Effects of storage methods and seasons on seed quality of jute mallow morphotypes (Corchorus olitorius) in Siaya and Kakamega counties, Kenya

Jute mallow is an important source of nutrients, income and traditional medicine inKenya. It is extensively grown and consumed in Western Kenya. However, itsproduction is constrained by lack of quality seeds due to varied farmers’ agronomic andpostharvest practices. The aim of the study was to investigate the effect of storagemethods on seed quality of jute mallow in Western Kenya. Seeds of two morphotypesof C. olitorius(with 70% and above germination)were stored in clay pots, transparentplastic jars, brown paper bags and polythene bags at room temperature in Kakamegaand Siaya Counties. Seeds were also stored in a freezer at Chepkoilel campus in Eldoretat -20C. In Kakamega County, average room temperature was 230C and relativehumidity was 85% during the storage period of May to July 2006. In Siaya County, theaverage room temperature was 250C and relative humidity was 80% during the sameperiod. Between December and February 2006, the average room temperature was260C while relative humidity was 80% in Kakamega County. In Siaya County, theaverage temperature was 280C and relative humidity 65% for the same period. Storageduration was 90 days, which is the length of time farmers in the study areas store jutemallow seeds to avoid seed dormancy. Seed viability and vigourof the seeds wasdetermined. Data obtained were subjected to Analysis of Variance (ANOVA) and Ttestsusing Statistical Analysis Software (SAS) programme. Season of growth andstorage methods influenced the seed quality. Seeds stored in clay pots, brown paperbags, plastic transparent jars and freezer had higher seed quality than those stored inpolythene bags. Even though there was varied response to different storage methods,generally it was recommended that in order to obtain high quality seeds, farmers shouldstore jute mallow seeds in clay pots or brown paper bags or plastic transparent jars orfreezer.Key words: jute mallow, seed vigour, seed viability, storage methods, Corchorusolitoriu

Inhibition of predator attraction to kairomones by non-host plant volatiles for herbivores: a bypass-trophic signal

Background Insect predators and parasitoids exploit attractive chemical signals from lower trophic levels as kairomones to locate their herbivore prey and hosts. We hypothesized that specific chemical cues from prey non-hosts and non-habitats, which are not part of the trophic chain, are also recognized by predators and would inhibit attraction to the host/prey kairomone signals. To test our hypothesis, we studied the olfactory physiology and behavior of a predaceous beetle, Thanasimus formicarius (L.) (Coleoptera: Cleridae), in relation to specific angiosperm plant volatiles, which are non-host volatiles (NHV) for its conifer-feeding bark beetle prey. Methodology/Principal Findings Olfactory detection in the clerid was confirmed by gas chromatography coupled to electroantennographic detection (GC-EAD) for a subset of NHV components. Among NHV, we identified two strongly antennally active molecules, 3-octanol and 1-octen-3-ol. We tested the potential inhibition of the combination of these two NHV on the walking and flight responses of the clerid to known kairomonal attractants such as synthetic mixtures of bark beetle (Ips spp.) aggregation pheromone components (cis-verbenol, ipsdienol, and E-myrcenol) combined with conifer (Picea and Pinus spp.) monoterpenes (α-pinene, terpinolene, and Δ3-carene). There was a strong inhibitory effect, both in the laboratory (effect size d = −3.2, walking bioassay) and in the field (d = −1.0, flight trapping). This is the first report of combining antennal detection (GC-EAD) and behavioral responses to identify semiochemical molecules that bypass the trophic system, signaling habitat information rather than food related information. Conclusions/Significance Our results, along with recent reports on hymenopteran parasitoids and coleopteran predators, suggest that some NHV chemicals for herbivores are part of specific behavioral signals for the higher trophic level and not part of a background noise. Such bypass-trophic signals could be of general importance for third trophic level players in avoiding unsuitable habitats with non-host plants of their prey