HOST SUITABILITY OF RED PUMPKIN BEETLE, AULACOPHORA FOVEICOLLIS (LUCAS) AMONG DIFFERENT CUCURBITACEOUS HOSTS
The red pumpkin beetle, Aulacophora foveicollis (Lucas) is a common, serious and major pest of a wide range of cucurbitaceous vegetables. It is injurious to the crops and cause severe damage to almost all cucurbits. The present study was conducted to find out the host suitability of red pumpkin beetle, Aulacophora foveicollis (Lucas) among different cucurbit hosts in the Laboratory and Field Laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh. This study was investigated with a view to explore a resistant host to this pest. The experiment was laid out in the completely randomized design (CRD) and Randomized Complete Block Design (RCBD) in laboratory and field respectively with five replications. Three cucurbit hosts such as sweet gourd (Var. BARI Sweet gourd1), bitter gourd (Var. Hybrid Nepali) and bottle gourd (Var. Kajla) were selected to conduct this research work. Host suitability was determined depending on the average number of beetles present per plant in field. But in the laboratory host suitability was measured following force feeding and choice feeding bioassays. In the field at three different stages of the plant the highest number of beetle per plant was observed on the sweet gourd and the lowest number was found on bitter gourd. Similarly both in force feeding and choice feeding bioassays the highest leaf feeding was observed on sweet gourd and the lowest leaf feeding was determined on the bitter gourd. Both in the laboratory and field among the three cucurbit hosts sweet gourd was the most suitable and bitter gourd was the least suitable host for red pumpkin beetle.
Role of Host and Temperature on the Feeding and Oviposition Behaviour of Red Pumpkin Beetle Aulacophora foveicollis (Lucas)
The research was carried out in the field and laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh during December, 2011 to October, 2012 on the effect of host and temperature on oviposition and food consumption of red pumpkin beetle (RPB), Aulacophora foveicollis (Lucas). Three cucurbitaceous vegetables viz. sweet gourd (BARI Misti Kumra-1, BARI Misti Kumra-2 and Local Misti Kumra), bitter gourd (BARI Karola-1, Taj Karola-88 and Local Karola) and bottle gourd (BARI Lau-3, BARI Lau -4 and Local Lau) were selected to conduct this research. Host plants had the clear role on the feeding of red pumpkin beetle. Due to feeding of A. foveicollis , the highest percentage of weight loss of leaf was recorded from sweet gourd among the selected cucurbits while Local Misti Kumra was found the most preferred host by beetle considering their feeding efficacy compared to other varieties. Results also showed that temperature had a profound effect on the oviposition and food consumption by A. foveicollis while 30 o C was the optimum temperature both for oviposition and food consumption for all selected cucurbits and their varieties. DOI:  http://dx.doi.org/10.3329/pa.v24i1-2.19099 Progress. Agric. 24(1&2): 53 - 60, 2013
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.