On December 21, 2010, 6000 genetically modified (GM) mosquitoes were released in an uninhabited forest in Malaysia. The purpose of the deliberate release was a limited “marked release and recapture” (MRR) experiment, a standard ecological method in entomology, to evaluate under field conditions, the flight distance and longevity of the sterile male Aedes aegypti strain OX513A(My1), a GM strain. As with any other GM technologies, the release was received with mixed responses. As the scientific community debate over the public engagement strategies for similar GM releases, dengue incidence continues to rise with a heavy toll on morbidity, mortality and healthcare budgets. Meanwhile the wild female Aedes aegypti continues to breed offspring, surviving and evading conventional interventions for vector control.
Matched MeSH terms: Pest Control, Biological/methods*
The long-term usefulness of Bacillus thuringiensis Cry toxins, either in sprays or in transgenic crops, may be compromised by the evolution of resistance in target insects. Managing the evolution of resistance to B. thuringiensis toxins requires extensive knowledge about the mechanisms, genetics, and ecology of resistance genes. To date, laboratory-selected populations have provided information on the diverse genetics and mechanisms of resistance to B. thuringiensis, highly resistant field populations being rare. However, the selection pressures on field and laboratory populations are very different and may produce resistance genes with distinct characteristics. In order to better understand the genetics, biochemical mechanisms, and ecology of field-evolved resistance, a diamondback moth (Plutella xylostella) field population (Karak) which had been exposed to intensive spraying with B. thuringiensis subsp. kurstaki was collected from Malaysia. We detected a very high level of resistance to Cry1Ac; high levels of resistance to B. thuringiensis subsp. kurstaki Cry1Aa, Cry1Ab, and Cry1Fa; and a moderate level of resistance to Cry1Ca. The toxicity of Cry1Ja to the Karak population was not significantly different from that to a standard laboratory population (LAB-UK). Notable features of the Karak population were that field-selected resistance to B. thuringiensis subsp. kurstaki did not decline at all in unselected populations over 11 generations in laboratory microcosm experiments and that resistance to Cry1Ac declined only threefold over the same period. This finding may be due to a lack of fitness costs expressed by resistance strains, since such costs can be environmentally dependent and may not occur under ordinary laboratory culture conditions. Alternatively, resistance in the Karak population may have been near fixation, leading to a very slow increase in heterozygosity. Reciprocal genetic crosses between Karak and LAB-UK populations indicated that resistance was autosomal and recessive. At the highest dose of Cry1Ac tested, resistance was completely recessive, while at the lowest dose, it was incompletely dominant. A direct test of monogenic inheritance based on a backcross of F1 progeny with the Karak population suggested that resistance to Cry1Ac was controlled by a single locus. Binding studies with 125I-labeled Cry1Ab and Cry1Ac revealed greatly reduced binding to brush border membrane vesicles prepared from this field population.
Four subpopulations of a Plutella xylostella (L.) strain from Malaysia (F(4) to F(8)) were selected with Bacillus thuringiensis subsp. kurstaki HD-1, Bacillus thuringiensis subsp. aizawai, Cry1Ab, and Cry1Ac, respectively, while a fifth subpopulation was left as unselected (UNSEL-MEL). Bioassays at F(9) found that selection with Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai gave resistance ratios of >95, 10, 7, and 3, respectively, compared with UNSEL-MEL (>10,500, 500, >100, and 26, respectively, compared with a susceptible population, ROTH). Resistance to Cry1Ac, Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai in UNSEL-MEL declined significantly by F(9). The Cry1Ac-selected population showed very little cross-resistance to Cry1Ab, B. thuringiensis subsp. kurstaki, and B. thuringiensis subsp. aizawai (5-, 1-, and 4-fold compared with UNSEL-MEL), whereas the Cry1Ab-, B. thuringiensis subsp. kurstaki-, and B. thuringiensis subsp. aizawai-selected populations showed high cross-resistance to Cry1Ac (60-, 100-, and 70-fold). The Cry1Ac-selected population was reselected (F(9) to F(13)) to give a resistance ratio of >2,400 compared with UNSEL-MEL. Binding studies with (125)I-labeled Cry1Ab and Cry1Ac revealed complete lack of binding to brush border membrane vesicles prepared from Cry1Ac-selected larvae (F(15)). Binding was also reduced, although less drastically, in the revertant population, which indicates that a modification in the common binding site of these two toxins was involved in the resistance mechanism in the original population. Reciprocal genetic crosses between Cry1Ac-reselected and ROTH insects indicated that resistance was autosomal and showed incomplete dominance. At the highest dose of Cry1Ac tested, resistance was recessive while at the lowest dose it was almost completely dominant. The F(2) progeny from a backcross of F(1) progeny with ROTH was tested with a concentration of Cry1Ac which would kill 100% of ROTH moths. Eight of the 12 families tested had 60 to 90% mortality, which indicated that more than one allele on separate loci was responsible for resistance to Cry1Ac.
Long-term field studies were conducted on two government managed small ruminant research farms, located in different geo-climatic regions and approximately 300 km separate from each other, on Peninsula Malaysia. The Infoternak trial (48 weeks) and the Chalok trial (43 weeks) each compared nematode parasite control in separately managed groups of young sheep, either short-term rotationally grazed around a suite of 10 paddocks in addition to receiving a daily supplement of Duddingtonia flagrans spores (Fungus Group); or similar groups of sheep being rotationally grazed alone (Control Group). The prevailing weather conditions at Infoternak farm were of below average rainfall conditions for the most of the trial. As a consequence, only very low worm infections (almost exclusively Haemonchus contortus) were acquired by the 17 sets of tracer lambs that grazed sequentially with the experimental lambs. However on all except 2 occasions in the early part of the trial, the mean tracer worm burdens were significantly lower (P < 0.05) and the experimental lambs grew significantly better (P = 0.054) in the Fungus Group. Rainfall at Chalok farm during the course of the trial was also below average. As a consequence infectivity of pastures was assumed to be relatively low based on faecal egg counts (epg) of the experimental sheep, which following an anthelmintic treatment prior to allocation, remained very low in both treatment groups. Faecal egg counts of undosed replacement lambs in the latter half of the Chalok study, showed a progressive increase in the Control Group to levels exceeding 3000 epg, whereas the Fungus Group remained static at approximately 500 epg. These results show that the deployment of the nematophagous fungus, D. flagrans, can improve the level of parasite control of sheep in the tropics above that which can be achieved by the short-term rotational grazing strategy alone.
Matched MeSH terms: Pest Control, Biological/methods*
This study explored the efficacy of Toxorhynchites splendens, predator of Aedes albopictus as a biocontrol agent. There was a negative correlation between Ae. albopictus larval population and Tx. splendens larval population in ovitraps (r=-0.287, R²=0.0821). The correlation is higher between the mean number of Ae. albopictus larvae per ovitrap and the number of Tx. splendens larvae in an ovitrap (r=-0.987, R²=0.9737). Larvae of Tx. splendens were observed to co-exist with larvae of Ae. albopictus and Culex fuscocephala in the ovitraps placed in the study area. The existence of Tx. splendens larvae in the study area coincides with their habit, preferring to breed in bamboo stumps. A total of 480 ovitraps were inspected for 30-week study period and 281 ovitraps were positive with Ae. albopictus larvae respectively. There was a significant difference between numbers of ovitrap positive for Ae. albopictus larvae with number of Tx. splendens larvae in the ovitraps (ANOVA, F((4,475)) 2.655, p<0.05). Of 281 ovitraps positive with Ae. albopictus larvae, 255 ovitraps contained only one Tx. splendens larva each. Only one ovitrap contained four, the most number of Tx. splendens larvae (p< 0.05). Thus, Tx. splendens could be utilised as an alternative for dengue vector control programme.
Matched MeSH terms: Pest Control, Biological/methods*
Deltacide (S-bioallethrin 0.71% w/v, deltamethrin 0.5% w/v, piperonyl butoxide 8.9% w/v excipients to 100% w/v) and Solfac UL 015 (cyfluthrin 1.5% w/v) were evaluated against the sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti at 17 storey high-rise apartments in Malaysia using ULV applications. The impact of both insecticides on field populations of Ae. aegypti and Ae. albopictus larvae was monitored weekly using bottle containers. Both Deltacide and Solfac UL 015 showed adulticidal and larvicidal effects. This was the first field trial using Deltacide against dengue vectors in Malaysia and showed its potential for use in dengue vector control programs.
The efficacy of three formulations of Bacillus thuringiensis var. israelensis was studied against Aedes albopictus in discarded tires. The formulations were: Vectobac G (corn cob formulation), Vectobac 12AS (aqueous suspension), and Bactimos WP (wettable powder formulation). Both Vectobac G and Vectobac 12AS were effective for 24 hr with more than 80% mortality. Both Vectobac formulations were significantly more effective than Bactimos WP for 24 hr after treatment (P < 0.0005). A week after treatment, Vectobac 12AS was significantly different than Bactimos WP (P < 0.05). However, Vectobac G did not differ significantly from Bactimos WP (P > 0.05); two weeks after spraying there was no significant difference among the various formulations (P > 0.05).
Matched MeSH terms: Pest Control, Biological/methods*
Studies were carried out on the residual efficacy of Bacillus thuringiensis H-14 (water dispersible granule, VectoBac ABG 6511) as direct application in the control of Aedes larvae in the field. Field Aedes sp populations in the earthen and glass jars were predetermined before initiation of the trial. On confirmation of the presence of Aedes species in the designated area, Sungai Nibong Kecil, Penang Island, Malaysia, Bti was introduced in the 55L earthen and 3L glass jars). Two test designs were carried out. The first design had treated water replenished daily with 6L of seasoned water and the second design is without the replenishment of water but evaporated water was replenished. Bti was effective in the field for at least 35 days with more than 80% reduction in the Aedes larvae in the treated containers. For earthen jars with daily replenishment of water, 100% reduction was recorded for the first 3 days, while more than 80% reduction was recorded up to day 40. At day 60, Bti still provided an efficacy of 54.32 +/- 4.61 (%) of reduction. Whilst for earthen jars without daily replenishment of water, 100% reduction was recorded for the first 5 days, while more than 80% of reduction was recorded up to day 40. For the glass jars studied, similar efficacy was observed. In jars with daily replenishment of water a better larval control was observed. Percentage of reduction from day 50 to 60 for replenishment of water was between 50 to 70% compared to without replenishment of water with less than 40%.
Matched MeSH terms: Pest Control, Biological/methods*
A screening program searching for indigenous microbial control agents of mosquitos in Malaysia is initiated since 1987 and to date at least 20 isolates of mosquitocidal Bacillus thuringiensis serotypes have been obtained. Preliminary field evaluation of several isolates indicated that they are highly effective in the control of medically important mosquito species. For operational purposes, there is an urgent need to produce this agent utilizing cheap and locally available wastes through fermentation biotechnology. Fermentation studies in shake-flasks containing standard nutrient broth and soya bean waste, respectively, indicate that it takes about 37 hours for a Malaysian isolate of B. thuringiensis serotype H-14 to mature. In the grated coconut waste, fishmeal and rice bran, the bacteria took 28 hours, 26 hours and 126 hours respectively to mature. The endotoxin was harvested from the standard nutrient broth at 55 hours and at 50 hours from soybean, grated coconut waste and fishmeal. The endotoxin could only be harvested 150 hours after inoculation from rice bran medium. However, no bacterial growth was detected in palm oil effluent. In terms of endotoxin and biomass production, fishmeal appears to be a suitable medium. Variations in the pH of the fermenting media were also noted.
Matched MeSH terms: Pest Control, Biological/methods*
Bactrocera carambolae and B. papayae are major fruit fly pests and sympatric sibling species of the B. dorsalis complex. They possess distinct differences in male pheromonal components. In the 1990's, wild Bactrocera fruit flies with morphological traits intermediate between those of B. carambolae and B. papayae were often captured in traps baited with methyl eugenol (ME). Chemical analyses of rectal glands of ME-fed males revealed that the laboratory Fl, F2, and backcross hybrids possessed ME-derived sex pheromonal components ranging from that typical of B. papayae to that of B. carambolae without any specific trend, which included a combination of pheromonal components from both parental species within an individual hybrid. ME-fed hybrids without any ME-derived pheromonal components were also detected. Further chemical analysis of rectal glands from wild Bactrocera males, after ME feeding in the laboratory, showed a combination of pheromonal components similar to that found in the ME-fed, laboratory-bred hybrids. These findings present circumstantial evidence for the occurrence of a natural hybrid of the two Bactrocera species.
There was high mortality in late larval instars of Aedes albopictus (Skuse) from laboratory and field populations in the 24 h after application of three Bactimos formulations of Bacillus thuringiensis H-14. Mortalities were higher and residual effects longer in field populations than in laboratory ones. Briquets were the most effective formulation (mortality 96-100% after five weeks; 76-92% after eight weeks). Culex quinquefasciatus Say larvae were tested only against the briquet formulation. In the laboratory, 100% mortality of late instars persisted for six weeks and dropped to 48-88% after eight weeks. In the field, late instars were reduced by 62-87% after 24 h and 69-72% after one week compared to increases in an untreated population of 160% and 176% respectively.
The objective of this study was to evaluate the potential of Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae) to control American cockroaches, Periplaneta americana (L.) (Dictyoptera: Blattidae), in sewer manholes and in crevices around buildings. Parasitoids were released weekly for 12 wk from laboratory parasitized heat-killed oothecae, and parasitism monitored using sentinel oothecae of American cockroaches. In addition, preference of A. hagenowii for 1- to 4-wk-old oothecae was evaluated in the laboratory. A. hagenowii females showed no preference for any ootheca age. Twenty of the 30 tested females parasitized one ootheca, whereas the other 10 parasitized two oothecae. The total progeny (males, females, and total) that emerged from a single ootheca parasitized by a female was not significantly different to the total progeny that emerged from two oothecae parasitized by a female. The number of males, females, and total progeny that emerged from the second parasitized ootheca was significantly less than the number that emerged from the first parasitized ootheca. The weekly mean sentinel oothecal parasitism rate in wall crevices was 18.1 +/- 3.2% and in sewer manholes was 13.3 +/- 2.0%. The mean number of released A. hagenowii females per number of parasitized sentinel oothecae recorded in crevices was 189 +/- 18, whereas it was 428 +/- 50 in sewers. A. hagenowii females were more effective at parasitizing sentinel oothecae placed at high and middle levels in manholes than at a low level when releases were made at the midpoint of the manhole shaft.
Matched MeSH terms: Pest Control, Biological/methods*
Dengue has enormous health impacts globally. A novel approach to decrease dengue incidence involves the introduction of Wolbachia endosymbionts that block dengue virus transmission into populations of the primary vector mosquito, Aedes aegypti. The wMel Wolbachia strain has previously been trialed in open releases of Ae. aegypti; however, the wAlbB strain has been shown to maintain higher density than wMel at high larval rearing temperatures. Releases of Ae. aegypti mosquitoes carrying wAlbB were carried out in 6 diverse sites in greater Kuala Lumpur, Malaysia, with high endemic dengue transmission. The strain was successfully established and maintained at very high population frequency at some sites or persisted with additional releases following fluctuations at other sites. Based on passive case monitoring, reduced human dengue incidence was observed in the release sites when compared to control sites. The wAlbB strain of Wolbachia provides a promising option as a tool for dengue control, particularly in very hot climates.
Matched MeSH terms: Pest Control, Biological/methods*
Basal Stem Rot (BSR) disease caused by Ganoderma boninense is the most destructive disease in oil palm, especially in Indonesia and Malaysia. The available control measures for BSR disease such as cultural practices and mechanical and chemical treatment have not proved satisfactory due to the fact that Ganoderma has various resting stages such as melanised mycelium, basidiospores and pseudosclerotia. Alternative control measures to overcome the Ganoderma problem are focused on the use of biological control agents and planting resistant material. Present studies conducted at Indonesian Oil Palm Research Institute (IOPRI) are focused on enhancing the use of biological control agents for Ganoderma. These activities include screening biological agents from the oil palm rhizosphere in order to evaluate their effectiveness as biological agents in glasshouse and field trials, testing their antagonistic activities in large scale experiments and eradicating potential disease inoculum with biological agents. Several promising biological agents have been isolated, mainly Trichoderma harzianum, T. viride, Gliocladium viride, Pseudomonas fluorescens, and Bacillus sp. A glasshouse and field trial for Ganoderma control indicated that treatment with T. harzianum and G. viride was superior to Bacillus sp. A large scale trial showed that the disease incidence was lower in a field treated with biological agents than in untreated fields. In a short term programme, research activities at IOPRI are currently focusing on selecting fungi that can completely degrade plant material in order to eradicate inoculum. Digging holes around the palm bole and adding empty fruit bunches have been investigated as ways to stimulate biological agents.
Matched MeSH terms: Pest Control, Biological/methods*
Clostridium bifermentans serovar malaysia (C.b.m.) is highly toxic to mosquito larvae. In this study, the following aquatic nontarget invertebrates were treated with high C.b.m. concentrations (up to 1,600-fold the toxic concentration for Anopheles stephensi) to study their susceptibility towards the bacterial toxin: Planorbis planorbis (Pulmonata); Asellus aquaticus (Isopoda); Daphnia pulex (Cladocera); Cloeon dipterum (Ephemeroptera); Plea leachi (Heteroptera); and Eristalis sp., Chaoborus crystallinus, Chironomus thummi, and Psychoda alternata (Diptera). In addition, bioassays were performed with mosquito larvae (Aedes aegypti, Anopheles stephensi, and Culex pipiens). Psychoda alternata larvae were very susceptible, with LC50/LC90 values comparable to those of mosquito larvae (about 10(3)-10(5) spores/ml). The tests with Chaoborus crystallinus larvae showed significant mortality rates at high concentrations, but generally not before 4 or 5 days after treatment. The remaining nontarget organisms did not show any susceptibility. The investigation confirms the specificity of C.b.m. to nematocerous Diptera.
Matched MeSH terms: Pest Control, Biological/methods
Dermatophagoides pteronyssinus and Dermatophagoides farinae mites are commonly found in house dust, and are important sources of allergens affecting humans. Various approaches to killing the mites have been examined. This study investigated the mortalities of adult mites exposed to 2,450 MHz microwave radiation produced by 3 ovens at various exposure times and power settings. The ovens all had 3 power settings. The average maximum water temperatures generated at high, medium and low power settings were 99.4 +/- 0.2, 84.1 +/- 0.4 and 44.8 +/- 0.9 degrees C, respectively. At high and medium settings, there was 100.0% mortality in both species when exposed for 300 seconds. The mean mortality rates at low power were 10.8 +/- 0.7% for D. pteronyssinus and 9.7 +/- 2.6% for D. farinae. When mites were exposed in the presence of culture media, the mortality rates decreased with increasing weight of media. The mean mortality with the largest amount of media tested at high power setting was 61.4%.
The effect of ten microalgal chlorophytes isolated from mosquito breeding containers on the survival, larval development and adult body size of the mosquito Aedes aegypti was investigated. All larvae fed with six of the microalgal isolates died after 7 days. These isolates were found to be resistant to digestion by mosquito larvae. Delayed pupation and body size reduction of the mosquitos fed with Chlorococcum UMACC 218 and Scenedesmus UMACC 220 were observed. In contrast, larvae fed with Ankistrodesmus convolutus UMACC 101 and Chlorococcum UMACC 213 were bigger in size than those fed with normal insectory feed. The present study showed that microalgal chlorophytes have the potential to be used as larvicidal agents for mosquitos.
Matched MeSH terms: Pest Control, Biological/methods*
To investigate the short and long term efficacy of a commercial air ionizer in killing Dermatophagoides pteronyssinus (D. pteronyssinus) and Dermatophagoides farinae (D. farinae) mites.
Tapinoma indicum is a household pest that is widely distributed in Asian countries. It is known as nuisance pest that causes annoyance and disturbance by constructing nests and foraging in building for food and water. This article documents the draft genome dataset of T. indicum collected in Penang Island, Malaysia using the next-generation sequencing known as the Illumina platform. This article presents the pair-end 150 bp genome dataset and the quality of the sequencing result. This dataset provides the information for further understanding of T. indicum in the molecular aspect and the opportunity to develop a novel method for pest control and regulation. The dataset is available under Sequence Read Archive (SRA) databases with the accession number SRR10848807.
Tapinoma indicum (Forel) (Hymenoptera: Formicidae) is a nuisance pest in Asia countries. However, studies on T. indicum are limited, especially in the field of molecular biology, to investigate the species characteristic at the molecular level. This paper aims to provide valuable genetic markers as tools with which to study the T. indicum population. In this study, a total of 143,998 microsatellite markers were developed based on the 2.61 × 106 microsatellites isolated from T. indicum genomic DNA sequences. Fifty selected microsatellite markers were amplified with varying numbers of alleles ranging from 0 to 19. Seven out of fifty microsatellite markers were characterized for polymorphism with the Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) analysis. All seven microsatellite markers demonstrated a high polymorphic information content (PIC) value ranging from 0.87 to 0.93, with a mean value of 0.90. There is no evidence of scoring errors caused by stutter peaks, no large allele dropout, and no linkage disequilibrium among the seven loci; although loci Ti-Tr04, Ti-Tr09, Ti-Te04, Ti-Te13, and Ti-Pe5 showed signs of null alleles and deviation from the HWE due to excessive homozygosity. In conclusion, a significant amount of microsatellite markers was developed from the data set of next-generation sequencing, and seven of microsatellite markers were validated as informative genetic markers that can be utilized to study the T. indicum population.