Progeny Ratios Research Articles

Lethal and sublethal effects of selected insecticides and an insect growth regulator on the boll weevil (Coleoptera: Curculionidae) ectoparasitoid Catolaccus grandis (Hymenoptera: Pteromalidae).

A laboratory culture of Catolaccus grandis (Burks), an ectoparasitoid of the boll weevil, Anthonomus grandis grandis Boheman, was exposed to lethal and sublethal doses of insecticides and an insect growth regulator using a spray chamber bioassay. Materials tested were azinphos-methyl, endosulfan, fipronil, malathion, cyfluthrin, dimethoate, spinosad, methyl parathion, acephate, oxamyl, and tebufenozide. At full rates, spinosad was significantly less toxic to female C. grandis than other treatments except endosulfan. Fipronil and malathion were significantly more toxic to females than other treatments. Most of the chemicals tested were highly toxic to male C. grandis; spinosad was least toxic. At reduced rates, most of 4 selected chemicals tested were low in toxicity to C. grandis; however, a reduced rate of malathion was significantly more toxic to females than other treatments. No C. grandis pupae developed from parasitism during a 24-h treatment period with malathion or spinosad. The sex ratio of progeny from sprayed adults appeared to be unaffected by the treatments.

Haldane's rule and other aspects of reproductive isolation observed in the Anastrepha fraterculus complex (Diptera: Tephritidae)

Some aspects of reproductive isolation between allopatric populations of two closely related species of the Anastrepha fraterculus complex (A. fraterculus sp. 1 and sp. 2) were evaluated in laboratory conditions. Most of the crosses were fertile in each species as well as between sp. 2 females and sp. 1 males. In the reciprocal cross only 41.7% of the matings yielded viable progeny. Egg hatching occurred at similar rates within the two species, but was significantly lower in the crosses between the species. Adult emergence did not differ significantly among crosses. The sex ratio of adult progeny within each species, as well as in the hybrid progeny derived from sp. 1 females crossed to sp. 2 males, did not differ from the expected 1:1 ratio. However, in the crosses between sp. 2 females to sp. 1 males, a significant deviation in the sex ratio in favor of females was observed, according to the Haldane's rule. The results reinforce previous data which indicated that A. fraterculus sp. 1 and A. fraterculus sp. 2 are distinct biological entities.

Life History of Bracon hebetor (Hymenoptera: Braconidae) on Plodia interpunctella (Lepidoptera: Pyralidae) on a Dried Vegetable Commodity

Life history of Bracon hebetor Say was studied on Plodia interpunctella Hübner. The life span of female (mean±s.e.) was estimated to be 20.88±0.97 days. The females laid eggs from the first day on after emergence and the oviposition period ranged from 11 to 27 days. But 65% of the total eggs were laid in the first 10 days. The progeny sex ratio (female/total) in the first 15 days was female-bias ranged from 0.51±0.08 to 0.88±0.02, but changed into male-bias ranged from 0.14±0.04 to 0.34±0.12. The overall sex ratio of progeny produced per female was estimated to be 0.66. Total number of progeny per female and net reproduction rate were estimated to be 205.17±13.03 and 136.21, respectively. Other life table statistics were presented.

Effects of Protect-It on Efficacy ofAnisopteromalus calandrae(Hymenoptera: Pteromalidae) Parasitizing Rice Weevils (Coleoptera: Curculionidae) in Wheat

The parasitoid Anisopteromalus calandrae (Howard) was very sensitive to direct contact with Protect-It, an inert dust formulation containing 90% diatomaceous earth and 10% silica aerogel. LT 50 s at room temperature and humidity were 49 min (95% CL = 48-51) and 72 min (95% CL = 69-74) for males and females, respectively, in petri dishes containing 2.5 mg dust per square centimeter. Under the same conditions, adults of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), a host of A. calandrae, were much less sensitive. Mortality of S. oryzae after a 24-h contact period was 50% for females and 62% for males. When tested in no-choice laboratory bioassays at 27°C, label rates of Protect-It (200 and 400 ppm) dusted onto hard red winter wheat, Triticum aestivum. L. (13.9% moisture content) that was infested with immature rice weevils reduced the longevity of parent A. calandrae females and significantly reduced parasitization of the weevils at 3 tested humidities, 43, 60, and 75% RH. Parasitoid progeny production was also significantly reduced. At 75% RH, 92.8 ± 2.9 parasitoid progeny were produced in untreated wheat compared with 12.6 ± 2.6 progeny in the treated wheat. Sex ratio of parasitoid progeny was not significantly affected by the dust treatments at any relative humidity. In two-choice tests in divided petri dish arenas, single A calandrae females showed a strong avoidance of Protect-It-treated wheat and a significant preference for parasitizing weevils in untreated wheat. However, significantly more parasitoid progeny were produced in dishes in which one-half contained Protect-It-treated wheat and the other half contained untreated wheat compared with dishes in which both halves of the divided dishes held untreated wheat. Reasons for the Protect-It-stimulated oviposition response by A. calandrae are not known, but may be related to stress induced by the dust. In separate tests, there was no significant difference in emergence of weevils from treated or untreated wheat, regardless of the weevil age at time of dusting, or the relative humidity at which the dusted wheat was maintained. Our studies provide evidence that any natural control of pest insects exerted by local populations of parasitoids, or enhanced biological control by augmentative releases of parasitoids, would be adversely affected by the use of Protect-It or other diatomaceous earth products on stored grain.

SELECTION OF TRICHOGRAMMA SPECIES FOR CONTROLLING THE DIAMONDBACK MOTH PLUTELLA XYLOSTELLA(L.)

Abstract The parasitization of twenty‐nine species or strains of Trichogramma and Trichogrammatoidea on the eggs of diamondback moth (DBM), Plutella xylostella(L.), was tested in the laboratory. Five indexes were evaluated: proportion of female wasps of egg‐laying, the number of parasitized host eggs by each female wasp, survival ratio of progeny in each host‐egg, emergence ratio and sex ratio of offsprings. The results showed that 23 species or strains were able to parasitize the eggs of DBM and significant difference was found not only between species but also between strains. According to the five indexes, T. trijapitzni (from former USSR), T. pretiosum (from USA), T. nagarkattii (from France), Trichogrammatoidea bactrae(from Taiwan, China), T. chilonis (from Guangdong, China), and T. sp. (from France) showed better performance, among which T. pretiosum, Trichogrammatoidea bactrae and T. chilonis(Guangdong)were considered as suitable candidates to control DBM in the field.

Inheritance of gramine content in barley

The inheritance of gramine indole alkaloid was studied in F1 and F2 generations derived from crosses between wild ( Hordeum vulgare subsp. spontaneum) and cultivated ( H. vulgare subsp. vulgare) barley at adult stage in the field. The means of gramine content were very low in F1s and F2s in April and May. The ratio of progeny containing gramine to those without gramine (near zero or undetectable) fit a mono-genic or di-genic model in F2 generation. However, the content of gramine might be controlled by minor genes in the gramine-containing plants. The direction of dominance was toward lower gramine content. The averages of dominance ( h/d) in F1 and F2 ranged from partial to complete. Broad-sense heritabilities were high (0.70 to 0.77). The usefulness of hybrids for breeding aphid resistance and possibility increasing palatability of grazing pasture for sheep and cattle is discussed.

The effect of varying Bemisia argentifolii and Eretmocerus mundus ratios on parasitism

We investigated the effects of different host: parasitoid ratios on the efficacy of the parasitoid Eretmocerus mundus attacking the silverleaf whitefly, Bemisia argentifolii. When host density was held constant (100 second instars) and parasitoid density was decreased from 15 to 1 females, the percentage of total host mortality was significantly lower at low parasitoid densities. The number of host nymphs killed, and the number of female parasitoid progeny per female, increased 3.6 and 20.4 times, respectively. The emergence rate, sex ratio, longevity, and body lengths of progeny were significantly larger at the lowest parasitoid density while developmental time was significantly shorter. When the number of hosts was increased from 5 to 250 and parasitoid density was held constant (5 females), the percentage of nymphal mortality decreased 1.6 times. The percentage of desiccated nymphs was significantly highest (65.7%) at the lowest host density, while percentage parasitism (34.3%) was significantly lowest at the lowest host density. The data could be described using a Type I functional response curve. We propose a generalized index of efficacy (GIE) to summarize and compare the total effects of parasitoid--host ratios. This index showed that the most efficient ratio was one parasitoid female per ten second instar host nymphs.

Effects of Pieris host species on life history parameters in a solitary specialist and gregarious generalist parasitoid (Cotesia species)

AbstractHost specificity and host selection by insect parasitoids are hypothesized to be correlated with suitability of the hosts for parasitoid development. The present study investigates the correlation between host suitability and earlier studied host‐finding behaviour of two closely related braconid larval parasitoid species, the generalist Cotesia glomerata (L.) and the specialist C. rubecula (Marshall) (Hymenoptera: Braconidae). We compared the capability of both parasitoid species to parasitize and develop in three Pieris host species, i.e. P. brassicae (L.), P. rapae (L.) and P. napi (L.) (Lepidoptera: Pieridae). In laboratory experiments, we measured the effect of host species on fitness parameters such as survival, development, sex ratio and size of parasitoid progeny. The results show that C. glomerata is capable of developing in the three host species, with significant differences in parasitoid survival, clutch size and adult weight among Pieris species. The host range for development was more restricted for C. rubecula. Although C. rubecula is physiologically able to develop in P. brassicae larvae, parasitoid fitness is negatively affected by this host species, compared to its most regular host, P. rapae. A comparison of the present data on host suitability with earlier studies on host‐searching behaviour suggests that the host‐foraging behaviour of both parasitoid species not only leads to selection of the most suitable host species for parasitoid development, but also plays a significant role in shaping parasitoid host range.

Identification of a RAPD marker linked to sex determination in the basket willow (Salix viminalis L.)

In many dioecious plants, gender influences economic value, breeding schemes, and/or opportunities for commercial use of genetically transformed materials. The objective of this study was to identify molecular markers linked to sex determination loci in the dioecious plant Salix viminalis L. A 4 3 4 factorial mating design was used to identify sex ratios in full-sibling progeny, to generate a working genetics model for segregating sex ratios, and to search for molecular markers linked to sex determination genes. Bulked segregant analysis, utilizing 380 arbitrary decamer primers to generate randomly amplified polymorphic DNA (RAPD) products was initially applied to progeny sets from 3 of the 16 full-sibling families. Of the 1080 RAPD bands examined, only a single 560 bp band was shown to be linked to a sex determination locus. The same 560 bp band occurred in three additional fullsibling families and was present in one female parent and one male parent involved in the factorial mating design. This marker, UBC354560, is biparentally inherited, is associated with femaleness in certain genetic backgrounds, and is linked to allele A1 in the proposed two-locus epistatic genetic model of sex determination for S. viminalis. Southern blots confirmed marker homology among progeny and parents used in this study.

Bayesian procedures for discriminating among hypotheses with discrete distributions: inheritance in the tetraploid Astilbe biternata.

Discrimination between disomic and tetrasomic inheritance aids in determining whether tetraploids originated by allotetraploidy or autotetraploidy, respectively. Past assessments of inheritance in tetraploids have used analyses whereby each inheritance hypothesis is tested independently. I present a Bayesian analysis that is appropriate for discriminating among several inheritance hypotheses and can be used in any case where hypotheses are defined by discrete distributions. The Bayesian approach incorporates prior knowledge of the probability of occurrence of disomic and tetrasomic hypotheses so that the results of the analysis are not biased by the fact that there is a single tetrasomic hypothesis and multiple disomic hypotheses. This analysis is used to interpret data from crosses in the tetraploid Astilbe biternata, a herbaceous plant native to the southern Appalachians. The progeny ratios from all crosses favored the hypothesis of disomic inheritance at both the PGM and slow-PGI loci. These results support earlier cytogenetic evidence for the allotetraploid origin of Astilbe biternata.

Quantitative trait dissection analysis in Eucalyptus using RAPD markers: 1. Detection of QTL in interspecific hybrid progeny, stability of QTL expression across different ages

The objective of this study was to use random amplified polymorphic DNA (RAPD) to determine the genetic location and effects of genomic regions controlling wood density, stem growth and stem form in two species of Eucalyptus. Two hundred F1 trees generated from an interspecific cross E. urophylla×E. grandis between two elite trees were used. Genetic maps were constructed for each parent with markers segregating in the 1:1 ratio in FS progeny. A total of 86 and 92 markers distributed among 11 linkage groups covered 1295 cM and 1312 cM for the E. urophylla and E. grandis parent, respectively. Traits were measured three times up to selection age (38 months). The magnitude of the phenotypic variation explained by the joint action of the segregating quantitative trait alleles indicated that genetic factors of large effect were involved in the control of the studied characters. Several regions controlling part of the variation for the studied traits were identified by interval mapping. Some regions of the genome exerted effects on more than one trait, providing a genetic explanation for at least some of the correlation between the traits. On the basis of an age-by-age analysis, a partial stability of QTL expression was observed with 68% of the QTL being expressed at two ages and 32% being age-specific. No QTL were significant for all three ages. Taking advantage of repeated measurements on the same material across different ages, we investigated with a maximum statistical power, the effect of marker genotype on traits, with age and QTL×age interaction effects being removed. A two-way analysis of variance made it possible to detect significant marker-trait associations over the period studied. Most of them had already been detected in the annual analysis. This result is very encouraging for the application of marker information to the early selection of hybrid trees to be vegetatively propagated for the production of clonal varieties.

Female size and fitness in the leaf‐cutter bee Megachile apicalis

1. The effects of female size on fitness of the leaf‐cutter bee Megachile apicalis Spinola (Hymenoptera: Megachilidae) were examined using artificial nesting sites in the field.2. Although female size had no significant effect on female longevity or sex ratio of progeny, it did have a significant effect on fecundity; larger females attained greater realized fecundity than did smaller females.3. This significant effect of female size on fecundity occurred because larger females produced cells faster than did smaller females.4. Female size also had a significant effect on egg size; larger females laid larger eggs than did smaller females.5. Female size had a significant effect on the size of investment in each progeny. The size of investment estimated by brood cell weight was greater for larger females than for smaller females. This pattern was largely absent, however, when the size of investment was estimated by adult progeny weight.6. Female size had a significant effect on nest usurpation behaviour; larger females had a higher capacity to usurp nests than did smaller females.

Genetic Analysis of Avirulence/Virulence of an Isolate of Magnaporthe grisea from a Rice Field in Texas

ABSTRACT An isolate of Magnaporthe grisea, Tm4, from a rice field in Texas was crossed with a fertile laboratory strain, 70-6. The progenies showed segregation of avirulence/virulence on rice cvs. Newbonnet, Lemont, Lebonnet, Leah, and Katy. The avirulent/virulent segregation ratios were 29:6 on Newbonnet, Lemont, and Lebonnet; 28:7 on Leah; and 33:2 on Katy. There was cosegregation on the first three cultivars. Several avirulent progenies were backcrossed to virulent parent 70-6. Three generations of backcrossing avirulent progenies to 70-6 led to segregation ratios that suggested certain strains had only one avirulence gene. Strains avirulent only on cv. Katy or only on cvs. Newbonnet, Lemont, and Lebonnet were test crossed with virulent siblings. Strains that gave progeny ratios approximating 1 avirulent:1 virulent when crossed with virulent siblings were selected for further test crossing. Intercrosses between strains with possible single avirulence genes were made to determine whether these strains had the same or different avirulence genes. Many lines still segregated two genes for avirulence after three generations of backcrossing. This is based on the recovery of virulent progenies from crossing two avirulent siblings.

The use of transposable P-elements of Drosophila melanogaster for introductory genetics laboratory courses.

Laboratories in introductory genetics courses often use Drosophila melanogaster as a tool for the students to understand how genes are transmitted and mapped. We demonstrate three advantages of using P-element containing inserts with the wild-type alleles of the genes to be mapped. First, inserts can be positioned at many places in the genome with relative ease; second, stocks can be chosen which have excellent viability; and third, inserts can be selected for precision in mapping with regard to marker genes. The results of a preliminary test with a beginning genetics laboratory are presented. The inserts exhibit excellent Mendelian ratios in F2 and backcross progeny and were reproducibly mapped by different student groups.

Fecundity, Longevity, and Sex Ratio ofGoniozus nigrifemur(Hymenoptera: Bethylidae)

Abstract Longevity, fecundity, and sex ratio of progeny at emergence of Goniozus nigrifemur Ashmead, a gregarious ectoparasitic bethylid, were investigated. Males lived 17.5 ± 5.8 (95% CI) days. Females provided with pink bollworm hosts lived 90.2 ± 17.4 days, while females deprived of hosts lived only 41.5 ± 7.1 days. Females provided with hosts oviposited an average 184.42 ± 33.94 eggs during their lifetime. While the number of eggs in a clutch was positively associated with the number of males in a clutch, the proportion of males in a clutch was negatively correlated with the number of eggs in a clutch. Females always oviposit the haploid, male egg last in a sequence of eggs comprising a clutch. The significance of females ovipositing haploid and diploid eggs in a predictable sequence is addressed and related to sex ratio in the Hymenoptera.

Embryonic and host-associated skewed adult sex ratios in dwarf mistletoe

Embryonic sex ratios were determined for the first time in dioecious flowering plants by utilizing malate dehydrogenase (Mdh-3) as a genetic marker. In three populations of Arceuthobium tsugense ssp. tsugense (hemlock dwarf mistletoe) the embryonic sex ratio was 1:1, as it also was at first reproduction. Mixed-age, adult sex ratios of these and other populations from Oregon to south-eastern Alaska, however, were significantly female-biased (59 per cent) on western hemlock, its primary host. We suggest that these female-skewed, adult sex ratios are the result of increased longevity among females. On a secondary host, noble fir, the embryonic and the adult sex ratios were both 1:1. On still another secondary host, shore pine, the embryonic sex ratio is unknown, but the adult sex ratio was significantly male-biased (55.1 per cent). Host environment apparently influences adult sex ratios in hemlock dwarf mistletoe. However, in the European mistletoe Viscum album, a gametic system apparently controls the production of the adult female-predominant sex ratios (69.9 per cent) at fertilization (or perhaps by abortion during embryogenesis). In V. album, the sex ratio of progeny raised from seed is already similarly biased at first reproduction (67.3 per cent), and the sex ratios are not influenced by host shifts.

Embryonic and host-associated skewed adult sex ratios in dwarf mistletoe

Embryonic sex ratios were determined for the first time in dioecious flowering plants by utilizing malate dehydrogenase (Mdh-3) as a genetic marker. In three populations of Arceuthobium tsugense ssp. tsugense (hemlock dwarf mistletoe) the embryonic sex ratio was 1:1, as it also was at first reproduction. Mixed-age, adult sex ratios of these and other populations from Oregon to south-eastern Alaska, however, were significantly female-biased (59 per cent) on western hemlock, its primary host. We suggest that these female-skewed, adult sex ratios are the result of increased longevity among females. On a secondary host, noble fir, the embryonic and the adult sex ratios were both 1:1. On still another secondary host, shore pine, the embryonic sex ratio is unknown, but the adult sex ratio was significantly male-biased (55.1 per cent). Host environment apparently influences adult sex ratios in hemlock dwarf mistletoe. However, in the European mistletoe Viscum album, a gametic system apparently controls the production of the adult female-predominant sex ratios (69.9 per cent) at fertilization (or perhaps by abortion during embryogenesis). In V. album, the sex ratio of progeny raised from seed is already similarly biased at first reproduction (67.3 per cent), and the sex ratios are not influenced by host shifts.

Genetic regulation of border zone formation in female mastomys (Praomys coucha) adrenal cortex.

The unique border zone between the zona fasciculata and z. reticularis of the female adrenal cortex is formed in the wild-colored inbred mastomys (Praomys coucha) strain, MWC, but never in the chamois-colored inbred strain, MCC. This clear strain-specific trait was genetically analyzed using F1, F2, and backcross progenies produced between MWC and MCC. Reciprocal crosses gave no significant differences in the phenotypic ratio of F1 or F2 progeny. Border zone formation was detected in 0% of F1 females, 25.8% of F2 females, 0% of backcross females between F1 and MCC, and 47.7% of backcross females between F1 and MWC. From these results, it was concluded that border zone formation in the female MWC adrenal is regulated by a single autosomal recessive gene and this gene was named bzf (border zone formation).

SPERM COMPETITION IN THE SIMULTANEOUS HERMAPHRODITE FRESHWATER SNAIL BIOMPHALARIA GLABRATA (GASTROPODA: PULMONATA)

An isolated heterozygous Cc Biomphalaria glabrata produces, in strict self-fertilization involving C and c oocytes and spermatozoa, an excess of pigmented progeny, when compared with the expected 3.1 Mendelian ratio. When isolated after insemination by an albino partner, an heterozygous Cc snail shows for 17 days an expected 1:1 Mendehan ratio of pigmented and albino progeny; after the 17th day, self-fertilization is progressively resumed. When fertilized by only c spermatozoa, the two kinds (C and c) of oocytes play a similar role and do not explain the excess of pigmented progeny obtained by selfing. After a similar pairing (Cc X cc), the isolated albino parent also produces, from the 2nd to 20th day, a significant excess of pigmented progeny These experimental results confirm previous observations obtained from homozygous lineages. In both homozygous strains (CC and cc), around 50% of spermatozoa are apyrene or oligopyTene. C spermatozoa are significantly longer than c spermatozoa, this difference, which is classically related to better kinetics, could explain the present results.

Natural radionuclide and plutonium content in Black Sea bottom sediments.

The content of uranium, thorium, radium, lead, polonium, and plutonium in bottom sediments and algae from two locations at the Bulgarian Black Sea coast have been determined. Some parent:progeny ratios for evaluation of the geochemical behavior of the nuclides have been estimated as well. The extractable and total uranium and thorium are determined by two separate radiochemical procedures to differentiate the more soluble chemical forms of the elements and to estimate the potential hazard for the biosphere and for humans. No distinct seasonal variation as well as no significant change in total and extractable uranium (also for 226Ra) content is observed. The same is valid for extractable thorium while the total thorium content in the first two seasons is slightly higher. Our data show that 210Po content is accumulated more in the sediments than 210Pb, and the evaluated disequilibria suggest that the two radionuclides belong to more recent sediment layers deposited in the slime samples compared to the silt ones for the different seasons. The obtained values for plutonium are in the lower limits of the data cited in literature, which is quite clear as there are no plutonium discharge facilities at the Bulgarian Black Sea coast. The obtained values for the activity ratio 238Pu:239 + 240Pu are higher for Bjala sediments compared to those of Kaliakra. The ratio values are out of the variation range for the global contamination with weapon tests fallout plutonium which is probably due to Chernobyl accident contribution. The dependence of natural radionuclide content on the sediment type as well as the variation of nuclide accumulation for two types of algae in two sampling locations for five consecutive seasons is evaluated. No serious contamination with natural radionuclides in the algae is observed.