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The objective of the presented study was to demonstrate the potential of a bottom-up "ethological" approach and individual-based model of Markov-like stochastic processes, employed to gain insights into the factors driving behavior and fate of the invasive propagule, which determine the initial stages of pest invasion and "cryptic" existence of the localized, ultra-low density incipient pest populations. The applied model, PESTonFARM, is driven by the parameters derived directly from the behavior and biology of the target insect species, and spatiotemporal traits of the local terrain and climate. The model projections are actively generated by behavior of the primary causative actors of the invasion processes-individual "virtual" insects-members of the initial propagules or incipient populations. Algorithms of the model were adjusted to reflect behavior and ecology of the Mediterranean fruit fly, Ceratitis capitata , used as a case-example in the presented study. The model was parametrized based on compiled published experimental information about C. capitata behavior and development, and validated using published data from dispersion and trapping studies. The model reliably simulated behavior, development and dispersion of individual members of an invasive cohort, and allowed to quantify pest establishment and detection chances in landscapes of varying spatiotemporal complexity, host availability and climates. The results support the common view that, under optimal conditions (farmland with continuous fruit availability and suitable climate), even a single propagule of medium size (100 females) usually results in pest establishment and detection within the first year post-invasion. The results demonstrate, however, that under specific sub-optimal conditions determined by the local climate, weather fluctuations and landscape topography (e.g., sub-urban), the incipient cryptic populations may occasionally continue for several generations, and remain undetected by typical pest surveillance grids for the periods extending beyond 2-years post-invasion.

The paper reports application of a Markov-like stochastic process agent-based model and a "virtual farm" concept for enhancement of site-specific Integrated Pest Management. Conceptually, the model represents a "bottom-up ethological" approach and emulates behavior of the "primary IPM actors"-large cohorts of individual insects-within seasonally changing mosaics of spatiotemporally complex faming landscape, under the challenge of the local IPM actions. Algorithms of the proprietary PESTonFARM model were adjusted to reflect behavior and ecology of R. cerasi. Model parametrization was based on compiled published information about R. cerasi and the results of auxiliary on-farm experiments. The experiments were conducted on sweet cherry farms located in Austria, Germany, and Belgium. For each farm, a customized model-module was prepared, reflecting its spatiotemporal features. Historical data about pest monitoring, IPM treatments and fruit infestation were used to specify the model assumptions and calibrate it further. Finally, for each of the farms, virtual IPM experiments were simulated and the model-generated results were compared with the results of the real experiments conducted on the same farms. Implications of the findings for broader applicability of the model and the "virtual farm" approach-were discussed.

Bactrocera invadens Drew, Tsuruta & White (Diptera: Tephritidae) invaded Kenya in 2003. Before the arrival of B. invadens, the indigenous fruit fly species Ceratitis cosyra (Walker) was the predominant fruit fly pest of mango (Mangifera indica L.). Within 4 yr of invasion, B. invadens has displaced C. cosyra and has become the predominant fruit fly pest of mango, constituting 98 and 88% of the total population in traps and mango fruit at Nguruman, respectively. We tested two possible mechanisms responsible for the displacement namely; resource competition by larvae within mango fruit and aggression between adult flies. Under interspecific competition, larval duration in B. invadens was significantly shorter (6.2 +/- 0.6-7.3 +/- 0.3 d) compared with C. cosyra (8.0 +/- 1.2-9.4 +/- 0.4 d). Pupal mass in C. cosyra was affected by competition and was significantly reduced (7.4 +/- 0.3-9.6 +/- 0.6 mg) under competitive interaction compared with the controls (12.1 +/- 1.5-12.8 +/- 1.1 mg). Interspecific competition also had a significant adverse effect on C. cosyra eclosion, with fewer adults emerging under co-infestation compared with the controls. Interference competition through aggressive behavior showed that fewer C. cosyra (3.1 +/- 0.8) landed on mango dome compared with the controls (14.2 +/- 1.5) when adults were mixed with B. invadens adults in Plexiglas cages. Similarly the number of times C. cosyra was observed ovipositing was significantly lower (0.2 +/- 0.2) under competitive interaction compared with the controls (6.1 +/- 1.8). Aggressive encounters in the form of lunging/ head-butting and chasing off other species from the mango dome was higher for B. invadens compared with C. cosyra. Our results suggest that exploitative competition through larval scrambling for resources and interference competition through aggressive behaviors of the invader are important mechanisms contributing to the displacement of C. cosyra by B. invadens in mango agroecosystems.

The influence of food sources comprising the natural diet on the reproductive behaviour, fecundity and longevity of three African fruit flies Ceratitis cosyra (Walker), C. fasciventris (Bezzi) and C. capitata (Wiedemann) was investigated. Three natural food sources, varying in protein and sugar content, were evaluated. These included bird droppings (farm chicken), aphid honeydew and guava (Psidium guajava L.) juice. For C. fasciventris and C. capitata, flies fed on a protein-rich diet displayed higher frequency of calling, mating and oviposition than flies fed on a protein-poor diet, whilst for C. cosyra, quality of diet significantly influenced the mating behaviour of the flies, but not the calling and oviposition behaviour. Net fecundity rates were lowest for C. fasciventris and C. capitata when fed only on guava juice (0.1, 2.6 eggs per female, respectively), and higher for those on a diet of honeydew only (9.5, 33.8 eggs per female, respectively) and a combined diet of guava, honeydew and chicken faeces (11.8, 25.8 eggs per female, respectively). For C. cosyra, due to low numbers of eggs collected, no significant differences in fecundity between diets could be detected. All species fed only on a diet of chicken faeces since emergence died within the first three days of adult life without laying eggs, but when carbohydrates were provided by addition of guava juice and honeydew, the longevity of the flies was sustained for more than four weeks after adult emergence. The practical implications of these findings for control purposes are discussed.

A set of 10 microsatellite markers was used to survey the levels of genetic variability and to analyse the genetic aspects of the population dynamics of two potentially invasive pest fruit fly species, Ceratitis rosa and C. fasciventris, in Africa. The loci were derived from the closely related species, C. capitata. The degree of microsatellite polymorphism in C. rosa and C. fasciventris was extensive and comparable to that of C. capitata. In C. rosa, the evolution of microsatellite polymorphism in its distribution area reflects the colonization history of this species. The mainland populations are more polymorphic than the island populations. Low levels of differentiation were found within the Africa mainland area, while greater levels of differentiation affect the islands. Ceratitis fasciventris is a central-east African species. The microsatellite data over the Uganda/Kenya spatial scale suggest a recent expansion and possibly continuing gene flow within this area. The microsatellite variability data from C. rosa and C. fasciventris, together with those of C. capitata, support the hypothesis of an east African origin of the Ceratitis spp.

The infectivity of 4 isolates of Metarhizium anisopliae to puparia of Ceratitis capitata treated as late third-instar larvae in unsterilized soil was investigated in the laboratory under controlled temperature and moisture. At 20-30 degrees C, mortality in puparia was highest at water potential of -0.1 and -0.01 mega Pascal (MPa) and lowest at water potential of -0.0055 and -0.0035 MPa in all the isolates. In wetter soil however, isolates ICIPE 20 and 60 caused significantly higher mortality than ICIPE 18 and 69. The survival of conidia in drier soil (-0.1 MPa) was not adversely affected at all temperatures. However, in wet soil (-0.0035 MPa) there was drastic reduction in colony counts in ICIPE 18 and 69 at 25 and 30 degrees C but conidial density in ICIPE 20 and 60 remained at the initial level at 14 days after inoculation at all temperatures. When ICIPE 20 was evaluated against three other fruit fly species (Ceratitis cosyra, Ceratitis rosa, and Ceratitis fasciventris), significant reduction in adult emergence and higher pupal mortality occurred in C. cosyra and C. fasciventris than in C. rosa at a combination of 15 and 20 degrees C and -0.1 and -0.0035 MPa. However, at higher temperature and the same moisture level, the isolates were equally pathogenic across the 3 species. It is probable that in addition to pathogen cycling and multiplication from dead infected insects in the soil, a balance between microbial degradation and replenishment of inoculum of virulent isolates occur through fluctuations in, and intricate interactions between temperature and moisture levels. This study is indicative of the potential of using isolate ICIPE 20 for soil inoculation against pupariating third-instar larva of fruit flies, thus providing a novel alternative to chemical soil application.

The possibility to cross-species amplify microsatellites in fruit flies of the genus Ceratitis was tested with the polymerase chain reaction (PCR) by analysing 23 Ceratitis capitata (Wiedemann) microsatellite markers on the genomic DNA of three other economically important, congeneric species: C. rosa (Karsch), C. fasciventris (Bezzi) and C. cosyra (Walker). Twenty-two primer pairs produced amplification products in at least one of the three species tested. The majority of the products were similar, if not identical in size to those expected in C. capitata. The structures of the repeat motifs and their flanking sequences were examined for a total of 79 alleles from the three species. Sequence analysis revealed the same repeat type as the homologous C. capitata microsatellites in the majority of the loci, suggesting their utility for population analysis across the species range. A total of seven loci were differentially present/absent in C. capitata, C. rosa, C. fasciventris and C. cosyra, suggesting that it may be possible to differentiate these four species using a simple sequence repeat-based PCR assay. It is proposed that medfly-based microsatellite markers could be utilized in the identification and tracing of the geographical origins of colonist pest populations of the four tested species and in the assessment of their risk and invasive potentials; thereby assisting regulatory authorities in implementing quarantine restrictions and other pest control measures.

The pathogenicity of two isolates of Beauveria bassiana and 12 of Metarhizium anisopliae towards adult fruit flies, Ceratitis capitata and Ceratitis rosa var. fasciventris was tested in the laboratory. Fruit flies were exposed to dry conidia evenly spread on velvet material covering the inner side of a cylindrical plastic tube. All isolates tested were pathogenic to both species of fruit flies. Mortality ranged from 7 to 100% in C. capitata and from 11.4 to 100% in C. rosa var. fasciventris at 4 days post-inoculation. Six isolates, M. anisopliae ICIPE 18, 20, 32, 40, 41 and 62, were highly pathogenic to both C. capitata and C. rosa var. fasciventris. The LT90 values of the most pathogenic isolates ranged between 3-4 days in both insects. Because of the difficulties in rearing C. cosyra, only the isolates that were highly pathogenic to both C. rosa var. fasciventris and C. capitata were tested against adult C. cosyra. They caused mortality of between 72-78% at 4 days post-inoculation. The LT90 values in all the isolates did not exceed 4 days. One of the most pathogenic isolates, M. anisopliae ICIPE 20, was evaluated against C. capitata and C. rosa var. fasciventris in cage experiments using three autoinoculators (maize cob, cheesecloth and Petri dish) in an autoinoculative device consisting of plastic mineral bottle. Mortality of between 70-93% was observed in flies of both species that were captured from the cages and held under laboratory conditions. These results indicate the possibility of fruit fly suppression with entomopathogenic fungi using an autoinoculative device.

The effect of proximity of the release points of the two pheromone components (Z)-11-hexadecenal and (Z)-11-hexadecen-1-ol of the spotted stem borer,Chilo partellus (Lepidoptera: Pyralidae) on behavior of the males and on trapping efficiency was investigated. Separating the dispensers of the two components in the trap by a mere 3 cm resulted in a threefold decrease in trap performance, compared to very close release of the components. The result is attributed to possible distortion of the pheromone signal, resulting in confused behavior ofC. partellus males in the vicinity of the trap. The ethological and practical implications of the phenomenon are discussed.