Evaluation of some plant products for the management of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in stored maize (Zea mays) and their effect on nutritional composition of the kernels

The bioactivity of powder from the leaves of Aristolochia ringens, Dalbergia saxatilis, Dioclea reflexa, Ocimum gratissimum, Chrysophyllum albidum, Moringa oleifera, Citrus limon and Newbouldia laevis was tested against the larger grain borer (LGB) in maize kernels and the effect of the powder on the nutritional composition of the kernels was determined. A total of 72 glass bottles containing 100?g maize kernels was divided into four groups. In the first group of 32 glass bottles, 5?g powder of the experimental plants was admixed uniformly with the kernels (5%?w/w). Ten 1–5-day-old LGB adults were introduced into each of the glass bottles. A second group of 32 glass bottles contains 100?g maize kernels admixed with the plant powder as described above, but LGB were not added. In the third group of four glass bottles, 100?g maize kernels received insects only, while in the fourth group of four glass bottles 100?g maize kernels were neither mixed with plant products nor infested with LGB. The treatments were arranged on worktables using completely randomised design and left for three months. The plant products-treated samples (insect free) were passed through a 30?mesh sieve to sieve out the powder and the clean kernels were analysed for proximate composition. The untreated maize kernel had a significantly (p?<?0.05) higher % of grain weight loss (17.33), grain damage % (70.96), number (122.0) of adult LGB, weight (14.46?g) of grain dust and lower % of grain germination. The adsorption and absorption of some of the plant powder by the kernels had significant effect on the kernel composition of protein, fibre and carbohydrate, but not on moisture, dry matter and fat and ash content. Control of LGB with the powder of the test plants could be used as green insecticide for the management of LGB.     

A core set of microsatellite markers for western corn rootworm (Coleoptera: Chrysomelidae) population genetics studies

Interest in the ecological and population genetics of the western corn rootworm, Diabrotica virgifera virgifera LeConte, has grown rapidly in the last few years in North America and Europe. This interest is a result of a number of converging issues related to the increasing difficulty in managing this pest and the need to characterize and understand gene flow in the context of insect resistance management. One of the key components needed for successful population genetics studies is the availability of suitable molecular markers. Using a standard group of microsatellite markers enables researchers from different laboratories to directly compare and share their data, reducing duplication of effort and facilitating collaborative work among laboratories. We screened 22 candidate microsatellite loci against five criteria to create a core set of microsatellite markers for D. v. virgifera population genetics studies. The criteria for inclusion were moderate to high polymorphism, unambiguous readability and repeatability, no evidence of null alleles, apparent selective neutrality, and no linkage between loci. Based on our results, we recommend six microsatellite markers to be included as a core set in future population genetics studies of D. v. virgifera along with any other microsatellite or genetic markers. As more microsatellites are developed, those meeting the criteria can be added to the core set. We encourage other groups of researchers with common interests in a particular insect species to develop their own core sets of markers for population genetics applications.     

Characterization of microsatellite loci in the spruce bark beetle Ips typographus (Coleoptera: Scolytinae)

Ips typographus is an economically important pest of Norway spruce stands. We developed five polymorphic microsatellite markers using a biotin enrichment protocol. The number of alleles ranged from three to 11 per locus and no strong evidence for null alleles was found. Heterozygosity ranged from 0.3 to 0.97. These markers could be useful tools to study the population structure and genetic consequences of I. typographus population outbreaks.     

Five microsatellite DNA markers for the ground beetle Abax parallelepipedus (Coleoptera,Carabidae)

We characterized five microsatellite loci from Abax parallelepipedus, one of the most common forest ground beetles in central Europe. The polymorphism of the loci was assessed in 30 individuals from one population. The number of alleles ranged between two and 19 and the observed heterozygosities between 0.10 and 0.97. No deviations from Hardy–Weinberg equilibrium were detected for any of the markers.     

Isolation and characterization of 16 microsatellite loci in the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae)

We isolated 16 polymorphic microsatellite loci in the mountain pine beetle (Dendroctonus ponderosae Hopkins) and developed conditions for amplifying these markers in four multiplex reactions. Three to 14 alleles were detected per locus across two sampled populations. Observed and expected heterozygosities ranged from 0.000 to 0.902 and from 0.100 to 0.830, respectively. Three loci deviated from Hardy-Weinberg equilibrium in one sampled population. One of these loci may be sex linked. These markers will be useful in the study of population structure in this important pest species.     

Population genetic characterization of the endangered dung beetle Copris tripartitus (Coleoptera: Scarabaeidae) using novel microsatellite markers

The dung beetle Copris tripartitus (Coleoptera: Scarabaeidae) has long been considered an endangered insect in South Korea; the detection of recent population increases leaves its endangered status uncertain. Population genetic analysis subsequent to development of molecular markers is essential for establishing proper conservation strategies. In this study, we developed ten microsatellite markers specifically for C. tripartitus. Sixty-eight individuals of C. tripartitus collected from six South Korean localities were genotyped to validate these markers and preliminarily assess population genetic characteristics. Per-locus observed number of alleles, observed heterozygosity (H_O), and expected heterozygosity (H_E) ranged from 5–12, 0.499–0.958, and 0.54–0.743, respectively. All populations showed higher H_O than H_E, negative values of inbreeding coefficient, and, overall, no sign of recent population bottlenecks (excluding one population, Seosan). This suggests that C. tripartitus did not suffer from genetic drift and inbreeding, which are typically severe in small, isolated populations. Nevertheless, detection of only one of the two gene pools in some populations and resultant genetic subdivision into two population groups may suggest that the population size is not enough to cover both gene pools. Thus, a more extended period of protection may be required to ensure higher genetic diversity of widespread populations and achieve the long-term conservation goal.     

Characterization of microsatellite loci in Amphitmetus transversus (Kolbe, 1897) (Coleoptera,Curculionidae)

We developed six microsatellite markers for Amphitmetus transversus (Kolbe, 1897) (Coleoptera, Curculionidae), a beetle widely distributed in the guineo‐congolian rainforests of east Africa. The numbers of alleles per locus range from three to eight, with a mean number of 4.6. They will be used for population genetic analysis. The ongoing study concentrates on the genetic differentiation and variability of isolated populations in the Kakamega Forest, a highly degraded and fragmented rainforest remnant in western Kenya.     

Characterization of five microsatellite loci in the pine shoot beetle Tomicus piniperda (Coleoptera: Scolytidae)

Tomicus piniperda is a bark beetle that causes damage to various pine species across a wide geographical range. We developed five microsatellite polymorphic markers using an enrichment protocol. All loci could be successfully amplified with no evidence of null alleles and will be useful for population genetic studies. Cross‐species amplifications show that at least some of the markers could be useful in four other Tomicus species.     

Phylogeographic structure of Teretrius nigrescens (Coleoptera: Histeridae) predator of the invasive post harvest pest Prostephanus truncatus (Coleoptera: Bostrichidae)

The invasive larger grain borer Prostephanus truncatus (Horn) is the most important pest of farm-stored maize in Africa. It was introduced into the continent from Mesoamerica in the late 1970s and by 2008 had spread to at least 18 countries. Classical biological control using two populations of the predator Teretrius nigrescens Lewis achieved long-term and cost effective control in warm-humid areas, but not in cool and hot-dry zones. The present study investigated the phylogenetic relationships between geographical populations of the predator. Ten populations of T. nigrescens were studied using randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), sequence analysis of mitochondrial Cytochrme oxydase 1 (mtCOI) gene and ribosomal internally transcribed spacers (ITS) 1, 5.8S and ITS2. The mtCOI variation revealed two clades associated with geographical regions in Central America. It also reveals a significant isolation by distance between populations and considerable genetic shifts in laboratory rearing. RAPD-PCR did not reveal any potential SCAR diagnostic markers. The ITS variation mainly involved insertions and deletions of simple sequence repeats even within individuals. This study reveals the existence of two different mitochondrial lineages of the predator, associated with the geographical origin of populations distinguishable by fixed mutations on the mtCOI gene. The populations of T. nigrescens released in Africa belonged to two different clades from Meso America, namely south (released in West Africa) and north (released in eastern Africa). However, more polymorphic markers are required to clarify the observations in demographic time scales.     

Quantitative trait locus mapping of pyrethroid resistance in Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

Quantitative trait locus (QTL) mapping is a valuable new tool for locating genomic regions that underlie variation in important traits such as insecticide resistance. Because QTL mapping complements a candidate gene strategy for understanding the genetic architecture of important traits, it may also facilitate the identification of genes causing important variation. After mapping the QTL locations, markers closely linked to QTL can be used for genetic analysis of population structure and to measure the spread and increase of resistance-causing QTL alleles. In this study, QTL influencing resistance to the pyrethroid insecticide esfenvalerate were mapped in the Colorado potato beetle Leptinotarsa decemlineata (Say) (CPB). Three QTL contributing to esfenvalerate resistance were identified from a mapping population of 79 individuals analyzed at 90 marker loci. One QTL had a large effect and two QTL had smaller effects. The major QTL occurs on the X chromosome, overlapping the position of a candidate gene (Leptinotarsa decemlineata Voltage sensitive sodium channel [LdVssc1]) previously implicated in pyrethroid resistance. Resistance-increasing alleles at the two minor-effect QTL originated with the susceptible parent, suggesting that alleles of small effect may be segregating in susceptible populations. Comparison of the New York population from which the susceptible parent originated with a more-susceptible population from North Carolina suggests that the minor-effect loci identified here may explain some of the variation in tolerance observed among susceptible populations. DNA sequencing of a portion of LdVssc1 shows that the resistance-conferring allele from the resistant parent does not contain the kdr mutation previously found in CPB and typically observed in other insects that are resistant to pyrethroid insecticides because of changes in this gene.     

Isolation of nine polymorphic microsatellite loci from the burying beetle,Nicrophorus quadripunctatus (Coleoptera: Silphidae)

The burying beetle, Nicrophorus quadripunctatus Kraatz, is a common species in Japan, and its biparental care has been well studied. It exploits small vertebrate carrion as food for its young. Therefore, its reproductive success is restricted to large habitats in which carrion is abundant and available. Hence, the abundance of Nicrophorus species can be used as an indicator of forest fragmentation. Forests have recently become fragmented due to anthropogenic activities, and thus the population sizes of Nicrophorus species have decreased. To investigate the population genetic structure of N. quadripunctatus, we developed polymorphic microsatellite markers using magnetic particles. Nine microsatellites were polymorphic, with two to 12 alleles observed in the samples collected from our study sites, Matsunoyama and Nagaoka A and B. Deviation from the Hardy–Weinberg equilibrium was detected at five to seven loci in each population examined, which is indicative of significant heterozygous deficiencies. Higher genetic diversity was found in the Matsunoyama and Nagaoka B populations, the collection plots of which were covered by continuous woodlands, compared to Nagaoka A. The isolated microsatellite markers will be used to determine the genetic structures of the fragmented populations of N. quadripunctatus.     

Successful development of microsatellite markers in a challenging species: the horizontal borer Austroplatypus incompertus (Coleoptera: Curculionidae)

The analysis of microsatellite loci has allowed significant advances in evolutionary biology and pest management. However, until very recently, the potential benefits have been compromised by the high costs of developing these neutral markers. High-throughput sequencing provides a solution to this problem. We describe the development of 13 microsatellite markers for the eusocial ambrosia beetle, Austroplatypus incompertus, a significant pest of forests in southeast Australia. The frequency of microsatellite repeats in the genome of A. incompertus was determined to be low, and previous attempts at microsatellite isolation using a traditional genomic library were problematic. Here, we utilised two protocols, microsatellite-enriched genomic library construction and high-throughput 454 sequencing and characterised 13 loci which were polymorphic among 32 individuals. Numbers of alleles per locus ranged from 2 to 17, and observed and expected heterozygosities from 0.344 to 0.767 and from 0.507 to 0.860, respectively. These microsatellites have the resolution required to analyse fine-scale colony and population genetic structure. Our work demonstrates the utility of next-generation 454 sequencing as a method for rapid and cost-effective acquisition of microsatellites where other techniques have failed, or for taxa where marker development has historically been both complicated and expensive.     

Multiple cryptic genetic units in Hypothenemus hampei (Coleoptera: Scolytinae): evidence from microsatellite and mitochondrial DNA sequence data

Hypothenemus hampei is the most important insect pest of coffee and has spread to most coffee‐growing countries worldwide. There have been very few studies and none have addressed the population genetics of the beetle using microsatellite markers. In the present study, 683 individuals collected from 37 locations in 18 countries worldwide were screened at nine polymorphic microsatellite loci. Sixty‐five out the 683 and six additional individuals were analyzed on a 400‐bp fragment of the mitochondrial cytochrome oxidase I gene. Bayesian clustering analysis and phylogenetic approaches were used to infer the genetic structure of H. hampei over the sampling that encompassed almost all its range. Microsatellite markers made it possible to achieve sufficiently significant power for the delineation of five morphocryptic evolutionary units. Supported by 27 new COI haplotypes, an unexpected considerably high level of genetic differentiation and genetic divergence was revealed between five geographically delineated clusters. Both markers and approaches showed that the clusters included specimens from (1) Ethiopia, (2) Kenya and Uganda, (3) Brazil, (4) Central America excluding Jamaica, and (5) all samples from Asia, West Africa, and Jamaica. These findings clearly suggest the existence of a ‘species complex in H. hampei’. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 113–129.     

Isolation and characterization of eight polymorphic microsatellite loci for the coconut pest, Brontispa longissima (Coleoptera: Hispidae)

Brontispa longissima is one of the most serious insect pests of coconut in Southeast Asia; it was first discovered on Hainan Island in June 2002. Despite the economic risk associated with this pest, genetic aspects of the invasion process have remained relatively unexplored. Using microsatellite markers, we investigated the population structure, genetic variability and pattern of invasion in various geographic populations. The methodology was based on a modified biotin-capture method. Eight polymorphic microsatellite loci were isolated and characterized for the pest. The allele number per locus varied from 2 to 3 (N = 30). The expected and observed heterozygosities of the eight loci ranged from 0.042 to 0.509 and from 0.042 to 0.963, respectively. Although the frequency of polymorphisms was not very high in this population, the microsatellite loci that were isolated will be useful for investigating the genetic diversity and migration routes of B. longissima populations.     

Population metabolism of Nebria brevicollis (F.) (Coleoptera: Carabidae)

Summary The respiratory metabolism of all life stages of a predatory beetle was investigated. Measurements were made throughout the year in a continuously recording respirometer. The Warburg respirometer was used to examine the relationship between oxygen cosumption and temperature.Respiration was affected by several factors. No periodicity in respiration was observed during the 24 hour period. During the breeding season the males showed a significantly higher respiratory rate than the females. Temperature influence was slightly greater on Instar I and adults in a breeding condition. Laboratory data were adjusted to field rates by using field temperature data and the regressions obtained from respiratory measurements made at different temperatures. Population estimates per m² were low. The seasonal trend in population metabolism was related to temperature. Population density and population production did not follow temperature closely.Population metabolism totalled 1735.95 Joules/m², of which 55.0% was due to adults. The production/respiration ratio (P/R) was 1:1. Total annual energy flux through the beetle population was 3365.13 Joules/m². The larvae accounted for 65% of this total.     

Dynamics ofSitotroga cerealella (olivier) (lepidoptera: gelechiidae) andSitophilus zeamais motschulsky (Coleoptera: Curculionidae) populations in a small bulk of stored corn

The dynamics of Angoumois grain moth, Sitotroga cerealella (Olivier ), and maize weevil, Sitophilus zeamaisMotschulsky , populations breeding in a small bulk (initially 5.36 t) of shelled corn were studied over an 8-year period by monthly sampling. The weevil population showed wide fluctuations in density superimposed on a general decline with time. The moth population showed no upward or downward trend for the first 60 months, although it fluctuated widely. Following a decline that occurred between 56 and 60 months, the moth population fluctuated within a much narrower range, and there was a general decrease in density with time. The decline of the weevil population paralleled deterioration of the corn as did that of the moth population after ca 60 months, and the decline of both species probably resulted from increasing scarcity of suitable breeding sites. Both populations exhibited seasonal variation in density with minima in late summer and early fall, following periods of adversely high temperatures in the storage shed. The populations increased during the fall, leveled off or declined slightly during the winter months, and then increased to maximum levels in late spring or early summer. It thus appears that high temperatures had a greater adverse effect on the populations than low temperatures. The grain moth and the maize weevil both tended to be randomly dispersed at low population levels and moderately aggregated at intermediate and high levels, although the degree of aggregation was not correlated with population density when low population levels were considered separately, and the maize weevil showed a greater tendency for aggregation than did the grain moth. Analysis of individual samples at fixed points in time showed a conspicuous bias for negative correlation between numbers of the two species within sampling quadrats, suggesting a tendency for the two species to segregate within the grain mass. This process could have resulted from behavioral differences or from the destruction of one species by the other. Competitive displacement of the grain moth by the maize weevil has been demonstrated in laboratory experiments but has rarely been observed under natural conditions, and in our study the two species coexisted for 8 years in a relatively small grain bulk.     

Polymorphic microsatellite loci from the western corn rootworm (Insecta: Coleoptera: Chrysomelidae) and cross‐amplification with other Diabrotica spp

Corn rootworms (Diabrotica spp.) make up the major insect pest complex of corn in the US and Europe, and there is a need for molecular markers for genetics studies. We used an enrichment strategy to develop microsatellite markers from the western corn rootworm (Diabrotica virgifera virgifera). Of 54 loci isolated, 25 were polymorphic, and of these, 17 were surveyed for variability in 59 wild individuals. In addition, the potential for cross‐amplification of these microsatellites was surveyed for Mexican, northern, and southern corn rootworms. Nine microsatellite loci showed Mendelian inheritance and are likely to be useful in population genetics studies.     

Mitochondrial nucleotide variability in invasive populations of the root weevil Diaprepes abbreviatus (Coleoptera: Curculionidae) of Florida and preliminary assessment of Diaprepes sp. from Dominica

Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae) is a root weevil introduced into the United States from the Caribbean in 1964. It is associated with >300 plants, including citrus, sugarcane, and potatoes. D. abbreviatus is widespread in Florida, and it has recently been detected in limited areas of California and Texas. The purpose of this research is to evaluate the utility of 16S ribosomal (16S rRNA) and cytochrome oxidase I (COI) mitochondrial markers for the delineation of genetic populations of D. abbreviatus in Florida and for the characterization of patterns of dispersion among these populations. We also assessed these markers as genetic tools for the clarification of taxonomic uncertainties in specimens from Dominica (Lesser Antilles). We analyzed 111 weevils from six Florida populations and six specimens from Dominica. In Florida, we found three haplotypes with only one haplotype in each population. Florida haplotypes differed by one to three nucleotide substitutions, possibly the result of a recent divergence from one source population or three different introductions from closely related populations from the Caribbean. In contrast, specimens from Dominica showed a high genetic variability with three 16S haplotypes and six unique COI haplotypes, delineating two mitochondrial clades. We show that these mitochondrial markers are useful for phylogeographic studies of D. abbreviatus.     

Isolation and characterization of polymorphic microsatellite loci in the boll weevil,Anthonomus grandis Boheman (Coleoptera: Curculionidae)

The boll weevil (Anthonomus grandis Boheman) is a major insect pest of cotton in North America. Dispersal activity poses a threat to ongoing eradication efforts in the US, but little is known about the frequency of long‐distance migration. Nuclear molecular markers are needed to assess gene flow in relation to geographical distance. A biotin‐enrichment strategy was employed to develop microsatellite markers for the boll weevil. Of 23 loci isolated, 14 were polymorphic with three to 10 alleles per locus. Twelve of the polymorphic loci showed Mendelian inheritance and are likely to be useful in population genetics studies.