insects was collected during 1983 and 1984. Homoptera, Hemiptera, Hymenoptera, and Diptera accounted for 89% of the total fauna captured. The Chalcididae were the most abundant insects captured from the foliage of action sites. The major herbivores identified from ECB adult action sites were Athysanus argentarium Metcalf, Draeculacephala anticox (Walker), and Leptopterna spp. Coleomegilla maculata (De Geer) and Hippodamia convergens (Guerin-Meneville) were the most abundant predators inhabiting the grassy canopy of ECB adult action sites. Peak predator abundance coincided with early season population peaks of the foliage herbivores. The role of ECB adult action sites as a possible source of predators for Iowa cornfields is discussed. The effects of carbaryl and fen valerate applied for spring- and summer-generation adult ECB control were tested on the foliage-dwelling insects in action sites. Only one species, A. argentarium , was significantly reduced by spring applications of carbaryl and fenvalerate to the foliage of ECB adult action sites. A. argentarium was significantly reduced for 28 d post treatment during 1983 and for 7 d in 1984. Summer adult control had minimal impact on the foliage insects. Foliage predator populations were not negatively affected by the application of insecticides. Therefore, application of carbaryl and fenvalerate for controlling ECB adults in action sites resulted in minimal disruption of the foliage-dwelling insect community.

Soybean Foliage Insects in Conservation Tillage Systems: Effects of Tillage, Previous Cropping History, and Soil Insecticide Application

A 3-yr study was initiated to examine individual and interactive effects of tillage (conventional [moldboard plowing], reduced tillage, and no tillage); previous cropping history (corn, Zea mays L., versus soybeans, Glycine max Merrill); and soil insecticide application (phorate versus none) on insect communities inhabiting soybean foliage. Although, as expected, insect abundance varied seasonally and yearly, there were a number of cropping, tillage, and toxicant effects on herbivore and predator species. Japanese beetle, Popillia japonica Newman, populations were influenced more consistently by previous cropping history, with more beetles following corn, than they were by tillage, although highest beetle density occurred in reduced-tillage systems. Neither tillage treatment, previous cropping history, nor insecticide application significantly affected population density of green cloverworm, Plathypena scabra (F.). Potato leafhopper, Empoasca fabae (Harris), numbers were consistently greater in moldboard-plowed than in either reduced- or no-tillage treatments. Also, soil insecticide application lowered potato leafhopper density during 1 yr of the study. Grasshopper density was lower in moldboard-plowed than in reduced- and no-tillage treatments. Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), were influenced by both tillage and previous crop treatments. Numbers of nabids (dealt with collectively), the most abundant predator collected during the study, were reduced with soil insecticide treatment and were positively affected by no-tillage practice and having soybeans as a previous crop. Results demonstrated that three management practices, tillage, previous cropping history, and soil insecticide application, can all have separate and interactive influences on foliage insect communities on soybeans, even when these practices impact most directly on the soil.

Control of Cabbage Looper and Imported Cabbageworm on Collards with Viruses and Bacillus Thubingiensis Formulations, 1986

Abstract Collards were direct seeded in 4 row plots 20 ft long on 7 Jul. Plants were spaced 2 inches apart in the row and 36 inches between rows. The treatments were arranged in a randomized complete block design with 4 replications. Each row was buffered by a guard row. The soil was a Norfolk “A” loamy sand. All spray treatments were mixed in 0.5 liter of water to which 0.01% of a liquid detergent was added as a spreader and applied with a trombone type garden sprayer calibrated to deliver 30 gal/acre. The nuclear polyhedrosis virus (NPV) treatments were made up to a 0.1% concentration with the respective dye to determine the UV protection value to the virus. All of the virus treated rows also had Artogeia rapae granulosis virus (GV) applied so that damage primarily from cabbage looper could be assessed since the NPVs do not infect the imported cabbageworm. All rows were treated with their respective applications on 11, 18, 25 Aug; 2 and 8 Sep. On 2 and 8 Sep 50 second instar T. ni larve were applied to each of the virus test rows. On 15 Sep the foliage injury ratings and insect counts were taken. Foliage injury ratings ranged from 1-5 and were indexed as follows: (1) 0-3% damage—odd holes on leaves; (2) 4-10% damage—few leaves with holes; (3) 11-25% damage—moderate number of leaves with holes; (4) 26-50% damage—most leaves with holes; and (5) 51-100% damage—crown damage and/or all leaves with holes.

Patch Utilization by Migrating Birds: Resource Oriented?

Use of gap (created by tree falls) and non-gap forest understory sites by migrating birds in central Illinois was studied during spring and autumn for three years (19781980). Fruit and understory foliage were concentrated in gaps. Birds that relied on these resources (foliage-gleaning insectivores, frugivores in autumn) used gaps more than non-gaps. Birds that fed on food other than fruit and foliage insects (frugivores in spring, other insectivores) did not use gaps more than non-gaps. Bird abundance varied markedly among gap and non-gap sites, potentially reflecting differences in site preferences. Site selection, as determined by bird abundances, was consistent (correlated) between years for birds that fed on items that were concentrated in gaps but not for birds that did not rely on these patchy resources. Foliage density is a measure of foraging substrates for foliage-gleaning birds to search. Abundance of foliage-gleaning insectivores was highly correlated with foliage density in both spring and autumn. Frugivore abundance was highly correlated with fruiting foliage density during autumn when they are frugivorous, but not during spring when they are insectivorous. Insectivores not relying on foliage insects or fruit were uncorrelated with either index of resource availability. These same relationships hold even when examining gap sites only. Thus, migrants can be consistent in their selection of foraging sites and this consistency appears to exist when resource densities are markedly different among sites (patchy) but not when resources are more dispersed.

Control of Cabbage Looper and Imported Cabbageworm Larvae on Collards with Insect Viruses and Bacillus Thvringiensis Formulations, 1984

Abstract On 11 Jul collards were direct seeded in Norfolk “A” loomy sand in 4 row plots 20 ft long. Each row was buffered by a guard row. The treatments were arranged in a randomized complete block design with 4 replications. All spray treatments were mixed in 0.5 1 of water to which 0.01% of a liquid detergent was added as a spreader and applied with a trombone type garden sprayer calibrated to deliver 30 gal/acre. Since the nuclear polyhedrosis viruses (NPVs) do not infect the imported cahbageworm all of the micrisporidian and virus treated rows also had Artogeia rapae granulosis virus applied so that damage primarily from cabbage looper could be assessed. All rows were treated with their respective applications on 14, 21, 28 Aug and 5 Sep and on 11 Sep the foliage injury ratings and insect counts were taken. Foliage injury ratings ranged from 1-5 and were indexed as follows:(1) 0-3% damage = odd holes on leaves; (2) 4-10% damage = few leaves with holes; (3) 11-25% damage = moderate number of leaves with holes; (4) 26-50 damage = most leaves with holes; and (5) 51-100% damage = crown damage and/or all leaves with holes.

Ecologically seIective coIoured traps

Abstract. 1. This paper analyses catches of flower thrips, grass thrips and predatory flies in water‐traps of seven colours.2. A correlation is demonstrated between type of host‐plant of thrips and the relative numbers caught by traps of different colours.3. The literature is reviewed and some general relationships with the effectiveness of different trap colours are hypothesized for: non‐grass foliage insects and their predators and parasites; grass foliage insects; flower‐dwelling insects; predators and parasites not associated with foliage; biting insects; and wood‐borers.4. This may permit trap colours to be chosen, in particular circumstances, that are ecologically selective for different types of insect.

Leaf surface specializations of birds and Arthropods in a Panamanian forest.

Most species of Panamanian lowland forest birds specialize on leaf undersurfaces when hunting foliage insects. The few species of leaf surface generalists and leaf upper surface specialists are omnivorous gleaners. We estimate that while over 90% of the avian understory insectivory is directed towards leaf undersurfaces, only 50% of canopy foliage insectivory is directed towards the undersides of leaves. In the low understory we found 70-80% of the arthropods on leaf undersides. The excess use of leaf-bottoms by understory birds may be a result of their greater visibility. It is hypothesized that less proficient insectivores are unable to take advantage of the greater effective density of underleaf insects because they can only efficiently attack the closest leaf surfaces; these closest surfaces will usually be the leaf tops from the branch on which the bird is perched. Alternatively, leaf-top specialists may have special foraging adaptations for overcoming the disadvantages of leaf-top foraging. These adaptations may involve attack behavior (Tachyphonus luctuosus) or searching behavior (Dacnis cayana). Dacnis often used leaf damage as a foraging cue; this may be the first report of a bird using leaf damage for searching for insects. The greater use of leaf upper surfaces by canopy birds may be influenced by four factors: greater seasonality of insects in the canopy favoring omnivores which may be less efficient insectivores; more insects on leaf tops; fewer planar leaf arrangements in canopy plants; or the greater visibility of leaf upper surfaces of the outer shell of foliage of massive trees. Based on the greater number of arthropods on leaf bottoms in the dry season, the higher abundance of smaller insects on leaf bottoms, as well as the greater proportion of insects on leaf tops at cooler higher elevations, we suggest that arthropods prefer leaf bottoms in tropical areas for physiological, not predator avoidance reasons.

The Abundance and Diversity of the Herpetofaunas of Tropical Forest Litter

Quantitative and qualitative samples of amphibian and lizard faunas were taken from forest litter in Costa Rica and compared with similar samples collected in Borneo, the Philippines, and Panama. Animal abundance is about ten times greater in Costa Rican lowland wet forest than in Borneo. Radically different routes and rates of energy flow are postulated to account for the difference. In a series of upland (1010-1425 m) samples in the Philippines, the number of litter lizards and frogs increases with elevation. A single upland (1200 m) Costa Rican sample contains about three times as many animals per 100 m2 as two lowland sites. This increase with altitude correlates well with hypotheses that overall tropical forest productivity is greatest at intermediate elevations. Herpetofaunal densities are greater in wet areas compared to dry sites and flat terrain compared to slopes. These observations are linked to the greater variation and lesser total litter fall in dry sites and/or slopes. The number of species of amphibians and lizards regularly inhabiting the litter is similar in all wet lowland forests studied. Increasing elevation and decreasing rainfall correlate with faunas having fewer species. The former is seen as the result of the differential ability of lowland species to invade uplands, and the latter as a decrease in the kind and duration of frog-spawning sites. Reduced equitability with increasing elevation is principally due to the much greater proportional increase of the commonest species. In the evolution of American and Bornean-Philippine wet lowland faunas, frogs with direct development (Eleutherodactylus) have radiated in the former in the same fashion that skinks have in the latter. SEVERAL RECENT STUDIES have accumulated a large body of data on the density and composition of the reptile and amphibian faunas inhabiting tropical forest litter. Samples are available from undisturbed forest in the Philippines (Brown and Alcala 1961), Borneo (Lloyd et al. 1968), Panam'a (Heatwole and Sexton 1966; Sexton et al. 1964) and Costa Rica (this study). Analysis of the Bornean samples has raised basic ecological questions (Lloyd et ai. 1968), and a detailed comparison and analysis of all of the available data is now appropriate. These studies give an opportunity to make the first quantitative comparisons between Old and New World tropical vertebrate faunas. The techniques are uniform enough to make rough comparisons between numbers of species, distribution of animals among species, and animal densities. There are enough samples to compare: 1) Old and New World wet lowlands and uplands, 2) different altitudes within a single region, 3) different climates in the lowland Neotropics, and 4) different seasons and topography in the same Neotropical area. Most of the samples are drawn from relatively undisturbed forested areas where the faunas are assumed to have achieved some sort of equilibrium, at least with regard to number of species, animal density, and species-abundance relationships. These kinds of comparisons have not been made for any vertebrate group. The only geographically extensive quantitative comparisons of tropical forest faunas have been those of understory foliage insects by Janzen (1973a, b). Many of his samples were taken near the same sites as the Costa Rican herpetofaunal samples reported here.

Sweep Samples of Tropical Foliage Insects: Effects of Seasons, Vegetation Types, Elevation, Time of Day, and Insularity

Detailed data (numbers of species, numbers of individuals, measures of species diversity, evenness, dry weight) are presented on the adult beetles, adult bugs, or all arthropods, in sweep samples from Costa Rican secondary vegetation and primary forest understory during night and day, over a 3,340—m elevational transect, during the wet and dry seasons, and from Caribbean Island secondary vegetation. Adult bugs were found to be reduced much more severely than adult beetles in moving from secondary vegetation to primary forest understory. The number of species and individuals of insects is severely reduced in this transition, though the reduction in number of species is probably an artifact of inadequate samples from the forest understory. There is a strong movement of insects into moist refugia during the dry season, and a strong reduction in numbers of species and individuals during the dry season in areas with a severe dry season. In areas with a very mild dry season, the numbers and species of insects appear to rise during the dry season. There is very low overlap in insect species composition between secondary vegetation and the adjacent forest understory. The numbers of insects and species above intermediate elevations show a general decrease, and intermediate elevations appear to have the highest insect density. This is believed due to a higher harvestable productivity from the plant community at intermediate elevations owing to lowered plant maintenance costs on cool nights.The insect community changes little from day to night, except during the dry season in areas that have a severe dry season. Here there is a dramatic increase in individuals and numbers of species at night, in dry sites with nearby moist refugia. It appears that a high proportion of the insect community passes the dry season as active adults in reproductive diapause. The islands have dramatically reduced numbers of individuals as well as species of insects in both the wet and dry seasons. Part of the large insectivorous lizard community supported by these depauperate islands may be due to the lizards turning vegetarian. In order to digest vegetable matter, lizards probably have to bask in the sun; this exposes them to predators, but lizard predators are absent from the islands.

Sweep Samples of Tropical Foliage Insects: Description of Study Sites, With Data on Species Abundances and Size Distributions

Samples of 800 sweeps each were taken in 25 different Costa Rican and Caribean Island sites in order to analyze community—level structure of foliage—inhabiting insects. Physical environmental data and important biotic features of the sites are recorded. Sampling methods, taxonomic problems in sorting samples, and summary statistics are described. Species abundances and size distributions of the insects are appended. Interpretation of the results of the sweep samples is left for a companion paper (Janzen 1973). See full-text article at JSTOR

Trunk-Implanted Systemics for Control of Foliage Insects on Shade Trees in California

In trials in northern California during 1965—66, implantation at 6-inch intervals around the tree-trunk circumference with either Bidrin® (3-hydroxy-N,N-dimethyl-cis-crotonamide dimethyl phosphate) or oxydemetonmethyl provided effective and long-term control of various aphids on ash, Fraxinus spp., and elm, Ulmus spp., trees. Reductions were only moderate on linden, Tilia cordata Miller, and erratic on birch, Betula spp., and maple, Acer spp. Aphid control on oak, Quercus spp., with Bidrin was poor. Bidrin and oxydemetonmethyl provided effective control of Neoborus spp. on ash and elm leaf beetle, Pyrrhalta luteola (Muller), on elm. Impiant treatment failed to control Empoasca satula Delong on birch, and Stomacoccus platani Ferris and Lithocolletis felinella Heinrich on western sycamore, Platanus racemosa Nuttall. In ash, elm, oak, and sweet gum, Liquidambar styraciflua L., uptake of Bidrin was slower during the period of rapid shoot elongation in the spring than immediately before or after this period. In elm during September, uptake of Bidrin was more rapid during the period 10 AM to 6 PM than at any other time of day or night.

A Study of Summer Foliage Insect Communities in the Great Smoky Mountains

A Study of Summer Foliage Insect Communities in the Great Smoky Mountains

Foliage Insects of Spruce in Canada, by A. W. A. Brown [Review

Foliage Insects of Spruce in Canada, by A. W. A. Brown [Review