Population structure of the boll weevil in cotton fields and subtropical forests of South America: a bayesian approach

The main goal of this contribution is to investigate the genetic structure of boll weevil populations from South America (Argentina and Brazil) and to make further comparisons with a putative source population from USA. Samples were collected in a Paranaense forest under reserve protection, cotton fields and non-cultivated areas. Data from anonymous molecular markers were analysed using both traditional methods of population genetics and Bayesian approaches. Results help to support a previous hypothesis on the presence of two lineages of boll weevil populations in South America: one with characteristics of recent invaders and the other with characteristics of ancient populations. The sample from Urugua-í Provincial Park (Misiones, Argentina) shows the highest percentage of polymorphic loci, the highest values of mean heterozigosity, and the largest number of population-specific alleles, all being typical features of ancient populations. Furthermore, the Urugua-í sample shows two gene pools occurring in sympatry, probably as a consequence of a secondary contact. The remaining samples reveal not only lower percentages of polymorphic loci and heterozygosity values, but also an almost negligible presence of specific alleles. Bayesian methods also suggest the occasional migration of some individuals of ancient lineages from their natural habitats in fragments of the Paranaense forest into cotton fields, and vice versa.     

Reducing boll weevil populations by clipping terminal buds and removing abscised fruiting bodies

Cotton pests damaging fruiting bodies (squares and young bolls) are difficult to control and their damage results in direct yield loss. Small growers, with low technological inputs, represent a large portion of cotton growers worldwide comprising more than 76 countries; they rely mainly on cultural practices to counteract pest attack in their crops. Boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), oviposition involves puncturing cotton squares and young bolls, causing abscission. We examined the impact on boll weevil population of collecting abscised cotton fruiting bodies and clipping plant terminals at 50% boll maturation in the field during two cotton‐growing seasons and under field cage conditions. Greatest numbers of damaged squares occurred ca. 117 days after planting and clipped plants resulted in reduction of abscised structures and adult boll weevils compared with non‐clipped plants, irrespective of cotton variety. Damaged young bolls were found ca. 128 days after planting in 2009 and 2011, but clipping had no effect. Numbers of boll weevils found in plants of the varieties BRS 201 and BRS Rubi (both in 2009) and BRS Rubi (in 2011) were, respectively, 13‐, 17‐, and 20‐fold greater when clipping plus collecting abscised fruiting bodies were not practiced. Furthermore, the average percentage of the boll weevil parasitoid Bracon vulgaris Ashmead (Hymenoptera: Braconidae) emerging from abscised and collected structures was similar between clipped and non‐clipped plant terminals in both seasons. Clipping plant terminals did not result in yield reduction and reduced adult boll weevil production. Collecting abscised reproductive structures, clipping plant terminals, and using both practices together reduced boll weevil populations by as much as 63, 57, and 79%, respectively, in cage trials. Thus, these practices cause significant impact on boll weevil populations and are feasible of adoption, especially for smallholder cotton growers.     

Molecular genetic variation of boll weevil populations in North America estimated with microsatellites: Implications for patterns of dispersal

The boll weevil (Anthonomus grandis Boheman) is an insect pest of cotton that underwent a well-documented range expansion across the southeastern U.S. from Mexico beginning about 110 years ago. Eleven microsatellite loci were surveyed to infer the magnitude and pattern of genetic differentiation among boll weevil populations from 18 locations across eight U.S. states and northeast Mexico. Estimates of genetic diversity (allelic diversity and heterozygosity) were greater in Southern than Northern populations, and were greater in the west than the east among Northern populations. Boll weevil populations were genetically structured as a whole across the geographic range sampled, with a global F _ST of 0.241. South-central populations exhibit classic isolation by distance, but evidence suggests that populations within the Eastern and Western regions have not yet reached genetic equilibrium. Gene flow appears to be relatively high among populations within the Eastern region. Population assignment data and estimates of gene flow indicate that migration between locations separated by < 300 km is frequent. The database of microsatellite genotypes generated in this study now makes it possible, through population assignment techniques, to identify the most likely geographic source of a boll weevil reintroduced to an eradication zone, which will help action agencies decide the most appropriate mitigation response. Kyung Seok Kim - Formerly: USDA-ARS, Areawide Pest Management Research Unit, 2771 F & B Rd., College Station,TX 77845, USA.     

Interaction of Anthonomus grandis and cotton genotypes: biological and behavioral responses

The boll weevil, Anthonomus grandisBoheman (Coleoptera: Curculionidae), is a key pest of cotton, Gossypium hirsutumL. (Malvaceae). Knowledge about boll weevil feeding and oviposition behavior and its response to plant volatiles can underpin our understanding of host plant resistance, and contribute to improved monitoring and mass capture of this pest. Boll weevil oviposition preference and immature development in four cotton genotypes (CNPA TB90, TB85, TB15, and BRS Rubi) were investigated in the laboratory and greenhouse. Volatile organic compounds (VOCs) produced by TB90 and Rubi genotypes were obtained from herbivore‐damaged and undamaged control plants at two phenological stages – vegetative (prior to squaring) and reproductive (during squaring) – and four collection times – 24, 48, 72, and 96 h following herbivore damage. The boll weevil exhibited similar feeding and oviposition behavior across the four tested cotton genotypes. The chemical profiles of herbivore‐damaged plants of both genotypes across the two phenological stages were qualitatively similar, but differed in the amount of volatiles produced. Boll weevil response to VOC extracts was studied using a Y‐tube olfactometer. The boll weevil exhibited similar feeding and oviposition behavior at the four tested cotton genotypes, although delayed development and production of smaller adults was found when fed TB85. The chemical profile of herbivore‐damaged plants of both genotypes at the two phenological stages and time periods (24–96 h) was similar qualitatively, with 30 identified compounds, but differed in the amount of volatiles produced. Additionally, boll weevil olfactory response was positive to herbivory‐induced volatiles. The results help to understand the interaction between A. grandis and cotton plants, and why it is difficult to obtain cotton genotypes possessing constitutive resistance to this pest.     

Survival of boll weevil （Coleoptera： Curculionidae） adults after feeding on pollens from various sources

The survival of overwintering boll weevil, Anthonomus grandis grandis （Boheman）, adults on non-cotton hosts in the Lower Rio Grande Valley （LRGV） of Texas was examined from 2001 to 2006. The success of the Boll Weevil Eradication Program, which was reintroduced into the LRGV in 2005, depends on controlling overwintering boll weevil populations. Laboratory studies were conducted using boll weevil adults that were captured in pheromone traps from September through March. The number of adults captured per trap declined significantly in the field from fall to the beginning of spring （3.5-7.0-fold）. The proportion of trapped males and females did not differ significantly. The mean weight of boll weevil adults captured in September was 13.3 mg, while those of captured adults from November to February were significantly lower and ranged from 6.7 to 7.8 mg. Our results show that boll weevil adults can feed on different plant pollens. The highest longevity occurred when adults were fed almond pollen or mixed pollens （72.6 days and 69.2 days, respectively） and the lowest when they fed on citrus pollen or a non-food source （9.7 days or 7.4 days, respectively）. The highest adult survival occurred on almond and mixed pollens [88.0%-97. 6% after 1st feeding period （10 days）, 78.0%-90.8% after 3rd feeding period （10 days）, 55. 0%-83.6% after 5th feeding period （10 days）, and 15.2%-32.4% after lOth feeding period （10 days）]. The lowest adult survival occurred on citrus pollen [52.0%-56.0% after 1st feeding period （10 days）, 13.3% after 3rd and 5th feeding periods （10 days）, and 0 after 6th feeding period （10 days）]. Pollen feeding is not a behavior restricted to adult boll weevils of a specific sex or physiological state. Understanding how boll weevil adults survive in the absence of cotton is important to ensure ultimate success of eradicating this pest in the subtropics.     

Characterization of microsatellite loci in Brachyderes rugatus,the Canary Islands pine weevil (Coleoptera: Curculionidae)

The Canary Island pine weevil Brachyderes rugatus (Wollaston) consists of four allopatric subspecies that are thought to have arisen from several historic colonization events within the archipelago. We have isolated and optimized seven microsatellite loci from Brachyderes rugatus calvus from Gran Canaria. Six of these loci are polymorphic within B. rugatus (11–22 alleles per locus; heterozygosity between 0.43 and 0.84). There is no evidence for heterozygote deficit within populations or for linkage disequilibrium between pairs of loci. These molecular markers are likely to prove useful tools for quantifying the genetic variability of bottlenecked island populations.     

Characterization of 28 microsatellite loci for the butterfly Bicyclus anynana

We present 28 polymorphic microsatellite loci, including a sex‐linked W‐chromosome marker, for the Afrotropical butterfly, Bicyclus anynana. Our primary motivation to develop these markers was to apply them in quantitative trait loci (QTL) mapping studies. A technique is also proposed that may be useful in avoiding redundant sequences which are common in lepidopteran‐enriched libraries. Pedigree analysis was performed to test Mendelian segregation of the markers and to address the issue of null alleles.     

Development of microsatellite markers in black locust (Robinia pseudoacacia) using a dual‐supression‐PCR technique

Black locust (Robinia pseudoacacia) is an economically and ecologically important tree species in the world. We isolated seven polymorphic microsatellite loci from R. pseudoacacia using a dual‐suppression‐PCR technique. These loci provided microsatellite markers with high polymorphism ranging from three to 12 alleles per locus and expected heterozygosity between 0.538 and 0.944. The markers are now available for more detailed investigation of population genetic structure and pollen and seed dispersal.     

Isolation and characterization of nine polymorphic microsatellite loci from the desert locust,Schistocerca gregaria

Because of the scarcity of polymorphic genetic markers, only a few genetic studies on the population structure of the desert locust, Schistocerca gregaria, have been carried out. We isolated and characterized nine polymorphic dinucleotide microsatellite loci. These markers were evaluated using individuals from Niger and Senegal. Seven of these microsatellite markers are also applicable to the nongregarious subspecies Schistocerca gregaria flaviventris. Cross‐species applicability was limited to one of the loci in the sister species S. americana and in the locust Locusta migratoria.     

Development and characterization of microsatellite markers for a monoecious Ficus species,Ficus insipida,and cross‐species amplification among different sections of Ficus

The animal‐mediated pollination and seed‐dispersal mutualisms of Ficus species give them key roles in tropical ecosystems, but may make them vulnerable to habitat fragmentation. The development of highly polymorphic markers is needed to analyse their genetic diversity and investigate the effects of fragmentation on gene flow. Of thirteen microsatellite loci isolated from Ficus insipida, a monoecious species in French Guiana, eleven were polymorphic (two to six alleles each). High levels of variation were found among loci; expected heterozygosities ranged from 0.151 to 0.715. All markers revealed a broad cross‐species affinity when tested in 23 other Ficus species.     

Isolation and characterization of polymorphic microsatellite markers in Amorphophallus paeoniifolius (Dennst.) Nicolson,Araceae

Amorphophallus paeoniifolius is an herbaceous perennial tuber crop distributed widely in many Asian countries. We isolated 19 polymorphic loci from A. paeoniifolius using a dual‐suppression‐PCR technique. These loci provide microsatellite markers with high polymorphism ranging from three to 24 alleles per locus. The observed and expected heterozygosities ranged from 0.521 to 0.854 and from 0.766 to 0.930, respectively. This high allelic diversity indicates that our markers are suitable for a population study in A. paeoniifolius.     

Polymorphic microsatellite DNA markers from the marine gastropod Littorina saxatilis

Seven polymorphic microsatellite loci are described in the marine intertidal gastropod Littorina saxatilis. Preliminary data on allelic variation of these loci in a White Sea population of L. saxatilis are presented in order to assess their potential utility as high‐resolution genetic markers for this model species.     

Isolation and characterization of 125 microsatellite DNA markers in the blacklip abalone,Haliotis rubra

Australian abalone species are subject to wild harvest and aquaculture production. This study characterized 125 polymorphic microsatellite markers in the blacklip abalone, Haliotis rubra, and evaluated cross‐species amplification in Haliotis laevigata and Haliotis coccoradiata. Segregation analysis of a mapping family revealed non‐amplifying polymerase chain reaction null alleles at 34 loci. Cross‐species amplification was achieved for 89 loci.     

Development of polymorphic microsatellite markers in a perennial herbaceous plant,Polygonum cuspidatum (Polygonaceae)

Six single‐locus, polymorphic microsatellite markers in a perennial herbaceous plant, Polygonum cuspidatum, were developed. Tests to amplify these six loci in another Polygonum species failed, suggesting that the six markers are specific to P. cuspidatum.     

Isolation and identification of 21 microsatellite loci in the Copper redhorse (Moxostoma hubbsi; Catostomidae) and their variability in other catostomids

Catostomidae represent an important family of freshwater fishes mainly distributed in North America, but also found in Eurasia. This paper describes the development of microsatellite DNA markers for a highly threatened member of this family, the Copper redhorse (Moxostoma hubbsi), as well as cross‐catostomids amplifications. 168 tetra‐nucleotide loci were screened to develop 21 polymorphic markers, with an average number of 8.5 alleles per locus and observed heterozygosity ranging between 0.52 and 1.00. Successful amplification was obtained for 12 other members of the family at between seven to 19 loci, with between two to 18 loci being polymorphic per species.     

Isolation and cross‐species amplification of microsatellite loci from the fucoid seaweeds Fucus vesiculosus,F. serratus and Ascophyllum nodosum (Heterokontophyta,Fucaceae)

The Fucaceae is a family of brown seaweeds that dominate and frequently co‐occur on North Atlantic rocky shores. We developed nine polymorphic microsatellite markers for the fucoid seaweeds Fucus vesiculosus, F. serratus and Ascophyllum nodosum using a combined, enriched library. Six of these loci were polymorphic in at least two species, showing from two to eight alleles with heterozygosities ranging from 0.41 to 0.85. Loci were also tested on F. spiralis, revealing five polymorphic microsatellite loci in this species.     

Characterization and PCR multiplexing of polymorphic microsatellite loci for the invasive ant Wasmannia auropunctata

Highly polymorphic genetic markers provide a useful tool for estimating genetic parameters in studies of the evolution of sociality in insects. We isolated and characterized 12 polymorphic microsatellite loci in the invasive ant, Wasmannia auropunctata, and described experimental conditions for PCR (polymerase chain reaction) multiplexing and simultaneously genotyping these loci in two sets of five and seven markers. The number of alleles per locus ranged from two to 14 and the observed heterozygosity ranged from 0.233 to 0.967. Moreover, results of cross‐species amplification tests are reported in three other species of Wasmannia and in two species of the genus Allomerus.     

Isolation and characterization of microsatellite DNA loci from Russell's snapper (Lutjanus russellii)

A total of 37 microsatellite loci from the Russell's snapper, Lutjanus russellii, were successfully isolated and characterized. Thirty‐four loci were polymorphic in L. russellii samples. Twenty of the 37 markers did not differ significantly from Hardy–Weinberg expected genotype proportions. Significant linkage disequilibrium was detected in one pairwise comparison. The numbers of alleles and observed heterozygosities in polymorphic loci ranged from two to 16 and from 0.41 to 0.95, respectively. These markers will be useful for studying the population genetic structure of this species.     

Novel tetranucleotide microsatellite markers from the Del Norte salamander (Plethodon elongatus) with application to its sister species the Siskiyou Mountain salamander (P. stormi)

Eleven tetranucleotide microsatellite loci were developed for the Del Norte salamander (Plethodon elongatus). The loci were variably polymorphic, ranging from two to 20 alleles per locus, with expected heterozygosities ranging from 0.07 to 0.86. The loci also amplified in a congener, the Siskiyou Mountain salamander (P. stormi). The microsatellite loci will be used to assess the utility of highly polymorphic markers to assay within‐ and between‐species differentiation between these two closely related species.