Life cycle of Raoiella indica (Acari: Tenuipalpidae) on ornamental plants, mostly Arecaceae

The red palm mite, Raoiella indica Hirst, has been primarily found associated with coconut and musaceous plants in the New World. However, it has also been recorded on several other palms, heliconiaceous and zingiberaceous species. This study was conducted to evaluate the suitability of different botanical families on which R. indica has been collected in the field and of arecaceous plants of the natural vegetation of the neotropics. In total, ten species of Arecaceae as well as Heliconia psittacorum [Heliconiaceae] and Alpinia purpurata [Zingiberacae] were evaluated, using coconut as a control. The study was carried out under controlled conditions (29 +/- A 0.5 A degrees C, 60 +/- A 10 % RH and photoperiod 12 h of light). Raoiella indica was able to complete immature development only on coconut, Adonidia merrillii, Ptychosperma macarthurii, H. psittacorum and A. purpurata. Duration of the immature phase (egg-adult) ranged between 21.5 days on coconut to 34.1 days on A. purpurata. Longevity was at least 50 % greater and oviposition at least 38 % higher on coconut than on other plants. Intrinsic rate of increase (r(m)) was higher on coconut (0.166) and A. merrillii (0.042), but negative on the other two plant species. Raoiella indica could not reach adulthood on any of the other ten arecaceous species considered in the study. The results suggested R. indica to be a threat to A. merrillii in addition to coconut, but not to other evaluated plants. However, complementary studies should be conducted to investigate whether the experimental procedures adopted in this study could not have prevented the mite from a better performance than it could have been under field conditions, especially in relation to Mauritia flexuosa, one of the dominant arecaceous plants in South America.

Modelling and determination of metabolic pools by stable carbon isotopes in the avian duodenal mucosa and albumen

Stable isotope analyses have helped in assessing dietary switches if the diet undergoes metabolic alteration (isotopic exchange). However, when considering the effects over time of switching from one diet to another, one can assess how quickly the new diet is incorporated into tissues via the isotopic renewal or incorporation rate, or turnover. Turnover is obtained using exponential curves that fit the original data, allowing the determination of practical order parameters such as the half-life (T) and the turnover constant (k). Researchers have found that metabolic incorporation can be fractionated. The resulting fractions, called metabolic pools, are identified using the linearization of the isotopic exchange model and its linear fit. This fractionation methodology is still not well defined. The objective of this study was to assess the behaviour of the metabolic renewal rate (turnover) in fractionated form, explain the theory, and apply it to data from the avian duodenal mucosa and albumen. We concluded that the duodenal mucosa has one metabolic pool, with a half-life of 1.23 days, and that the albumen has two metabolic pools, with half-lives of 1.89 and 6.32 days.