Rita Muhamad

Biotype and insecticide resistance status of Bemisia tabaci populations from Peninsular Malaysia

Bemisia tabaci, a resistance‐prone insect pest, is a cryptic species complex with important invasive biotypes such as B and Q. The biotype and resistance statuses of this pest in Malaysia remain unclear. This study assessed the biotype and resistance status of a number of contemporary populations of B. tabaci based on the mtCO1 marker and the dose‐response method, respectively. The Pahang (PHG) population was labelled as the Q biotype, while the remainder of the populations belonged to the Asia 1 biotype. A very low level of resistance for profenofos, cypermethrin, and imidacloprid was detected for all populations [resistance factor (RF) < 10]. Resistance to diafenthiuron ranged from very low to very high (RF > 100). All populations showed a very low level of resistance against pymetrozine except Q‐type PHG population, which exhibited a very high level of resistance. For most insecticides, the highest level of resistance was detected in the PHG population. The implications of these findings for better management of this noxious pest are discussed.

Studies on Beauveria bassiana isolated from the cocoa mirid, Helopeltis theobromae.

Abstract A white entomogenous fungus was found growing on Helopeltis theobromae , a serious pest of cocoa. With the aid of light and scanning electron microscopy techniques, the fungus was identified as Beauveria bassiana . The fungus grew and sporulated on several artificial media at temperatures between 5° and 30°C but not at temperatures higher than 35°C; it grew and sporulated best at 25°C. The fungus was highly pathogenic to Helopeltis adults which were sprayed or dusted with fungal spores.

FIRST REPORT OF BEMISIA TABACI (HEMIPTERA: ALEYRODIDAE) BIOTYPE Q IN MALAYSIA

This article was originally published on May 28, 2013, and has been corrected (June 13, 2013). View this article in BioOne

Genetic Diversity of Bemisia tabaci (Hemiptera: Aleyrodidae) Species Complex Across Malaysia

Abstract The tobacco whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex with members capable of inducing huge economic losses. Precise identification of members of this complex proves essential in managing existing populations and preventing new incursions. Despite records of serious outbreaks of this pest in Malaysia little is known about species status of B. tabaci in this region.To address this, a comprehensive sampling of B. tabaci from different host plants was conducted in 10 states of Malaysia from 2010 to 2012. Members of the complex were identified by sequencing partial mitochondrial cytochrome oxidase subunit I (mtCOI) gene and constructing a Bayesian phylogenetic tree. Seven putative species were identified including Asia I, Mediterranean (MED), China 1, China 2, Asia II 6, Asia II 7, and Asia II 10.The most important finding of the study is the identification of the invasive MED species from locations without previous records of this species. All putative species except Asia I and MED are recorded from Malaysia for the first time. This study provided the first introductory map of B. tabaci species composition in Malaysia and emphasizes the urgent need for further studies to assess the status of MED invasion in this country.

Analysis of quality retentions in cocoa beans exposed to solar heat treatment in cardboard solar heater box

Abstract The use of heat treatment for the disinfestation of insect pests of stored products has been demonstrated to hold great potential as an ecofriendly alternative technique of choice in the feature grain storage systems. However, the success of this method depends on the application of heat on the commodity at levels that cause maximum mortality on the target population and insignificant effect on commodity quality deterioration. Experiments were conducted to assess the effect of heat treatment in solar heater box on the proximate and mineral composition of cocoa beans over series of exposure times. The result shows that solar heat treatment in cardboard solar heater box at temperatures lethal to stored-product insect pest did not affect any of the quality characteristics of the cocoa beans over the tested periods. The implication of this for the application of the cardboard solar heater box for the disinfestation of insect pests on cocoa beans was discussed.