Visual Signalling in Plant-Animal Interactions

The process of visual signalling between plant and animals is often a combination of exciting discoveries and more often than not; highly controversial hypotheses. Plants and animals interact mutualistically and antagonistically creating a complex network of species relations to some extent suggesting a co evolutionary network. In this study, I investigate two basic research questions: the first is how plants utilize aposematic and cryptic colours? The second is how animals are affected by the colour signals broadcasted by plants? By using the avian eye model, I discover how visual signals/colours from plants are actually perceived, and the effects of these signals on birds (not human) perception. Aposematism and crypsis are common strategies utilized by animals, yet little evidence is known of such occurrences in plants. Aposematic and cryptic colours were evaluated by studying different colouration strategy through the ontogeny of two native heteroblastic New Zealand plants: Pseudopanax crassifolius and Elaeocarpus hookerianus. To determine the potential effect of colour signals on animals, I investigated an evolutionary theory of leaf colours constraining the conspicuousness of their fruit colour counterparts. Based on the available data, I also conducted a community level analysis about the effects of fruit colours and specific avian frugivores that might be attracted to them. Finally, I examined the fruit colour selection by a frugivorous seed dispersing insect; the Wellington Tree Weta (Hemideina crassidens). My result shows that aposematic and cryptic colours are successfully applied by plants to either warn or remain inconspicuous from browsing herbivores. The evidence I presented lends support to the Moa browsing hypothesis in relation to constraining the conspicuousness of their fruit colour counterparts. Based on the cryptic plant colourations. However, the same level of selective interaction could not be inferred for frugivore fruit colour selection based on avian vision. I demonstrated that leaf reflectance does not constrain/influence the conspicuousness of fruit colours. There was also no fruit colour diversity based on geographical location. Fruit colour alone is not sufficient to influence a specific frugivore assemblage. Other environmental factors and species interaction must be taken into account. Weta proved to possess colour vision capable of colour perception even in low light conditions. Weta also consistently selected naturally blue streaked and manipulated blue coloured fruits of Coprosma acerosa in a binary test. This supports the idea of weta co- evolving with fruit colours of certain divaricating plants in New Zealand. I suggest that the fruit colours of New Zealand are shaped by the combined selection pressure from birds, lizards/geckos and weta

Larvicidal efficacy screening of Anacardaciae crude extracts on the dengue hemorrhagic vector, Aedes aegypti

Vector-borne diseases are still rife because of the re-emergence of diseases transmitted by mosquitoes. The objective of this paper is to evaluate the larvicidal efficacy of crude leaf extract of Mangifera indica, Gluta renghas, and Melanochyla fasciculiflora against vector of dengue hemorrhagic fever, Aedes aegypti. These plant species are endemic species and widely distributed in Malaysian forests. Leaves of Ma. indica, G. renghas and M. fascculiflora were collected from Teluk Bahang National Park, Penang Malaysia. Fractions of leaves were segregated, air-dried, powdered and extracted using Soxhlet with methanol. The solvent was removed by using rotary evaporator to obtain the crude extract. Using WHO standard larval bioassay test method, third instar larvae of Aedes aegypti were exposed to concentration ranging from 200- 4500 ppm of methanol extract for all plant species. Larval mortality was observed after 24 hours exposure. The highest susceptibility and toxicity was recorded by Mangifera indica with the lowest concentration at 800 ppm followed by M. fasciculiflora and G. renghas. This indicates that crude plant extract is very effective in killing Ae. aegypti mosquitoes. This finding may lead to new low cost alternative, environmentally friendly method for mosquito control programs. To our knowledge, this is the first report on larvicidal bioefficacy from endemic Malaysian plants

Contribution of rice fields to bird diversity in Peninsular Malaysia

There is a lack of documentation on rice fields as an important habitat that harbour different bird diversity compared to natural habitats in Peninsular Malaysia. This study investigated the contribution of rice fields to bird diversity in Peninsular Malaysia. A total of 83 rice fields and 53 natural habitats throughout Peninsular Malaysia were included in this study. Birds were observed and counted using point-count and mist-netting methods. A total of 10,707 bird-sightings, with rice fields, recorded 129 species from 15 orders and 50 families from October 2013 to December 2014; whilst natural forests recorded a total of 438 species from 14 order and 59 families from February 1992 to January 2015. Diversity t-test showed a significant difference in the species richness between the two different habitats (t=11.009, p<0.05). The high values of Δ+and ʌ+ in many areas of rice fields were significantly influenced by the presence of waterbirds, albeit low species richness. This temporary wetland habitat harbours land birds and waterbirds in one place. The data presented here suggest that waterbirds and migratory birds in rice fields contribute significantly to the total bird species found in Peninsular Malaysia

Presence of a predator image in potential breeding sites and oviposition responses of a dengue vector

In dengue vector control, attempts to minimize or replace the use of pesticides have mostly involved use of predators, but success has been severely impeded by difficulties associated with financial and environmental costs, predator mass production, and persistence in target habitats. Visual deterrents have been used successfully to control animal pests, in some cases in an effort to replace pesticide use. Despite evidence that visual signals are crucial in site choice for egg deposition by dengue vectors, and that female mosquitoes respond to artificial predation, the role of predator intimidation as it affects the oviposition behavior of dengue vectors remains largely unexplored. Here, we examined the oviposition responses of Aedes aegypti exposed to various mosquito predator pictures. Gravid females were presented with equal opportunities to oviposit in two cups with predator images [Toxorhynchites splendens—TXI, Goldfish (Carassius auratus)—small (SFI) and large (LFI) and Tx. splendens + Goldfish—TXFI] and two others without pictures. Differences in egg deposition were examined between sites with and without these images. When given a chance to oviposit in cups with and without TXI, Ae. aegypti females were similarly attracted to both sites. When provided an opportunity to oviposit in cups displaying pictures of fish (SFI or LFI) and blank cups, egg deposition rates were much lower in the fish picture sites. Females showed a preference for blank cups over TXFI for egg deposition. They also equally avoided cups with pictures of fish, regardless of the size of the picture. Our results indicate that the presence of images of goldfish and their association with Tx. larvae significantly reduced egg deposition by Ae. aegypti, and this was not the case with the predatory larvae alone. The observations that the images of natural predators can repel gravid females of a dengue vector provide novel possibilities to develop effective and inexpensive alternative tools to harmful insecticides

Practical training and the audit expectations gap: The case of accounting undergraduates of Universiti Utara Malaysia

The accounting profession has long faced the issue of an audit expectation gap; being the gap between the quality of the profession’s performance, its objectives and results, and that which the society expects.The profession believes that the gap could be reduced over time through education.Studies have been carried out overseas and in Malaysia to determine the effect of education in narrowing the audit expectation gap. Extending the knowledge acquired, this paper investigates whether academic internship programs could reduce the audit expectation gap in Malaysia.Using a pre-post method, the research instrument adapted from Ferguson et al.(2000) is administered to the Universiti Utara Malaysia’s accounting students at the beginning and end of their internship program.The results show there is a significant change in perceptions among students after the internship program. However, changes in perceptions do not warrant an internship program as a means of reducing the audit expectation gap as misperceptions are still found among respondents on issues of auditing after the completion of the internship program. Nevertheless, an internship program can still be used to complement audit education in a university as it is an ideal way to expose students to professional issues and enables them to have a better insight of the actual performance and duties of auditors

Visual Signalling in Plant-Animal Interactions

The process of visual signalling between plant and animals is often a combination of exciting discoveries and more often than not; highly controversial hypotheses. Plants and animals interact mutualistically and antagonistically creating a complex network of species relations to some extent suggesting a co evolutionary network. In this study, I investigate two basic research questions: the first is how plants utilize aposematic and cryptic colours? The second is how animals are affected by the colour signals broadcasted by plants? By using the avian eye model, I discover how visual signals/colours from plants are actually perceived, and the effects of these signals on birds (not human) perception. Aposematism and crypsis are common strategies utilized by animals, yet little evidence is known of such occurrences in plants. Aposematic and cryptic colours were evaluated by studying different colouration strategy through the ontogeny of two native heteroblastic New Zealand plants: Pseudopanax crassifolius and Elaeocarpus hookerianus. To determine the potential effect of colour signals on animals, I investigated an evolutionary theory of leaf colours constraining the conspicuousness of their fruit colour counterparts. Based on the available data, I also conducted a community level analysis about the effects of fruit colours and specific avian frugivores that might be attracted to them. Finally, I examined the fruit colour selection by a frugivorous seed dispersing insect; the Wellington Tree Weta (Hemideina crassidens). My result shows that aposematic and cryptic colours are successfully applied by plants to either warn or remain inconspicuous from browsing herbivores. The evidence I presented lends support to the Moa browsing hypothesis in relation to constraining the conspicuousness of their fruit colour counterparts. Based on the cryptic plant colourations. However, the same level of selective interaction could not be inferred for frugivore fruit colour selection based on avian vision. I demonstrated that leaf reflectance does not constrain/influence the conspicuousness of fruit colours. There was also no fruit colour diversity based on geographical location. Fruit colour alone is not sufficient to influence a specific frugivore assemblage. Other environmental factors and species interaction must be taken into account. Weta proved to possess colour vision capable of colour perception even in low light conditions. Weta also consistently selected naturally blue streaked and manipulated blue coloured fruits of Coprosma acerosa in a binary test. This supports the idea of weta co- evolving with fruit colours of certain divaricating plants in New Zealand. I suggest that the fruit colours of New Zealand are shaped by the combined selection pressure from birds, lizards/geckos and weta

Evaluation of sublethal effects of ipomoea cairica linn. extract on life history traits of dengue vectors

Plant derived insecticides have considerable potential for mosquito control because these products are safer than conventional insecticides. This study aimed to investigate sublethal activities of Ipomoea carica or railway creeper crude acethonilic extract against life history trait of dengue vectors, Aedes albopictus and Aedes aegypti. The late third instar larvae of Ae. albopictus and Ae. aegypti were exposed to a sublethal dose at LC50 and larvae that survived were further cultured. Overall, Ipomea cairica crude extracts affected the whole life history of both Aedes species. The study demonstrated significantly lower egg production (fecundity) and eggs hatchability (fertility) in Ae. albopictus. The sublethal dose of crude extracts reduced significantly the width of larval head capsule and the wing length of both sexes in both Aedes species. The significance of sublethal effects of I. cairica against Aedes mosquitoes was an additional hallmark to demonstrate further activity of this plant despite its direct toxicity to the larvae. The reduced reproductive capacity as well as morphological and physiological anomalies are some of the effects that make I. cairica a potential candidate to be used as a new plant-based insecticide to control dengue vectors

Current observation on Aedes mosquitoes: A survey on implication of dengue infection, human lifestyle and preventive measure among Malaysia resident in urban and sub-urban areas

Objective: To evaluate the current knowledge level and information on Aedes mosquitoes and dengue among Penang resident in urban (Sungai Dua) and sub- urban areas (Batu Maung). Methods: The questionnaire comprises of twenty-three questions, surveyed on 202 respondents regarding socio-demographic, the observation of general Aedes’ mosquito behaviour, dengue infection threat, preventive measures against mosquitoes and lifestyle (on usage of artificial light) in changing the behaviour of Aedes mosquitoes. Results: The respondents in sub-urban Batu Maung showed less knowledge level regarding Aedes mosquitoes as compared to respondents in urban Sungai Dua. There was a positive association between biting frequency of mosquitoes with the lifestyle of respondents (in relation to the light use), the use of personal protection and fogging operations conducted by the Ministry of Health. There is a positive relationship between the knowledge of preferred mosquitoes resting place and the respondent aged between 17 to 24 (78.2%) in sub-urban Batu Maung. Urban Sungai Dua respondents showed a significant relation between the use of lights and the resting places for Aedes mosquitoes. The preventive measures chosen by both sub-distinct areas against mosquitobites were significantly affected by the biting time and the mosquitoes biting frequency (P < 0.05). Conclusions: In this study, we concluded that there is a direct link between the knowledge of the Aedes biting frequency with dengue infection, human lifestyle on the light use and preventive measures against mosquitoes. However, the level of knowledge is poor on the subject of Aedes mosquitoes and dengue for both urban and sub-urban respondents

Discarded cigarette butts attract females and kill the progeny of aedes albopictus

Discarded cigarette butts (DCB) waste occurs worldwide, pollutes landscapes, is unsightly, and results in added debris removal costs. There is, therefore, a great deal of current interest in making use of DCBs in beneficial ways. Despite evidence that DCBs are harmful to water fleas (Daphnia magna), which breed in aquatic environments as do mosquito larvae, their impact on dengue vectors is unknown. We examined whether Aedes albopictus alters its ovipositional responses, larval eclosion, and development in response to presence of DCBs in its habitats. We found oviposition activity in DCB-treated water similar to that of control water and that ovipositional activity in DCB solutions steadily increased over time as those solutions aged to 10 days. Larval eclosion was initially suppressed on day 1 in DCB solution, but increased thereafter to levels similar to control larval eclosion rates. The DCB-water solutions produced significantly higher mortality in both 1st and 2nd instars over control larvae for several days after initial exposure. Mortality rates decreased sharply 3 to 5 days postexposure as DCBs continued to decompose. We found increased survival rates during late development, but daily input of fresh DCBs prevented most young larvae from completing development. Taken together, these observations suggest that decomposing did not deter gravid Ae. albopictus females from ovipositing in treated containers and that DCB solutions had larvicidal effects on early instars. Our results are discussed in the context of DCB use to control container-breeding Ae. albopictus, a competent dengue vector in Asia and other parts of the world