Ahmad Said Sajap

Evaluation of Hexaflumuron for Controlling the Subterranean Termite Coptotermes curvignathus (Isoptera: Rhinotermitidae) in Malaysia

Abstract Cellulosic bait matrices containing 0.5% hexaflumuron were tested against field colonies of the subterranean termite Coptotermes curvignathus Holmgren in Malaysia. Foraging activities of the termites were first monitored for several months by using survey stakes and wood bundles placed in underground monitoring traps. Infested stakes were replaced with bait devices. Termite workers to act as recruits were collected from infested stakes and placed in the bait devices. Subsequent activities of the termites were monitored by examining and weighing the wood in the monitoring traps. Data show that the four colonies had populations of 166,288–709,052 foragers and mean wood consumption rates of 305.9–508.2 g/mo per trap. These colonies ceased their activities at all monitoring devices 25–44 d after baiting had commenced. Colonies consumed ≈27–79 g of bait matrix or 137.5–395 mg of hexaflumuron. Thus, C. curvignathus colonies could be monitored, characterized, baited, and foraging eliminated by using a bait matrix containing hexaflumuron.

Feeding Response of Subterranean Termites Coptotermes curvignathus and Coptotermes gestroi (Blattodea: Rhinotermitidae) to Baits Supplemented With Sugars, Amino Acids, and Cassava

ABSTRACT Feeding responses of subterranean termites Coptotermes curvignathus (Holmgren) and Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae) to bait matrices supplemented with various sugars, amino acids, and cassava were evaluated both in the laboratory and field. The results indicated that the two termite species consumed significantly different amount of filter papers that had been treated with various types and concentrations of sugars and amino acids. Based on consumption and survival data, filter papers with 3% glucose and 3% xylose were among the most consumed by C. curvignathus and C. gestroi, respectively. Both termite species consumed more of the filter papers treated with 3% casein than filter papers treated with L-alanine. Both species had a comparable survival rate compared with those in the controls. Results from laboratory and field trials on bait prototypes indicated that C. gestroi consumed more bait prototypes containing cellulose, 3% xylose, 3% casein, and cassava, whereas C. curvignathus consumed more bait prototype containing cellulose, 3% glucose, and cassava, than on pure crystalline cellulose baits. Thus, with an improved and cost-effective bait formulation, a much wider control of subterranean termite colonies could be achieved.

Effect of pH, rearing temperature and sunlight on infectivity of Malaysian isolate of nucleopolyhedrovirus to larvae of Spodoptera litura (Lepidoptera: Noctuidae)

The effects of pH, sunlight and rearing temperature on infectivity of nucleopolyhedrovirus (SpltNPV) were investigated against larvae of Spodoptera litura (Fabricius). The infectivity of virus increased with increased larval rearing temperature. The LT50 values were significantly reduced from 24 to 6 days when rearing temperature was increased from 20 to 35 °C. The pH of the substrate significantly affected the infectivity of the virus. The LT50 values increased to about fourfold when the pH of suspension was raised from 7 to 11. Infectivity of the virus was more adversely affected in alkaline than in acidic suspension. Sunlight also deleteriously affected infectivity of the virus. The LT50 values increased with the increase in the period of sunlight exposure. A complete viral inactivation occurred after 12 h of direct sunlight exposure.

Expression profiles of lysozyme- and prophenoloxidase-encoding genes in Spodoptera species challenged with entomopathogenic fungus, Metarhizium anisopliae (Metchnikoff) Sorokin using qRT-PCR

Lysozyme and prophenoloxidase are two immunity-related enzymes in insect. In our attempt to understand their roles in defence, we profiled expressions of the encoding genes in Spodoptera exigua Hübner and Spodoptera litura Fabricius, during the infection process by an entomopathogenic fungus, Metarhizium anisopliae var. anisopliae. Gene expressions were analysed using quantitative real-time reverse transcription-PCR. Sampling was done at 0, 2, 12 and 24 h after infection, and when the infected larvae reached the moribund stage at 36 and 60 h after infection. The expression profiles of the two genes were similar in both larvae. At 24 h after infection, the lysozyme gene was expressed at a higher level in the infected larvae (fivefold) when compared to the healthy larvae, and reached the highest level (13-fold in S. exigua and 7-fold in S. litura) at the moribund stage. The expression levels of the prophenoloxidase gene in the infected larvae were similar to that of the control, except for a slight increase in expression at 2 and 24 h (~1.5-fold) after infection. These findings provide new information on the changes in transcriptional levels of LYZ and PPO, and indicate the importance of these genes in insect defence response against fungal infection.

PATHOGENICITY OF Metarhizium anisopliae (METCHNIKOFF) SOROKIN (DEUTEROMYCOTINA: HYPHOMYCETE) ISOLATES FROM PENINSULAR MALAYSIA AGAINST SUBTERRANEAN TERMITES, Coptotermes curvignathus (BLATTODEA: RHINOTERMITIDAE)

The termite, Coptotermes curvignathus has been reported in Malaysia and it is responsible for the destruction of various timberbased products, plantation and orchard trees. Controlling this pest population using biological pesticide agents, such as entomopathogenic fungi are highly desirable when compared to chemical pesticides because the latter often leads to many environmental concerns. In this study, we isolated Metarhizium anisopliae from four different locations in Peninsular Malaysia and tested their pathogenicity on C. curvignathus. Another six isolates from a previous work were also included. Conidia in the form of suspension at 1x10 7 conidia/mL were applied on worker termites and observed for their mortality within a 12dayperiod. In addition, fungal progression rate was calculated based on the number of days it took for the mycelia to emerge and the conidia to form on the infected termites. Among the ten fungal isolates tested, PR1 yielded the highest mortality (97%) and the shortest median lethal time (LT50= 1.5 days), while TFFH3 and PKLG isolates had the highest rate in mycelia (88%) and conidia (80%) formation, respectively, and they both caused mortality of 93% and LT50 within2 days. PR1’s performance in infecting C. curvignathus evidently could augment its potential use as a microbial pesticide for a sustainable and environment friendly management of termites,

Preferential Use of Carbon Sources in Culturable Aerobic Mesophilic Bacteria of Coptotermes curvignathus’s (Isoptera: Rhinotermitidae) Gut and Its Foraging Area

ABSTRACT The lower termite, Coptotermes curvignathus, is one of the most prominent plantation pests that feed upon, digest, and receive nourishment from exclusive lignocellulose diets. The objective of this study was to examine the utilization of sole carbon sources by isolated culturable aerobic bacteria among communities from the gut and foraging pathway of C. curvignathus. We study the bacteria occurrence from the gut of C. curvignathus and its surrounding feeding area by comparing the obtained phenotypic fingerprint with Biologs extensive species library. A total of 24 bacteria have been identified mainly from the family Enterobacteriaceae from the identification of Biolog Gen III. Overall, the bacteria species in the termite gut differ from those of foraging pathway within a location, except Acintobacter baumannii, which was the only bacteria species found in both habitats. Although termites from a different study area do not have the same species of bacteria in the gut, they do have a bacterial community with similar role in degrading certain carbon sources. Sugars were preferential in termite gut isolates, while nitrogen carbon sources were preferential in foraging pathway isolates. The preferential use of specific carbon sources by these two bacterial communities reflects the role of bacteria for regulation of carbon metabolism in the termite gut and foraging pathway.

Spatial Distribution of Flower Visiting Beetles in Pasoh Forest Reserve and Its Study Technique

To recognize how to maintain sustainable biodiversity in tropical forests, the spatial distributions of flower-visiting beetles were investigated using flower fragrance traps in the Pasoh Forest Reserve (Pasoh FR). 1) The vertical distribution of flower-visiting beetles was investigated using the balloon system and treetowers. Most flower-visiting beetles (Scarabaeidae) were trapped from 10 m to 25 m above ground, indicating that they are active in the continuous middle layer of the canopy, where most trees and climbers bear flowers. Mecinonota regia sumatrana were, however, distributed in the relatively low layer, while Dasyvalgus dohlni was distributed in the upper part of the canopy. 2) The horizontal distribution of flowervisiting beetles was investigated using flower fragrance traps in the Pasoh FR to analyze fragmentation and edge effects. Since this forest is surrounded by oil palm plantations and rubber plantations, it remains as an island of forest within them. The number of Dasyvalgus, one of the main flower-visiting groups, was significantly greater in the primary forest area than in the regenerating area whilst Mecinonota showed no difference. The community structure of scarabaeid beetles was different between the primary forest area and the regenerating forest area. However, difference of beetle fauna between the primary forest area and the regenerating forest area might be more affected by selective logging ca. 40 years ago than the fragmentation or edge effects. This suggests that the effects of selective logging on the beetle fauna still remain even after more than 40 years. Thus, both the observations on vertical and horizontal distributions of flower-visiting beetles imply that management of tropical rain forests should aim to conserve the complex spatial structure of primary forests. 3) Comparison among the trapping systems for canopy fauna in tropical forests were discussed. Balloon trap system and tree-tower with fragrance traps of linalool, eugenol and methyl benzoate were effective for collection of flower-visiting insects on tropical rain forest canopy. The effectiveness of the balloon trap system and tower systems were not different.