Influence of sexual organs on corpora allata biosynthetic activity in Locusta migratoria

ABSTRACT. Using an in vitro radiochemical assay, juvenile hormone (JH) biosynthesis by corpora allata was screened during the first 2 weeks of adult maturation in both male and female migratory locusts, Locusta migratoria migratorioides (R. & F.). The patterns of change of glandular activities in the sexes were different, but the overall rates of JH production were similar. Testisectomy did not appear to affect corpus allatum activity, male sexual behaviour, or yellow coloration. Removal of the testes together with the seminal vesicle and the accessory glands resulted in a disturbance of the pattern of JH biosynthesis, but had no effect on sexual behaviour or coloration. These observations are discussed in relation to available evidence on JH-mediated sexual events in the adult.     

Purification and properties of closterovirus-like particles associated with a whitefly-transmitted disease of sweet potato

A virus causing sunken veins on ‘Georgia Jet’ sweet potato, and yellow brittle leaves and stunting on Ipomoea setosa, was purified and a specific antiserum was prepared. Flexuous particles with a normal length of 850 nm and a diameter of 12 nm with an open helical structure typical of closteroviruses were observed. The virus particle protein has an apparent mol. wt of c. 34 kD. Double-stranded RNA isolated from SPSVV-infected I. setosa and subjected to electrophoresis in agarose consisted of one major band with an estimated M_r of 10.5 kbp and two minor bands with M_r of 9.0 and 5.0 kbp. Fibril-containing vesicles in phloem cells were observed in ultrathin sections of infected leaf tissues. The virus was transmitted by the whitefly Bemisia tabaci in a semi-persistent manner and by grafting, but not mechanically. The virus could be transmitted to various Ipomoea species, to Nicotiana clevelandii, N. benthamiana and Amaranthus palmeri. The virus did not react with an antiserum to lettuce infectious yellows virus. Based on particle morphology, serology and symptom expression, the virus appears unique and different from all other reported whitefly-transmitted closteroviruses. We propose it be named “sweet potato sunken vein virus” (SPSVV).