Utilization of Fungi for the Biological Control of Insect Pests and Ganoderma Disease in the Indonesian Oil Palm Industry

Biological control is usually the first choice of control and prevention method for integrated pest management （IPM） strategies and has now been widely implemented by Indonesian oil palm plantations. Entomopathogenic fungus, i.e., Metarhizium anisopliae, Cordyceps militaris and Beauveria bassiana have been demonstrated to control renowned pests of oil palm. Metarhizium has been used to control Oryctes larvae and the mortality has ranged from 91.67% to 100% in laboratory and 7.4% to 88.75% in the field. Metarhizium has been applied in combination with a termite baiting system （TBS） to control termites in the field for preventive and curative action as well. In many oil palm plantations in Indonesia, Cordyceps has been used to reduce the field moth population ofSetothosea asigna. Application of Cordyceps within the oil palm circle was able to infect S. asigna pupae up to 80%. Meanwhile, Beauveria in an effervescent formulation was demonstrated to have better efficacy on Darna trima larvae. A significant finding on the biological control of basal stem rot disease （Ganoderma） was the isolation of Trichoderma sp. and Gliocladium sp.. The efficacy was conducted with promising result and techniques on the application of Triehoderma have been developed, i.e., hole-in-hole system, surgery and a mounding method. However, as the roots developed, Trichoderma was no longer able to protect the palm from Ganoderma. In spite of that, the use of Trichoderma still prolonged the life ofoil palms by up to 2-3 years. Another fungi belonging to vesicular arbuscular mychorrhiza （VAM） has been developed to control Ganoderma. The efficacy in the nursery showed promising results and the Ganoderma incidence remained low compared to the untreated control. Large scale field trials are ongoing. Challenges on the implementation of biological control in oil palm plantations are because of application and availability of biopesticides/natural enemies. Therefore, advances in research on the formulation of biological control agents are still needed.     

Hunting of Sumatran orang-utans and its importance in determining distribution and density

To conserve species it is essential to understand which factors determine their distribution and density. Here we focus on the critically endangered Sumatran orang-utan and examine factors that influence the distribution and density in the Batang Toru area, the southernmost area where wild orang-utans occur on Sumatra. We contrast a scenario in which orang-utan distribution is mainly determined by ecological, and topographic variables with a model that includes hunting and human impact. We show that orang-utan distribution and density are best explained by hunting pressure and elevation. These results indicate that an assessment of anthropogenic factors that might influence density such as hunting needs to be included in surveys that aim to predict orang-utan distribution and density. As anthropogenic impact becomes higher with increasing human population density and increased forest access in most areas where orang-utans occur the consequence is that orang-utan conservation will have to be achieved in an environment modified by humans. In such areas the potential for a range of conflicts such as hunting that lead to human-caused mortality for orang-utans will remain a constant threat and need to be mitigated.     

Acid-insoluble ash is a better indigestible marker than chromic oxide to measure apparent total tract digestibility in pigs

The aim of this study was to determine the apparent total tract digestibility (ATTD) of nutrients in cottonseed meal (CSM) and soybean meal (SBM) in simple carbohydrate and more complex wheat-based diets using 2 indigestible markers and total faecal collection. Twenty-five Large White × Landrace boars (57.8 kg) were randomly allocated to either a pure wheat diet, 40% CSM or SBM in either a sugar-starch- (1:1) or wheat-based diet for 18 d. Acid-insoluble ash (AIA) and chromic oxide (Cr₂O₃) were included in all diets as indigestible markers. Diets were offered (1,800 g/d per pig) in 3 meals/d from d 1 to 11 and 8 meals/d from d 12 to 17. On d 9, the pigs were moved to individual metabolism cages to allow total faecal collection. On d 18, the pigs were fed hourly for 8 h. After the 8th meal, pigs were anaesthetized and digesta sampled from the terminal ileum and rectum before lethal injection. There were no differences between ATTD of nitrogen (N) determined using AIA as a marker and measured by total faecal collection. On the other hand, the ATTD of N of diets containing CSM in sugar-starch- or wheat-based diets and the pure wheat diet determined using Cr₂O₃ as a marker was less (−3.11%, −4.46% and −6.59%; P < 0.001) than that measured by total faecal collection. The ATTD of N determined using AIA as a marker was highly correlated with that measured using total faecal collection (P < 0.001; R² = 0.95). Similarly, the ATTD of N determined using Cr₂O₃ as a marker was correlated with that measured using total faecal collection, although the correlation was not quite as strong as using AIA (P < 0.001; R² = 0.87). Also, the slope of the regression line and the intercept were closer to unity and zero for the relationship when the ATTD of N was determined using AIA compared to Cr₂O₃ as an indigestible marker. The ATTD of organic and dry matter behaved similarly. These data demonstrate that the basal diet and choice of indigestible marker can substantially influence the ATTD and that the use of AIA as an indigestible marker is more suitable than Cr₂O₃ in digestibility studies in pigs.