Non-synonymous mutations mapped to chromosome X associated with andrological and growth traits in beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Genome-wide association study of reproductive traits in Nellore heifers using Bayesian inference

An important goal of Zebu breeding programs is to improve reproductive performance. A major problem faced with the genetic improvement of reproductive traits is that recording the time for an animal to reach sexual maturity is costly. Another issue is that accurate estimates of breeding values are obtained only a long time after the young bulls have gone through selection. An alternative to overcome these problems is to use traits that are indicators of the reproductive efficiency of the herd and are easier to measure, such as age at first calving. Another problem is that heifers that have conceived once may fail to conceive in the next breeding season, which increases production costs. Thus, increasing heifer's rebreeding rates should improve the economic efficiency of the herd. Response to selection for these traits tends to be slow, since they have a low heritability and phenotypic information is provided only later in the life of the animal. Genome-wide association studies (GWAS) are useful to investigate the genetic mechanisms that underlie these traits by identifying the genes and metabolic pathways involved. Data from 1853 females belonging to the Agricultural Jacarezinho LTDA were used. Genotyping was performed using the BovineHD BeadChip (777 962 single nucleotide polymorphisms (SNPs)) according to the protocol of Illumina - Infinium Assay II ® Multi-Sample HiScan with the unit SQ ™ System. After quality control, 305 348 SNPs were used for GWAS. Forty-two and 19 SNPs had a Bayes factor greater than 150 for heifer rebreeding and age at first calving, respectively. All significant SNPs for age at first calving were significant for heifer rebreeding. These 42 SNPs were next or within 35 genes that were distributed over 18 chromosomes and comprised 27 protein-encoding genes, six pseudogenes and two miscellaneous noncoding RNAs. The use of Bayes factor to determine the significance of SNPs allowed us to identify two sets of 42 and 19 significant SNPs for heifer rebreeding and age at first calving, respectively, which explain 11.35 % and 6.42 % of their phenotypic variance, respectively. These SNPs provide relevant information to help elucidate which genes affect these traits.

PHENOLOGY AND FRUIT TRAITS OF ARCHONTOPHOENIX CUNNINGHAMIANA, AN INVASIVE PALM TREE IN THE ATLANTIC FOREST OF BRAZIL

The Australian palm Archontophoenix cunninghamiana was introduced into Brazil as an ornamental species, and became a dangerous invader of remnant Atlantic forest patches, demanding urgent management actions that require careful planning. Its fruits are greatly appreciated by generalist birds and its sudden eradication could be as harmful as its permanence in the native community. Our hypothesis was that A. cunninghamiana phenology and fruit traits would have facilitated the invasion process. Hence the aim of the study was to characterize the reproductive phenology of the palm by registering flowering and fruiting events, estimating fruit production, and evaluating fruit nutritional levels. Phenological observations were carried out over 12 months and analyzed statistically. Fruit traits and production were estimated. Pulp nutritional levels were determined by analyzing proteins, lipids, and carbohydrates. Results showed constant flowering and fruiting throughout the year with a weak reproductive seasonality. On average, 3651 fruits were produced per bunch mainly in the summer. Fruit analysis revealed low nutrient contents, especially of proteins and lipids compared with other Brazilian native palm species. We concluded that the abundant fruit production all year round, and fruit attractivity mainly due to size and color, :may act positively on the reproductive performance and effective dispersion of A. cunninghamiana. As a management procedure which would add quality to frugivore food resources we suggest the replacement of A. cunninghamiana by the native palm Euterpe edulis, especially in gardens and parks near to Atlantic forest fragments.

Genetic associations between flight speed and growth traits in Nellore cattle

The aim of the present study was to estimate genetic parameters for flight speed and its association with growth traits in Nellore beef cattle. The flight speed (FS) of 7,402 yearling animals was measured, using a device composed of a pair of photoelectric cells. Time interval data (s) were converted to speed (m/s) and faster animals were regarded as more reactive. The growth traits analyzed were weaning weight (WW), ADG from weaning to yearling age, and yearling scrotal circumference (SC). The (co)variance components were estimated using REML in a multitrait analysis applying an animal model. The model included random direct additive genetic and residual effects, fixed effects of contemporary groups, age of dam (classes), and age of animal as covariable. For WW, the model also included maternal genetic and permanent environmental random effects. The direct heritability estimate for FS was 0.26 +/- 0.05 and direct heritability estimates for WW, SC, and ADG were 0.30 +/- 0.01, 0.48 +/- 0.02, and 0.19 +/- 0.01, respectively. Estimates of the genetic correlation between FS and the growth traits were -0.12 +/- 0.07 (WW), -0.13 +/- 0.08 (ADG), and -0.11 +/- 0.07 (SC). Although the values were low, these correlations showed that animals with better temperaments (slower FS) tended to present better performance. It is possible to infer that long-term selection for weight and scrotal circumference can promote a positive genetic response in the temperament of animals. Nevertheless, to obtain faster genetic progress in temperament, it would be necessary to perform direct selection for such trait. Flight speed is an easily measured indicator of temperament and can be included as a selection criterion in breeding programs for Nellore cattle.

Taxonomy, phylogeny and reproductive ecology of Gentiana lutea L.

This research focuses on taxonomy, phylogeny and reproductive ecology of Gentiana lutea. L.. Taxonomic analysis is a critical step in botanical studies, as it is necessary to recognize taxonomical unit. Herbarium specimens were observed to assess the reliability of several subspecies-diagnostic characters. The analysis of G. lutea genetic variability and the comparison with that of the other species of sect. Gentiana were performed to elucidate phylogenetic relationships among G. lutea subspecies and to propose a phylogenetic hypothesis for the evolution and the colonization dynamics of the section. Appropriate scientific information is critical for the assessment of species conservation status and for effective management plans. I carried out field work on five natural populations and performed laboratory analyses on specific critical aspects, with special regard to G. lutea breeding system and type and efficiency of plant-pollinator system. Bracts length is a reliable character to identify subsp. vardjanii, however it is not exclusive, hence to clearly identify subsp. vardjanii, other traits have to be considered. The phylogenetic hypotheses obtained from nuclear and chloroplast data are not congruent. Nuclear markers show a monophyly of sect. Gentiana, a strongly species identity of G. lutea and clear genetic identity of subsp. vardjanii. The little information emerging from plastid markers indicate a weak signal of hybridization and incomplete sorting of ancestral lineages. G. lutea shows a striking variation in intra-floral dichogamy probably evolved to reduce pollen-stigma interference. Although the species is partially self-compatible, pollen vectors are necessary for a successful reproduction, and moreover it shows a strong inbreeding depression. G. lutea is a generalist species: within its spectrum of visitors is possible to recognize "nectar thieves" and pollinators with sedentary or dynamic behaviour. Pollen limitation is frequent and it could be mainly explained by poor pollen quality.

Variation in life-history traits and their plasticities to elevational transplantation among seed families suggests potential for adaptative evolution of 15 tropical plant species to climate change

• Premise of the study: Because not all plant species will be able to move in response to global warming, adaptive evolution matters largely for plant persistence. As prerequisites for adaptive evolution, genetic variation in and selection on phenotypic traits are needed, but these aspects have not been studied in tropical species. We studied how plants respond to transplantation to different elevations on Mt. Kilimanjaro, Tanzania, and whether there is quantitative genetic (among-seed family) variation in and selection on life-history traits and their phenotypic plasticity to the different environments. • Methods: We reciprocally transplanted seed families of 15 common tropical, herbaceous species of the montane and savanna vegetation zone at Mt. Kilimanjaro to a watered experimental garden in the montane (1450 m) and in the savanna (880 m) zone at the mountain’s slope and measured performance, reproductive, and phenological traits. • Results: Plants generally performed worse in the savanna garden, indicating that the savanna climate was more stressful and thus that plants may suffer from future climate warming. We found significant quantitative genetic variation in all measured performance and reproductive traits in both gardens and for several measures of phenotypic plasticity in response to elevational transplantation. Moreover, we found positive selection on traits at low and intermediate trait values levelling to neutral or negative selection at high values. • Conclusions: We conclude that common plants at Mt. Kilimanjaro express quantitative genetic variation in fitness-relevant traits and in their plasticities, suggesting potential to adapt evolutionarily to future climate warming and increased temperature variability.

MYB-FL controls gain and loss of floral UV absorbance, a key trait affecting pollinator preference and reproductive isolation

Adaptations to new pollinators involve multiple floral traits, each requiring coordinated changes in multiple genes. Despite this genetic complexity, shifts in pollination syndromes have happened frequently during angiosperm evolution. Here we study the genetic basis of floral UV absorbance, a key trait for attracting nocturnal pollinators. In Petunia, mutations in a single gene, MYB-FL, explain two transitions in UV absorbance. A gain of UV absorbance in the transition from bee to moth pollination was determined by a cis-regulatory mutation, whereas a frameshift mutation caused subsequent loss of UV absorbance during the transition from moth to hummingbird pollination. The functional differences in MYB-FL provide insight into the process of speciation and clarify phylogenetic relationships between nascent species.

Biostimulation methods associated with early weaning and reproductive rhythms in primiparous rabbit does

El objetivo general de esta Tesis Doctoral ha sido tratar de mejorar los parámetros reproductivos de las conejas primíparas lactantes, empleando dos métodos de manejo (destete temprano y extensificación del ritmo reproductivo), que están directamente relacionados con su balance energético. Para ello, se diseñaron 2 experimentos en este tipo de hembras. En el primero, se estudió el efecto del destete a 25 días post-parto (dpp) sobre la actividad ovárica y el metabolismo energético de las conejas una semana más tarde (32 dpp). Un total de 34 primíparas lactantes con 8 gazapos fueron distribuidas en tres grupos: 10 conejas se sacrificaron a los 25 dpp (grupo L25), 13 fueron destetadas a los 25 dpp y sacrificadas a los 32 dpp (grupo NL32), y 11 conejas no se destetaron y fueron sacrificadas a los 32 dpp (grupo L32). No se observaron diferencias significativas entre grupos en el peso corporal, el peso del ovario, ni en las concentraciones séricas de ácidos grasos no esterificados y de proteínas totales. A pesar de que el grupo NL32 presentó un bajo consumo de alimento (122 ± 23,5 g / día, p <0,001), su contenido corporal estimado de lípidos (16,9 ± 1,09%, P <0,008), proteínas (19,7 ± 0,07%, P <0,0001), y energía (1147 ± 42,7 MJ / kg, p <0,006) fueron más elevados y las concentraciones séricas de glucosa (158 ± 24,5 mg/dl, p <0,04) más bajas que en los grupos L25 (11,9 ± 1,3%, 18,5 ± 0,08%, 942 ± 51,3 MJ/kg y 212 ± 27,9 mg/dl) y L32 (13,4 ± 1,03%, 18,5 ± 0,1%, 993 ± 40,4 MJ/kg y 259 ± 29,5 mg/dl), respectivamente. En el grupo L25 se observó un menor número medio de folículos ≥ 1 mm en la superficie ovárica en comparación con los grupos NL32 y L32 (12,7 ± 1,5 vs. 18,0 ± 1,45 y 17,6 ± 1,67, p <0,05). La población folicular ovárica en las secciones histológicas y la inmunolocalización de los receptores de prolactina fueron similares en todos los grupos. En el grupo L25, tanto la maduración nuclear de oocitos, medida en términos de tasas alcanzadas de Metafase II (67,0 vs. 79,7 y 78,3%, P <0.05) y la maduración citoplasmática, medida por el porcentaje de gránulos corticales (GC) total o parcialmente migrados en los oocitos, fueron significativamente menores que en los grupos NL32 y L32 (16,0 vs 38,3 y 60,0%, P <0.05). En conclusión, a pesar de que el destete precoz a 25 dpp pareció mejorar las reservas de energía de las conejas primíparas, este hecho no se reflejó claramente a nivel ovárico a los 32 dpp y fue similar independientemente del destete, por lo que éste último podría llevarse a cabo más tarde. En el segundo experimento, se compararon dos ritmos reproductivos. Se utilizaron un total de 48 conejas primíparas lactantes con 8 gazapos que se asignaron al azar en dos grupos experimentales: a) lactantes sacrificadas a comienzos del post-parto (11 dpp) de acuerdo a un ritmo semi-intensivo (n = 24), y b) lactantes sacrificadas al final del período post-parto (25 dpp) de acuerdo con un ritmo más extensivo (n = 24). En ellas, se estudió el peso vivo, la composición corporal estimada, parámetros metabólicos y endocrinos (estradiol y progesterona) y características ováricas como la población folicular y la tasa de atresia, así como la maduración nuclear y citoplásmica de los oocitos. En este estudio, el peso vivo, el contenido de energía corporal, los depósitos grasos y los ácidos grasos no esterificados disminuyeron a lo largo del post-parto con respecto al momento del parto (P <0,05). Las concentraciones séricas de proteínas y glucosa aumentaron en el mismo periodo post-parto (P <0,05). Se observaron similares niveles de estradiol y progesterona en ambos ritmos, así como una población folicular, tasas de maduración nuclear (tasa de oocitos en metafase II) y citoplasmática (porcentaje de oocitos con gránulos corticales migrados), similares en ambos momentos del post-parto. Sin embargo, el número de folículos preovulatorios en la superficie ovárica fue menor (P <0,05) y la tasa de atresia tendió a ser mayor con un porcentaje también menor de folículos sanos (P <0,1) en los ovarios de las hembras sometidas al ritmo extensivo. En conclusión, al final del post-parto (25 días), las conejas primíparas sin destetar muestran un deterioro de sus reservas corporales, de sus parámetros metabólicos séricos y de la calidad de sus oocitos; incluso se ha observado una ligera influencia negativa en el desarrollo de sus folículos ováricos. Por esta razón, se considera que en las conejas primíparas lactantes el manejo reproductivo extensivo (25 dpp) no presenta ninguna ventaja en comparación con el semi-intensivo (11 dpp). A la vista de los resultados de estos dos experimentos, podemos decir que ni el destete temprano, ni la extensificación del ritmo reproductivo han conseguido una mejora en los parámetros reproductivos de una hembra primípara. Por ello, son necesarios más estudios sobre el estado metabólico de la coneja primípara lactante para conseguir métodos o estrategias que lo mejoren y tengan consecuencias directas sobre la actividad reproductiva y sobre su éxito productivo. The general aim of this Thesis was to study two management methods (early weaning and extensive reproductive rhythm) linked to the energy balance of the primiparous rabbit does to improve their reproductive performance. In this sense, 2 experiments were conducted using this kind of females. In the first experiment, the effect of weaning at 25 days post-partum (dpp) on ovarian activity and energetic metabolism one week later (32 dpp) was studied. A total of 34 primiparous lactating rabbit does were used and distributed among three groups: 10 does euthanized at 25 dpp (group L25), 13 does weaned at 25 dpp and euthanized at 32 dpp (group NL32), and 11 non weaned does euthanized at 32 dpp (group L32). No significant differences were observed in live body weight, ovary weight, serum non esterified fatty acids (NEFA) and total protein concentration among groups. Although NL32 does had a low feed intake (122±23.5 g/Day; P < 0.001), their estimated lipids (16.9±1.09%, P < 0.008), protein (19.7±0.07%, P < 0.0001), and energy (1147±42.7 MJ/kg, P < 0.006) body contents were higher and their serum glucose concentrations (158±24.5 mg/dl, P < 0.04) were lower compared to L25 does (11.9±1.3%, 18.5±0.08%, 942±51.3 MJ/kg and 212±27.9 mg/dl) and L32 does (13.4±1.03%, 18.5±0.1%, 993±40.4 MJ/kg and 259±29.5 mg/dl, respectively). A lower number of follicles ≥1mm was observed compared to NL32 and L32 groups (12.7±1.5 vs. 18.0±1.45 and 17.6 ±1.67; P < 0.05) in the ovarian surface of L25 does. Follicular population in the histological ovarian sections and immunolocalization of prolactin receptor were similar in all groups. In group L25, both nuclear maturation of oocytes in terms of Metaphase II rate (67.0 vs. 79.7 and 78.3%; P < 0.05) and cytoplasmic maturation measured by percentage of cortical granules (CG), totally or partially migrated in oocytes were significantly lower than in groups NL32 and L32 (16.0 vs. 38.3 and 60.0%; P < 0.05). Consequently, a higher rate of oocytes with non-migrated CGs was found in group L25 than in groups NL32 and L32 (76.0 vs. 46.8 and 33.3%; P < 0.05). In conclusion, even though early weaning at 25 dpp seemed to improve body energy stored in primiparous does, this fact was not well reflected on the ovarian status at 32 dpp, which was similar regardless of weaning time. In the second experiment, two reproductive rhythms were compared. A total of 48 primiparous Californian x New Zealand White rabbit does suckling 8 kits were randomly allocated in two experimental groups: a) lactating does euthanized at early post-partum period (11 dpp) according to a semi-intensive rhythm (n = 24), and b) lactating does euthanized on later post-partum period (25 dpp) according to a more extensive rhythm (n = 24). Live weight, estimated body composition, serum metabolic and endocrine parameters (oestradiol and progesterone concentrations) and ovarian features like follicle population and atresia rate, and oocyte maturation were studied. Live weight, body energy content, lipid depots and serum non esterified fatty acids (NEFA) concentrations diminished from parturition time to post-partum period (P < 0.05). In addition, serum protein and glucose concentrations increased along postpartum time (P < 0.05). Similar oestradiol and progesterone levels were shown in rhythms as well as similar follicle population and nuclear and cytoplasmic maturation rates measured as metaphase II and cortical granule migration, respectively in both postpartum times. However, number of preovulatory follicles on the ovarian surface was lower (P < 0.05) and atresia rate tended to be higher with also lower percentage of healthy follicles (P < 0.1) in ovaries of females of extensive group. In conclusion, primiparous non-weaned rabbits does at late post-partum time (25 days), Did no show any improvement regarding body reserves, serum metabolic parameters and oocyte quality; even a slight negative influence has been observed in the development of their ovarian follicles. Thus this reproductive management does not present any advantage compared to earlier post-partum (11 days) reproductive rhythm. In summary, according to the obtained results from these two experiments, we can say that the application of early weaning and the extensive rhythms did not achieve an improvement in the reproductive performance of primiparous does. Thus, it is necessary to conduct more studies about the metabolic status of the primiparous lactating doe to achieve strategies in order to improve it and consequently, to improve the reproductive activity and their productive success.

Influence of the main cereal and feed form of the rearing phase diets on performance, digestive tract, and body traits of brown-egg laying pullets from hatch to 17 weeks of age

We hypothesize that pullets could respond similarly, independent of feed form, to the feeding of diets based on corn or wheat supplemented with adequate NSP enzymes. Also, pullets would quickly adapt their gastrointestinal tract and modify productive performance accordingly, when switched from crumbles to mash feeds. The aim of this research was to evaluate the effects of feeding crumbles for different periods of time, followed by feeding mash to 17 wk of age, on performance, gastrointestinal tract development, and body measurements of brown-egg laying pullets fed diets based on corn or wheat.

A Suite of Prey Traits Determine Predator and Nutrient Enrichment Effects in a Tri-Trophic Food Chain

Predation, predation risk, and resource quality affect suites of prey traits that collectively impact individual fitness, population dynamics, and community structure. However, studies of multi-trophic level effects generally focus on a single prey trait, failing to capture trade-offs among suites of covarying traits that govern population responses and emergent community patterns. We used structural equation models (SEM) to summarize the non-lethal and lethal effects of crayfish, Procambarus fallax, and phosphorus (P) addition, which affected prey food quality (periphyton), on the interactive effects of behavioral, morphological, developmental, and reproductive traits of snails, Planorbella duryi. Univariate and multivariate analyses suggested trade-offs between production (growth, reproduction) and defense (foraging behavior, shell shape) traits of snails in response to non-lethal crayfish and P addition, but few lethal effects. SEM revealed that non-lethal crayfish effects indirectly limited per capita offspring standing stock by increasing refuge use, slowing individual growth, and inducing snails to produce thicker, compressed shells. The negative effects of non-lethal crayfish on snails were strongest with P addition; snails increased allocation to shell defense rather than growth or reproduction. However, compared to ambient conditions, P addition with non-lethal crayfish still yielded greater per capita offspring standing stock by speeding individual snail growth enabling them to produce more offspring that also grew faster. Increased refuge use in response to non-lethal crayfish led to a non-lethal trophic cascade that altered the spatial distribution of periphyton. Independent of crayfish effects, snails stimulated periphyton growth through nutrient regeneration. These findings illustrate the importance of studying suites of traits that reveal costs associated with inducing different traits and how expressing those traits impacts population and community level processes.

In-situ seawater pH and temperature during and fitness traits of a calcifying polychaete after a reciprocal transplant experiment in June-July near Ischia, italy

Ocean acidification (OA) is likely to exert selective pressure on natural populations. Our ability to predict which marine species will adapt to OA, and what underlies this adaptive potential, are of high conservation and resource management priority. Using a naturally low pH vent site in the Mediterranean Sea (Castello Aragonese, Ischia) mirroring projected future OA conditions, we carried out a reciprocal transplant experiment to investigate the relative importance of phenotypic plasticity and local adaptation in two populations of the sessile, calcifying polychaete /Simplaria /sp. (Annelida, Serpulidae, Spirorbinae): one residing in low pH and the other from a nearby ambient (i.e. high) pH site. We measured a suite of fitness related traits (i.e. survival, reproductive output, maturation, population growth) and tube growth rates in laboratory-bred F2 generation individuals from both populations reciprocally transplanted back into both ambient and low pH /in situ/ habitats. Both populations showed lower expression in all traits, but increased tube growth rates, when exposed to low pH compared to high pH conditions, regardless of their site of origin suggesting that local adaptation to low pH conditions has not occurred. We also found comparable levels of plasticity in the two populations investigated, suggesting no influence of long-term exposure to low pH on the ability of populations to adjust their phenotype. Despite high variation in trait values among sites and the relatively extreme conditions at sites close to the vents (pH < 7.36), response trends were consistent across traits. Hence, our data suggest that, for /Simplaria /and possibly other calcifiers, neither local adaptations nor sufficient phenotypic plasticity levels appear to suffice in order to compensate for the negative impacts of OA on long-term survival. Our work also underlines the utility of field experiments in natural environments subjected to high level of /p/CO_2 for elucidating the potential for adaptation to future scenarios of OA.

Pathogenicity and reproductive fitness of Pratylenchus brachyurus on cowpea

The lesion nematode Pratylenchus brachyurus is widespread in cowpea plantations throughout the tropics and sub-tropics. However, the pathogenicity of P. brachyurus on cowpea has been scarcely studied. In this work, it was demonstrated in two glasshouse experiments that an isolate (Pb-20) of P brachyurus was pathogenic to cowpea cv. IPA-206, adversely affecting the plant growth and pod formation and filling. Initial population levels of 5000 and 15 000 nematodes per plant caused reduction of root growth and typical decay of root tissue. The third experiment demonstrated that all six cowpea cultivars selected for evaluation supported reproduction of three isolates of P. brachyurus (Pb-20, Pb-21 and Pb-23) in their roots, although the reproduction factor values obtained indicated that they were dissimilar in their reproductive fitness. Low resistance to R brachyurus was reported for at least one tested cultivar, but apparently of an insufficient degree to be effective for field management of the nematode.

Allopatric speciation in ticks: genetic and reproductive divergence between geographic strains of Rhipicephalus (Boophilus) microplus

Background: The cattle tick, Rhipicephalus (Boophilus) microplus, economically impact cattle industry in tropical and subtropical regions of the world. The morphological and genetic differences among R. microplus strains have been documented in the literature, suggesting that biogeographical and ecological separation may have resulted in boophilid ticks from America/Africa and those from Australia being different species. To test the hypothesis of the presence of different boophilid species, herein we performed a series of experiments to characterize the reproductive performance of crosses between R. microplus from Australia, Africa and America and the genetic diversity of strains from Australia, Asia, Africa and America. Results: The results showed that the crosses between Australian and Argentinean or Mozambican strains of boophilid ticks are infertile while crosses between Argentinean and Mozambican strains are fertile. These results showed that tick strains from Africa (Mozambique) and America (Argentina) are the same species, while ticks from Australia may actually represent a separate species. The genetic analysis of mitochondrial 12S and 16S rDNA and microsatellite loci were not conclusive when taken separately, but provided evidence that Australian tick strains were genetically different from Asian, African and American strains. Conclusion: The results reported herein support the hypothesis that at least two different species share the name R. microplus. These species could be redefined as R. microplus (Canestrini, 1887) (for American and African strains) and probably the old R. australis Fuller, 1899 (for Australian strains), which needs to be redescribed. However, experiments with a larger number of tick strains from different geographic locations are needed to corroborate these results.

Morphological variation and reproductive incompatibility of three coconut-mite-associated populations of predatory mites identified as Neoseiulus paspalivorus (Acari: Phytoseiidae)

Predatory mites identified as Neoseiulus paspalivorus DeLeon (Phytoseiidae) have been considered as agents for classical biological control of the coconut mite, Aceria guerreronis Keifer (Eriophyidae), in Africa and elsewhere. Preliminary identification of geographically distinct populations as belonging to the same species (N. paspalivorus) was based on their morphological similarity. However, laboratory studies recently conducted have shown large differences in feeding behaviors and biological characteristics among individuals collected from three geographic origins: Brazil (South America), Benin and Ghana (West Africa). As morphologically similar specimens do not necessarily belong to the same species, we evaluated under laboratory conditions, reproductive compatibility between the specimens from three geographic locations to ascertain their conspecificity. Morphological measurements were also made to determine whether there is a means of discriminating between them. Inter-population crosses showed complete reproductive isolation between the three geographic populations, but interpopulation discontinuities in morphometric characters were absent. These results indicate that the tested specimens are distinct biological entities despite morphological similarity. Further molecular genetic studies are therefore proposed, including screening for endosymbionts and assessment of genetic differentiation, to determine the cause of reproductive incompatibility and to clarify the taxonomic relationship between those populations.

Predation and reproductive output of the ladybird beetle Stethorus tridens preying on tomato red spider mite Tetranychus evansi

Predatory behaviour and reproductive output of the ladybird beetle Stethorus tridens Gordon as function of the tomato red spider mite (TRSM), Tetranychus evansi Baker & Pritchard, densities was investigated in the laboratory. Adult female of S. tridens were isolated in cylindrical plastic arenas, containing a leaf disc of Solanum americanum Mill. with 5, 20, 40, 60, 80 or 100 T. evansi nymphs. The number of prey consumed and eggs laid were evaluated daily for ten consecutive days, starting at the oviposition. Oviposition of S. tridens was positively correlated with prey consumption and lower threshold prey consumption for S. tridens laying eggs was 16.3 mites per day. The instantaneous rate of attack (ca. discovery area) and the handling time were 0.0062 h(-1) and 0.83 h, and 0.00254 h(-1) and 0.78 h, respectively, for predators at the 1st- and 10th-oviposition day. The predator exhibited a type II functional response at 1st- and 10th-oviposition day with a maximum consumption per predator of 33 T. evansi nymphs per day at the highest prey density. The ladybird beetle S. tridens is often collected associated with red spider mite colonies on solanaceous wild plants and the results suggest the potential of this ladybird beetle to control T. evansi in tomatoes crops.