Dirhinus Giffardii Research Articles

Partial exploitation of host egg patches resulting from a high rejection rate of healthy hosts cautions the mechanistic use of functional response models

Abstract The functional response of parasitoids is a main component of models that describe host–parasitoid interactions. When the functional response assumed in a model (e.g., a population model) is inaccurate, predictions by the model based on the functional response also become unreliable. This study reports that conventional functional response models may commonly fail to capture the actual functional response of parasitoids and discuss its implications. To assist the discussion, an experiment was conducted to describe interactions between the pupal parasitoid Dirhinus giffardii (Hymenoptera: Chalcididae) and its host Bactrocera dorsalis (Diptera: Tephritidae) in the laboratory. Results showed that the parasitoids typically interacted with all hosts in the environment but parasitised a small fraction of them (e.g., most encountered hosts were rejected), which deviates from the assumption of mechanistic functional response models. An increasing number of published studies on functional response also suggest (although circumstantially) the rejection of unparasitised hosts is common, suggesting that this behaviour is widespread among parasitoid species. By using the experimental results, the study discusses why existing hypotheses are insufficient for the observed behaviour and the implications of this behaviour within the realm of theories surrounding host–parasitoid interactions.

Effects of Host and Parasitoid Ages on Parasitism Efficiency of Dirhinus giffardii (Silvestri)1 against Zeugodacus cucurbitae2

Pesticides threaten the environment and increase amounts of resistance by pests. Ecologically friendly biological control of pests is being considered in scientific and political spheres. Fruit flies cause huge economic losses to more than 81 fruit and vegetable species. They are major pests in tropical and subtropical areas. This study used pupae of melon fly, Zeugodacus cucurbitae (Coquillett), as a host and Dirhinus giffardii (Silvestri) as the parasitoid, the biological control agent. During host-parasitoid interaction at different conditions of exposure, the rate of parasitism of a host by D. giffardii differed significantly in time. Least parasitism was of 1-day-old pupae (13.41 ± 1.10) exposed for 6 hours. Greatest percentage of parasitism was to 3-day-old pupae (43.5 ± 1.12) exposed for 24 hours. Few pupae younger than 3 days old were parasitized. Parasitoid emergence rate from pupae increased from 6 hours (21.49 ± 1.46), to 12 hours (28.30 ± 2.00), and 24 hours (33.93 ± 0.66). Percentage of emergence of 3-day-old pupae was 28.40 ± 0.59 at 6 hours, 29.51 ± 0.45 at 12 hours, and 34.11 ± 0.224 at 24 hours. To maximize in vivo production of parasitoids, 5-day-old female D. giffardii should be provided pupae ≤3 days old. Results contribute to further understanding host-parasitoid interaction important for sustainable and integrated pest management practices throughout the world.

Searching of Underground Host Patches by a Pupal Parasitoid.

When hosts are distributed in discrete patches, ways in which parasitoids search and move between patches affect variability in parasitism risk among hosts and host-parasitoid population dynamics. This study examined the patch searching behavior of the solitary pupal parasitoid Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on its host Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) which pupates underground. In a series of two laboratory experiments, host patches were created by burying pupae in peat moss, and the foraging behavior of the parasitoid was recorded. If D. giffardii can detect underground patches, the parasitoid would preferentially exploit high quality patches where the quality of a patch is represented by the number of unparasitized hosts in the patch. The first experiment investigated the effect of patch size (i.e., number of hosts) and host status (whether hosts are parasitized or unparasitized) on patch searching behavior. Results showed parasitoids were more likely to exploit a large patch than a small patch regardless of host status. The second experiment examined the effect of relative locations of patches by establishing three patches (one large patch and two small patches with unequal inter-patch distances from the large patch). The probability of parasitism was lower for the small patch close to the large patch than the small patch far from the large patch. The parasitism patterns described in the experiments have important implications on the distribution of parasitism risk among hosts and population dynamics.

Potential biological control agents of Zeugodacus cucurbitae (Coquillett): A review

AbstractZeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) is a serious agro‐economic pest of cucurbits around the world. Management of tephritid fruit flies is till date mainly dependent on the use of chemical pesticides. In a rising concern about environment quality and rapid development of resistance in insect pests, biological control of insect pests is being contemplated, and in response, research approaches are constantly evolving. Various naturally occurring control agents of melon fruit fly such as parasitoids, bacteria, fungi and nematodes have potential in the management of Z. cucurbitae. Many parasitoids including Psyttalia fletcheri, Fopius arisanus, Dirhinus giffardii and Spalangia endius are known to attack various life stages of Z. cucurbitae. Although parasitoids are being principally exploited for control of Z. cucurbitae, various other entomopathogens such as fungi (Beauveria bassiana, Paecilomyces fumosoroseus, Metarhizium anisopliae), bacteria (Bacillus thuringiensis), nematodes (Heterorhabditis indica, Steinernema feltiae) and microbial toxins/products (spinosad, avermectin) are being investigated or used for biological control. The development of farming methodologies with greater credence on ecosystem services such as biological control of Z. cucurbitae will increase sustainability of agroecosystems. This review provides a concise compilation of these biological control agents along with their effectiveness and will help researchers in designing various integrated pest management strategies against Z. cucurbitae that involve biological control agents.

Parasitism preference of Chalcid hymenopteran Dirhinus giffardii (Silvestri) confirms higher parasitism against housefly (Musca domestica) (Diptera: Muscidae) pupae.

The housefly, Musca domestica (Diptera: Muscidae), is capable of transmitting many pathogens that cause severe diseases in humans and animals. Mostly the management tactics rely on synthetic chemicals, but these chemicals creates lethal effects on biological ecosystem. For natural and safe options, bio-control strategy is one of the choice. The present study was a part of such effort to use this strategy and validate the biological performance of the potential pupal parasitoid Dirhinus giffardii (Silvestri) against house fly and provide alternative and safe control of filthy flies. This is the first report on parasitism potential and preference of D. giffardii against house fly. The D. giffardii, early reported as an effective pupal parasitoid of tephritid flies, here in the case presented, showed overall 70% reduction in the house fly population by parasitizing pupae. The parasitism efficiency and longevity of hymenopteran parasitoid was remarkably noted two-fold higher and one-fold more female production on house fly pupae as compared to primary hosts (Tephritids). Furthermore, sex ratio of the resultant progeny was also confirmed the dominancy of female by 74% as compared to males. Based on the novel findings we therefore conclude that D. giffardii is the best bio-control agent for controlling house flies.

Digging and burying of hosts by a pupal parasitoid

1. This study describes the host‐handling behaviour of the parasitoid Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae). Dirhinus giffardii sometimes excavates underground hosts, parasitises them, and buries them in the soil. Considering that the parasitoid can parasitise underground hosts without excavating them, we hypothesised that the parasitoid excavates hosts to evaluate the host quality. We also hypothesised that the parasitoid buries them to reduce the risk of superparasitism because superparasitism is common in D. giffardii.2. Pupae of the oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae) were buried in or placed on peat moss as an experimental treatment, and the behavioural responses of the parasitoid towards the hosts were examined. Small and large hosts, and empty puparia were simultaneously presented to a parasitoid.3. The probability of excavation was greater for larger hosts than for smaller hosts or empty puparia. However, while it appeared that parasitoids could evaluate the size of the hosts, they did not preferentially parasitise large hosts in the soil. In addition, unusable empty hosts were readily excavated. Parasitism risk was higher for hosts located on a peat moss surface than for the buried hosts, which is consistent with the hypothesis that the hiding hosts reduces the risk of superparasitism. Alternative hypotheses for the mixed results have been discussed in the paper.

Parasitism potential of Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on pupae of the fruit fly species, Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), during variable exposure durations

BackgroundFruit flies are important insect pests of horticultural crops. Pesticides used to control them which cause environmental and health hazards; therefore, other alternative sustainable management measures are required.Main bodySuccessful implementation of an integrated pest management program, using biological control agents, needs synchronization of parasitoids with hosts selection and exposure time. The present study was conducted to assess the biological activity of the parasitoid species, Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae), against the melon fruit fly, Zeugodacus cucurbitae (Coquillett), and the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), at different exposure durations (24, 48, and 72 h). The experiments were conducted under standard laboratory conditions. Significant differences in the parasitism rate of D. giffardii were observed for both species at different exposure durations. The maximum parasitism rate of D. giffardii (52.60 ± 2.84%) and (42.73 ± 2.74%) was observed at 48-h exposure period for Z. cucurbitae and B. dorsalis, respectively. Also, a comparison between both species showed a difference in parasitism rate at 24 and 48 h and a positive correlation between percent parasitism and exposure duration. Adult emergence of D. giffardii showed a maximum emergence rate from pupae of Z. cucurbitae (63.55 ± 4.02%) and B. dorsalis (51.61 ± 2.33%) at 10 days interval, respectively. However, the daily emergence of the parasitoid was not correlated to exposure duration in both species. The results of the present study may serve in the mass rearing of D. giffardii.ConclusionThe biological activity of D. giffardii was maximum at 48 h of exposure for both fruit fly species, and this important information may improve the mass rearing technology of D. giffardii.

Host selection is not expressed for underground hosts in a pupal parasitoid

AbstractHost–parasitoid dynamics is critically influenced by variability in parasitism risk among hosts, and the host preference of the parasitoid is one of the factors causing such variability. This study examined the host preferences of the pupal parasitoid Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on pupae of the oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) in the laboratory. Dirhinus giffardii prefers large hosts and avoids hosts nearing eclosion when hosts are exposed to the parasitoid. This study reexamined the preferences when host pupae are in the soil (simulated by peat moss) because tephritid hosts, including B. dorsalis, pupate in the soil. Results showed that D. giffardii preferentially parasitized large hosts when hosts were exposed, but host size‐dependent parasitism was absent when hosts were in the soil. Preference on host age was absent even when hosts were exposed, contradicting the results of previous studies. The discrepancy was examined by performing a follow‐up experiment to test the hypothesis that D. giffardii cannot distinguish host age, but eggs that are laid on older hosts cannot develop successfully. The parasitoid successfully hatched regardless of host age, and the hypothesis was rejected. Potential explanations for the discrepancy are discussed.

Exposure Time and age Links Parasitism, Emergence and Development of Pupal Parasitoid Dirhinus giffardii Against Bactrocera zonata

The parasitism, emergence and development of pupal parasitoid, Dirhinus giffardii (Silvestri) was assessed against the pupae of the fruit fly, Bactrocera zonata (Saunders), under laboratory conditions. The fruit fly and D. giffardii were reared in glass cages on the artificial diet, and a known number of different 1-hour (fresh), 1-day, 2-day, 3-day and 4-day old pupae were offered to the respective parasitoids for a period of 6, 12, 18 and 24 hours. It was noted that the parasitism was increased gradually with an increase in pupal age and exposure time. The highest parasitism occurred on 3-day old pupae followed by 4-day, 2-day, 1-day and 1 hour (fresh) old pupae. The studies also manifested that exposure time and host age have a significant effect on the oviposition, per female parasitism, percent parasitism, emergence and development of pupal parasitoid, D. giffardii. The average developmental time of parasitoid was recorded significantly longer in 1-hour (fresh) old pupae than in the older pupae. The study revealed that D. giffardii is a virtuous candidate for the biological control of B. zonata and the pupae of B. zonata might be the perfect host for laboratory rearing of this parasitoid.

Dirhinus giffardii (Hymenoptera, Chalcididae), affecting Black Soldier Fly (Hermetia illucens) (Diptera, Stratiomyidae) production systems in Tanzania, review on its hosts and notes on its worldwide repartition

Dirhinus giffardii (Hymenoptera, Chalcididae), affecting Black Soldier Fly (Hermetia illucens) (Diptera, Stratiomyidae) production systems in Tanzania, review on its hosts and notes on its worldwide repartition

Diversity of parasitoids associated with fruit flies on cultivated and wild plants in southern Togo

Fruit flies (Diptera: Tephritidae) are major constraints on the production and marketing of fruits in African tropical and subtropical countries. In a perspective to manage these fly pests, an inventory of parasitoids associated with fruit flies was carried out from 2009 to 2011 in southern Togo through various fruit incubations. Nine species of native hymenopteran parasitoids associated with eight fly species belonging to five genera Bactrocera, Ceratitis, Dacus, Trirhithrum and Zeugodacus were recovered. Trichopria sp. (Diapriidae) was the most abundant parasitoid. However, the numbers of Braconidae (Diachasmimorpha fullawayi Silvestri, Fopius caudatus Szepligeti and Asobara sp.), Figitidae (Aganaspis sp.), Pteromalidae (Pachycrepoideus vindemmiae Rondani and Spalangia sp.), Eulophidae (Tetrastichus giffardianus Silvestri) and Chalcididae (Dirhinus giffardii Silvestri) species were relatively low. The rate of parasitism of different species of recovered parasitoids ranged from 0.6 to 40%. This is an asset for future surveys in the center and northern regions and studies of interactions between fruit flies and their natural enemies in Togo.

Functional response of the pupal parasitoid, Dirhinus giffardii towards two fruit fly species, Bactrocera zonata and B. cucurbitae

Functional response of the pupal parasitoid, Dirhinus giffardii towards two fruit fly species, Bactrocera zonata and B. cucurbitae

Concurrently burrowing host fly larvae reciprocally enhance pupation depth to minimise parasitism risk

1. Variation in parasitism risk among hosts is a key factor influencing host–parasitoid interactions; however, within‐patch variation (as opposed to between‐patch variation) in parasitism risk has hardly been studied. This study investigated the mechanisms of within‐patch variation in parasitism risk in the oriental fruit fly,Bactrocera dorsalis(Hendel) (Diptera: Tephritidae).2.Bactrocera dorsalispupates underground. Previous studies have shown that pupae at greater depths have a reduced risk of parasitism by a pupal parasitoidDirhinus giffardii(Silvestri) (Hymenoptera: Chalcididae). When a pupa near the ground surface is parasitised, the victim may decrease the risk of parasitism risk for pupae located at deeper depths. It was hypothesised that larvae will pupate at greater depths when they perceive the presence of conspecifics because of the benefit of pupating deeper than other individuals.3. In a series of laboratory experiments, the effects of three factors on pupation depth were examined, including: (i) the density of larvae during development; (ii) the density of concurrently burrowing larvae; and (iii) the presence of pre‐existing pupae in the pupation substrate. Only the density of concurrently burrowing larvae influenced pupation depth, which suggests that when a burrowing larva perceives the presence of other burrowing larvae, it aims to burrow deeper than them.4. This study shows not only that parasitism risk is variable among pupae within a patch, but also that it is density‐dependent. A commonly made assumption (i.e. the absence of within‐patch variability in parasitism risk) needs to be re‐evaluated in a wide range of host–parasitoid systems.

Assessment of the parasitism potential of three parasitoids of fruit fly, Bactrocera spp. (Diptera: Tephritidae) under laboratory conditions

The parasitism potential of a pupal parasitoid, Dirhinus giffardii Silvestri and two larval-pupal parasitoids, Diachasmimorpha longicaudata (Ashmead) and Aganapis daci (Weld) was assessed against Bactrocera spp. under laboratory conditions. Three different types of hosts, viz. Bactrocera zonata (Saunders), Bactrocera dorsalis (Hendel) and Bactrocera cucurbitae (Coquillett) were reared on artificial larval diet and known number of pupae and larvae of each fruit fly species were offered to the respective parasitoids in glass cages in a no choice test. Results on the parasitism potential of D. giffardii towards pupae of different fruit fly species revealed that the highest per female parasitism was recorded on B. zonata (16.72 ±1.67). Adult emergence percentage of D. giffardii did not differ significantly among all the three Bactrocera spp. Sex ratio of the emerged parasitoids revealed maximum percent females (61.64 ± 2.67) from pupae of B. cucurbitae. Similarly per female parasitism by D. longicaudata was also significantly the highest on larvae of B. zonata (26.40 ± 1.79) with maximum adult emergence percentage of 93.41 ± 2.54. Sex ratio of the emerged D. longicaudata did not differ significantly. Parasitism rate of A. daci was significantly the highest on larvae of B. zonata (24.88 ± 2.01) with insignificant differences in the adult emergence percentage. Sex ratio of A. daci showed that percent females from the emerged parasitoids were the highest (54.2 ± 3.44) on B. dorsalis. Relative collective parasitism per female by all the three fruit fly parasitoids revealed that highest parasitism rate (23.7 ± 2.26) was exhibited by D. longicaudata followed by A. daci (22.72 ± 2.14). The study manifested that B. zonata could be the ideal host for laboratory rearing of these parasitoids. Keywords: Bactrocera; Emergence; Fruit fly; Host; Parasitoids; Parasitism; Sex ratio http://dx.doi.org/10.19045/bspab.2019.80099

Density-dependent distribution of parasitism risk among underground hosts.

Variation in parasitism risk among hosts can arise from between-patch and within-patch factors, but considerably less information is known about the latter. This study investigated how distributions of the oriental fruit fly Bactrocera dorsalis influenced its parasitism by the pupal parasitoid Dirhinus giffardii in the laboratory. Because B. dorsalis larvae pupate underground, pupation depth was considered as an important factor that affects the risk of parasitism. When the density of B. dorsalis larvae was varied (1, 10, and 100 larvae per arena), average pupation depth increased with the density. When the depth of pupae was manipulated, the rate of parasitism differed by depths. Parasitism at 0 cm differed from the random parasitoid model expectation, but parasitism at 1 cm was not different from the model expectation. Few pupae at 2 cm were parasitized. In another experiment, when pupae were simultaneously presented at 0 cm and 1 cm depths, parasitism at 1 cm was weakened by the presence of puape at 0 cm. These results imply that the density of the host influences pupation depth as well as the distribution of parasitism and plays an important role in host-parasitoid dynamics.

Host-age effects and the efficiency of the pupal parasitoid Dirhinus giffardii (Silvestri, 1913) (Hymenoptera: Chalcididae) against the melon fly Bactrocera cucurbitae (Coquillett, 1849) (Diptera: Tephritidae)

Abstract Dirhinus giffardii is an efficient and aggressive pupal parasitoid of tephritid flies, including Bactrocera cucurbitae. Here we report on the various biological aspects of Dirhinus giffardii, mainly host-age preference, potential as well as the survival of this parasitoid from the pupae of different ages and its in vivo release against Bactrocera cucurbitae. The emergence rate of parasitoids was higher in old pupae than in fresh pupae. Similarly, the lifespan and potential of parasitoids emerged from older pupae were higher than those emerged from younger ones. The parasitoids reared on older pupae significantly controlled melon fly infestation in vivo. These findings suggest that parasitoids reared on older pupae of B. cucurbitae have a greater potential regarding fecundity, parasitism performance and survival, as these parasitoids effectively suppressed populations of B. cucurbitae under greenhouse conditions.

Parasitoid aggregation and interference in host-parasitoid dynamics

1. Parasitoids do not distribute themselves evenly among available patches, which has an important bearing on the dynamics of host–parasitoid interactions. This study examined the density-dependent nature of aggregation of the parasitoid Dirhinus giffardii Silvestri on the oriental fruit fly host, Bactrocera dorsalis (Hendel) distributed among discrete patches. 2. Four artificial patches were created in a cage, and the number of hosts in each patch was manipulated. Parasitoids were released into the cage, and whether parasitoid density and host density influence the degree of parasitoid aggregation was examined. 3. Parasitoid aggregation became stronger (e.g. uneven distribution among patches) as the parasitoid density decreased and also as the host density increased. The index of parasitoid aggregation was not influenced by the distribution of hosts among patches. 4. The empirically characterised aggregation pattern was incorporated in a host–parasitoid model that consists of one host and one parasitoid species. The analysis of the model shows that an unstable system (i.e. the coexistence of the host and parasitoid is impossible) can be stabilised (i.e. coexistence is possible) when the parasitoid aggregates in a way that is consistent with the pattern found in the experiment.

Searching Ability of Pupal Parasitoid, Dirhinus giffardii (Silvestri) on Bactrocera zonata (Saunders) at Various Depths of Plant Debris

The present study was carried out to determine the searching ability of pupal parasitoid, Dirhinus giffardii of Bactrocera zonata in the Bio Control Research Laboratory, | department of Entomology, SAU, Tandojam, at temperature 27 ± 1ºC and 60 ± 5% relative humidity. Adults of fruit fly were fed with water, sugar and needo milk powder, whereas, Dirhinus giffardii were fed with honey and water solution. Ten days old D. giffardies were used against 20 pupae of Bactrocera zonata in the experiment and data recorded on parasitized pupae and un-parasitized pupae after 24, 48, 72 and 96 hours. The results in all treatments indicates that highest parasitized pupae were at peak level of (16.66) after 72 hours age of pupae on the depth of 0 cm in plant debris followed by 4 cm depth (16.33), whereas lowest parasitized pupae were recorded at 5cm depth (13.66) after 72 hours of age inside plant debris. Likewise, the highest un-parasitized pupae were at peak level of (14.00) after 24 hours of age of pupae on the depth of 3cm in plant debris followed by 1cm depth (13.00), whereas lowest un parasitized pupae were recorded at 4cm depth (11.66) after 24 hours of age inside plant debris. The analysis of variance indicated that there wasno significant difference among the parasitized and unparasitized pupae of flies in the different depths of plant debris and age intervals (P

Dirhinus giffardii (Hymenoptera: Chalcididae), parasitoid affecting Black Soldier Fly production systems in West Africa

Interest for insect farming is currently growing globally. Conditions in West Africa appear suitable for developing such farming systems that can benefit communities by improving livelihoods, food and feed security or sanitation. In Ghana and Mali, the Black Soldier Fly (Hermetia illucens Linnaeus, 1758) is being produced for waste recycling and animal feed. In a two stages process (egg and larvae production), egg production was hampered by a pupal parasitoid, Dirhinus giffardii Silvestri, 1913 (Hymenoptera: Chalcididae), which reduced future broodstock by almost 72%. This is the first time D. giffardii is reported as a parasitoid of H. illucens pupae and one of the first reports of parasitism in this commercially important fly species. The introduction of precautionary measures is highly recommended for the success of H. illucens production systems in West Africa.

Diversity and Abundance of House Fly Pupal Parasitoids in Israel, with First Records of Two Spalangia Species.

Filth flies (Diptera: Muscidae), particularly the house fly, Musca domestica L., are global pests of livestock production. In this study, we characterized the fauna of house fly pupal parasitoids in Israel and identified factors affecting their diversity and abundance. The study, which included one round of sampling during the fall of 2013 and another round of sampling in the spring of 2014, encompassed 26 locations of common fly-breeding habitats: dairy, egg-laying, and goat farms throughout Israel. Nine parasitoid species were found: Spalangia cameroni Perkins, Spalangia endius Walker, Spalangia drosophilae Ashmead, Spalangia gemina Boucek, Spalangia nigroaenea Curtis, Pachycrepoideus vindemmiae Rondani, Muscidifurax raptor Girault and Sanders, Muscidifurax zaraptor Kogan & Legner (all Hymenoptera: Pteromalidae), and Dirhinus giffardii Silvestri (Hymenoptera: Chalcididae). This is the first record of S. gemina from the Palearctic, as well as the first record of S. drosophilae from the Middle East. The composition and relative abundance of parasitoid species varied markedly among localities, climatic regions (Mediterranean vs. desert), habitat types (dairy vs. egg-laying vs. goat farm), and seasons. Overall, parasitoid richness in egg-laying farms was two- and sevenfold higher than in dairy and goat farms, respectively, and three times higher in Mediterranean than desert climate. The significance and implications of our results for inundative biological control programs of filth flies are discussed.