Rosli Hashim

Bioethanol production from fermentable sugar juice.

Bioethanol production from renewable sources to be used in transportation is now an increasing demand worldwide due to continuous depletion of fossil fuels, economic and political crises, and growing concern on environmental safety. Mainly, three types of raw materials, that is, sugar juice, starchy crops, and lignocellulosic materials, are being used for this purpose. This paper will investigate ethanol production from free sugar containing juices obtained from some energy crops such as sugarcane, sugar beet, and sweet sorghum that are the most attractive choice because of their cost-effectiveness and feasibility to use. Three types of fermentation process (batch, fed-batch, and continuous) are employed in ethanol production from these sugar juices. The most common microorganism used in fermentation from its history is the yeast, especially, Saccharomyces cerevisiae, though the bacterial species Zymomonas mobilis is also potentially used nowadays for this purpose. A number of factors related to the fermentation greatly influences the process and their optimization is the key point for efficient ethanol production from these feedstocks.

Patterns of the crematogaster-macaranga association: the ant partner makes the difference

Summary. One of the most species-rich ant-plant mutualisms worldwide is the palaeotropical Crematogaster-Macaranga system. Although the biogeography and ecology of both partners have been extensively studied, little is known about the temporal structuring and the dynamics of the association. In this study we compared life-history traits of the specific Crematogaster (Decacrema) partner-ants and followed the development of ant colonies on eight different Macaranga host plant species, from colony founding on saplings to adult trees in a snapshot fashion. We found differences in the onset of alate production, queen number and mode of colony founding in the ant species and examined the consequences of these differences for the mutualism with the host plant.The lifespan of some host plants and their specific ant partners seemed to be well matched whereas on others we found an ontogenetic succession of specific partner ants. The partner ants of saplings or young plants often differed from specific partner ants found on larger trees of the same species. Not all specific Crematogaster species can re-colonize the crown region of adult trees, thus facilitating a change of ant species. Therefore lifespan of the ant colony as well as colony founding behaviour of the different partner ant species are important for these ontogenetic changes. The lifespan of a colony of two species can be prolonged via secondary polygyny. For the first time, also primary polygyny (pleometrosis) is reported from this myrmecophytic system.

Foraging of a hypogaeic army ant: a long neglected majority

Summary: Army ants have been studied thoroughly for more than a century. The conduction of column and swarm mass raids, featured by epigaeicly active species, is believed to be a central characteristic of army ant behavior. Most army ant species, however, lead a hypogaeic life. Due to the difficulties to observe them, nothing is known about their hypogaeic behavior in the field. Using palm oil baits, trail excavations, and laboratory observations, the hypogaeic foraging of Dorylus (Dichthadia) laevigatus was observed in Malaysia. D. laevigatus was found to construct stable hypogaeic trunk trail systems providing quick and easy access to all parts of its foraging area. Small column raids were conducted throughout the ground stratum and above the ground surface. These raids were caste specific, with the smallest workers predominantly following existing cracks and tunnels in the soil. In case of food location, larger workers were recruited from nearby trunk trails. Exploratory trails leading to prey had to be widened before larger workers could gain access and help to process the food. Bulky food sources such as baits or termite mounds could be exploited over several weeks to months. Besides raiding in columns, D. laevigatus came occasionally to the ground surface at night to conduct swarm raids. This combination of swarm and column raids with the use of trunk trails has never been demonstrated for a classical army ant species. The omnipresence of D. laevigatus within its foraging area stands in sharp contrast to epigaeicly active species, characterized by a very localized and temporary presence at foraging sites. D. laevigatus stayed in the same foraging area for several weeks to months. Having a broad diet and the ability to exploit bulky food sources over long periods of time, D. laevigatus seems to follow a sustainable use of the soil fauna. Summing up these particularities demonstrates a remarkable divergence of the hypogaeic foraging of D. laevigatus from that of epigaeicly foraging army ant species.

Trade-off between chemical and biotic antiherbivore defense in the South East Asian plant genus Macaranga

The plant genus Macaranga is known for its manifold mutualistic associations with ants. The plants provide food for the ants and in turn get protection from herbivores. Depending on the strength of the plant–ant interaction, the plants investment in ants and the biotic defense derived from them is more or less effective. We conducted a comparative study on tannin content in 12 Macaranga species that were selected based on their associations with ants (three nonmyrmecophytes and nine myrmecophytes, three of which start their ontogeny as nonmyrmecophytes). Different developmental stages were investigated in three Macaranga species. Extracts of every individual plant analyzed for tannins were also tested for their effects on larval growth employing larvae of the common cutworm (Spodoptera littoralis). The studied Macaranga species differed significantly in their tannin contents as well as in the effects of their leaf extracts on the growth of S. littoralis larvae. A correlation analysis shows a connection between tannin contents and larval growth. High tannin contents and, thus more effective chemical defense, were observed in nonmyrmecophytic Macaranga species associated only facultatively with ants as compared to obligate myrmecophytes. Our study supports the hypothesis of a trade-off between chemical and biotic defense in the genus Macaranga.

A review of strategies to monitor water and sediment quality for a sustainability assessment of marine environment

The basic aim of this work is (1) to review and present practically operational requirements for a sustainability assessment of marine environment, such as describing the monitoring process, research approaches, objectives, guidelines, and indicators and (2) to illustrate how physico-chemical and biological indicators can be practically applied, to assess water and sediment quality in marine and coastal environment. These indicators should meet defined criteria for practical usefulness, e.g. they should be simple to understand and apply to managers and scientists with different educational backgrounds. This review aimed to encapsulate that variability, recognizing that meaningful guidance should be flexible enough to accommodate the widely differing characteristics of marine ecosystems.

Symbiont microcosm in an ant society and the diversity of interspecific interactions

Colonies of the ponerine army ant Leptogenys distinguenda are regularly inhabited by a highly diverse symbiont fauna including insects, spiders, mites, crustaceans and even molluscs. Each of these myrmecophiles has adapted in a highly specific way to the lifestyle of its host. We studied this diverse myrmecophile fauna of L. distinguenda as a new model for multispecies parasitism to gain a better understanding of fundamental coevolutionary processes. Our study focused on behavioural and on chemical integration and exploitation strategies of the different symbiont species. In addition, we examined potential counterstrategies of the host ant. Myrmecophiles were studied both in large free-living L. distinguenda colonies and in more detail in parts of colonies separated for observation. We found that at least five myrmecophile species imposed cost on their host by exploiting its resources. Their impact varied considerably depending on both the type of resources exploited and their abundance. Myrmecophile species were well integrated into host societies either by chemical mimicry of host cuticular hydrocarbons or by remaining chemically insignificant, lacking most characteristic recognition cues. Despite these chemical integration strategies, host ants were able to recognize and kill the alien intruders to various degrees. This important finding demonstrates that symbiont populations are actively counter-regulated by the host. By constructing a host–parasite interaction network, we finally suggest that host defences can maintain myrmecophile diversity by keeping parasite populations small. This reduces interguild competition, comparable to top–down effects of predators on lower trophic levels in ecological food webs.

Eyespan reflects reproductive quality in wild stalk-eyed flies

Handicap models of sexual selection propose that females use male sexual ornaments as a cue in mate choice because they reflect commodities that increase female fitness, either directly or indirectly. In contrast to studies on vertebrates, most investigations of ornaments in insects and other invertebrate taxa have been conducted under laboratory conditions. There is a pressing need to address questions relating to sexual signalling of quality in natural populations, as the arbitrary and uniform environments found in the laboratory fail to reflect the world under which animals have evolved. We investigated associations between male ornaments (exaggerated eyespan), attractiveness, and reproductive quality in a wild population of the sexually ornamented stalk-eyed fly, Teleopsis dalmanni. We also explored the relationship between eyespan and reproductive quality in females to evaluate the potential for sexually antagonistic selection on eyespan. We show that eyespan is a generic correlate of reproductive quality, acting as a reliable mirror of variation in reproductive fitness in both sexes. Our findings suggest that male ornaments signal commodities that are of interest to females in the natural environment in which they, and mate preferences for them, have evolved. In addition, the covariance between female eyespan and reproductive output suggests that the former may be a reliable cue of quality in its own right. Our data provide important insights into the evolutionary forces that shape the evolution of exaggerated eyespan in wild populations of this species.

Polycyclic Aromatic Hydrocarbons in Coastal Sediment of Klang Strait, Malaysia: Distribution Pattern, Risk Assessment and Sources

Concentration, source, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) were investigated in 22 stations from surface sediments in the areas of anthropogenic pollution in the Klang Strait (Malaysia). The total PAH level in the Klang Strait sediment was 994.02±918.1 µg/kg dw. The highest concentration was observed in stations near the coastline and mouth of the Klang River. These locations were dominated by high molecular weight PAHs. The results showed both pyrogenic and petrogenic sources are main sources of PAHs. Further analyses indicated that PAHs primarily originated from pyrogenic sources (coal combustion and vehicular emissions), with significant contribution from petroleum inputs. Regarding ecological risk estimation, only station 13 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the Klang Strait.

Maintaining an ant-plant symbiosis: secondary polygyny in the Macaranga triloba-Crematogaster sp. association.

Ant-plant associations are common and important elements of tropical forest ecosystems. Their relationships vary from loosely facultative to obligate symbiosis (for an overview see Davidson and McKey 1993). In SE Asia many species of the pioneer tree genus Macaranga are myrmecophytes that provide their ant-partners with nutrients and nesting space in exchange for herbivoreprotection by the ants. The majority of the associated ant species belong to Decacrema, a subgenus of the myrmicine Crematogaster (Fiala et al. 1999) and they are obligatorily and specifically associated with their Macaranga plant-partners. Ants and plants are highly dependent on each other in this myrmecophytic complex. In most Macaranga species even very young saplings develop stem domatia, which are colonised by queens throughout the year. It is very rare to find more than one founding queen in one domatium but frequently several queens occupy different domatia of the same young plant. After claustral colony foundation and the emergence of the first workers, however, only one monogynous colony survives per host tree (Fiala and Maschwitz 1990). Generally it is supposed that the monogynous status is maintained throughout the entire existence of the symbiosis. The death of either partner – ant colony or host tree – can result in severe damage or even the death of the other partner. In the case of the death of the queen the colony dies out and the tree is highly endangered by herbivores (Fiala et al. 1989; Heil et al. 1997). Small trees may be colonised again by their specific ant-partners and then suffer only little damage during the development of the new colony which will soon be large enough to patrol the whole tree effectively. In mature trees, however, with their much larger leaf area, the establishment of a worker force would take too long. Do we find other mechanisms in ant colonies on mature trees that might enable the ants to further protect the tree against herbivoredamage as well as safeguard its territory and resources against competing ant species? Whereas much information now exists on the founding and growth of colonies on saplings (Fiala and Maschwitz 1990), no survey has ever been conducted on the development of mature ant colonies on larger Macaranga trees. We therefore studied queen numbers and colony development in maturing trees in the common myrmecophyte Macaranga triloba (Bl.) Muell. Arg., that is obligatorily associated with Crematogaster msp. 4 (Fiala et al. 1999).

Differential host defense against multiple parasites in ants

Host–parasite interactions are ideal systems for the study of coevolutionary processes. Although infections with multiple parasite species are presumably common in nature, most studies focus on the interactions of a single host and a single parasite. To the best of our knowledge, we present here the first study on the dependency of parasite virulence and host resistance in a multiple parasite system. We evaluated whether the strength of host defense depends on the potential fitness cost of parasites in a system of two Southeast Asian army ant hosts and five parasitic staphylinid beetle species. The potential fitness costs of the parasites were evaluated by their predation behavior on host larvae in isolation experiments. The host defense was assessed by the ants’ aggressiveness towards parasitic beetle species in behavioral studies. We found clear differences among the beetle species in both host–parasite interactions. Particular beetle species attacked and killed the host larvae, while others did not. Importantly, the ants’ aggressiveness was significantly elevated against predatory beetle species, while non-predatory beetle species received almost no aggression. As a consequence of this defensive behavior, less costly parasites are more likely to achieve high levels of integration in the ant society. We conclude that the selection pressure on the host to evolve counter-defenses is higher for costly parasites and, thus, a hierarchical host defense strategy has evolved that depends on the parasites’ impact.