Biological and genetic aspects of experimental hybrids from species of the Phyllosoma complex (Hemiptera: Reduviidae: Triatominae)

The present work is a thorough investigation of the degree of reproductive isolation between Meccus mazzottii and Meccus longipennis, Meccus picturatus, Meccus pallidipennis and Meccus bassolsae, as well as between M. longipennis and M. picturatus. We examined fertility and segregation of morphological characteristics in two generations of hybrids derived from crosses between these species. The percentage of pairs with (fertile) offspring was highest in the set of crosses between M. longipennis and M. picturatus, and lowest between M. mazzottii and M. picturatus. Most first-generation (F1) individuals from crosses involving M. mazzottii were morphologically similar to this species, while only F1 x F1 progeny of parental crosses between M. mazzottii and M. longipennis had offspring second generation that looked like M. mazzottii. The results indicate that different degrees of reproductive isolation apparently exist among the species of the Phyllosoma complex examined in this study. The biological evidence obtained in this study does not support the proposal that M. longipennis and M. picturatus are full species. It could indicate on the contrary, that both could be considered as subspecies of a single polytypic species. On the other hand, biological evidence supports the proposal that M. mazzottii is a full species.

In vitro anti-microbial activity of the Cuban medicinal plants Simarouba glauca DC, Melaleuca leucadendron L and Artemisia absinthium L

In the present study, an extensive in vitro antimicrobial profiling was performed for three medicinal plants grown in Cuba, namely Simarouba glauca, Melaleuca leucadendron and Artemisia absinthium. Ethanol extracts were tested for their antiprotozoal potential against Trypanosoma b. brucei, Trypanosoma cruzi, Leishmania infantum and Plasmodium falciparum. Antifungal activities were evaluated against Microsporum canis and Candida albicans whereas Escherichia coli and Staphylococcus aureus were used as test organisms for antibacterial activity. Cytotoxicity was assessed against human MRC-5 cells. Only M. leucadendron extract showed selective activity against microorganisms tested. Although S. glauca exhibited strong activity against all protozoa, it must be considered non-specific. The value of integrated evaluation of extracts with particular reference to selectivity is discussed.

Influence of temperature and humidity on the biology of Triatoma mexicana (Hemiptera: Reduviidae: Triatominae) under laboratory conditions

Several biological parameters related to the Triatoma mexicana life-cycle were evaluated in this study. Three cohorts were maintained under different combinations of temperature and relative humidity (RH): 25ºC/50% RH; 25ºC/75% RH; and 30ºC/75% RH. Observed hatching rates varied from 49-57.5% whereas the average time of hatching varied from 19.5-22.7 days. In the three cohorts studied, the mean time-lapse between presentation of the blood meal and the beginning of feeding was less than 5 min in all instars; the mean feeding time was longer than 10 min in all the instars; the post-feed defecation delay was over 10 min in all the instars. Less than 50% of nymphs in each cohort completed the cycle and the average time from 1st instar nymph to adult was more than 255 days for the three cohorts. The number of blood meals before molt at each nymphal instar varied from 1-9. Our results appear to indicate a lack of influence of temperature and RH on the biological parameters of T. mexicana that were studied, which could reflect the adaptation capacity of this species. We also conclude that T. mexicana can not be considered an effective transmitter of Trypanosoma cruzi to human populations in areas where this species is currently present.