The Effect of Methionine Sulphoximine on the Absorption of Ammonium by Maize and Barley Roots over Short Periods

Pre-treating intact, ammonium-grown plants of maize and barleywith the glutamine synthetase inhibitor, L-methionine sulphoximine(MSO), increased subsequent accumulation of ¹³N or ¹⁵N fromlabelled ammonium very markedly—up to 8-fold in extremecases. The phenonemon could not be satisfactorily explainedin terms of an effect of MSO on the cation-exchange propertiesof the root free space, because neither potassium (⁸⁶Rb⁺) norsodium absorption was enhanced by MSO pretreatment, and rapidabsorption of ammonium continued for too long in relation tothe likely free-space content of a monovalent cation. Instead,the response is seen as a consequence of the enlargement ofthe cytoplasmic and vacuolar ammonium pools that occurs whenammonium assimilation is inhibited by MSO. The results, whichincluded comparisons between short-term and longer-term ratesof ammonium absorption, provide tentative evidence of rapidfluxes of ammonium through the plasma membrane. Key words: Cytoplasm, vacuole, flux, transport     

Review of the East Asian species of the genera Hybrizon Fallén and Ghilaromma Tobias (Hymenoptera: Ichneumonidae: Hybrizontinae)

East Asian species of the genera Hybrizon and Ghilaromma are reviewed. Four species of Hybrizon, H. buccatus (Brébisson 1825), H. ghilarovi Tobias, 1988, H. juncoi (Ceballos 1957) and H. flavofacialis Tobias, 1988 and two species of Ghilaromma, G. orientalis Tobias, 1988 and G. ussuriensis Tobias, 1988, were recognized. H. ghilarovi was recorded from Korea, Japan and China, while H. juncoi was recorded from Korea, for the first time. The specimens recorded from Japan as G. fuliginosi (Wilkinson, 1930) by Watanabe (1984) are referred to G. orientalis herein. This species is newly recorded from Korea and Japan. Keys to East Asian species of Hybrizon and the world species of Ghilaromma are also provided.     

Flight periodicity and infestation size of Sitona lineatus

Sitona lineatus displays two distinct flight periods; a post-teneral flight in the late summer and a post-diapausal flight in the spring. The late summer flight begins as soon as adults start to emerge from pupal cells during late July and continues until mid-October. Maximum aerial density is observed in late August. Less than 10% of newly emerged adults leave the crop by flight, the rest remain in the soil or move to overwintering sites by walking. Spring flight begins in late March if temperatures are above the 12.5°C flight threshold and reaches a peak in mid-April. Most migratory flight is downwind. Little trivial flight occurs and once individuals have located a crop, redistribution is by walking. Laboratory studies indicate that adults fly most often during the day, particularly at noon. The size of infestations appeared to be independent of the area of legumes grown in a locality with large differences occurring even between neighbouring fields. Examination of the yields of field experiments at Rothamsted demonstrate an unexpected trend for higher yields in later sown spring bean crops. This may be because late sowing avoids infestation by spring migrants.     

First record of the family Embolemidae (Hymenoptera: Chrysidoidea) from Korea

The family Embolemidae Westwood, 1833 is recorded for the first time in Korea, based on a species Embolemus ruddii Westwood. A diagnosis of this species complemented by digital images are provided.     

Effects of optimum doses of nitrogen,phosphorus, potassium and calcium on silkworm,Bombyx mori L., growth and yield

Silkworm rearing has been an income source for small-holding farmers in Pakistan. Over the years efforts have been made to improve silkworm quality and quantity and thus develop better prospects for increasing yield and income. Mulberry leaves Morus alba L. in a series of experiments have been supplemented with various nutrients in different doses and combinations. Relative success has been achieved in this context. In our present experiments on silkworm Bombyx mori L., we fed the larvae on mulberry leaves supplemented with different doses of N (0.2%), P (0.1%), K (0.3%) and Ca (0.1%) at 26 ± 3°C with 65 ± 5% relative humidity. The results showed better outputs in terms of food consumption (72.55 g/10 larvae), coefficient of utilization (76.45%), body weight (70.07 g/10 larvae) and body length (8.56 cm/larvae) than where simple mulberry leaves were offered. Our net gains with these production parameters have been in terms of heavier cocoons with and without pupa (2.25 and 0.69 g/cocoon), respectively.