Silicon influence on resistance induction against Bemisia tabaci biotype B (Genn.) (Hemiptera: Aleyrodidae) and on vegetative development in two soybean cultivars

The potential of populations of Bemisia tabaci (Genn.) to become resistant to insecticides has stimulated research into alternative tactics of integrated pest management such as the induction of host-plant resistance. Recent data have shown that silicon can increase the degree of resistance of host plants to insect pests. Therefore the aim of our work was to study the effects of silicon application on the vegetative development of soybean plants and on the induction of resistance to the silverleaf whitefly, B. tabaci biotype B. We performed choice and no-choice tests of oviposition preference on two soybean cultivars, IAC-19 (moderately resistant to B. tabaci biotype B) and MONSOY-8001 (susceptible), with and without application of silicon. Silicon did not affect silverleaf whitefly oviposition preferences, but caused significant mortality in nymphs. Thus, silicon increased the degree of resistance to silverleaf whitefly. Silicon decreased the production of phenolic compounds, but did not affect lignin production. However, when applied to cultivar IAC-19, it increased the production of non-protein organic nitrogen. Silicon had no effect on the vegetative development of soybean plants, but it increased the degree of resistance to the silverleaf whitefly. We conclude that silicon applications combined with cultivar IAC-19 can significantly decrease silverleaf whitefly populations, having a positive impact both on the soybean plant and on the environment.

Intradermal administration of measles vaccines

The aim of the study reported here was to determine if bifurcated needles or multiple puncture cylinders would prove suitable for administation of measles vaccines. Children 9 to 11 months old in Sao Paulo, Brazil, were assigned to receive either Biken-Cam 70 (5 000 TCID 50/0.5 ml) or Edmonston-Zagreb (7 000 TCID 50/0.5 ml) measles vaccine intradermally with a bifurcated needle or a multiple puncture cylinder. These devices are usually used to administer smallpox of BCG vaccine. The volume of vaccine inoculated was aproximately 0.003 ml. Measles IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) at the time of vaccination and 8 week later. The study participants were examined 14 days after inoculation for possible adverse reactions. Overall, the children's average age was 9.5 + 0.66 months at vaccination. None of the 45 recipiests of Biken-Cam vaccine responded serologically. The 49 Edmonston-Zagreb vaccine recipients immunized with the multiple puncture cylinder had a somewhat higher serologic response rate (35 percent) and mean concentration of measles antibodies ( 323 mIU/ml) than those 51 who received the same vaccine administered with the bifurcated needle (26 percent and 291 mIU/ml, respectively). The rates of reported symptoms after vaccination did not differ significantly among the groups. Overall, the low serologic response rates following intradermal immunization with the devices tested in this study indicate that this route of administration is not suitable for routine administration of standard-titer vaccines

Intradermal administration of measles vaccines

The aim of the study reported here was to determine if bifurcated needles or multiple puncture cylinders would prove suitable for administation of measles vaccines. Children 9 to 11 months old in Sao Paulo, Brazil, were assigned to receive either Biken-Cam 70 (5 000 TCID 50/0.5 ml) or Edmonston-Zagreb (7 000 TCID 50/0.5 ml) measles vaccine intradermally with a bifurcated needle or a multiple puncture cylinder. These devices are usually used to administer smallpox of BCG vaccine. The volume of vaccine inoculated was aproximately 0.003 ml. Measles IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) at the time of vaccination and 8 week later. The study participants were examined 14 days after inoculation for possible adverse reactions. Overall, the children's average age was 9.5 + 0.66 months at vaccination. None of the 45 recipiests of Biken-Cam vaccine responded serologically. The 49 Edmonston-Zagreb vaccine recipients immunized with the multiple puncture cylinder had a somewhat higher serologic response rate (35 percent) and mean concentration of measles antibodies ( 323 mIU/ml) than those 51 who received the same vaccine administered with the bifurcated needle (26 percent and 291 mIU/ml, respectively). The rates of reported symptoms after vaccination did not differ significantly among the groups. Overall, the low serologic response rates following intradermal immunization with the devices tested in this study indicate that this route of administration is not suitable for routine administration of standard-titer vaccines

This article will also be published in Spanish in the BOSP. Vol. 118, 1995