Sap Feeders Research Articles

Species richness of herbivorous insects on Nothofagus trees in South America and New Zealand: The importance of chemical attributes of the host

Abstract Several studies have evaluated the relative contribution of various host-plant attributes to the species richness of the associated insect herbivores, with and without the inclusion of the phylogeny of the host species for Northern hemisphere trees. In general these studies reached the same conclusion: tree availability (range and abundance) was a good predictor of insect species richness, although chemical attributes of the trees were not tested. The present study evaluates the relative contribution of ecological attributes of host-plant species within the Southern hemisphere genus Nothofagus, to the species richness of their associated insect fauna in South America and New Zealand. The variables included were: area of distribution (a), including longitudinal (rln) and latitudinal ranges (rlt), architectural complexity (c) and phytochemical attributes of the species, including chemical diversity (d) and chemical uniqueness (u). The analysis by independent contrasts revealed that the latitudinal range is an important factor, which explained the insect richness associated with Nothofagus for all guilds and taxonomic orders, except for the sap feeders. Compared to the non-phylogenetic analyses, including host-plant phylogeny led to the inclusion of additional variables in the regression equations. Phytochemical uniqueness of the host plants was an important factor to explain insect species richness. For example, Nothofagus alessandrii, the species with the most unique chemistry, had very few and mostly specialised herbivores, whereas Nothofagus dombeyi, with the least unique chemistry, had the highest number of related insect species. We conclude that, in addition to geographic range and phylogenetic relatedness, studies of insect herbivore diversity must also examine plant chemical composition.

How can alien species inventories and interception data help us prevent insect invasions?

Information relevant to invasion processes and invasive alien insect species management in Central Europe was extracted from two databases: a compilation of two inventories of alien insects in Austria and Switzerland, and a list of interceptions of non-indigenous plant pests in Europe gathered by the European and Mediterranean Plant Protection Organisation (EPPO) for the period 1995-2004. For one-third of the insects established in Switzerland and Austria, the region of origin is unclear. Others come mainly from North America, Asia and the Mediterranean region. Among the intercepted insects, 40% were associated with commodities from Asia, 32% from Europe and only 2% from North America. Sternorrhyncha, Coleoptera and Psocoptera were particularly well represented in the alien fauna compared to the native fauna. In the interception database, Sternorrhyncha were also well represented but Diptera accounted for the highest number of records. Sap feeders and detritivores were the dominant feeding niches in the alien insect fauna. In contrast, external defoliators, stem borers, gall makers, root feeders, predators and parasitoids were underrepresented. Nearly 40% of the alien insects in Switzerland and Austria live only indoors. Another 15% live outdoors but exclusively or predominantly on exotic plants. Less than 20% are found mainly in 'natural' environments. The majority of introductions of alien insects in Europe are associated with the international trade in ornamental plants. An economic impact was found for 40% of the alien insects in Switzerland and Austria, whereas none is known to have an ecological impact. The implications of these observations for further studies and the management of alien species in Europe are discussed.

Composition of Arthropod Species Assemblages in <I>Bt</I>-expressing and Near Isogenic Eggplants in Experimental Fields

The environmental impact of genetically modified (GM) plants in experimental fields has been examined in several ways, in particular with respect to the dynamics of specific nontarget organisms. The approach of sampling for biodiversity in agroecosystems to compare complex patterns could also be useful in studying potential disruptions caused by GM crops. In this study, we set up replicated field plots of Bt-expressing eggplants and near isogenic untransformed eggplants as a control. We monitored the presence and abundance of herbivore and predator arthropods in weekly visual samplings of the plant canopy for three growing seasons (2001-2003). Insect species were pooled in organismal taxonomic units (OTUs); three multivariate methods were used to compare species assemblage as an estimate of insect biodiversity. This multistep statistical approach proved to be efficient in recognizing association patterns, as evidenced by the data for the target species Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) clearly showing a significant association with the control plots. All the analyses indicate a comparable species assemblage between transgenic and near isogenic eggplant areas. Our results suggest that some taxa may warrant more specific study. For example, Alticinae beetles (Coleoptera: Chrysomelidae) were alternatively more abundant in either of the two treatments, and their overall abundance was significantly higher on transgenic eggplants. In light of these results and because of their taxonomic proximity to the target species, these herbivores may represent an important nontarget group to be further studied. Moreover, some sap feeders (e.g., Homoptera: Cicadellidae) were more abundant on Bt-expressing plants in some samples in all 3 yr.

Resistance to insect pests: What do legumes have to offer?

Insect pests are major problems for all crops, worldwide. In this review we will focus on legumes, which are attacked by a range of insect pests including pod/seed feeders, defoliators and sap feeders. We review the history of breeding for resistance to insect pests in legumes, which has had mixed success, and discuss further opportunities in this area. We also review the extraordinary array of direct and indirect mechanisms contributing to insect defence in legumes, the understanding and exploitation of which offer opportunities for both legume and non-legume crops. There is also good potential to improve insect resistance in legume crops through a detailed understanding of the signaling pathways that regulate induced responses to insect feeding, and recent progress in this area, primarily obtained from non-legume systems, is reviewed. The importance legumes play in farming systems, their wide range of novel chemistry and the emergence of model systems suitable for genomic approaches present opportunities for research in this area strongly linked to breeding programs to help develop legume crops with enhanced insect resistance.

Sirococcus clavigignenti‐juglandacearum

<i>Sirococcus clavigignenti‐juglandacearum</i>

Survey of phytophagous insects and foliar pathogens in China for a biocontrol perspective on kudzu, Pueraria montana var. lobata (Willd.) Maesen and S. Almeida (Fabaceae)

A three-year survey of kudzu foliage, seed, stems, and roots for associated phytophagous insects was conducted to establish basic information about the insect communities that kudzu harbors in China and to assess the abundance, diversity and damage caused by these insects. Diseases of kudzu were also surveyed in southern China. A total of 116 phytophagous insect species in 31 families and 5 orders were collected from kudzu in China, in six feeding guilds: foliage, sap, stem, terminal, seed and root feeders. The impact of foliage feeders varied from site to site and year to year, and over the course of the growing season. The mean percent defoliation of kudzu over all plots and years was 13.3 ± 1.9%, but ranged as high as 34%. Two insect species fed on shoots and clipped off terminals. Infestation of new shoots was high, with nearly half of all shoots clipped. Nearly half of the vines showed damage from stem borers, again varying through the season. Two species of insects attacked kudzu roots, mainly the cerambycid beetle Paraleprodera diophthalma (Pascoe), which caused considerable damage to both small (young, <3.4 cm diameter) and large (older, >6 cm diameter) roots. Insects also caused substantial seed damage. Imitation rust, caused by Synchytrium minutum [= S. puerariae (P. Henning) Miyabe], was the most commonly observed disease of kudzu. Several of these species have potential as biological control agents for kudzu in the US.

Importance of canopy herbivores to dissolved and particulate organic matter fluxes to the forest floor

Few studies deal with the origin and contribution of organic matter (OM) fluxes from forest canopies to the variability of DOM and nutrient dynamics in the forest floor. Recent studies indicate a microbial and phytophages origin of OM in the throughfall of temperate forest ecosystems and reported inputs of dissolved (<0.45 μm) organic carbon (DOC) with throughfall range between 40 and 160 kg C ha −1 year −1. Data on particulate organic matter (0.45 μm<POM<2 mm) associated with throughfall fluxes are rare and not often considered in terrestrial ecosystem element budgets. Using field and laboratory experiments, we investigated the direct effects of canopy infestation by two functional groups of herbivores (sap and leaf feeders) on dissolved and particulate organic matter fluxes in throughfall and their impact on forest floor processes. Throughfall fluxes of particulate amino-nitrogen beneath infested spruce were about 60% and those of hexose-carbon beneath infested hardwood trees up to 70% higher compared to uninfested control trees. Corresponding fluxes to filtered samples showed no statistically significant differences. In column irrigation experiments, different levels of aphid infestation (uninfested, moderately, heavy infested) were simulated by adding honeydew to the irrigation solution. Forest floor solution chemistry from forest floor showed a significant reduction in NH 4–N and NO 3–N fluxes, slightly reduced DON fluxes and significantly increased CO 2 effluxes following honeydew application. We suggest that the amount of POM compounds transported with throughfall solution and its subsequent effects on forest floor processes depend on the herbivore functional group and on the level of infestation. From both a quantitative and qualitative point of view, our data indicate that herbivory-mediated organic matter in particulate and dissolved forms contribute considerably to the overall throughfall input of organic substances into the forest floor.

Beetles feeding on bugs (Coleoptera, Hemiptera): repeated shifts from mycophagous ancestors

A review of the literature shows that predation on Hemiptera (mainly Sternorrhyncha) by Coleoptera is widespread in the order, but little understood, even from a biocontrol perspective. Phylogenetic information indicates that feeding on hemipterans evolved predominantly in lineages containing fungus feeders (Derodontidae, Silvanidae, Laemophloeidae, Nitidulidae, Endomychidae, Anthribidae) and whose ancestors were fungus feeders (Coccinellidae) or were sap feeders (cetoniine Scarabaeidae). Other predators on Hemiptera whose ancestry could not be determined unequivocally (predatory/phytophagy or phytophagy/mycophagy) are included in families that contain a large number of species that are mycophagous (Trogossitidae, Mycetophagidae, and Salpingidae). Because changes in diet to feeding on hemipterans have repeatedly occurred in mycophagous taxa, and this shift is not present in other largely predatory groups of beetles, it is presumed that certain preconditions, which have promoted this specialised behaviour, only exist in these lineages. Ancestral associations with sooty moulds that grow on honeydew may have mediated shifts from mycophagy to predation, rather than having ancestors that were predatory and attracted to a novel prey type. Natural history data show that species that prey on Hemiptera also feed on honeydew and sooty moulds and a model is presented for the host shift from mycophagy to feeding on Hemiptera. An annotated list of Hemiptera prey for beetles (exclusive of Coccinellidae) includes records for species in the families Adelgidae, Aleyrodidae, Aphididae, Coccidae, Diaspididae, Kermesidae, Kerriidae, Margarodidae, Membracidae, Phoenicococcidae, and Pseudococcidae.

A Hidden Past: the Hypermetamorphic Development of &lt;I&gt;Marmara arbutiella&lt;/I&gt; (Lepidoptera: Gracillariidae)

Development in Marmara arbutiella Busck is hypermetamorphic, with 3 behaviorally and morphologically distinct larval forms. There are 6–8 sap-feeding and 2 nonfeeding, structurally differentiated instars. The early instars are legless, dorsoventrally compressed, prognathous sap feeders. The 1st of the nonfeeding instars, which we call the transition instar, never issues from the cuticle of the previous (feeding) instar; instead there is apolysis without ecdysis. It is characterized by reduction—the cuticle is transparent, the feeding structures are nonfunctional, and the legs are vestigial. Moreover, the stadium is ephemeral, lasting no ≤24 h. The 2nd nonfeeding stage is a fully legged and ambulatory instar, with rudimentary feeding structures and a functional spinneret. Upon issuing from the mine, this instar spins a cocoon that is elaborately decorated with clusters of 31–114 pearly bubbles that are extruded from its anus and then individually attached to the exterior of the cocoon. We contrast the unique development of Marmara with other gracillariids and interpret the transition instar as an ontogenetic bridge, a stage of risk and metabolic cost without function.

Trophic Control across a Natural Productivity Gradient with Sap-Feeding Herbivores

Experiments examining the role that predators play in controlling herbivore damage to plant biomass are common in ecology. The interactive effect of productivity and predation on standing plant biomass in terrestrial ecosystems, however, remains poorly understood. Here we examine the role of predation and productivity on the damage sap-feeding herbivores inflict on goldenrod. Sap feeders are the dominant herbivores in this community. Sap is poor in nutrients and does not carry many of the chemical defense compounds of goldenrod. Sap-feeders should then be sensitive to changes in productivity and relatively impervious to the production of chemical defenses. We examined the effect of predation and fertilization on goldenrod across a productivity and successional gradient. We found that the effect of predators on controlling herbivore damage increased with increasing productivity. Some of these results are consistent with the Exploitation hypothesis proposed by Oksanen while others seem to reflect alternative mechanisms of trophic control across productivity gradients. Top-down control was strong in high productivity sites while plant competitive interactions may have obscured any pattern of top-down control in intermediate and low productivity sites.

Infection and Colonization of Sugar Cane and Other Graminaceous Plants by Endophytic Diazotrophs

Agriculturally important grasses such as sugar cane (Saccharum sp.), rice (Oryza sativa), wheat (Triticum aestivum) sorghum (Sorghum bicolor), maize (Zea mays), Panicum maximum, Brachiaria spp., and Pennisetum purpureum contain numerous diazotrophic bacteria, such as, Acetobacter diazotrophicus, Herbaspirillum spp., Azospirillum spp. These bacteria do not usually cause disease symptoms in the plants with which they are associated and the more numerous of them, for example, Herbaspirillum spp. and A. diazotrophicus, are obligate or facultative endo-phytes that do not survive well (or at all) in native soil; these are thought to be spread from plant generation to plant generation via seeds, vegetative propagation, dead plant material, and possibly by insect sap feeders. By contrast, Azospirillum spp. are not wholly endophytic but are root-associated, soil-dwelling bacteria that are also often found within plants, probably entering host plants via seeds or via wounds/cracks at lateral root junctions. Endophytic diazotrophs have been isolated from a number of grasses in which significant biological N2 fixation (BNF) has been demonstrated, particularly Brazilian sugar cane varieties, but also in rice, maize, and sorghum. However, although the endophytic diazotrophs are held to be the causative agents of the observed BNF, direct evidence for this is lacking. Therefore, in this review we examine probable sites of bacterial multiplication and/or BNF within endophyte-containing grasses and discuss these in terms of potential benefits (or not) to both host plants and bacteria. In particular, we examine how potentially large numbers of bacteria, especially Herbaspirillum spp., A. diazotrophicus, and Azospirillum spp., can exist extracellularly within non-specialized (for symbiotic purposes) regions such as xylem vessels and intercellular spaces. The processes of infection and colonization of various grasses (particularly sugar cane) by diazotrophic endophytes are also described, and these are compared with those of important (nondiazotrophic) endophytic sugar cane pathogens such as Clavibacter xyli subsp. xyli and Xanthomonas albilineans.

Infection and Colonization of Sugar Cane and Other Graminaceous Plants by Endophytic Diazotrophs

Agriculturally important grasses such as sugar cane (Saccharum sp.), rice (Oryza sativa), wheat (Triticum aestivum) sorghum (Sorghum bicolor), maize (Zea mays), Panicum maximum, Brachiaria spp., and Pennisetum purpureum contain numerous diazotrophic bacteria, such as, Acetobacter diazotrophicus, Herbaspirillum spp., Azospirillum spp. These bacteria do not usually cause disease symptoms in the plants with which they are associated and the more numerous of them, for example, Herbaspirillum spp. and A. diazotrophicus, are obligate or facultative endo-phytes that do not survive well (or at all) in native soil; these are thought to be spread from plant generation to plant generation via seeds, vegetative propagation, dead plant material, and possibly by insect sap feeders. By contrast, Azospirillum spp. are not wholly endophytic but are root-associated, soil-dwelling bacteria that are also often found within plants, probably entering host plants via seeds or via wounds/cracks at lateral root junctions. Endophy...

Influence of feeding guild on insect response to host plant fertilization

Abstract. The densities of insect herbivores in fertilized and unfertilized field plots of goldenrods, Solidago altissima (Compositae), were monitored over a period of 4 years. A total of seventeen insect taxa occurred on the plots over the course of the study, including sap feeders, leaf chewers, leaf miners, leaf gallers and stem gallers with multiple representatives in each of these feeding guilds. Nine of the seventeen taxa significantly increased in density on fertilized plots in at least one year of the study, two taxa showed marginally significant increases on fertilized plots, two significantly decreased in density on fertilized plots in at least one year, and the remaining taxa were unaffected by the fertilizer treatment. The effects of fertilization on the insects were not strongly related to feeding guild; the group of insects that increased on fertilized plots was functionally diverse, and for the most part members of the same guild did not respond to the fertilizer treatment in consistent ways. Differences between fertilized and unfertilized plots were greatest in the fourth year. The insects that showed delayed responses to fertilizer treatment may have been affected by changes in microclimate that developed slowly over the course of the study, suggesting that long‐term studies may be necessary to detect effects of host plant stress on insect herbivores.

Interspecific Interactions in Phytophagous Insects: Competition Reexamined and Resurrected

This review reevaluates the importance of interspecific competition in the population biology of phytophagous insects and assesses factors that mediate competition. An examination of 193 pair-wise species interactions, repre­ senting all major feeding guilds, provided information on the occurrence, frequency, symmetry, consequences, and mechanisms of competition. Inter­ specific competition occurred in 76% of interactions, was often asymmetric, and was frequent in most guil ds (sap feeders, wood and stem borers, seed and fruit feeders) except free-living mandibulate folivores. Phytophagous insects were more likely to compete if they were closely related, introduced, sessile, aggregative, fed on discrete resources, and fed on forbs or grasses. Interference 297 0066-4170/95/0101-0297$05.00 A nn u. R ev . E nt om ol . 1 99 5. 40 :2 97 -3 31 . D ow nl oa de d fr om w w w .a nn ua lr ev ie w s. or g by T ex as S ta te U ni ve rs ity S an M ar co s on 0 5/ 16 /1 3. F or p er so na l u se o nl y. 298 DENNO, McCLURE & OTT competition was most frequent between mandibulate herbivores living in con­ cealed niches. Host plants mediated competitive interactions more frequently than natural enemies, physical factors, and interspecific competition. Sufficient experimental evidence exists to reinstate interspecific competition as a viable hypothesis warranting serious consideration in future investigations of the structure of phytophagous insect communities.

Exploitation of the xylem stream by parasitic organisms

A taxonomically diverse group of angiosperms and certain homopteran insects derive water, inorganic and organic solutes from angiosperm xylem sap. Parasitic angiosperms are connected to their host(s) by a specialized organ (the haustorium) and form close cellular contacts with host xylem tissue, while insects tap xylem vessels by means of stylets. Adaptations to phytophagy are discussed with respect to gaining access to xylem tissue and the nutrition of sap feeders. Parasitic angiosperm-host interactions are examined in relation to recent advances in our understanding of root-to-shoot communication via the xylem (the influence of host-sourced signals on the parasite) and the functional significance of high rates of transpiration in parasitic angiosperms.

Types of Parasitoid-Induced Mortality, Host Stage Preferences, and Sex Ratios Exhibited by Pnigalio flavipes (Hymenoptera: Eulophidae) Using Phyllonorycter elmaella (Lepidoptera: Gracillariidae) as a Host

The different types of parasitoid-induced mortality, host stage preferences, and sex ratio exhibited by Pnigalio flavipes (Ashmead) to its host, Phyllonorycter elmaella Doganlar & Mutuura, was investigated in commercial apple orchards in central Washington. The parasitoid-induced mortality of Phyllonorycter elmaella consisted on average of 57.2% host stinging with oviposition, 32.7% host feeding, and 10.1% host stinging without oviposition. Pnigalio flavipes laid eggs on Phyllonorycter elmaella tissue feeders (fourth and fifth instars) an average of 5.4 times more than it did on sap feeders (first-third instars), but host-fed on sap feeders an average of 12.1 times more than on tissue feeders. When healthy tissue feeders became scarce late in the season, Pnigalio flavipes began to lay eggs on previously attacked tissue feeders (superparasitize) and then switched to laying eggs on sap feeders. The sex ratio (M:F) of Pnigalio flavipes reared from tissue feeders was almost 1 to 1. Only male Pnigalio flavipes were reared from sap feeders.

Temporal Distribution of Phyllonorycter elmaella (Lepidoptera: Gracillariidae) and Its Major Parasitoid, Pnigalio flavipes (Hymenoptera: Eulophidae), in Washington Apple Orchards

The seasonal occurrence of Phyllonorycter elmaella Doganlar & Mutuura, a tentiform leafminer, and its parasitoid, Pnigalio flavipes (Ashmead), in insecticide-free blocks located in commercial apple orchards was determined. P. elmaella had three complete generations each year; population densities increased in each generation. P. elmaella sap feeders (first to third instars) were “abnormally” abundant in the blocks at the end of each season, possibly because of a delay in their development. P. flavipes had at least the same number of generations as P. elmaella . Parasitoid activity decreased as the season progressed. Phenology data showed adult P. flavipes emerged almost concurrently with adult P. elmaella during the spring and summer generations, 2–3 wk before tissue feeders (fourth and fifth instars), were present in the orchard. This emergence pattern may be caused by a reproductive advantage for female P. flavipes to feed on sap feeders before oviposition. The number of individuals of P. elmaella that are able to overwinter successfully, rather than the seasonal levels of parasitism, seems to determine the leafminer's year-to-year population dynamics. However, parasitoid activity reduced the leafminer's intraseasonal population increase and kept its densities below treatment threshold levels in all orchard blocks examined.

Arthropod Faunas of Monocultures and Polycultures in Reseeded Rangelands

Sap-feeding and predaceous arthropod faunas of forage bunchgrasses in reseeded rangeland vegetation were examined. Four major species of sap feeders were found; the major predators were spiders. Grass monoculture had very high densities of sap feeders compared with grass biculture, shrub-grass, tree-grass, and native areas; this was reflective of the large contribution from the mirids Irbisia brachycera Uhler and Conostethus americanus (Knight). They were present during the leaf stages of crested wheatgrass when it had its lowest carbohydrate root reserves. Homoptera and predator densities were not significantly related to the pattern of vegetation. The lowest number of sap-feeder species occurred in the grass monoculture, and sap-feeder faunas in this plot were dissimilar to those of all other plots. One-season dispersal experiments did not support the hypothesis that grass density caused the differences between arthropod faunas in different vegetation, whereas big sagebrush, common in reseeded pastures, repelled I. brachycera during short-term dispersal. The data indicate that reseeding to monocultures may result in high densities of Miridae during the leaf stages compared with moderate densities of Homoptera during the flower and seed stages in bicultures. The implications for pest management are discussed.

PHYTOPHAGOUS INSECTS ASSOCIATED WITH CULTIVATED MARIJUANA, CANNABIS SATIVA, IN NORTHERN MISSISSIPPI

During the growing seasons of 1983 and 1985, a general survey of insects associated with cultivated marijuana, Cannabis sativa, on the University of Mississippi campus was conducted. Of the species collected that were using the plants for food, the majority (43) were sap feeders, 15 were leaf chewers, nine ate or gathered pollen and one was possibly a root feeder. Only sap feeders appeared to be successfully reproducing on the marijuana. Species collected in greatest abundance were Agallia constricta and Graphocephala versuta (Cicadellidae), Spissistillus festinus (Membracidae), Clastoptera xanthocephala (Ceropidae), Halticus bractatus (Miridae), Systena elongata (Chrysomelidae) and Schizocerella pilicornis (Argidae).

Potato pests in India and their control

Abstract Potatoes are reported to be attacked by more than 80 insects and many nematode pests in the field and in store in India. They can be broadly classified into soil pests, sucking pests and sap feeders, defoliators and storage pests. Nematode pests are mainly classified into the root knot nematodes and the cyst‐forming nematodes. This article deals with their identification, damage, biology and control measures.