Date of Award

1-1-2000

Thesis Type

PhD

Document Type

Thesis

Divisions

Faculty of Science

Department

Institute of Biological Sciences

Institution

Universiti Malaya

Abstract

Bactrocera ( = Dacus ) papayae bred from chillies collected from Klang (MARDI Station) and kept in laboratory cages, laid 5.6 eggs per female per day with a maximum of 34 eggs. The net egg hatchability was 46.2 % . Egg hatchability declined with age of females. The intrinsic rate of increase (r) was 0.1150 while the finite rate of increase (A) was 1.13 .The net reproductive (􀀋)was 170 female eggs per female, and generation time was 45 . The intrinsic rate of increase under laboratory conditions was similar to Bactrocera Malaysian A ( bred from Star-fruit ) and B. cucurbitae but higher than of B. /at1frons . Ovipositing females showed a distinct preference for riped fruits particularly, reddish orange colour over green chillies. Females seemed to be able to regulate egg laying according to availability of fruits. Hence the number of eggs laid per female was higher when exposed to 8 of chillies compared to 2,3 and 4 available chillies. In a laboratory study on the suitability of fruits for larval development, 8 fruits species (papaya, guava, mango, banana, chilli, tomato, starfruit and eggplant ) were selected to determine the fruits preferences as host. Papaya was the best preferenced fruit, It was found that peptone and yeast extract were the best diets for the fecundity and longevity . The mean time ( sec. ) spent on oviposition activities of female upon arrival on a fruit were: I) surface examining phase, 34 ± 3.2 ( 2 ) ovipositor probing and ovipositor insertion phase 192 ± 0.82 and ( 3 ) postoviposition phase 11 ± 0.56, Adults were compared for.resistance to Malathion and Dichlorvous insecticies, the resistance to malathion 0.5x!0-3 was higher than to dichlorvous 0.5 x 10·1. Electrophoresis was used for enzyme esterase bands comprising the resistance and susceptible strains, Carboxylesrterase ( Car E ) ( 3.1.1.1 ) detected at the adult stage. Both (a-b) naphthyl acetate was equally affective but B· naphthyl acetate was more affective and so suitable as substrate for esterase detection. The strongest component of environment influencing the adult population of B. papayae was the availability of its favoured host fruits (papaya). Theree major parasitoids of B.papayae in papaya were Biosters vandenboschi, B. longicaudatus and B. arisanus. Relationships between total initial hosts (B.papayae immatures ) and total hosts killed by each parasitoid species good correlation and parasitoids relationships were not density dependent. The percentage of the larvae that survived through fruits factors was 84.2% in soil, the soil factors reduced survival to 21.3 %. Amongst the soil factors, weather accounted for 45.5 % biotic factors 16.5 % and physical factors 2.5 % of the mortality. Predator ants ( Dolicholderus and Componotus sp.) 19.1 %. Three major components in the sexual behaviour included (1) Signal emission through male - wing fanning followed by arrival of females, (2) Courtship behaviour involving male - wing fanning followed by attempted copulations; and (3) Copulation. Further test also showed that females that had mated once were neither attracted to males nor accepted subsequent mating as readily as virgin females. By modifying either the male's ability in emitting sexual signals, i.e. modification of wing fanning or the various sensory receptors in the females, i.e. the eyes for visual signals, the aristae for acoustic stimuli, and the antennae for olfactory cues, it was possible to investigate the separate modalities of sexual communication during the (1) attraction phase (i.e. the _bringing together of the two sexes over a distance of 50 cm ) and 2) courtship phase (i.e. signal emission at close range of about 5 cm). The wing fanning in males was found to play a significant role in the production of signals for the attraction of and mating with females . Experiments conducted in the females showed that acoustic as well as olfactory signals were crucial in attracting females to wing fanning males, but only olfactory stimuli were important for mating acceptance of the females. Differential sexual success among males and female choice played an important role in the complex mating system in this species. Sexual success in males was measured in terms of ability to attract and mate with females. For the most part , both qualities could be found in the same male. It was also found that sexually successful males had the capacity of signaling for a longer duration, and 􀀵ad top rank in male-male aggressive interactions more frequently than males. Thus inter-male competition could possibly be another component of sexual selection operating in this species.

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Additional Information

Dissertation (PhD) -- Faculty of Science, Universiti Malaya, 2000.

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