Papers by Solomon Balagawi
bioRxiv (Cold Spring Harbor Laboratory), Aug 30, 2023
The host use patterns of tephritids (fruit flies) range from those that are highly specific (mono... more The host use patterns of tephritids (fruit flies) range from those that are highly specific (monophagous, oligophagous) to those that use a wide range of hosts from different plant families (polyphagous). Knowledge of the mechanisms responsible for such host use patterns is critical in understanding the insect-plant relationship and developing successful population management strategies. Several studies have revealed that the behavioural and environmental factors play a significant role in host use. A key theory thought to explain host use patterns of phytophagous insects has been optimality theory (preference-performance hypothesis), however, this has seldom been investigated in fruit flies. In this thesis I compared the host use pattern of the specialist (oligophagous) cucumber fruit fly, Bactrocera cucumis (French), and the generalist (polyphagous) Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae: Dacinae), both serious agricultural pests in Queensland, Australia. I primarily focussed on investigating the role of the preference-performance hypothesis in explaining the host use pattern of these two species at different plant taxonomic levels. I also examined the life history consequences of host use patterns by investigating the demographies of these two dacines on different host plants. The preference-performance hypothesis postulates that the host preference executed by an insect should be positively correlated to its offspring performance. While there were some correlations between preference and performance parameters for both B. cucumis and B. tryoni, these were dependent on the parameter used and were more relevant in explaining host use patterns in B. cucumis than B. tryoni. Both species exhibited significant host discrimination among the different hosts presented to them. More significantly, they preferentially used certain host plants even when hosts of purportedly equivalent status were presented to them simultaneously. The efficiency with which they used their hosts differed even when offered different varieties of a host species from their primary host family. These patterns, observed in both these dacine species, indicated that host use is more plausibly explained by behavioural and physiological factors associated with host use.
Austral entomology, Jul 21, 2021
Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt), is a major quarantine pest of fresh ho... more Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt), is a major quarantine pest of fresh horticultural commodity along the eastern coastal region of Australia and restricts market access of its host commodity. Consequently, various post‐harvest disinfestation treatments are used to facilitate trade and one such treatment for Qfly is ‘cold disinfestation’. Our study evaluated the effect of cold storage as a post‐harvest disinfestation treatment for Qfly on ‘gold3’ kiwifruit (Actinidia chinensis var. gold3‐sungold), a cultivar grown in New Zealand. Qfly is not present in New Zealand but due to its close proximity to Australia, New Zealand's trading partners have shown concern that Qfly presents a biosecurity risk to their own industry. Our study specifically aimed to demonstrate how this risk would be addressed. Experiment 1 investigated developmental rate of the individual life stages of Qfly in ‘gold3’ kiwifruit under optimal Qfly development conditions of 26 ± 1°C and 65 ± 5% rh, while experiment 2 focused on determination of the most cold tolerant life stage of Qfly in ‘gold3’ kiwifruits. Experiment 3 was a large‐scale confirmatory trial undertaken using the most cold tolerant life stage. The results revealed that Qfly successfully developed in ‘gold3’ kiwifruit and that the most‐cold tolerant Qfly life stage was the 1st instar. Our study further demonstrated that storage of ‘gold3’ kiwifruit at 2.5°C (fruit temperature) for a period of ≥12 days resulted in zero Qfly survival. The large‐scale verification trial treated 61,412 first instar and confirmed that storage of ‘gold3’ kiwifruit at 2.5°C for a 14‐day period resulted in 99.9951% mortality of first instar at the 95% confidence level, hence demonstrating a probit 8.7 level of efficacy. A 14‐day cold storage period was used in this confirmatory trial to ensure additional quarantine security. We recommend that if there was any Qfly infestation on ‘gold3’ kiwifruit, a post‐harvest quarantine treatment of cold storage at 2.5°C (fruit temperature) for a 14‐day period must be used to disinfest Qfly from ‘gold3’ kiwifruit.
Bulletin of Entomological Research, Nov 26, 2009
Multiple mating was investigated in two tephritid species when females were under minimal male pr... more Multiple mating was investigated in two tephritid species when females were under minimal male pressure because they were each confined with a single male in cages 20r20r20 cm and observed daily until they died. Laboratory-reared females of Bactrocera cucumis (French) lived up to 274 days and refractory periods averaged 59-63 days. However, the distribution of matings among B. cucumis females was not significantly different to that expected by chance. Wild females of Bactrocera cacuminata (Hering) reared from field-collected fruits of Solanum mauritianum Scopoli lived for up to 134 days and mated up to three times with refractory periods between matings averaging 27-39 days. The distribution of the number of matings among females of B. cacuminata was non-random because of the high proportion of non-maters (50%); but, when only females mating more than once were considered, there was no significant departure from random expectation.
Journal of Tropical Ecology, 2005
Frugivorous dacine fruit flies were studied in a lowland tropical rain forest in Papua New Guinea... more Frugivorous dacine fruit flies were studied in a lowland tropical rain forest in Papua New Guinea to determine their host specificity, abundance, and the number of species attacking various plant species. Plant species hosted 0-3 fruit fly species at median (1-3 quartile) densities of 1 (0-17) fruit flies per 100 fruits. Fruit flies were mostly specialized to a single plant family (83% species) and within each family to a single genus (88% species), while most of the species (66%) were able to feed on >1 congeneric plant species. Only 30 from the 53 studied plant species were colonized by fruit flies. The plant-fruit fly food web, including these 30 plant species and the total of 29 fruit fly species feeding on them, was divided into 14 compartments, each including 1-8 plant species hosting mutually disjunct assemblages of fruit flies. This structure minimizes indirect interactions among plant species via shared herbivores. The local species pool was estimated at 152 ± 32 (± SE) fruit fly species. Forty per cent of all taxonomically described species known from Papua New Guinea were reared or trapped in our study area. Such a high proportion indicates low beta-diversity of fruit flies. Steiner traps were highly efficient in sampling the lure-responsive fruit fly species as they recollected 84% of all species trapped in the same area 5 y before. Fruit fly monitoring by these traps is a cheap, simple and efficient method for the study of spatial and temporal changes in rainforest communities.
Journal of Applied Entomology, Dec 4, 2013
ABSTRACT The spot or strip application of poisoned protein bait is a lure-and-kill technique used... more ABSTRACT The spot or strip application of poisoned protein bait is a lure-and-kill technique used for the management of fruit flies. Knowledge of where flies occur in the crop environment is an important part of maximizing the efficacy of this tool. Bactrocera tryoni is a polyphagous pest of horticulture for which very little is known about its distribution within crops. With particular reference to edge effects, we monitored the abundance of B. tryoni in two crops of different architecture; strawberry and apple. In strawberries, we found more flies on the crop edge early in the fruiting season, which lessened gradually and eventually disappeared as the season progressed. In apple orchards, no such edge effect was observed and flies were found equally throughout the orchard. We postulated these differences may be due to differences in crop height (high vs. short) and/or crop canopy architecture (opened and branched in apple, dense and closed in strawberry). In a field cage trial, we tested these predictions using artificial plants of different height and canopy condition. Height and canopy structure type had no significant effects on fly oviposition and protein feeding, but the ‘apple’ type canopy significantly influenced resting. We thus postulate that there was an edge effect in strawberry because the crop was not providing resting sites and flies were doing so in vegetation around the field margins. The finding that B. tryoni shows different resting site preferences based on plant architecture offers the potential for strategic manipulation of the fly through specific border or inter-row plantings.
Arthropod-plant Interactions, Jan 18, 2013
The preference-performance and phylogenetic conservatism hypotheses have been postulated to expla... more The preference-performance and phylogenetic conservatism hypotheses have been postulated to explain the mechanisms driving host-use patterns of phytophagous insects. The preference-performance hypothesis predicts that insects will use plants that provide higher offspring fitness, while the phylogenetic conservatism hypothesis predicts that insects will use phylogenetically closely related plants over more distantly related plants. Although some studies have supported these two hypotheses, others have not. Simultaneous tests of the two hypotheses on more than one species are lacking, and this limits comparative interpretation of previous studies. We undertook a comparative investigation to determine whether preference-performance and/or the phylogenetic conservatism hypothesis can explain host-use patterns of two phytophagous insects, the fruit flies Bactrocera cucumis and B. tryoni. Within a nested, plant phylogenetic framework, oviposition preference and offspring performance of the two fruit fly species were tested on fruits of plant species from across different plant families, from within a family and across cultivars within a species. The results show that both the preference-performance and the phylogenetic conservatism hypotheses can, depending on the host plant taxonomic level, explain host usage patterns in B. cucumis, while neither theory explained the host patterns seen in B. tryoni. In the light of increasing recognition of the complexity of host plant–herbivore relationships, and of ongoing studies which as often as not fail to find support for these theories as those that do, we discuss the limited value of either theory as a basis for future research.
Background: Queensland fruit fly, Bactrocera tryoni, is the major pest fruit fly in Australia. Pr... more Background: Queensland fruit fly, Bactrocera tryoni, is the major pest fruit fly in Australia. Protein bait sprays, where insecticides are mixed with spot applications of a protein based food lure, are one of the sustainable pre-harvest fruit fly management strategies used in Australia. Although protein bait sprays do manage fruit fly infestation in the field, there is little science underpinning this technique and so improving its efficacy is difficult. Lacking information includes where and when to apply protein bait in order to best target foraging B. tryoni. As part of new work in this area, we investigated the effect of height of protein on tree and host plant fruiting status on the spatial and temporal protein foraging patterns of B. tryoni. MEthod: The work was conducted in the field using nectarine and guava plants and wild B. tryoni at Redland Bay, Queensland, Australia. Spot sprays of protein bait were applied to the foliage of randomly selected fruiting and non-fruiting trees. Each tree received protein bait spot sprays on the lower and higher foliage at 0530hrs. The number, sex and species of flies that fed on each protein spot were recorded hourly from 0600hrs through to 1800hrs.Results: For nectarines, there was a significant difference in the number of B. tryoni feeding on protein bait placed at different locations within the tree (ANOVA, F = 8.898, p = 0.001). More flies fed on protein placed on higher foliage relative to lower, irrespective of the fruiting status of the nectarine trees. A significant difference was also observed in the diurnal protein feeding pattern of B. tryoni (ANOVA, F = 2.164, p = 0.024), with more flies feeding at 1600hrs. Results for guava are still being collected and will be presented at the meeting.Conclusions: We conclude that B. tryoni effectively forages for protein at heights higher than 1.3m from ground, indicating greater efficacy of protein bait when applied at foliage higher in the canopy. Bactrocera tryoni actively forages for protein throughout the day, with a highest feeding peak at 1600hrs. The lack of significant difference in the spatial protein foraging pattern between fruiting and non-fruiting nectarine trees may be a real result, or may have resulted from the fruiting tree being very close (within 1 – 2 metres) of the non-fruiting tree. This hypothesis is being tested in the guava trial.
Science & Engineering Faculty, Apr 1, 2013
ABSTRACT The males of many Bactrocera species (Diptera: Tephritidae) respond strongly and positiv... more ABSTRACT The males of many Bactrocera species (Diptera: Tephritidae) respond strongly and positively to a small number of plant-derived chemicals (=male lures). Males that have imbibed the lures commonly have a mating advantage over unfed males, but no female benefits have been demonstrated for females mating with lure-fed males. It has been hypothesized that the strong lure response is a case of runaway selection, where males receive direct benefits and females receive indirect benefits via &#39;sexy sons&#39;, or a case of sensory bias where females have a lower threshold response to lures. To test these hypotheses we studied the effects of lure feeding on male mating, remating and longevity; while for females that had mated with lure-fed males we recorded mating refractoriness, fecundity, egg viability and longevity. We used Bactrocera tryoni as our test animal and as lures the naturally occurring zingerone and chemically related, but synthetic chemical cuelure. Feeding on lures provided direct male benefits in greater mating success and increased multiple mating. For the first time, we recorded direct female effects: increased fecundity and reduced remating receptivity. Egg viability did not differ in females mated with lure-fed or unfed males. The life span of males and females exposed to lures was reduced. These results reveal direct, current-generation fitness benefits for both males and females, although the male benefits appear greater. We discuss that while lure response is indeed likely to be a sexual selection trait, there is no need to invoke runaway selection to explain its evolution.
Crop Protection, 2022
Abstract Sugar flotation procedures have been used for many years to separate insects from soil a... more Abstract Sugar flotation procedures have been used for many years to separate insects from soil and other substrates. In this study we investigated whether brown sugar flotation (BSF) could be used for detecting eggs and larvae of Bactrocera tryoni (Froggatt) and Ceratitis capitata (Wiedemann) in cherries. Our first study involved both species and combined BSF with either manually or mechanically crushed fruit to quantify the egg and larval detection ability of BSF in conjunction with these sample preparation methods. A second set of experiments (using B. tryoni only) focused on determining the sensitivity of BSF for detecting fruit fly infestation and determining the proportions of different life stages recoverable. This was done by varying oviposition periods to generate fruits with different infestation levels. Our final experiments were used to develop an optimized cherry fruit sampling regime for detecting B. tryoni using BSF. Wet sieving/maceration of the fruit residue and incubation of the macerated fruit sample to allow further insect development were used to determine the number of eggs and larvae in each test sample that were not detected using BSF. Our results show that BSF is more effective when combined with mechanical (rather than manual) fruit crushing. BSF is highly sensitive, detecting at least one B. tryoni second instar from all the samples tested down to a pest density of 1–5 larvae in one fruit within a 35-fruit sample. BSF was less sensitive for egg detection, however when 6 or more eggs were present within a sample of 35 fruits, the probability of detecting at least one egg was ≥85%. Samples of 35 or 42 cherries provided a higher probability of detecting B. tryoni than larger samples when 1–5 eggs or larvae were present in total. BSF is an effective tool for detecting the presence of fruit fly eggs and particularly larvae in cherries and should be considered for incorporation into the current market access protocol for minimizing fruit fly risk in Australian cherry exports.
Annals of Applied Biology, Feb 5, 2023
Fruit flies require protein for reproductive development and actively feed upon protein sources i... more Fruit flies require protein for reproductive development and actively feed upon protein sources in the field. Liquid protein baits mixed with insecticide are used routinely to manage pest fruit flies, such as Bactrocera tryoni (Froggatt). However, there are still some gaps in the underpinning science required to improve the efficacy of bait spray technology. The spatial and temporal foraging behaviour of B. tryoni in response to protein was investigated in the field. A series of linked trials using either wild flies in the open field or laboratory-reared flies in field cages and a netted orchard were undertaken using nectarines and guavas. Key questions investigated were the fly's response to protein relative to: height of protein within the canopy, fruiting status of the tree, time of day, season and size of the experimental arena. Canopy height had a significant response on B. tryoni foraging, with more flies foraging on protein in the mid to upper canopy. Fruiting status also had a significant effect on foraging, with most flies responding to protein when applied to fruiting hosts. B. tryoni demonstrated a repeatable diurnal response pattern to protein, with the peak response being between 12:00-16:00 h. Season showed significant but unpredictable effects on fruit fly response to protein in the subtropical environment where the work was undertaken. Relative humidity, but not temperature or rainfall, was positively correlated with protein response. The number of B. tryoni responding to protein decreased dramatically as the spatial scale increased from field cage through to the open field. Based on these results, it is recommend that, to be most effective, protein bait sprays should be applied to the mid to upper canopies of fruiting hosts. Overall, the results show that the protein used, an industry standard, has very low attractancy to B. tryoni and that further work is urgently needed to develop more volatile protein baits.
ABSTRACT Bactrocera musae (Tryon), the banana fruit fly, is a pest of bananas and plantains on th... more ABSTRACT Bactrocera musae (Tryon), the banana fruit fly, is a pest of bananas and plantains on the Papua New Guinea mainland. In East New Britain Province (E. N. B.) trapping and host fruit surveying prior to mid 1999 indicated the absence of this fly, despite literature records to the contrary. In mid 1999, the possibility of an incursion of banana fruit fly into the Gazelle Peninsula ofE. N. B. was reported. Three trapping surveys were carried out from late 1999 to mid-2000 on the northeast tip of the Gazelle and confirmed the presence of well established banana fruit fly populations. In December 2000, a delimiting survey was carried out to map the then distribution of the fly. The fly was shown to be widespread over the Gazelle, with population foci around Rabaul and Kokopo. Market surveys of banana fruit and field assessments were also done to support the trapping surveys. Although banana finger infestation by banana fly was found to be well below 10 percent, these results confirm that B. musae populations are established and causing damage. Banana fly appears to be absent in West New Britain and Bougainville, but very low level populations have been detected in Manus and New Ireland. We speculate that the incursion of B. musae into E.N.B. maybe an indirect result of relief food supplies shipped to the Gazelle following the 1994 Rabaul volcanic eruptions.
Annals of Applied Biology, Jan 10, 2023
Host plants used by phytophagous insects can have significant consequences on demography paramete... more Host plants used by phytophagous insects can have significant consequences on demography parameters, overall lifetime fitness and their subsequent population dynamics. Here, we conduct a comparative demographic study between the specialist Zeugodacus cucumis (French) and generalist Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) to determine whether the host plants used by these fly species play any role in their overall lifetime fitness and explains current host use patterns. These two fly species are pests within the northeastern region of Australia and we further aimed to use complete life-history data to determine the population parameters and models that would help identify the sensitive life-history stage that could be targeted for effective field management. Eggs collected from laboratory-reared flies were inoculated into organically grown fruits of both the primary and alternate host plant cultivars of both fly species. The proportion surviving each life stage from egg through to adult and fecundity were monitored for all cohorts from the different plant cultivars. Complete stage-base life-tables for cohorts of each fly species developing from each fruit cultivar were constructed, and the key demographic parameters and population models were analysed using PopTools matrix model programme. Our results showed that the host used by each fly species had significant consequences on fly demographic parameters and hence their overall lifetime fitness. The generalist B. tryoni was able to compensate for the fitness loss experienced at the pre-adult stage by having adults with higher fecundity, but this was not the case for the specialist Z. cucumis. Stage-base population models revealed that the population growth rate of both species was highly sensitive at the adult reproductive stage, indicating that manipulating probability of survival at this life stage would effectively manage populations of these pest species. This study provides the empirical evidence of undertaking complete life history demography studies of phytophagous insects to accurately understand their lifetime fitness consequences of using a certain host, their observed host use patterns, and overall population dynamics. We suggest that any efforts to manage dacine fruit fly pest population should consider life-history consequences of host use.
Leblanc, L., S. Balagawi, A. Mararuai, D. Putulan, D. Tenakanai,, and A.C. Clarke. 2001. Fruit fl... more Leblanc, L., S. Balagawi, A. Mararuai, D. Putulan, D. Tenakanai,, and A.C. Clarke. 2001. Fruit flies in Papua New Guinea. SPC Pest Advisory Leaflet No. 37. 12 pages.
Journal of Animal Ecology, 2010
Plants and invertebrate herbivores are major constituents of terrestrial food webs. Identifying c... more Plants and invertebrate herbivores are major constituents of terrestrial food webs. Identifying component species and tracing their interactions in highly diverse communities are a monumental task. Novotny et al. 2010 present the first broad conspectus of herbivore–plant interactions in a forest in Papua New Guinea. In more than 15 years, nearly 7000 feeding links were traced between about 200 plants and 1500 insect herbivores. Although staggering, these figures might represent only 15% of the total herbivore richness and interaction diversity in that lowland forest. Standardized comparisons also showed distinctive specialization and diversification patterns in different feeding guilds, restricting the possibility of using any single guild as surrogate for the entire assemblage.
Australian Journal of Entomology, 2005
In Queensland, three tomato (Lycopersicon lycopersicum) cultivars, Grosse Lisse, Roma and Cherry,... more In Queensland, three tomato (Lycopersicon lycopersicum) cultivars, Grosse Lisse, Roma and Cherry, are infested by Queensland fruit fly, Bactrocera tryoni (Froggatt). In this study, we examined if there was a correlation between oviposition preference and offspring performance of B. tryoni among the three tomato cultivars. We also investigated host plant traits that may explain any variation in preference and performance. Choice and no-choice experiments were carried out under laboratory conditions. A positive correlation between oviposition preference and offspring performance of B. tryoni was observed in the three tomato cultivars. Grosse Lisse and Roma cultivars were highly preferred by B. tryoni over Cherry cultivar. Performance (measured as proportion of eggs developing to the pupal stage) was significantly higher in Grosse Lisse and Roma cultivars than in Cherry cultivar. The pericarp toughness of Cherry cultivar appears responsible for its low rate of infestation, while the presence of 2-butanol and 1,4-butanediamine in Roma and Grosse Lisse, respectively, may partly be responsible for the high oviposition preference shown by B. tryoni towards these cultivars.
Uploads
Papers by Solomon Balagawi