Fatimah Abang

Impacts of Horticultural Mineral Oils and Two Insecticide Practices on Population Fluctuation of Diaphorina citri and Spread of Huanglongbing in a Citrus Orchard in Sarawak

Aspects of the incidence and spread of the citrus disease huanglongbing (HLB) in relation to the vector Diaphorina citri population fluctuation were studied from January 1999 to December 2001 seasons in a 0.8 ha citrus orchard at Jemukan (1° 33′N, 110° 41′E), Southwest Sarawak in Malaysia. In relation to insecticide and horticultural mineral oils (HMOs) use, levels of HLB infection rose quite rapidly over the next 3 years in the unsprayed control and less rapidly in the other treatments such as imidacloprid, nC24HMO, and triazophos/cypermethrin/chlorpyrifos. Levels of HLB as determined by Polymerase Chain Reaction (PCR) were 42.2%, 9.4%, 11.4%, and 22.7%, respectively. The effects of nC24HMO and conventional pesticides on the citrus psyllid population and parasitoids in citrus orchard were also determined.

Indirect effects of cigarette butt waste on the dengue vector Aedes aegypti (Diptera: Culicidae).

Despite major insecticide-based vector control programs, dengue continues to be a major threat to public health in urban areas. The reasons for this failure include the emergence of insecticide resistance and the narrowing of the spectrum of efficient products. Cigarette butts (CBs), the most commonly discarded piece of waste, also represent a major health hazard to human and animal life. CBs are impregnated with thousands of chemical compounds, many of which are highly toxic and none of which has history of resistance in mosquitoes. This study was performed to examine whether exposure to CB alters various biological parameters of parents and their progeny. We examined whether the mosquito changes its ovipositional behaviors, egg hatching, reproductive capacity, longevity and fecundity in response to CB exposure at three different concentrations. Females tended to prefer microcosms containing CBs for egg deposition than those with water only. There were equivalent rates of eclosion success among larvae from eggs that matured in CB and water environments. We also observed decreased life span among adults that survived CB exposure. Extracts of CB waste have detrimental effects on the fecundity and longevity of its offspring, while being attractive to its gravid females. These results altogether indicate that CB waste indirectly affect key adult life traits of Aedes aegypti and could conceivably be developed as a novel dengue vector control strategy, referring to previously documented direct toxicity on the larval stage. But this will require further research on CB waste effects on non-target organisms including humans.

Genus Thubana Walker of the Malaysian Borneo (Lepidoptera, Lecithoceridae), with Descriptions of Seven New Species

The genus Thubana Walker, 1864 of the Malaysian Borneo is revised. Nine species are recognized including seven new species. The new species are: T. kumatai sp. nov., T. kubahensis sp. nov., T. kinabaluensis sp. nov., T. ochracea sp. nov., T. quadrata sp. nov., T. prolata sp. nov., and T. spinata sp. nov. With regard to the previously known species, photos of adults and the male or female genitalia are given, with some taxonomie notes. A key to the Thubana species of the Malaysian Borneo is provided.

Occurrence of a mosquito vector in bird houses: Developmental consequences and potential epidemiological implications

Even with continuous vector control, dengue is still a growing threat to public health in Southeast Asia. Main causes comprise difficulties in identifying productive breeding sites and inappropriate targeted chemical interventions. In this region, rural families keep live birds in backyards and dengue mosquitoes have been reported in containers in the cages. To focus on this particular breeding site, we examined the capacity of bird fecal matter (BFM) from the spotted dove, to support Aedes albopictus larval growth. The impact of BFM larval uptake on some adult fitness traits influencing vectorial capacity was also investigated. In serial bioassays involving a high and low larval density (HD and LD), BFM and larval standard food (LSF) affected differently larval development. At HD, development was longer in the BFM environment. There were no appreciable mortality differences between the two treatments, which resulted in similar pupation and adult emergence successes. BFM treatment produced a better gender balance. There were comparable levels of blood uptake and egg production in BFM and LSF females at LD; that was not the case for the HD one, which resulted in bigger adults. BFM and LSF females displayed equivalent lifespans; in males, this parameter was shorter in those derived from the BFM/LD treatment. Taken together these results suggest that bird defecations successfully support the development of Ae. albopictus. Due to their cryptic aspects, containers used to supply water to encaged birds may not have been targeted by chemical interventions.

Diversity of Macromoths (Lepidoptera: Heterocera) in the Poring Hill Dipterocarp Forest, Sabah, Borneo

The diversity and abundance of the macromoths were investigated in a hill dipterocarp forest, Poring, Sabah, using modified Pennsylvanian light traps conducted bimonthly for a total of 24 nights from March through December 1999. The light-traps were set for five continuous nights for every two months during the study period. A total of 1, 169 species from 9, 624 individuals and 15 families of the macromoths were recorded. The overall species diversity index for the macromoths was found to be extremely high (348.56 ± 12.56 (95% confidence range)). The hill dipterocarp forest at Poring was characterized by the dominance of Noctuidae and Geometridae and the presence of the single species of the Bornean Brahmaeidae and five rarely encountered species of Saturniidae. The results of this study show that most common species in Poring are Asura sp. (Arctiidae: Lithosiinae), Chamaita trichopteroides Walker (Arctiidae: Lithosiinae), Asura bizonoides Walker (Arctiidae: Lithosiinae) and Heterostegane warreni Prout (Geometridae: Ennominae. These species could be considered as characteristic of the hill dipterocarp macromoth fauna. Twenty-five percent of the total species collected (298 species) are considered as rare species, being represented by single individuals, or singletons. These singletons were highly represented in the Geometridae (33%), followed by Noctuidae (24%) and Lymantriidae (11%). Species diversity of the macromoth in Poring is further discussed.

Sweet waste extract uptake by a mosquito vector: Survival, biting, fecundity responses, and potential epidemiological significance

In nature, adult mosquitoes typically utilize nectar as their main energy source, but they can switch to other as yet unidentified sugary fluids. Contemporary lifestyles, with their associated unwillingness to consume leftovers and improper disposal of waste, have resulted in the disposal of huge amounts of waste into the environment. Such refuse often contains unfinished food items, many of which contain sugar and some of which can collect water from rain and generate juices. Despite evidence that mosquitoes can feed on sugar-rich suspensions, semi-liquids, and decaying fruits, which can be abundant in garbage sites, the impacts of sweet waste fluids on dengue vectors are unknown. Here, we investigated the effects of extracts from some familiar sweet home waste items on key components of vectorial capacity of Aedes aegypti. Adult mosquitoes were fed one of five diets in this study: water (WAT); sucrose (SUG); bakery product (remnant of chocolate cake, BAK); dairy product (yogurt, YOG); and fruit (banana (BAN). Differences in survival, response time to host, and egg production were examined between groups. For both males and females, maintenance on BAK extract resulted in marked survival levels that were similar to those seen with SUG. Sweet waste extracts provided better substrates for survival compared to water, but this superiority was mostly seen with BAK. Females maintained on BAK, YOG, and BAN exhibited shorter response times to a host compared to their counterparts maintained on SUG. The levels of egg production were equivalent in waste extract- and SUG-fed females. The findings presented here illustrate the potential of sweet waste-derived fluids to contribute to the vectorial capacity of dengue vectors and suggest the necessity of readdressing the issue of waste disposal, especially that of unfinished sweet foods. Such approaches can be particularly relevant in dengue endemic areas where rainfall is frequent and waste collection infrequent.

Pathogenicity of a Microsporidium Isolate from the Diamondback Moth against Noctuid Moths: Characterization and Implications for Microbiological Pest Management

Background Due to problems with chemical control, there is increasing interest in the use of microsporidia for control of lepidopteran pests. However, there have been few studies to evaluate the susceptibility of exotic species to microsporidia from indigenous Lepidoptera. Methodology/Principal Findings We investigated some biological characteristics of the microsporidian parasite isolated from wild Plutella xylostella (PX) and evaluated its pathogenicity on the laboratory responses of sympatric invasive and resident noctuid moths. There were significant differences in spore size and morphology between PX and Spodoptera litura (SL) isolates. Spores of PX isolate were ovocylindrical, while those of SL were oval. PX spores were 1.05 times longer than those of SL, which in turn were 1.49 times wider than those of the PX. The timing of infection peaks was much shorter in SL and resulted in earlier larval death. There were no noticeable differences in amplicon size (two DNA fragments were each about 1200 base pairs in length). Phylogenetic analysis revealed that the small subunit (SSU) rRNA gene sequences of the two isolates shared a clade with Nosema/Vairimorpha sequences. The absence of octospores in infected spodopteran tissues suggested that PX and SL spores are closely related to Nosema plutellae and N. bombycis, respectively. Both SL and S. exigua (SE) exhibited susceptibility to the PX isolate infection, but showed different infection patterns. Tissular infection was more diverse in the former and resulted in much greater spore production and larval mortality. Microsporidium-infected larvae pupated among both infected and control larvae, but adult emergence occurred only in the second group. Conclusion/Significance The PX isolate infection prevented completion of development of most leafworm and beet armyworm larvae. The ability of the microsporidian isolate to severely infect and kill larvae of both native and introduced spodopterans makes it a valuable candidate for biocontrol against lepidopteran pests.

Genus Tisis Walker in the Malaysian Borneo, with Descriptions of Three New Species (Lepidoptera: Lecithoceridae)

Twenty species of the genus Tisis Walker, including threee new species, are recognized in the Malaysian Borneo. The new species are: Tisis colubrialis sp. nov., T. penrissenica sp. nov., and T latiductalis sp. nov. Photos of adults and male or female genitalia for the new species are given. With regard to the previously known species, images of the types or voucher specimens, and figures of the male or female genitalia, that have not been well represented in previous papers, are provided. A key to species in Malaysian Borneo and a world catalogue of the genus are also provided.

Coffee, its roasted form, and their residues cause birth failure and shorten lifespan in dengue vectors

In dengue mosquitoes, successful embryonic development and long lifespan are key determinants for the persistence of both virus and vector. Therefore, targeting the egg stage and vector lifespan would be expected to have greater impacts than larvicides or adulticides, both strategies that have lost effectiveness due to the development of resistance. Therefore, there is now a pressing need to find novel chemical means of vector control. Coffee contains many chemicals, and its waste, which has become a growing environmental concern, is as rich in toxicants as the green coffee beans; these chemicals do not have a history of resistance in insects, but some are lost in the roasting process. We examined whether exposure to coffee during embryonic development could alter larval eclosion and lifespan of dengue vectors. A series of bioassays with different coffee forms and their residues indicated that larval eclosion responses of Aedes albopictus and Ae. aegypti were appreciably lower when embryonic maturation occurred in environments containing coffee, especially roasted coffee crude extract (RCC). In addition, the lifespan of adults derived from eggs that hatched successfully in a coffee milieu was reduced, but this effect was less pronounced with roasted and green coffee extracts (RCU and GCU, respectively). Taken together, these findings suggested that coffee and its residues have embryocidal activities with impacts that are carried over onto the adult lifespan of dengue vectors. These effects may significantly reduce the vectorial capacity of these insects. Reutilizing coffee waste in vector control may also represent a realistic solution to the issues associated with its pollution.

Response to the letter sent by Dr. Viroj Wiwanitkit entitled “Coffee waste, vector control and dengue”

The authors are happy to know that since its publication date— May 3, 2017 through June 2017—our paper has been read 135 times (according to Research Gate) by researchers and used as an element of reflection by Dr. Wiwanitkit. Testing the effects of coffee on insect vectors with respect to its potential use in control strategies is a common practice in Medical Entomology and did not start with our study. A more careful examination of the literature on coffee-mosquito research has shown that many scientists have done so in these last 14 years worldwide. For instance, Laranja and colleagues (Laranja et al. 2003) from the Universidade Estadual Paulista (Brazil) examined the effects of used coffee grounds on the biological features of Aedes aegypti. Derraik and Slaney (Derraik and Slaney 2005) from the University of Otago (New Zealand) have tested the toxicity of used coffee grounds against a container-breeding mosquito species. Laranja and colleagues (Laranja et al. 2006) from the Universidade Estadual Paulista (Brazil) assessed whether or not caffeine from coffee promotes an increase in insect resistance over time. Guirado and Bicudo from Instituto de Biociências, Letras e Ciências Exatas (Brazil) performed similar investigations in 2007 (Guirado and Bicudo 2007) and 2010 (Guirado and Bicudo 2010), as did Satho et al. (Satho et al. 2015) from Fukuoka University (Japan) in 2016. Others scientists have tested coffee against agricultural insect pests (Mostakim and Khan 2014). A common nature of these studies is that they found coffee as a promising alternative to less desirable synthetic insecticides. However, none of these research works has elaborated on coffee application methods or techniques. In addressing the issues of dengue vector control, theWorldHealth Organization has argued for the need to take eggs into account in containment strategies because this development stage is a prerequisite for the production of subsequent generations (Dieng et al. 2006) and can spread the viruses (Thenmozhi et al. 2007; Sarkar 2010). Rather than simply testing the extracts of coffee and its waste for embryocidal properties, our study also examined whether exposure to coffee could alter the lifespan of a dengue vector. So, it has never been a question of using coffee for operational vector control in our study. Despite encouraging results in these directions, there are still many unknowns such as the (i) insecticidal capacity of different coffee extract concentrations; (ii) variations in coffee insecticidal activity over time; (iii) reproductive capacity of females that escape coffee exposure; (iv) biting activity of such females; (v) sexual competitiveness of males that survived coffee exposure; (vi) relationship between coffee toxicity and oviposition attraction; and (vii) cytotoxicity and genotoxicity evaluations of selected coffee concentrations using animals, among others. Putting the expected results from these remaining studies together, we might be able to recommend or not coffee as a tool for dengue vector control. Particular advice will be given to scientists who want to use coffee in vector control to make sure that the coffee is not contaminated with molds or fungi, as these are common in coffee beans (Christensen 1975; Viegas et al. 2017) and exposure to mycotoxins can cause allergic Responsible editor: Philippe Garrigues