Effects of selected fertilizers on the life history of Bemisia tabaci (Hemiptera: Aleyrodidae) biotype B.

We tested the effects among a purportedly sustainable water-soluble fertilizer, a conventional water-soluble fertilizer, an alternation of these, a controlled-release fertilizer, and a clear water control on the life-history traits of sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae; =Bemisia argentifolii Bellows & Perring) biotype B reared on poinsettia (Euphorbia pulcherrima Willdenow ex Klotzch). Free amino acids in petioles were measured to estimate plant nutrient assimilation and phloem nutritional quality for B. tabaci biotype B. The sustainable fertilizer produced plants with the highest concentration of amino acids. In contrast, fecundity of whiteflies was lowest in plants treated with the sustainable fertilizer and the water control. The relationship between total amino acids in phloem and survival was significantly quadratic, with the highest survival at intermediate levels. Fecundity, however, was negatively correlated with total amino acid content of the maternal host plant. Variation in total amino acid concentration in petioles of plants treated within fertilizer treatments makes it difficult to predict whether a particular fertilizer will produce plants with enough amino acids to deleteriously affect both survivorship and fecundity and yet yield a plant of good quality. Despite this limitation, we can conclude that the use of this sustainable fertilizer will not cause increases in whitefly populations relative to plants fertilized with water-soluble and slow-release fertilizers that deliver the same level of nitrogen to the plant.

Lymphatic system: morphofunctional considerations.

The lymphatic system, consisting of the lymph nodes and the lymphatic vessels as well as the spleen and various sites of lymphoid tissue, is deputed to important tasks: the immune response, the transport of lipids absorbed at the intestinal level and the reabsorption of water and other substances from the interstitial spaces; the lymph nodes in particular are involved in immunity and lymph filtration-depuration. Therefore, the knowledge of lymph node cellular architecture as well as of the structure and course of lymphatic vessels is of great importance. The pathologic processes that affect the lymphatic system can involve the canalicular and/or nodal part, resulting in patterns directly correlated with their respective function: lymphedema and lymphagitis on one hand, and disorders induced by accumulation, inflammation and tumors, on the other.