Effects of interaction between cowpea variety and the application of plant powders on Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae) infestation of stored cowpea seeds

An integrated pest management scheme involving seed resistance and the application of powder of Cymbopogon citratus, Alstonia boonei, Hyptis suaveolens, Azadirachta indica, Loranthus braunii and Lycopersicum esculentum as protectant against the seed bettle, Callosobruchus maculatus (Fabricius), was evaluated in the laboratory at ambient temperature (29±3°C) and relative humidity (65±5%). Six resistant cowpea accessions selected from previous studies were treated with the six plant powders at 1.25% w/w in a 6×7 factorial arrangement fitted into a completely randomized design with five replicates. Seed treatment with any of the six plant powders on six accessions resulted in significantly higher adult mortality, lower oviposition rate, adult emergence inhibition, lower seed damage and higher seed germination over the control, Protection ability of the plant powders was influenced by the cowpea accessions used.

The Impact of Phenological and Artificial Factors on Seed Quality in a Nematode-resistant Pinus densiflora Seed Orchard

To clarify the relationship between the impact of phenological and/or artificial factors on seed quality, we measured the numbers of strobili on nematode-resistant Pinus densiflora clones grown in an immature and relatively small scale (700 m2) seed orchard. In addition, we established the clonal identities of all ramets, identified the paternal parent of the seeds, and assessed the resistance of seedlings to nematode infection. We also clarified the quantitative differences of strobili among clones; one clone produced 86.4% and 70.8% of all male strobili and female strobili, respectively. However, given that the total contamination ratio of the orchard was 82.0%, immigrant pollen had a larger impact on the success of actual crossing than phenology. Seedlings with a resistant maternal parent were resistant, even when their paternal parent was from outside the orchard. Two unselected clones were also planted in the seed orchard, one of which was not resistant and was associated with a maternal contribution of 34.7% of all seed stock. These findings suggest that, despite having a large impact on the crossing, immigrant pollen has a minor impact on seed resistance. Conversely, unselected and nonresistant clones have a marked impact on seed resistance. We concluded that artificial factors have larger impact on the seed quality than phenological factors in this orchard and the seeds will be of sufficient quality for supplying the market once nonresistant clones have been removed from the orchard.

Genetic analysis of pod and seed resistance to pea weevil in a Pisum sativum×P. fulvum interspecific cross

Interspecific populations derived from crossing cultivated field pea, Pisum sativum, with the wild pea relative, Pisum fulvum, were scored for pod and seed injury caused by the pea weevil, Bruchus pisorum. Pod resistance was quantitatively inherited in the F2 population, with evidence of transgressive segregation. Heritability of pod resistance between F2 and F3 generations was very low, suggesting that this trait would be difficult to transfer in a breeding program. Seed resistance was determined for the F2 population by testing F3 seed tissues of individual F2 plants and pooling data from seed reaction for each F2 plant (inferred F2 genotype). Segregation for seed resistance in the F2 population of the cross Pennant/ATC113 showed a trigenic mode of inheritance, with additive effects and dominant epistasis towards susceptibility. Seed resistance was conserved over consecutive generations (F2 to F5) and successfully transferred to a new population by backcross introgression. Seed resistance in the backcross introgressed population segregated in a 63 : 1 ratio, supporting the three-gene inheritance model. It is proposed that complete resistance to pea weevil is controlled by three major recessive alleles assigned pwr1, pwr2, and pwr3, and complete susceptibility by three major dominant alleles assigned PWR1, PWR2, and PWR3. It is recommended that large populations (>300 F2 plants) would be required to effectively transfer these recessive alleles to current field pea cultivars through hybridisation and repeated backcrossing.