Chinensis Larvae Research Articles

Biology, embryonic development and digestive enzyme activities of Callosobruchus chinensis (Coleoptera: Chrysomelidae) on four cultivars of horse gram seeds

Macrotyloma uniflorum (Lam.) Verdc., commonly known as horse gram, is an important source of nutrients in human but its nutrients are lost by the post-harvest infestation of Callosobruchus chinensis (L.) (Coleoptera: Chrysomelidae: Bruchinae). The biology, life table parameters and resistance of C. chinensis on four horse gram cultivars (AK 21, ANK Black, Paiyur 2 and Urmi) were evaluated. Nutrients (total proteins, carbohydrates, amino acids, lipids and nitrogen) and antinutrients (total phenols, tannins and flavonols) of these cultivars were estimated. Further, insect embryogenesis and several key digestive enzymes of C. chinensis larvae were studied on these four cultivars. Callosobruchus chinensis showed longer development time, lower fecundity and lower survival rate on Urmi due to lower amounts of nutrients and higher amounts of antinutrients than other cultivars. Adult emergence also decreased on Urmi. Based on growth index, Urmi is moderately resistant. The relative growth rate of C. chinensis was lowest on Urmi. The rm, R0 and λ of C. chinensis were lowest in Urmi, suggesting the lower increase of C. chinensis population on Urmi than other three cultivars. Larval post-embryonic development (cellular blastoderm formation, germ band extension or retraction, segmentation of embryo and dorsal closure) was delayed on Urmi than other cultivars. α-Amylase, cysteine protease, α-glucosidase and lipase enzyme activities were reduced in larvae developed on Urmi than other cultivars. Therefore, we could recommend the use of moderately resistant Urmi cultivar as a way to lessen C. chinensis infestation, and suggesting resistance mechanism is due to reduced activities of key digestive enzymes.

Genome analysis and genomic comparison of a fungal cultivar of the nonsocial weevil Euops chinensis reveals its plant decomposition and protective roles in fungus-farming mutualism.

Fungus-farming mutualisms are models for studying co-evolutionary among species. Compared to well-documented fungus-farming in social insects, the molecular aspects of fungus-farming mutualisms in nonsocial insects have been poorly explored. Euops chinensis is a solitary leaf-rolling weevil feeding on Japanese knotweed (Fallopia japonica). This pest has evolved a special proto-farming bipartite mutualism with the fungus Penicillium herquei, which provide nutrition and defensive protection for the E. chinensis larvae. Here, the genome of P. herquei was sequenced, and the structure and specific gene categories in the P. herquei genome were then comprehensively compared with the other two well-studied Penicillium species (P. decumbens and P. chrysogenum). The assembled P. herquei genome had a 40.25 Mb genome size with 46.7% GC content. A diverse set of genes associating with carbohydrate-active enzymes, cellulose and hemicellulose degradation, transporter, and terpenoid biosynthesis were detected in the P. herquei genome. Comparative genomics demonstrate that the three Penicillium species show similar metabolic and enzymatic potential, however, P. herquei has more genes associated with plant biomass degradation and defense but less genes associating with virulence pathogenicity. Our results provide molecular evidence for plant substrate breakdown and protective roles of P. herquei in E. chinensis mutualistic system. Large metabolic potential shared by Penicillium species at the genus level may explain why some Penicillium species are recruited by the Euops weevils as crop fungi.

Decrease in macrofauna density increases the sediment phosphorus release and maintains the high phosphorus level of water column in Lake Taihu: A case study on Grandidierella taihuensis

Internal phosphorus (P) loading can increase the P level in the water column and further sustains cyanobacterial blooms. This study focused on the role of benthic fauna bioturbation in affecting the sediment P release and the P level of water column in a eutrophic lake, Lake Taihu. The macrofauna density decreased from 4766.56 ± 10541.80 ind/m2 in 2007 to 345 ± 447.63 ind/m2 in 2020 due to the frequent bottom-water hypoxia in Lake Taihu. The reduced macrofauna density majorly resulted from Grandidierella taihuensis, Limnodrilus hoffmeisteri, and Tanypus chinensis larvae, and their total density decreased by approximately 97% in 2020 compared to 2007. G. taihuensis, one of the major benthic faunas, was further used as a representative to investigate the effects of bioturbation on sediment P release using high-resolution sampling and imaging techniques. The results show that G. taihuensis can increase the O2 penetration depth by more than 20 mm through bio-irrigation, and causes the redox conditions in burrows and surrounding sediments to change dramatically within a few minutes due to the intermittent ventilation. Subsequent oxidation of the soluble Fe(II) led to the formation of Fe-oxide bound P in the surface sediments, thereby increasing the P retention in the sediments. When the G. taihuensis density was 1563 ind/m2 at the sampling site, approximately 0.12 g m−2 yr−1 P can be retained in sediments. As previous studies have shown that L. hoffmeisteri and T. chinensis played a similar role in increasing the P retention in sediments through their bioturbation activities, the sharp decline in benthic fauna density and burrowing activities in Lake Taihu should be an important reason for maintaining the high P level in the water column by decreasing the P retention in sediments.

Investigating the Link between Microalgal Nutrition and the Environment in Hen Clam (Mactra chinensis) Larvae Growth and Survival

Historically, various types of shellfish inhabited the Jeju area to the extent that large mounds of shells were found. However, the most endangered of such species, Mactra chinensis, currently inhabits only a few villages on Jeju Island. This pioneering study aimed to explore the effect of the environment on M. chinensis larval growth on Jeju Island. First, we assume that the findings of this study are based on the specific environmental situations and conditions of Jeju Island. This study mostly explored the effects of environment and food diversity (microalgal species) on the growth and survival of M. chinensis (hen clam) larvae. The average seawater temperature ranges between 19 and 22 °C during the summer season. We tested analogous seawater temperature conditions specific to the Jeju coastal environment: 17, 22, 27 and 32 °C. M. chinensis larvae reared at higher temperatures experienced higher growth but lower survival rates, reaching shell lengths of >220 μm at 15 days after hatching. The larvae exhibited the lowest growth (149.3 μm shell length) at 17 °C. Moreover, the M. chinensis larvae had the highest daily growth and survival rate of 10.3 μm and 75.5%, respectively, at a salinity of 30 practical salinity units (psu). For breeding Jeju hen clams, we found that the optimal water temperature and salinity for larval rearing were 22 °C and 30–35 psu, respectively. Larvae fed only I. galbana or Isochrysis sp. also exhibited high growth and survival rates. However, larvae restricted to a diet containing only P. lutheri exhibited low growth and survival rates. Therefore, the optimal diet of M. chinensis larvae should include more than one species of microalga, particularly I. galbana and Isochrysis sp., to increase their growth and survival rates, and hence the productivity of this clam species.

Identify immune-related genes of adzuki bean weevil (Callosobruchus chinensis) in response to bacteria challenge by transcriptome analysis

BackgroundCallosobruchus chinensis is one of the important postharvest pests in legume growing areas. Bacterial pesticide is a potential alternative method to control storage pests. However, the effect of these pathogen bacteria on storage pests, and the molecular mechanisms of insect response remain to be to investigated. ResultsUsing the next generation sequencing technology, we established a transcriptomic library for C. chinensis larvae in response to Escherichia coli. Total of 355 differential expressed genes (DEGs) were identified, which 178 DEGs were upregulated, and 177 DEGs were downregulated compared to control group. To validate the RNA-seq analysis, 20 DEGs and 14 immune-related genes were selected to perform quantitative polymerase chain reaction (RT-qPCR). These immune-related genes were involved in recognition (peptidoglycan recognition proteins), signal transduction (fibrinogen-related proteins, serine proteinases and NF-κB), and execution effectors (phenoloxidase, defensin, attacin, and antimicrobial peptide). In addition, genes that encode digestive and respiratory enzymes were altered in C. chinensis larvae in response to infection. Some genes that involved in juvenile hormone and insulin pathway appeared to express differentially, suggesting that pathogen infection might lead to developmental arrest. Furthermore, iron homeostasis and chitin metabolism appeared significantly altered after infection. ConclusionIn this study, we characterized the immune response of C. chinensis larvae in response to E. coli using RNA-seq, from pathogen recognition, signal transduction, to execution. Some other identified genes were involved in iron homeostasis, respiration, and digestion. A better understanding of molecular response of beetle to pathogen will facilitate us to develop an available strategy to control storage pests.

Insecticidal activities and mechanism of extracts from neem leaves against Oxya chinensis

ABSTRACT In this study, neem leaves were successively extracted with petroleum ether, 95% ethanol and water and the insecticidal activities of these extracts against Oxya chinensis larvae were measured. The results showed that 95% ethanol extract gave the highest extraction yield and insecticidal activity, and it was further extracted with five different solvents. The petroleum ether extract from the 95% ethanol extract possessed the highest insecticidal activity with median lethal concentration values ranging from 14.93 to 55.66mg/mL. The gas chromatography-mass spectrometer analysis showed that the petroleum ether extract mainly composed of alkanes, olefin, esters and amide. The pathological examination revealed that the prominent lesions, including reduced regenerative cells in midgut and swelled and degenerated cylindrical cells, were observed in the 5th instar Oxya chinensis after treatment. The ultrastructural features showed that the cylindrical cells, microvilli and mitochondria were seriously damaged. These results suggested that the petroleum ether extract from neem leaves had potent insecticidal activity and could be a candidate insecticide.

Response of Callosobruchus chinensis L. to plant extracts and to the parasitoid Anisopteromalus calandrae

Present investigation was carried out to elucidate the extracts of botanicals i.e., Cichorium intybus, Glycyrrhiza glabra, Trachyspermum ammi and Terminalia chebula, for their possible toxic effect against C. chinensis population. The results revealed that mortality was highest (94.649%) in case of T. ammi treatment, followed by T. chebula with mortality value 56.929%. Mortality was 52.363% where application of C. intybus was carried out. Minimum mortality (34.500%) was observed in G. glabra treated grains. A natural ecto-parasitoid, Anisopteromalus calandrae was used to manage C. chinensis population. A. calandrae male and female adults (5, 10 and 15 pairs) were released to analyze the parasitism efficiency. A. calandrae was reared in the laboratory on C. chinensis larvae. Honey was offered as a suitable food to parasitoid. The parasitism data was recorded after the adult emergence of brunchid beetles. The experiment conducted under Completely Randomized Design and results statistically evaluated using statistical software at 5% level of significance. A. calandrae parasitized both larval and pupal stages of C. chinensis and preferred 4th instar larvae of C. chinensis. Large amount of A. calandrae may efficiently control the C. chinensis population. As compared to control (1558.7 host adult), the minimum host emergence (699.00 host adult) was observed with high population density of A. calandrae. It was also obvious from the results, that mortality was increased with the increase in concentration so, a direct dosemortality response was observed.

Effects of protease inhibitors on the activities of midgut proteases in Callosobruchus chinensis (Linnaeus) larvae.

To clarify the effects of protease inhibitors on the activities of midgut proteases in Callosobruchus chinensis (L.) larvae, the inhibitory effects of four kinds of protease inhibitors on the activities of midgut proteases of C. chinensis larvae were examined in vitro and in feeding conditions with indoor artificial insect inoculation. The activities of total protease, trypsin-like enzyme and chymotrypsin-like enzyme in the midgut of C. chinensis larvae fed on artificial mung bean that contained different contents of mung bean types in inhibitor (MBTI) were examined. The results showed that those four protease inhibitors had significant inhibitory effects on the activities of total protease, trypsin-like enzyme and chymotrypsin-like enzyme in C. chinensis larvae. The inhibitory effect was more significant when the concentration was higher. Among those inhibitors, the inhibitory effect of 20 μg·mL-1 MBTI on three kinds of enzyme activities was the strongest, with reduction of 62.5%, 41.2% and 38.7%, respectively. Ovomucoid inhibitor (OI) had the lowest inhibitory effect. The activities of three enzymes in the midgut were also inhibited by C. chinensis larvae fed with artificial mung bean containing different inhibitors. The activities of three enzymes increased with the prolongation of the instar after feeding, but they were significantly lower than that in control. The inhibitory effect of MBTI was the strongest. The inhibitory effect on the activities of total protease and trypsin-like enzyme was gradually enhanced with the increases of MBTI contents when C. chinensis larvae were fed with artificial mung bean with different contents MBTI. The inhibitory effect on chymotrypsin-like enzyme activity was not significant. When the content of MBTI was up to 20%, the activity of chymotrypsin-like enzyme was obviously inhibited.

Mung bean (Vigna radiata) cultivars mediated oviposition preference and development of Callosobruchus chinensis (Coleoptera: Chrysomelidae: Bruchinae)

The Azuki bean weevil, Callosobruchus chinensis (L.), is a destructive pest of stored mung bean [Vigna radiata (L.) Wilczek] as well as other leguminous seeds. The development of resistant seeds to manage this pest is of current great interest to plant breeders. In this study, we investigated the oviposition preference and development of C. chinensis on two susceptible mung bean cultivars (Seonhwa and Gyeongseon) and one previously reported resistant cultivar (Jangan), compared to the susceptible cowpea (Vigna unguiculata L.), cultivar (Yeonbun) using both multiple-choice and no-choice tests. In addition, the development of C. chinensis was also examined at four constant temperatures (20, 25, 30, and 35 °C). Both tests found cowpea to be the most suitable seed for oviposition. Total developmental time from oviposition to adult emergence ranged from 27.01 to 38.2 days, being shortest on cowpea and longest on the mung bean, cv. Jangan. However, no successful development of C. chinensis larvae on mung bean, cv. Jangan, occurred at any temperature. The highest rate of adult emergence and the longest adult longevity both occurred on cowpea and certain mung bean cultivars (Seonhwa and Gyeongseon), with the dramatic exception of cv. Jangan. These results suggest that the higher preference and performance of C. chinensis on cowpea (3.3 egg/seed) and least on mung bean, cv. Jangan (0.4 egg/seed). This information may facilitate the exploration of resistant genetic materials and chemicals associated with seeds for successful breeding. Further studies should examine the chemicals associated with mung bean cultivars and its resistant mechanism to develop a control method against bruchines.

Comparative Proteomics and Expression Analysis of Five Genes in Epicauta chinensis Larvae from the First to Fifth Instar

Blister beetle is an important insect model for both medicinal and pure research. Previous research has mainly focused on its biology and biochemistry, but very little data is yet available in the molecular biology. This study uses differential proteomics technology to analyze the soluble proteins extracted from each of the 5 instars larvae of Epicauta chinensis. 42 of the differentially-expressed proteins were identified successfully by MALDI-TOF/TOF-MS. Some of these proteins’ function and their expression profiles are analyzed. Our analysis revealed dynamics regulation of the following proteins: Axin-like protein pry-1 (APR-1), dihydrolipoyl dehydrogenase (DLD), vitellogenin (Vg) and lysozyme C (Lmz-S). APR-1 negatively regulates the Wnt signaling pathway. Its overexpression could result in embryo, leg, eye and ovary ectopica or malformation. DLD catalyzes the pyruvate into acetyl-CoA, the latter is the starting material of juvenile hormone (JH) and ipsdienol biosynthesis through the MVA pathway in insects. While Vg synthesis can be regulated by JH and stimulated by food factors. So DLD may affect the synthesis of JH, ipsdienol and Vg indirectly. The activity of lysozyme is an indicator of the immunity. Nutrition/food should be taken into account for its potential role during the development of larva in the future. Among the five genes and their corresponding proteins’ expression, only hsc70 gene showed a good correspondence with the protein level. This reflects the fluctuating relationship between mRNA and protein levels.

Distribution and elimination of Norfloxacin in Fenneropenaeus chinensis larvae

This study examined the distribution and elimination of Norfloxacin (NFLX) in Fenneropenaeus chinensis ovary and egg and newly hatched larvae. Mature parental shrimp were exposed to 4 or 10 mg L−1 NFLX for 2 or 5 d. Ovary and eggs of the shrimp were sampled after spawning in order to detect NFLX residue using high-performance liquid chromatography (HPLC). Results showed that NFLX residue accumulated in F. chinensis eggs after the parental exposure, with the highest residue detected in ovary. To examine the fate of NFLX residue in larvae, we further determined the concentration of NFLX residue in F. chinensis eggs and larvae at 4 different developmental stages after 24-h exposure. From the newly metamorphosed larvae (0 h post-metamorphosis, h.p.m), samples were taken at different time intervals to 72 h.p.m. HPLC assay showed that the concentrations of NFLX residue in zoea exposed to 4 and 10 mg L−1 NFLX were the highest at 1.5 h, i.e., 0.332 and 0.454 μg g−1, respectively. At the two NFLX exposure levels, the elimination time of half NFLX (half life) in nauplius was 45.36 and 49.85 h, respectively, followed by that in zoea (31.68 and 33.13 h), mysis larvae (42.24 and 47.28 h) and postlarvae (24.48 and 30.96 h). Both NFLX exposure levels had a germicidal effect. The distribution and elimination of NFLX residue in F. chinensis tissue, eggs and larvae correlated well with the drug exposure level. The disappearance of NFLX residue coincided with the larval growth, and the half-life of NFLX decreased with the larval development.

Prey selection by tiger frog larvae (Hoplobatrachus chinensis) of two sympatric anuran species' tadpoles

We examined the prey selection and behavioral responses of tiger frog Hoplobatrachus chinensis larvae exposed to unpalatable and palatable sympatric prey tadpoles, Bufo melanostictus and Pelophylax nigromaculatus. We found that after a short exposure to the toxic toad tadpoles B. melanostictus, predators may learn to decrease going after unpalatable prey, subsequently it seems they may express short-term behavioral memory in order to avoid the toxic prey. In general, H. chinensis showed no preference for either any of the two prey species, which may be the result of P. nigromaculatus using behavioral performance and chemical defense as antipredatation strategies. These results facilitate further investigation of other aspects of the behavioral ecology of these three anuran species and hint at some potentially interesting possibilities of memory in choice of prey which may suggest further study.

Studies on the rotifer ( Brachionus urceus Linnaeus, 1758) as a vector in white spot syndrome virus (WSSV) transmission

The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus–phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus–phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47 ± 15.44%) was higher than that in the control treatment (34.67 ± 15.11%), there was no significant difference in the mortality between them ( P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested.

京都府におけるネギハモグリバエの土着寄生バチ相

I investigated the stone leek leafminer, Liriomyza chinensis Kato (Diptera: Agromyzidae), and its hymenopterous parasitoids emerging from the leaves of Welsh onion collected in Kyoto Prefecture, Japan, from July to August 2002, from June to August 2003, and from May to June 2005. The parasitoids that emerged from L. chinensis larvae or pupae were Halticoptera circulus (Walker) (Pteromalidae), Pnigalio katonis (Ishii) (Eulophidae), Diglyphus isaea (Walker) (Eulophidae), Chrysocharis pentheus (Walker) (Eulophidae), Neochrysocharis formosa (Westwood) (Eulophidae), and Closterocerus trifasciatus Westwood (Eulophidae). The dominant parasitoid species in 2002 was D. isaea, and that in 2003 and 2005 was P. katonis.

Temporal settlement patterns of larvae of the broadcast spawning reef coral Favites chinensis and the broadcast spawning and brooding reef coral Goniastrea aspera from Okinawa, Japan

The faviid corals, Favites chinensis and Goniastrea aspera are widely distributed in the Indo-Pacific region. Both corals are hermaphroditic broadcast spawners, but G. aspera is also known to brood planula larvae in Okinawa. This study investigated the temporal settlement patterns of planula larvae of the scleractinian corals F. chinensis and G. aspera that developed from spawned gametes, and planula release and settlement of brooded larvae of G. aspera from Okinawa, Japan. Some of the broadcast-spawned larvae of F. chinensis and G. aspera had very short pre-competency periods of 1–2 and 2–3 days after spawning, and relatively long maximum settlement-competency periods of 56–63 and 63–70 days after spawning, respectively. These pre-competency periods are among the shortest reported for larvae of broadcast spawning coral species, and appear to be negatively correlated with seawater temperature. F. chinensis larvae tended to settle rapidly with 34–39% of larvae settling in the first week after spawning, while broadcast-spawned G. aspera larvae had a slower settlement pattern with 11–15% of larvae settling in the first week after spawning. Brooded larvae of G. aspera settled more rapidly, with settlement rates of 27–31% within the first 24 h and 45–65% within the first week after the start of the experiment. The production of planula larvae with rapid settlement capabilities may enable F. chinensis and G. aspera to establish and maintain populations in shallow reef sites at Okinawa. The release of the brooded planulae for up to 2 months may explain why G. aspera is locally more dominant on shallow reefs in Okinawa than F. chinensis. On a broader scale, the longer settlement competency periods of some of the broadcast-spawned larvae of these species increase their potential for longer-distance dispersal and may partly explain the wide biogeographic distribution of these species in the Indo-Pacific region.

Biology, Rearing, and Preliminary Evaluation of Host Range of Two Potential Biological Control Agents for Mile-a-Minute Weed,Polygonum perfoliatumL.

Abstract Basic biology and rearing methods were determined for Timandra griseata Peterson (Lepidoptera: Geometridae) and Homorosoma chinensis Wagner (Coleoptera: Curculionidae), two potential biological control agents of mile-a-minute weed (Polygonum perfoliatum L., Polygonaceae). Both species also were tested for their ability to feed and develop on crop plants in the family Polygonaceae. T. griseata defoliated potted mile-a-minute weed, developing from egg to adult in ≈26 d. However, T. griseata also fed and developed on common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tartaricum Gaertn), and accepted these species and mile-a-minute weed equally in choice tests. Thus, the host range of T. griseata appears to be too broad for it to be considered for release in the United States. Homorosoma chinensis had a relatively high reproductive rate and short generation time on potted mile-a-minute weed. Internal feeding by H. chinensis larvae caused mortality of entire stems. Adult w...

Vibrios associated with Penaeus chinensis (Crustacea: Decapoda) larvae in Chinese shrimp hatcheries

Bacteriological surveys were performed in 1995 and 1996 in three shrimp hatcheries located in the north of the People's Republic of China. Samples were taken from routine productions of healthy Penaeus chinensis larvae, their environment and from diseased larvae. A total of 186 isolates from the dominant bacterial flora was characterized by Biolog metabolic fingerprinting and identified by comparison to a database of 850 Vibrio type- and reference strains. Representative Vibrio harveyi strains were further genotypically analyzed by AFLP fingerprinting of whole-genomes. An overwhelming predominance of V. alginolyticus and V. harveyi was observed in the larval developmental stages from zoea stage on. The flora associated with larvae is not very stable and is influenced by the bacterial flora of the administered food and by the environment. In the 1995 survey, the bacterial flora of successful P. chinensis larvae productions was mainly dominated by V. alginolyticus and unidentified Gram negative strains, while V. harveyi was absent. The bacterial numbers gradually increased from nauplii stage to post-larval stage, but few vibrios were isolated from nauplii stage. High V. harveyi numbers (up to 10 5 CFU/larva) in the larvae are correlated with weak larvae and mass mortalities. Between V. harveyi strains, isolated from healthy and diseased larvae, no phenotypic or genotypic differences were found. The presence of V. alginolyticus might influence the pathogenicity of V. harveyi or might have an impact on the resistance of larvae to bacterial pathogens.

Studies on the histerid beetle Pachylister chinensis in Fiji, and its possible value in the control of buffalo-fly in Australia

P. chinensis, a predacious beetle that feeds on dipterous larvae breeding in dung of herbivores, was introduced from Java to Fiji in 1938 for the control of houseflies. The species is confined to areas having a wet tropical climate with a well-distributed annual rainfall exceeding 100 in. The beetle has a marked preference for cow pads in pastures with well-drained soils, and avoids areas shaded by trees. The female lays one or two eggs in the soil beneath a cow pad, and stays there from 2 to 3 days. P. chinensis larvae feed on active maggots as well as on fly puparia. Larval development occupies 16-20 days, and the pupal period some 30 days during the Fijian winter. In Fiji, P. chinensis has at least six generations per annum, and the adults live for more than a year. An abundance of prey ranging in length from 5 to 15 mm is essential for the survival of P. chinensis in Fiji, which attained a mean density ranging up to five beetles per cow pad in some localities. Laboratory tests at this density indicated that, due to the limited searching ability of the beetles and their larvae, only about 30-50 % of maggots in cow pads were destroyed. Because of its irregular density distribution and limited searching ability, no reliance should be placed on this predator for the control of the buffalo-fly in Australia. It is suggested that the efficiency of histerids in controlling flies could be enhanced by the introduction of dung beetles which would substantially reduce the breeding habitat of dipterous pests, thereby making them more vulnerable to predation. The evidence obtained during the course of this study did not suggest that P. chinensis influenced the abundance of houseflies in Fiji.