Insect-host Relationships Research Articles

Host‐use ability of a population of the herbivorous ladybird beetle Henosepilachna vigintioctomaculata depending on Solanum megacarpum in northern Honshu, Japan

AbstractInvestigating the well‐established relationships between insects and novel host plants will shed light on numerous aspects of evolution and ecology of phytophagous insects. However, in these systems, it is not always clear which plants were originally used as insect hosts, and how the focal insects adapted to the original host(s), before establishing the novel insect–host relationships. Henosepilachna vigintioctomaculata (Motschulsky) (Coleoptera: Coccinellidae) is a well‐known pest of the potato Solanum tuberosum (Solanaceae), however its original host in Honshu, the main island of Japan, before the potato introduction is uncertain. A wild solanaceous weed, So. megacarpum, is the most likely candidate for the original host, although the use of this plant by H. vigintioctomaculata has never been recorded in Honshu. This study reports the occurrence of a H. vigintioctomaculata population depending almost solely on So. megacarpum at Yamagata, northern Honshu. Additionally, the host‐use ability of this population was compared to that of a pest population under laboratory conditions. Based on the results obtained, it is discussed how the properties of beetles on So. megacarpum facilitated the use of the potato, assuming that So. megacarpum was the original host of H. vigintioctomaculata in Honshu.

Fundamental and specialized questions on host race formation and speciation – an introduction

AbstractHost race formation and speciation are at the core of the enormous insect diversification. Insect–host relationships can take many forms, ranging from parasitic to mutualistic. Despite its long history of study, many questions remain about host race formation and speciation. They are addressed in eight original papers of this special issue, including two review‐type articles. In line with the scope of Entomologia Experimentalis et Applicata, they include both fundamental and applied studies. They reveal that host race formation and speciation can take many forms and that they are still active topics of entomological research.

Antibacterial, Antifungal and Mosquitocidal Efficacy of Copper Nanoparticles Synthesized from Entomopathogenic Nematode: Insect–Host Relationship of Bacteria in Secondary Metabolites of Morganella morganii sp. (PMA1)

Antibacterial, Antifungal and Mosquitocidal Efficacy of Copper Nanoparticles Synthesized from Entomopathogenic Nematode: Insect–Host Relationship of Bacteria in Secondary Metabolites of Morganella morganii sp. (PMA1)

Evolutionary genomics of host plant adaptation: insights from Drosophila.

Variation in gene expression in response to the use of alternate host plants can reveal genetic and physiological mechanisms explaining why insect-host relationships vary from host specialism to generalism. Interpreting transcriptome variation relies on well-annotated genomes, making drosophilids valuable model systems, particularly those species with tractable ecological associations. Patterns of whole genome expression and alternate gene splicing in response to growth on different hosts have revealed expression of gene networks of known detoxification genes as well as novel functionally enriched genes of diverse metabolic and structural functions. Integrating trancriptomic responses with fitness differences and levels of phenotypic plasticity in response to alternate hosts will help to reveal the general nature of genotype-phenotype relationships.

Influence of various host plants on the consumption and utilization of food byPieris brassicae(Linn.)

Pieris brassicae (Linn.) is a destructive cosmopolitan pest of cruciferous crops. It is present wherever its host plants occur, and it is considered to be one of the most widely distributed of all the Lepidoptera. We investigated the affect of various host plants on the food consumption and utilization by P. brassicae. We quantified consumption of food, larval duration, pupal duration and weight on cabbage (Brassica oleracea var. capitata), cauliflower (Brassica oleracea var. botrytis), radish (Raphanus sativus), broccoli (Brassica oleracea var. italica) and mustard (Brassica campestris) under laboratory conditions. Insect-host relationships can be better understood by knowing the rate of food consumption, its digestibility and conversion of food eaten to body tissue. The consumption of food generally increased with the advancement of larval age. In our study we found that consumption of food was highest on radish and lowest on broccoli. The highest consumption of a particular host does not always indicate greater suitability of that host, until and unless other factors like consumption index (CI), relative growth rate (RGR), efficiency of conversion of ingested food (ECI), approximate digestibility (AD) and efficiency of conversion of digested food (ECD) are also considered. In the current investigation, factors like CI, RGR, ECI and ECD were highest on cabbage. Low body weight of pupa is associated with rapid development. On cabbage, the weight of pupa of both sexes was found lowest. Thus, from the present study, it can be concluded that cabbage is a more suitable host for P. brassicae than other host plants evaluated. Hence, on cabbage, the values of Waldbauer indices were highest and P. brassicae developed with a faster rate.

A fuzzy-constrained cellular automata model of forest insect infestations

Geographical and ecological processes are complex systems where individual elements interact to create complex behaviour. These systems can be examined with spatially explicit models such as cellular automata (CA) that explain how interactions at the local level lead to global patterns. Tree mortality patterns caused by forest insects provide a good case for CA as local interactions lead to changes at the landscape level. However, problems exist with defining aspects of insect–host relationships that explain the susceptibility of a tree to insect attack. The main objective of this study is to develop a GIS-based CA model of forest insect infestations that incorporates fuzzy set theory in order to obtain information from high resolution remote sensing (RS) images. The model is based on tree mortality patterns caused by outbreaks of mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, in the central interior of British Columbia, Canada. Fuzzy sets are used in order to represent the susceptibility of trees to MPB attack and to acknowledge the uncertainty inherent in dealing with geospatial data. Fuzzy values provide the input for the CA Sub-Model where MPB attack behaviour is constrained by the susceptibility level of trees. The results from the model reflect the process of MPB infestations as described in the literature and exhibit non-linear dynamics expected in ecological processes. This study reveals that fuzzy-constrained CA modelling can provide useful information for forest management in the presence of insect outbreaks.

Integrating high resolution remote sensing, GIS and fuzzy set theory for identifying susceptibility areas of forest insect infestations

The use of fuzzy set theory has become common in remote sensing and geographical information system (GIS) applications to deal with issues surrounding the uncertainty of geospatial datasets. The objective of this study is to develop a model that integrates the concept of fuzzy set theory with remote sensing and GIS in order to produce susceptibility maps of insect infestations in forest landscapes. Fuzzy set theory was applied to information extracted from multiple‐year high resolution remote sensing data and integrated in a raster‐based GIS to create a map indicating the spatial variation of insect susceptibility in a landscape. Variable‐specific fuzzy membership functions were developed based on expert knowledge and existing data, and integrated through a semantic import model. The results from a case study on mountain pine beetle (Dendroctonus ponderosae Hopkins) illustrate that the model provides a method to successfully estimate areas of varying susceptibility to insect infestation from high resolution remote sensing images. It was concluded that fuzzy sets are an adequate method for dealing with uncertainty in defining susceptibility variables. The susceptibility maps can be utilized for guiding management decisions based on the spatial aspects of insect–host relationships.

Insect–host relationships influencing disturbance by the spruce budworm in a boreal mixedwood forest

Demographic data from a 15-year outbreak of the spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), in a boreal mixedwood forest in Ontario, Canada, are used to interpret stand-level ecological disturbance in terms of susceptibility and vulnerability (mortality) of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) BSP). All three host-tree species are highly susceptible for oviposition by the spruce budworm and all are suitable for completion of the budworm life cycle. Host-related differences in susceptibility arise from the degree of synchrony between spruce budworm phenology during the feeding stages and host-tree phenology. Spruce budworm density was highest on white spruce throughout the budworm's life cycle and over the course of the outbreak, but more rapid flushing and growth of current-year buds in white spruce reduced damage relative to that on balsam fir. Conversely, later flushing of current-year buds on black spruce led to a reduction in budworm density early in the season and a corresponding reduction in defoliation. The combination of high budworm densities and severe defoliation caused mortality first on balsam fir. By the end of the outbreak, 89% of the balsam fir component >10 cm DBH was eliminated compared with 49% of the white spruce in the same size class. The lower susceptibility of black spruce resulted in survival of all but the smallest size classes of that species. Nonhost species such as trembling aspen (Populus tremuloides Michx.) nearly doubled their basal area during the outbreak. The results link processes inherent in the insect–host relationship with the population ecology of the insect and the disturbance ecology of the forest.

Population dynamics of bark beetles, with special reference to Ips typographus: contributions of applied bark beetle studies to basic research in ecology and population biology

Ecological is biased towards organisms which are easy to find. Birds and bees are easy to observe, moles and mites are not. Bark beetles are small, undistinguished cryptic insects. Until very recently, virtually all on this group had been stimulated by the impact potential or real of bark beetles on wood production. As noted by S. L. Wood (1986), even taxonomy had been largely left to (or forced upon!) forest entomologists. Recent work on a variety of bark beetle species has demonstrated the potential in this group for exciting comparative or experimental into topics as diverse as the ecological and evolutionary aspects of insect-host relationships (Janzen 1972, Beaver 1979, Cates and Alexander 1982, Raffa and Berryman 1983, Atkinson and Equihua 1986, Stevens 1986, Stenseth 1987), mutualism and symbiosis (Whitney 1982), population dynamics (Berryman 1982, Stenseth 1987; see also Berryman 1988), outbreeding and inbreeding mating systems (Kirkendall 1983), and parthenogenesis (Deyrup and Kirkendall 1983, Lanier and Kirkendall 1986). Scolytids are often quite abundant in appropriate habitats but are easily overlooked, and this may explain why they have gone unnoticed for so long by most ecologists and population biologists. Perhaps publishing this collection of articles funded for the most part as research for a general ecology readership will begin to remedy this situation. Basic is often defended by pointing out that it occasionally spins off something useful. Nevertheless, references by applied work to basic or ecological theory are not very common. However, publications from applied are often ignored or viewed with suspicion by the basic community, for a variety of reasons:

Extinction, reduction, stability and increase: The responses of checkerspot butterfly (Euphydryas) populations to the California drought.

The California drought of 1975-77 has been correlated with unusual size changes in populations of two species of Euphydryas butterflies. Several populations became extinct, some were dramatically reduced, others remained stable and at least one increased. These differences in population dynamic response are not concordant with predictions made earlier that populations with heavy density-dependent mortality should be more stable in the face of drought than unregulated populations. The different responses are related to the fine details of the relationships between the insects and their host plants, relationships which are variable between populations. Revised predictions are given in the light of better knowledge of the variability and complexity of these insect-host relationships. The diversity of responses underlines the dangers of generalizing about "the ecology" of a taxonomic species. The extinctions support the view that such events are frequent and significant in the biology of populations.

Callosobruchus maculatus: Observations of Attack on Cowpeas in Iran1

The high protein content of pulse crops makes them an important staple for human nutrition in developing nations (Aykroyd and Doughty 1964). Cowpeas, Vigna sinensis (L.) Savi ex Hassk., are one such important pulse mostly cultivated in Northern Iran (Kaiser et al. 1968) and can be damaged both in stomge and field by larvae of the cowpea weevil, Callosobruchus maculatus (F.) (Prevett 1961). To better understand the insect-host relationship, studies were begun to determine at what specific stage field-grown cowpea pods are most susceptible to attack from this bruchid and to investigate its biology in storage.

The Description of Insect Numbers1

In economic entomology, particularly forest entomology, the Description of insect numbers in absolute terms may be misleading. The effect of an individual on its host varies tremendously between species and this gives rise to unwarranted comparisons within current systems. The insect-host relationship between Recurvaria starki Freeman and Pinus contorta Dougl. is reviewed lind used as an example in the erection of a three-class system for the description of insect numbers based on the effect of the insect on its host.

THE CALIFORNIA FLATHEADED BORER (MELANOPHILA CALIFORNICA VAN DYKE) IN PONDEROSA PINE STANDS OF NORTHEASTERN CALIFORNIA

This paper reports the findings of studies on the biology of the California flatheaded borer (Melanophila californica Van Dyke). Until comparatively recently this insect had been regarded as a relatively unimportant element of the western pine beetle problem. It has been shown that larval broods may spend a period of up to several years in an incipient stage in the living host tree. During this period the gallery of the incipient stage larva is healed over and the abnormal tissues thus developed interfere with normal conduction in the wood. Undetermined factors associated with the dying of the host tree initiate a fast-growing larval stage in which feeding is voracious and growth rapid.No attempt is made to set forth the role of the species in the complex known as the western pine beetle problem. It is, however, suggested that this insect, at least in northeastern California, may play a more important role in insect caused losses in commercial stands of ponderosa and Jeffrey pine than had previously been believed. The contributions to the knowledge of the biology of the species may assist in an eventual better understanding of insect–host relationships in this particular problem.