Forecasting of jack mackerel landings (Trachurus murphyi) in central‐southern Chile through neural networks

In the present study, the performance of neuronal networks models in monthly landing forecasting of jack mackerel (Trachurus murphyi) in central‐southern Chile (32°S–42°S) was assessed. Thus, monthly estimations for 10 environmental variables, fishing effort (fe) and jack mackerel landings for the period 1973–2008 were used. A preliminary analysis was done in order to remove strongly correlated variables. Sea surface temperature (SST) and fe are established as input variables, then, a non‐linear cross correlation analysis was performed to estimate the lag between the input variables and jack mackerel landings. Two models were adjusted: model one includes both training and testing cases randomly selected using all data involved in the analysed period; for model 2, the data is divided into two time series: the first from 1973 to 2002 used for training and the second between 2003 and 2008 used for validation. The external validation process for model 1 showed an explained variance of 92%, with a standard forecasting error of 30%. The explained variance for model 2 was 81%, with a standard forecasting error of 38%. Finally, the sensitivity analysis for both models showed the fe as the most influential variable to jack mackerel landings, which presents functionality depending on anthropogenic effects rather than environmental conditions.     

An immunological method for granulovirus detection in larvae of Tuta absoluta: searching for isolates with prospects for biological control of this pest in Colombia

The tomato leafminer Tuta absoluta is an important insect pest of tomato crops worldwide. Biological control using entomopathogenic viruses such as isolates of Phthorimaea operculella granulovirus (PhopGV) can be a promising tool for suitably controlling this pest. However to date, few viral isolates from T. absoluta have been reported. Therefore, the aim of this study was to develop an economic, fast and accurate immunological technique for granulovirus detection and to evaluate viral presence in T. absoluta larvae from field samples collected in Colombia. Polyclonal antibodies against PhopGV were produced by using hens and rabbits. The production system in hen was selected as the most efficient and simple method. Then, a dot-blot test was developed, demonstrating the ability of antibodies to recognize granulovirus. Finally, granulovirus presence in 1186 T. absoluta larvae collected in the most important tomato production areas in Colombia was evaluated, and eight isolates were found in Boyacá and Cundinamarca (0.7% of occurrence). These results constitute the first report of a granulovirus isolated from T. absoluta larvae which had been naturally infected in Colombia's tomato producing-fields, and thereby validates the use of the immunological technique to detect granulovirus in field conditions.     

Dynamics of vanishing of maternally derived antibodies of Ungulate protoparvovirus 1 suggests an optimal age for gilts vaccination

The prevention of Ungulate protoparvovirus 1 (UPV1) infection and consequently the reproductive losses is based on vaccination of all pigs intended for breeding. As maternally derived antibodies (MDA) can interfere with the development of immunity following vaccination, it is important to know the duration of anti-UPV1 MDA to determine the optimal age for the best vaccination efficacy. To elucidate the association between dam and piglet antibody levels against UPV1 and to estimate the decrease rate of MDA, sera and colostrum of 127 gilts (before the first vaccination against UPV1; 15 days after the second vaccine dose; at farrowing; and during the second pregnancy) and sera of 276 piglets (prior to initial colostrum intake; at 7, 21, 57, 87, and 128 days-old) were tested by ELISA. Most gilts (85.8%) had anti-UPV1 antibodies before vaccination and after vaccination all were positive. At 7 days old, the majority of the piglets had anti-UPV1 antibodies, but around 57 days old, only 35.3% were positive and at 87 days old, all were negative. The estimated average half-life of MDA was 29.8 (28.8–30.9) days. A strong correlation was determined between piglet serum at 7 days old with gilt serum at farrowing time (r = 0.77, n = 248, P < 0.001) and with piglet serum at 7 days old with colostrum (r = 0.73, n = 248, P < 0.001). The MDA decreased earlier and the antibody half-life was a little longer than previously reported. Based on these findings, UPV1 vaccination can be performed earlier than usual.

     

The potential health effects of Melicoccus bijugatus Jacq. fruits: phytochemical, chemotaxonomic and ethnobotanical investigations

Most natural product research is market-driven and thus many plant species are overlooked for their health value due to lack of financial incentives. This may explain the limited information available about the health effects of the edible fruit species Melicoccus bijugatus, a member of the Sapindaceae family that grows mostly in the Caribbean and in parts of South America. However, recent phytochemical studies of these fruits have shed some light on their biological effects. In this review the health effects of M. bijugatus fruit pulp and seeds are assessed in relation to phytochemical and ethnobotanical studies, as well as chemotaxonomic information and medicinal uses of other Sapindaceae species. The chemistry of M. bijugatus fruits was found to be different than the other Sapindaceae fruits, although some of the medicinal uses were similar. Specific phenolics or sugars in M. bijugatus fruits may contribute to their therapeutic uses, especially for gastrointestinal problems, and to some extent toxicological effects. This review focuses our understanding about the specific biological effects of M. bijugatus fruits, which may be useful for predicting other medicinal uses, potential drug or food interactions and may benefit people where the fruits are prevalent and healthcare resources are scarce.