Parasitoid Fopius Arisanus Research Articles

Tri-trophic interactions among Fopius arisanus, Tephritid species and host plants suggest apparent competition.

When several polyphagous herbivore species share a parasitoid, the tri-trophic interaction networks can be difficult to predict. In addition to direct effects, the parasitoid may influence the herbivore community by mediating indirect interactions among hosts. The plant species can also modulate the parasitoid preference for a specific host. One of the indirect effects is apparent competition, a negative interaction between individuals as a result of the action of shared natural enemies. Here, we focus on the interactions between the parasitoid Fopius arisanus (Braconidae) and two generalist fruit fly pests: Bactrocera dorsalis and Bactrocera zonata (Tephritidae). This parasitoid was introduced into La Réunion in 2003 to control populations of B.zonata and can also interact with B.dorsalis since its invasion in 2017. Our main objective is to characterize the tri-trophic interactions between F.arisanus, fruit fly and host plant species. We developed a long-term field database of fruit collected before and after the parasitoid introduction and after the B.dorsalis invasion in order to compare parasitism rate and fruit fly infestation for the different periods. In laboratory assays, we investigated how the combination of fruit fly species and fruit can influence the preference of F.arisanus. In the field, before the invasion of B.dorsalis, the parasitism rate of F.arisanus was low and had a little impact on the fruit fly infestation rate. After the B.dorsalis invasion, we observed an increase in parasitism rate from 5% to 17%. A bioassay showed that females of F.arisanus could discriminate between eggs of different fruit fly and host plant species. The host plant species preference changed in relation to the fruit fly species inoculated. Field observations and laboratory experiments suggest the possible existence of apparent competition between B.dorsalis and B.zonata via F.arisanus.

Is Fopius arisanus (Hymenoptera: Braconidae) a suitable biological control agent of Bactrocera dorsalis (Diptera: Tephritidae) in multi-crop orchards?

In the present study, we investigated the bottom-up effects of four economically important host fruit species (guava, mandarin orange, plum, pear) on Bactrocera dorsalis parasitoid Fopius arisanus in terms of emergence, parasitism, sex ratio, developmental duration, longevity and body size. Our results showed that F. arisanus reared on guava infested with B. dorsalis had highest emergence, parasitism, sex ratio and longevity, while these parameters were lower on B. dorsalis-infested mandarin orange. Moreover, body size of F. arisanus (wing, hind tibia and body lengths for both sexes and ovipositor length for female) varied significantly among the B. dorsalis-infested fruits, with mandarin orange providing the biggest emergent body size for both sexes and guava providing the smallest. The shortest preimaginal developmental time for both sexes was in infested plums and the longest in infested mandarin orange. Therefore, we inferred that B. dorsalis-infested guava is the most suitable host–host plant combination for F. arisanus fitness among the tested fruit-host combinations. Our findings corroborates that the ability of some tested fruit species to serve for the permanent establishment of F. arisanus in the field, which will aid in boosting the efficiency of F. arisanus as a biological control agent, especially in multi-crop orchards.

Fruit fly parasitoids (Hymenoptera: Braconidae) in south‐east Queensland, Australia

AbstractOpiine braconids include natural enemies of tephritid fruit flies, and interest in their greater utilisation for fruit fly control is growing. However, there is a lack of basic data on the prevalence and impact of these wasps for most regions of Australia. We sampled fruit fly host fruits from urbanised and peri‐urban locations of south‐east Queensland and reared out parasitoids and their host flies to determine the regional parasitoid community and how parasitism varied across time and habitat type. A total of 4969 fruits were collected from which 21 277 tephritid puparia were obtained. Of 12 601 fruit flies that emerged, the Queensland fruit fly, Bactrocera tryoni, was the dominant species. A total of 5736 parasitoids, representing four species, were recovered from both suburban and peri‐urban sites. For all samples combined, the average parasitism rate was 30%. The exotic, egg–larval–pupal parasitoid Fopius arisanus represented 81% of the parasitoids collected and was recovered from all of the 13 host fruit species sampled. The second most common species, the native larval–pupal parasitoid, Diachasmimorpha kraussii, represented 15% of recovered parasitoids and was collected from a smaller range of host fruit species. The remaining two parasitoids, Diachasmimorpha tryoni and Psyttalia fijiensis, were rare in samples. Parasitoid infestation was highly variable across samples, with higher rates of parasitism observed from October to May. A targeted field experiment to measure differences in parasitism by D. kraussii between urban and peri‐urban habitats detected no variation in the abundance of D. kraussii across habitats, a result consistent with the general survey. The data show that for south‐east Queensland, parasitoids are a significant fruit fly mortality factor in both peri‐urban and urban landscapes. Any manipulation of parasitoids for regional pest management should focus on conservation of F. arisanus.

Non-target effects of the exotic generalist parasitoid wasp Fopius arisanus (Sonan) estimated via competition assays against Doryctobracon areolatus (Szepligeti) on both native and exotic fruit fly hosts

Biological control by the generalist egg parasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae) has been proposed against Bactrocera carambolae (Drew & Hancock) (Diptera: Tephritidae) in northern Brazil. This study assessed possible effects of F. arisanus on native parasitoids by focusing on competition with the native wasp Doryctobracon areolatus (Szepligeti) (Hymenoptera: Braconidae) on two hosts, Anastrepha fraterculus (Wiedemann), a native tephritid, and Ceratitis capitata (Wiedemann), an introduced pest tephritid. Laboratory and greenhouse cage studies showed that F. arisanus parasitized < 3% of the native host in competition or alone compared to 41–65% for C. capitata, while D. areolatus parasitized 12–42% of the native host and < 4% on C. capitata. The host origin of F. arisanus did not affect subsequent parasitism rates on native or exotic hosts. However, when reared on C. capitata, F. arisanus had higher parasitism on C. capitata than on A. fraterculus. Lab and greenhouse competition studies showed that F. arisanus had no measurable detrimental effect on the native parasitoid in either the native or introduced host, suggesting that F. arisanus interfered minimally with the native parasitoid. Based on these results and other relevant studies showing non-preference of F. arisanus for the native fruit fly species, as well as the non-preference of native parasitoids for exotic fruit flies, we infer that the release of F. arisanus against exotic tephritids such as C. capitata and B. carambolae in Brazil would not cause major disruption of the native populations of A. fraterculus parasitoids.

Parasitoids of fruit flies (Diptera: Tephritidae) and their distribution along mango production zones in Senegal

In this study, the diversity and distribution of fruit fly parasitoids and their reservoir plants along a latitudinal gradient in three zones of mango production in Senegal were reported. Fruits were collected from wild and cultivated plants at 15 different sites (5 sites per production zone) over a period of seven months. In the northern and middle zone (Niayes and Centre). Our results showed a significant contrast in the distribution of parasitoid species between zones and fruit types. In Niayes, Psytallia cosyrae (Hymenoptera: Braconidae) was the dominant species, while in Centre it was P. cosyrae and Diachasmimorpha spp. (Hymenoptera: Braconidae). The native plant species that were hosting the highest densities of fruit flies and parasitoids were Capparis tomentosa, Ziziphus mauritiana, Kedrostis hirtella, and Momordica balsamina. In the southern zone (Casamance), we measured parasitism rate by the introduced parasitoid Fopius arisanus (Hymenoptera: Braconidae) and found an average of 5% parasitism rate in mango orchards.There, the most abundant parasitoids found were F. caudatus and F. sylvestri. Additional research is needed to characterize the factors affecting the effectiveness of biological control with hymenopteran parasitoids and determine the role played by native host plants in the control of fruit flies.

Effects of toxic baits and food-based attractants for fruit flies on the parasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae).

This study aimed to evaluate the effects of toxic baits and attractants for fruit flies on the biology of its parasitoid Fopius arisanus. We tested two food-based attractants; hydrolysed corn protein (Biofruit® 3%) and sugarcane molasses (7%), their mixtures with spinosad and malathion-based insecticides, and a ready-to-use commercial bait (Success 0.02 CB®). Malathion-based lures were used as references for mortality (i.e., positive control), while negative control was honey. The formulations Biofruit® + malathion (T1), molasses + malathion (T2), and spinosad + molasses (T3) were toxic to F. arisanus, being classified as harmful (class 4). In addition, toxic baits composed of Biofruit + spinosad (T4) reduced parasitism by 97.99%, being rated as moderately harmful (class 3). Yet, Success 0.02 CB® (T7) was considered slightly toxic (class 2), causing a 64.55% reduction in parasitism. Regarding the biological parameters of F. arisanus, offspring number and parasitoid longevity were significantly reduced by using hydrolysed protein attractants when compared to the control (honey). However, sugarcane molasses improved parasitoid reproduction and longevity, as did the honey. Lastly, ingestion tests showed the major role of attractants in toxic-bait formulations against F. arisanus.

Modeling the climatic suitability for Fopius arisanus (Hymenoptera: Braconidae) and its host fly Bactrocera dorsalis (Diptera: Tephritidae)

Releases of the parasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae) have significantly reduced fruit fly populations, especially for its preferred host Bactrocera dorsalis (Hendel) (Diptera: Tephritidae, Dacinae) in climatically suitable areas where the species can become established for long-term control. The maximum entropy model (MaxEnt) was used to create niche models to find overlapping regions of climatic suitability for B. dorsalis and F. arisanus to pinpoint suitable release locations. Models for both species performed very well. Temperature seasonality contributed the most to the fly model, followed by precipitation of the wettest quarter, which also had the highest gain for the parasitoid model. The calculated niche overlap between the two species was high. The parasitoid model had less climatic suitability than for B. dorsalis. According to the fly model, parts of the Mediterranean, the Americas, most of Sub-Saharan Africa, northern China, and northern Australia are at risk for invasion. Suitable parasitoid release locations include parts of the Americas, regions of Sub-Saharan Africa, and coastal Queensland. Previously proposed release locations in most of California, Peru, and Argentina were unsuitable.

Interspecific competition between egg parasitoids: Native Fopius caudatus and exotic Fopius arisanus, in Ceratitis cosyra

Tephritidae fruit flies are parasitized by Braconidae wasps, of which some are used in biological control programs. Releases of exotic parasitoids might affect, or be affected by, native species exploiting a common host. We studied interspecific competition between the native African parasitoid Fopius caudatus (Szépligeti) and the exotic Asian parasitoid Fopius arisanus (Sonan) (both Hymenoptera: Braconidae) in African native Ceratitis cosyra Walker (Diptera: Tephritidae). Wasp behaviour on infested fruits and dissection of fruit fly eggs assessed acceptance, oviposition performance and suitability for egg development, parasitism, and effect of parasitism by heterospecific species. While F. arisanus outcompeted F. caudatus in parasitization of relatively younger eggs, chased away F. caudatus, and oviposited more, F. caudatus survived better than F. arisanus. Fopius caudatus parasitized more in 2-day-old C. cosyra eggs than in 1 or 3-day-old egg. More oviposition by F. caudatus was found in fruits previously exposed to F. arisanus, coinciding with presence of more developed host eggs, while such difference was not observed for F. arisanus. Fopius caudatus was an inferior competitor than F. arisanus in C. cosyra-infested African mango Irvingia gabonensis (Irvingiaceae).

Response of egg-pupal parasitoid Fopius arisanus (Sonan) to infochemicals from the host eggs' surface of Bactrocera dorsalis (Hendel)

To determine host-related infochemicals that facilitate contact between the egg-pupal parasitoid, Fopius arisanus (Sonan), and its host, Bactrocera dorsalis (Hendel), we analyzed the volatiles on the surface of B. dorsalis eggs by hydrocarbon profiling of the hexane extracts using Gas Chromatography–Mass Spectrometry (GC–MS). These analyses resulted in the identification of 12 components from the egg surface. Among these 6 were alkanes (Dodecane, Heneicosane, Docosane, Tricosane, Tetracosane and Pentacosane) and the proportion was 42.79%, 1 was a fatty acid (Palmitic acid) and the proportion was 3.88%, 3 were fatty acid derivatives (Dodecanoic acid methylester, Lauric acid ethyl ester and Ethyl tetradecanoate) and the proportion was 45.92%, and 2 were alcohols (Tetradecanol and Hexadecanol) and the proportion was 7.41%. 9 chemicals were chosen from the above 12 components to study the EAG and behavioral responses of male and female F. arisanus. The results showed that the EAG and behavioral responses of F. arisanus to same chemical had similar trends, and both EAG relative values and lure rates of females were higher than males' generally. However, for Dodecane and Tetracosane the EAG relative values and lure rates showed extremely significant differences between males and females respectively, for Tricosane there was significant difference, for Ethyl tetradecanoate there was no significant difference between males and females of the relative EAG values but of the lure rates there was significant difference. The results maybe provide new insights from the chemical relationship between parasitoid and host to biocontrol B. dorsalis using F. arisanus.

Preliminary surveys after release of the fruit fly parasitoidFopius arisanusSonan (Hymenoptera Braconidae) in mango production systems in Casamance (Senegal)

Introduction . Since its arrival in Senegal in 2004, Bactrocera invadens (Diptera Tephritidae) synonymized with Bactrocera dorsalis has caused much economic damage in mango crops. Effective and efficient control activities against B. invadens were necessary in order to continue mango production, and biological control measures were envisaged. In such conditions, the government of Senegal allowed the Asian parasitoid Fopius arisanus to be released in some orchards around Ziguinchor. Materials and methods . The dynamics of fruit fly species was studied with lure traps (methyl eugenol and terpinyl acetate with Dichlorvos). Mango fruit were sampled from the control orchard and orchards with released F. arisanus, to compare the differences in tephritid infestation. Results and discussion . The levels of B. invadens populations were 1.6−2.5 times higher in the control than in orchards where F. arisanus was released. The fruit were also 5–6 times more infested in the control orchard than in those that received F. arisanus . Between May and July 2012 the majority of the pupae (92%) collected from fruit samples developed into adult flies, while only 39% of the pupae transformed to adults between October and December after effective action of the parasitoids. In both orchard treatments, the level of native fruit fly populations was about the same. Wild fruit were infested mostly by Ceratitis cosyra, from which were reared native parasitoids such as Fopius caudatus, F. silvestrii, F. desideratus, Diachasmimorpha fullawayi, D. carinata, Psyttalia cosyrae, and P. concolor. In contrast with Mangifera indica, Citrus spp., Anacardium occidentale, Psidium guayava, Saba senegalensis, and Landolphia heudelotii were mainly infested by B. invadens which showed parasitism by F. arisanus . Pteromalidae and Eulophidae were also found from the pest fly pupae. Killer flies (Diptera: Muscidae) such as Coenosia attenuata Stein, C. atra Meigen and C. tigrina Fabricius emerged from the fruit samples. Conclusion . Sanitation against fruit flies in Casamance should take into account the conservation of natural enemies such as parasitoids and predators for an effective biological control of tephritids.

Genetic analysis of an introduced biological control agent reveals temporal and geographic change, with little evidence of a host mediated shift

The evolution of introduced biological control agents is largely un-explored. Although much is theorized, there is little empirical evidence quantifying the evolutionary dynamics of a biocontrol agent after release into a new environment. In this study we use Diachasmimorpha tryoni, a purposefully introduced biocontrol agent of Ceratitis capitata, to model and quantify spatial, temporal, and host-related evolutionary patterns. This parasitoid has undergone a host shift in its introduced environment, Hawaii, to the gall forming weed biocontrol agent, Eutreta xanthochaeta, an interaction likely mediated by competition for C. capitata with the egg-larval parasitoid Fopius arisanus. To elucidate potential evolutionary patterns we analyzed microsatellites and sequence data extracted from Hawaii and Australian population clusters defined by Structure, in Genepop, Canoco, and IBDWS. Our analysis revealed structuring of Hawaiian D. tryoni populations as defined by significant historic influences related to temporal structure, geographic space, host guild, and augmentative releases. The host-shift parasitoids were not genetically distinct from other Hawaii populations. There were small changes in microsatellite DNA at the population level, but only between Australia and Hawaii populations, not at the host level. These results show that D. tryoni has not undergone host-mediated evolution since introduction to Hawaii, despite the fact that they have expanded their host range in Hawaii to include the gall-forming E. xanthochaeta. To our knowledge this is the first study to quantify genetic differentiation of a biological control agent over geographic space and time using contemporary and museum specimens.

Effect of host Bactrocera dorsalis sex on yield and quality of the parasitoid Fopius arisanus

This study examines the effect of host Bactrocera dorsalis Hendel (Diptera: Tephritidae) sex on performance of the parasitoid Fopius arisanus Sonan (Hymenoptera: Braconidae) to enable use of a genetic sexing strain (GSS) to transfer this parasitoid to regions where B. dorsalis is not established with lower risk of accidental introduction of the host. Sex ratio and yield of F. arisanus did not significantly differ between the two sexes of a GSS, or between GSS and a standard colony strain. F1 parasitoids of individuals that emerged from the standard colony strain, male GSS hosts and female GSS hosts had similar hatching and parasitization rates on colony eggs. Survivorship of F1 parasitoids with parents from female hosts was significantly greater than for those from male hosts. Using GSS to improve the safety of parasitoid shipments is suggested to be viable, but there may be fitness effects of host sex on F1 parasitoid fitness.

Size, shape and hue modulate attraction and landing responses of the braconid parasitoid Fopius arisanus to fruit odour-baited visual targets

Female parasitoids are guided by multisensory information, including chemical and physical cues during host location. In the present study, we investigated the behavioural responses of naive Fopius arisanus (Sonan) females to visual targets baited with guava odour. In non-choice wind tunnel tests, the attraction and landing responses of parasitoids to spheres painted with different colours, and targets of different shapes and sizes were evaluated. Females were more frequently attracted and landed more often on dark yellow targets than on targets with other colours. There was no correlation between the brightness of each colour and the attraction or landing responses. In contrast, both responses were correlated with relative reflectance (hue) of the coloured targets. A positive correlation was observed between attraction and hue, and a negative correlation between landing and hue. F. arisanus was attracted to and landed more often on spheres than on other shape models. The attraction response of this parasitoid was affected by the size of the targets, with spheres of 10 and 12 cm diameter being more attractive than spheres of 8, 6 and 4 cm diameter. The fact that F. arisanus females were able to discriminate among visual targets that differ in colour, shape and size stresses the importance of vision during host location by this species.

A new parasitoid from Kenya, Fopius ceratitivorus, complements the extant parasitoid guild attacking Mediterranean fruit fly in Hawaii

The Mediterranean fruit fly (= medfly), Ceratitis capitata, is one of four tephritid species that are serious impediments to the development of a robust agricultural economy in Hawaii. Despite being the target of biological control programs dating back 100 years, medfly remains a direct pest and a quarantine pest, with high population reservoirs in coffee plantations, and limited parasitism at higher elevations. Fopius ceratitivorus, an egg-attacking parasitoid from Kenya, was introduced into quarantine and analyzed for its potential to complement the existing parasitoid guild attacking medfly in Hawaii. We determined host egg-stage preference, interactions of the new parasitoid with the extant egg-attacking parasitoid Fopius arisanus, and their relative performance under different thermal conditions. Both species prefer younger medfly eggs, but F. ceratitivorus is an inferior intrinsic competitor to F. arisanus on young eggs when both species have simultaneous access to hosts. Overall parasitism rates are higher in two species than in single-species exposures, mainly due to increased parasitization of older eggs. Fopius ceratitivorus has a broader temperature tolerance and a longer lifespan than F. arisanus over the temperature range from 22 to 30 °C. This suggests that establishment of F. ceratitivorus in Hawaii may improve overall suppression of medfly statewide. Broader temperature tolerance and longer lifespan may allow it to colonize cooler areas where F. arisanus is absent; and it is unlikely to interfere with the efficacy of F. arisanus at lower elevations, where the new species is an inferior competitor on young host eggs and does not successfully reproduce on the abundant alternate host Bactrocera dorsalis.

Irradiation of Anastrepha ludens (Diptera: Tephritidae) eggs for the rearing of the fruit fly parasitoids, Fopius arisanus and Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Irradiated eggs of Anastrepha ludens were evaluated as hosts of two fruit-fly parasitoids for mass rearing. Three different ages of A. ludens eggs (24-, 48- and 72-h-old) were analyzed for hatchability after being subjected to radiation doses of 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and 30 Gy. No significant reduction in hatchability occurred with the 72-h-old eggs at any of the radiation dose levels and no adult emergence occurred at radiation doses greater than 25 Gy. Seventy two-h-old eggs irradiated above 25 Gy were found to be the best age and dose for fruit fly egg hosts to be used in mass rearing the egg parasitoid Fopius arisanus. It was demonstrated that larvae hatching from the irradiated A. ludens eggs can also be used as hosts for Diachasmimorpha longicaudata. Parasitoid emergence of both species was not statistically different from the control group (parasitoids emerged from non-irradiated host). The fecundity of parasitoids emerged from irradiated hosts also was similar to that obtained with parasitoids reared with non-irradiated hosts. There were some statistical differences between the curves for longevity. However, these were not clearly correlated with radiation dose. The results of this study will aid in the design of improved methods for mass rearing and release of fruit-fly parasitoids.

Biological attributes of three introduced parasitoids as natural enemies of fruit flies, genus Anastrepha (Diptera: Tephritidae)

AbstractThe biological attributes of three introduced species of parasitoids which attack the fruit fly Anastrepha ludens were evaluated. Larvae and eggs of A. ludens were exposed to larval parasitoids Diachasmimorpha longicaudata and D. tryoni and the egg parasitoid Fopius arisanus. Parasitoid longevity and fecundity were determined using larvae and eggs of A. ludens. Likewise, the parasitism rates of these parasitoid species in infested host fruits were recorded. The intrinsic rate of increase for F. arisanus was 0.1019 followed by D. tryoni with a rate of 0.1641 and D. longicaudata with the highest rate of 0.2233. Although F. arisanus females had the highest levels of fecundity, only 50% of them remained alive until reproductive age. These results in combination with the longer generation time (in comparison with D. longicaudata and D. tryoni), can be considered as the most important factors explaining F. arisanus reduced rate of increase. However, we note that oviposition activity caused egg mortality which reduced Anastrepha egg hatch by ca. 20%. This result suggests that F. arisanus has a high potential as a natural enemy of A. ludens, in accordance with our research efforts to develop a new F. arisanus strain specialized for development in Anastrepha eggs. The results show that D. tryoni is not a good candidate for biological control of Anastrepha. Meanwhile, D. longicaudata continues to be the most important exotic parasitoid for suppression of Anastrepha fruit fly populations.

Evaluation of Fopius arisanus as a biological control agent for the olive fruit fly in California

Abstract1 The egg‐prepupal parasitoid Fopius arisanus (Hymenoptera: Braconidae) was evaluated in quarantine facilities as a potential biological control agent for the olive fruit fly Bactrocera oleae (Diptera: Tephritidae) in California, U.S.A.2 Nontarget testing of two weed biological control agents confirmed that F. arisanus will not attack Tephritidae that feed in inflorescences or galls. It may, however, pose risks to native Tephritidae that feed in fruit.3 Females preferentially oviposited in eggs, although first‐instar B. oleae were also attacked. Low lifetime reproductive potential and high rates of direct mortality inflicted on host eggs indicate that rearing on B. oleae may prove difficult.4 In multiparasitized B. oleae, F. arisanus prevailed in competition against two species of larval–pupal parasitoids, Diachasmimorpha kraussii and Psyttalia concolor (both Hymenoptera: Braconidae).5 The broad host‐range of F. arisanus with respect to fruit‐feeding Tephritidae may preclude its introduction to California, as may its low fecundity and its intrinsic competitive superiority over larva l–pupal parasitoids, which include specialists on B. oleae that are currently being introduced to California. High rates of direct mortality, however, point to potential uses in augmentative biological control. Whether or not F. arisanus is released in California, its biology as a parasitoid of B. oleae has been little studied to date and the results herein may be applied in other regions worldwide where B. oleae is a problem.

Intrinsic inter-specific competition in a guild of tephritid fruit fly parasitoids: Effect of co-evolutionary history on competitive superiority

Tephritid fruit fly parasitoid guilds are dominated by solitary koinobiont species that attack different host stages, but most emerge as adults from host puparia. Previous studies suggest intrinsic competitive superiority by the egg-attacking parasitoid Fopius arisanus (Sonan) against all larval-attacking parasitoids in Hawaii. In this study, we tested the early-acting competitive superiority prediction in relation to the co-evolutionary history of competition between an egg–larval parasitoid ( Fopius ceratitivorus Wharton), and each of three larval parasitoids [ Psyttalia concolor (Szépligeti), Diachasmimorpha kraussii (Fullaway), and Diachasmimorpha longicaudata (Ashmead)]. F. ceratitivorus and P. concolor share a common origin (eastern Africa), while D. kraussii is an Australian species, and D. longicaudata is from Southeast Asia. The outcomes of intrinsic competition between the egg-attacking parasitoid and each of the three larval-attacking parasitoids within their common host, the Mediterranean fruit fly Ceratitis capitata (Wiedemann) were compared. F. ceratitivorus invariably eliminated the co-evolved P. concolor through physiological suppression of the later-attacking parasitoid’s egg development, providing evidence that supports the early-acting-superiority hypothesis. However, F. ceratitivorus was unable to suppress development of the two non co-evolved larval parasitoids. Instead, the larvae of both later-acting parasitoid species physically killed F. ceratitivorus larvae inside the host. The results suggest that co-evolutionary history influences competitive superiority. The evolution of inter-specific competition and its implications for biological control are discussed.

Host Habitat Preference of &lt;I&gt;Fopius arisanus&lt;/I&gt; (Hymenoptera: Braconidae), a Parasitoid of Tephritid Fruit Flies

Abstract The braconid parasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae) is a candidate for augmentative biological control of tephritid fruit flies. In the Puna district of Hawaii Island, F. arisanus parasitized 41–72% of oriental fruit flies, Bactrocera dorsalis (Hendel), in wild common guava, Psidium guajava L.; strawberry guava, Psidium cattleianum Sabine; and tropical almond, Terminalia catappa L. In commercial papaya, Carica papaya L., in the same region, parasitism was only 22% in tree-collected fruit and 3% in ground-collected fruit. The low level of parasitism in papaya suggests that wild parasitoids may not track the host flies well in commercial fruit and that augmentative parasitoid releases could potentially increase parasitism and thus suppress host fly populations in this habitat. The very low parasitism in ground-collected papaya suggests that F. arisanus may avoid foraging on ground fruit. Field cage experiments support this hypothesis. Numbers of females observed on tree fruit ...

The effects of sterile males and two braconid parasitoids, Fopius arisanus (Sonan) and Diachasmimorpha krausii (Fullaway) (Hymenoptera), on caged populations of Mediterranean fruit flies, Ceratitis capitata (Wied.) (Diptera: Tephritidae) at various sites in Guatemala

Area-wide control of the Mediterranean fruit fly (=medfly), Ceratitis capitata (Wiedemann), typically involves sterile insect technique (=SIT), and at present the “Temperature Sensitive Lethal” (=TSL) strain is commonly mass-reared for such releases. In theory, and with some experimental support, the augmentative addition of parasitoids to sterile releases can suppress pest populations to a greater extent than either technique alone. The efficacies of TSL males, parasitoids, and TSL males and parasitoids were compared in large field cages erected over coffee grown at four locations and three altitudes (relatively high, medium and low for the crop) in Guatemala. Two species of opiine braconid parasitoids, the larval–pupal parasitoid Diachasmimorpha krausii (Fullaway) and the egg-pupal parasitoid Fopius arisanus (Sonan), were released either together or in combination with sterile males into cages along with fertile medflies. Results of this evaluation were assessed by comparing the number of pupae and adult insects that completed development (F1 generation) as a result of the reproduction of a parental generation released into each field cage. The TSL males significantly suppressed F1 fly populations but only in one of four study sites. However, the inclusion of F. arisanus and D. krausii always provided significant suppression and the effect was frequently substantial. In one site there was a significant interaction between the capacity of sterile males and parasitoids to suppress caged fly populations. There was no effect of host-fruit abundance on the numbers of flies recovered, however, there were significant interactions between maximum and minimum temperatures and the effects of sterile males and parasitoids, respectively. The results suggest that mass-reared sterile medflies and biological control agents should be tested for both consistent sexual-quality and their ability to perform in the various environments in which they will be released.