Effect of plant oils on quality parameters of Bactrocera tryoni (Froggatt) reared on liquid larval diet

Liquid larval diets have been developed for several tephritid fruit flies including Queensland fruit fly, Bactrocera tryoni (Frogatt) (Q‐fly). In liquid diets, wheat germ oil (WGO) is usually added to improve performance in some quality parameters of reared flies, especially flight ability. However, for some flies, other plant oils may be more readily available, cheaper or produce flies of superior performance. In the present study, four alternative types of plant oils – rice bran, canola, vegetable, and sesame – were incorporated into a fruit fly liquid larval diet to replace the currently used wheat germ oil and their efficacy on the quality parameters of reared Q‐fly was compared to diets containing wheat germ oil or no oil. The quality parameters included: total pupal yield (N), pupal recovery (%), larval duration (days), pupal weight (mg), adult emergence (%), adult fliers (%), rate of fliers (%), sex ratio (%), F₁ egg/female/day and egg hatching (%). There were significant differences among treatments in performance of Q‐fly. Vegetable oil appeared better in terms of total pupal yield, percentage of pupal recovery, percentage of adult emergence, percentage of fliers, mean egg/female/day and % F₁ egg hatch compared with other oil treatments, especially from that of WGO treated diet. The result suggests that WGO can be substituted with rice bran and vegetable oil to improve the liquid larval diet for rearing of B. tryoni, with vegetable oil being the best replacement.     

Laboratory evaluation of the chemosterilant lufenuron against the fruit flies Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons

Four species of tephritid fruit flies, Ceratitis capitata, Bactrocera dorsalis, B. cucurbitae, and B. latifrons were evaluated for toxic, developmental, and physiological responses to the chemosterilant lufenuron. No significant mortality of laboratory strains of the first three species was observed after their exposure up to 50 μg/mL of lufenuron in agar adult diet, whereas B. latifrons adults fed with 50 μg/mL of lufenuron in the diet caused significant mortality compared to the control. Fertility of C. capitata adults fed on 50 μg/mL lufenuron-fortified diet between 7 and 12 days of age was approximately 46% of the no lufenuron control. Fertility of B. dorsalis and B. latifrons adults fed on 50 μg/mL lufenuron-incorporated diet was about 45% and 62% of the control, respectively. Lufenuron did not significantly affect fertility of B. cucurbitae adults. Lufenuron did not affect fecundity of C. capitata and B. dorsalis. Fecundity of B. cucurbitae and B. latifrons was not evaluated due to difficulty to count the eggs laid deep in the agar diet. Larvae fed on a liquid larval diet with ≤ 0.1 μg/mL of lufenuron were also evaluated. Pupal recovery, adult emergence, adult fliers, mating, egg hatch, and egg production of C. capitata were significantly decreased, while for B. dorsalis, pupal recovery, larval duration and adult emergence were affected. No effect of lufenuron on B. cucurbitae larvae was observed. B. latifrons was not performed because shortage of eggs at the time of this research. Lufenuron is a potential agent for management and control of C. capitata and B. dorsalis.     

Host status of ‘Scifresh’ apples to the invasive fruit fly species Bactrocera dorsalis,Zeugodacus cucurbitae,and Ceratitis capitata (Diptera: Tephritidae)

We conducted no-choice cage and field infestation studies to determine if the fruit of apples (Malus x domestica L., ‘Scifresh’) are hosts for three invasive tephritid fruit fly species that may enter New Zealand or other apple growing areas. In screen cage tests, punctured and unpunctured (intact) fruit of ‘Scifresh’ apples were exposed to gravid females of Bactrocera dorsalis (Hendel) (Oriental fruit fly), Zeugodacus (Bactrocera) cucurbitae (Coquillet) (melon fly), or Ceratitis capitata (Wiedemann) (Mediterranean fruit fly), outdoors for 24 h and then held on sand in the laboratory for four weeks for pupal development and adult emergence. Unpunctured fruit produced an average of 269.4, 4.3 and 70.1 puparia per kg of fruit for B. dorsalis, Z. cucurbitae and C. capitata, respectively. Punctured fruit produced an average of 619.4, 0.8 and 129.5 puparia per kg of fruit for B. dorsalis, Z. cucurbitae and C. capitata, respectively. By comparison, unpunctured and punctured papaya fruit (Carica papaya, ‘Rainbow’, a preferred host) produced 206–675 and 464–735 puparia per kg of fruit, respectively, across all species. In general, the average weight of individual fruit fly puparia from apple was significantly less (41–71%) than that of puparia reared from papaya, and development times were slower on apple than on papaya. Overall, ‘Scifresh’ apples were a moderately good host for B. dorsalis and C. capitata, and a very poor host for Z. cucurbitae in cage tests. Field exposure of ‘Scifresh’ apples suspended from papaya trees resulted in no infestation by B. dorsalis or Z. cucurbitae under natural conditions. This information will help to inform decisions about quarantine restrictions and potential crop loss in the event of incursions of these fruit flies into apple-producing countries.     

Fruit fly liquid larval diet technology transfer and update

Since October 2006, the US Department of Agriculture–Agricultural Research Service (USDA–ARS) has been implementing a fruit fly liquid larval diet technology transfer, which has proceeded according to the following steps: (1) recruitment of interested groups through request; (2) establishment of the Material Transfer Agreement with agricultural research service; (3) fruit fly liquid larval diet starter kit sent to the requestor for preliminary evaluation; (4) problem‐solving through email or onsite demonstration; (5) assessment on feedback from the participants to decide whether to continue the project. Up to date, the project has involved 35 participants from 29 countries and 26 species of fruit flies. Fourteen participants have concluded their evaluation of the process, and 11 of these 14, have deemed it to be successful. One participant has decided to implement the project on a larger scale. The 14 participants were, Argentina (Ceratitis capitata and Anastrepha fraterculus), Bangladesh (Bactrocera cucurbitae, C. capitata, and Bactrocera dorsalis), China (Fujia province) (B. dorsalis), Italy (C. capitata), Fiji (Bactrocera passiflorae), Kenya (Bactrocera invadens, Ceratitis cosyra), Mauritius (Bactrocera zonata and B. cucurbitae), Mexico (Anastrepha species), Philippines (Bactrocera philippinese), Thailand (Bactrocera correcta), Austria (C. capitata, Vienna 8 and A. fraterculus), Israel (Dacus ciliatus and C. capitata), South Africa (C. capitata, Vienna 8) and Australia (C. capitata). The Stellenbosch medfly mass‐rearing facility in South Africa and the CDFA in Hawaii were two mass‐scale rearing facilities that allowed us to demonstrate onsite rearing in a larger scale. Demonstrations were performed in CDFA in 2007, and in Stellenbosch, South Africa in 2008; both were found to be successful. The Stellenbosch medfly mass‐rearing facility in South Africa decided to adopt the technology and is currently evaluating the quality control of the flies that were reared as larvae on a liquid diet.     

Effects of fruit fly host, fruit species, and host egg to female parasitoid ratio on the laboratory rearing of Biosteres arisanus

The host suitability of the oriental fruit fly, Bactrocera dorsalis (Hendel), for development of Biosteres arisanus (Sonan), a braconid parasitoid, was compared with three other fruit fly species, namely, Mediterranean fruit fly, Ceratitis capitata Weidemann, melon fly, Bactrocera cucurbitae Coquilett, and Malaysian fruit fly, Bactrocera latifrons (Hendel). In addition, effects of five different fruit species, namely, Carica papaya L. (solo papaya), Musa sapientum (L.) O. Ktze. (apple banana), Mangifera indica (L.) (Haden mango), Terminalia catappa (L.) (false kamani), and Citrus aurantiifolia (Christman) Swingle (common lime), on the parasitization rate of B. dorsalis and sex ratio of parasitoid progenies were evaluated. Effects of host egg to female B. arisanus ratios on parasitoid progeny yields were likewise determined. The host suitability of fruit flies for development of B. arisanus was ranked as: B. dorsalis>C. capitata=B. latifrons=B. cucurbitae. Based on percent parasitization of B. dorsalis, preference of B. arisanus females for host eggs varied with fruit species, however, preferential oviposition displayed by female parasitoids did not influence sex ratios of subsequent parasitoid progenies. Increases in host egg to female parasitoid ratios of 5:1, 10:1, 20:1, 25:1, and 30:1 corresponded with increases in parasitoid progeny yield reaching a plateau at 20:1.     

Fruit fly (Diptera: Tephritidae) diversity in cucurbit fields and surrounding forest areas of Himachal Pradesh,a north-western Himalayan state of India

During the course of studies, Bactrocera (Bactrocera) latifrons (Hendel), B. (B.) nigrofemoralis White and Tsuruta, Dacus (Callantra) longicornis Wiedemann, Dacus (Callantra) sphaeroidalis (Bezzi), Cyrtostola limbata (Hendel) and Pliomelaena udhampurensis Agarwal and Kapoor were recorded for the first time in Himachal Pradesh in a cucurbit ecosystem. Apart from these, other species viz. Bactrocera tau, Bactrocera cucurbitae, Bactrocera dorsalis, Bactrocera zonata, Bactrocera scutellaris, Bactrocera diversa and Dioxyna sororcula (Wiedemann) were also identified. Distribution records of B. (B.) dorsalis (Hendel), B. (B.) zonata (Saunders), Bactrocera (Hemigymnodacus) diversa (Coquillett), B. (Zeugodacus) cucurbitae (Coquillett), B. (Z.) scutellaris (Bezzi) and B. (Z.) tau (Walker) has been described.     

Toxicity of gallic acid to melon fruit fly,Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae)

Melon fruit fly, Bactrocera cucurbitae (Coquillett) is an important pest of cucurbits and other vegetable crops. It is not only a serious pest of cucurbit crops but sometimes also attacks non-host plants. In an endeavour to explore secondary metabolites as important and safe means of pest management, we investigated the effects of gallic acid, a phenolic compound, on the growth and development of melon fruit fly, B. cucurbitae. Larval survival and emergence were severely affected by gallic acid treatment. Both decreased in a concentration dependent manner with increase in concentration. Gallic acid-treated larvae took longer duration to pupate and reach the adult stage as compared to control larvae. Inhibitory effects of gallic acid were also observed on larval weight, pupal weight, mean relative growth rate and food assimilated which decreased with treatment. The ability of gallic acid to disrupt the development of B. cucurbitae suggests that the phenolic compound might have caused oxidative stress in the body of the insect.     

Synergistic and additive interactions among components of food-based baits underlie female fruit fly attraction

Attraction of tephritid fruit flies to some food sources can be enhanced by the presence of ammonia derivatives, compounds that are perceived as volatile cues for protein-rich food sources. Using a comparative approach, we (1) evaluated the behavioral responses of females of three invasive fruit fly species, Bactrocera (Zeugodacus) cucurbitae (Coquillett), Bactrocera dorsalis (Hendel), and Ceratitis capitata (Wiedemann) (all Diptera: Tephritidae) to trub (a protein-rich waste brewer’s yeast product generated during the production of beer), Concord grape juice (a protein-deficient material), and ammonium acetate, and (2) identified synergistic and additive interactions between low- and high-attractiveness materials and ammonium acetate. We established the attractiveness of fresh trub, grape juice, and ammonium acetate when tested singly to females of all three fly species. Although ammonium acetate did not enhance significantly the response of females of any species to fresh trub, the most attractive material, ammonium acetate, did significantly enhance females’ level of response to aged trub (a comparatively less attractive material) and to grape juice. Our research found a synergistic interaction between diluted grape juice and ammonium acetate for B. cucurbitae, as well as between aged trub and ammonium acetate for B. dorsalis. For C. capitata, additive effects among food attractants and ammonium acetate were identified. Our findings increase our understanding of fruit fly female olfactory-driven behavior in response to food-based materials and the extent to which ammonium acetate modulates female response to protein-rich and protein-deficient materials.     

蝇蛹俑小蜂对橘小实蝇和瓜实蝇的偏好性

【背景】蝇蛹俑小蜂是实蝇类害虫蛹期的一种重要寄生蜂,对压制下一代实蝇类害虫的种群数量具有重要作用,但有关其对不同实蝇害虫的寄生特性尚缺乏研究。【方法】采用"H"型装置和培养皿测定方法,研究了蝇蛹俑小蜂的寄主选择偏好性。【结果】蝇蛹俑小蜂在橘小实蝇蛹和瓜实蝇蛹共存的情况下,偏好在橘小实蝇蛹上停留,且寄生率较高,最高寄生率达61.11%。【结论与意义】本研究为合理利用蝇蛹俑小蜂控制实蝇类害虫提供了理论基础。     

Comparative rearing parameters for bisexual and genetic sexing strains of Zeugodacus cucurbitae and Bactrocera dorsalis (Diptera: Tephritidae) on an artificial diet

The Sterile Insect Technique (SIT) is an important component of area wide programs to control invading or established populations of pestiferous tephritids. The SIT involves the production, sterilization, and release of large numbers of the target species, with the goal of obtaining sterile male x wild female matings, which yield infertile eggs. A major advance in SIT involved sex-linked, genetic manipulations that allowed the production and release of male-only strains (also termed genetic sexing strains, GSS). The use of GSS avoids matings between sterile males and females, which may divert males from seeking and mating with wild females, and studies show that male-only releases result in greater suppression of wild populations than standard bisexual releases (i.e., those including both males and females). GSS based on sex-linked pupal color exist for Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel), two important agricultural pest species, but their rearing characteristics have not been documented in detail. The goal of the present study was to compare the pupal color sexing and bisexual strains for each of these species with respect to important rearing parameters, including egg production and eclosion of larvae from eggs (egg hatch), pupal recovery, and weight, emergence rate, and flight ability. In both species, most of these parameters were significantly greater for the bisexual strain than the GSS, and, for a given number of eggs, the production of flight-capable adults was approximately 2 times greater in the bisexual strains of both species. The potential usefulness of GSS in SIT against Z. cucurbitae and B. dorsalis is assessed based on these findings.     

MicroRNA Let‐7 targets the ecdysone signaling pathway E75 gene to control larval–pupal development in Bactrocera dorsalis

MicroRNAs (miRNAs) regulate various biological processes during insect developme nt;however, their role in larval-pupal development in oriental fruit fly, Bactrocera dorsalis (Hendel) remains unknown. In the current study, we address the biological function of a conserved miRNA, Bdo-Let-7 in the regulation of BdE75 gene, which belongs to the ecdysone signaling pathway and participates in the larval-pupal development in B. dorsalis. Using dual luciferase reporter assay in HEK293T cells we show that Bdo-Let-7 miRNA interacts with the 3' untranslated region of BdE75 gene and suppresses its expression. The Bdo-Let?7 and BdE75 are also co-expressed in the larval-pupal stages and in different tissues of B. dorsalis .In in vivo experiments, the injectio n of Bdo-Let-7 agomir and antagomir in third instar larvae down- and up-regulated the expression of BdE75、 respectively. The 20-hydroxyecdysone (20E) injection assay shows that 20E up-regulated the expression of Bdo-Let-7 on the 5th day of the larvae. Moreover, abnormal pupation and eclosion were observed after larval Bdo-Let-7 antagomir injection. Based on these results, we show that Bdo-Let-7 regulates the ecdysone signaling pathway through the exact dose of BdE75 gene, and is indispensable for normal larval-pupal development in B. dorsalis.     

Dietary wheat germ oil and age influences fatty acid compositions in adult oriental fruit flies

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is a serious pest of fruit crops in Asia, several Pacific Islands and sometimes the western United States, particularly California. Sterile insect technique programs have been developed for management of several tephritid fruit fly pests. These programs are based on continuous production of adult fruit flies. The high expense of mass-rearing oriental fruit flies drives research to improve the cost effectiveness of rearing programs. One recent improvement for mass rearing oriental fruit flies involves adding wheat germ oil (WGO) to the larval culture medium, which improved several parameters of biological performance. The performance enhancing influence of WGO is due to the presence of polyunsaturated fatty acids (PUFAs), some of which are nutritionally essential for many insect species. We considered the issue of whether WGO supplementation of the larval culture medium influences the fatty acid make up of adult tissues. We report that WGO supplementation led to substantial increases in adult tissue C18 PUFAs. Unlike the outcomes of unrelated nutritional studies on moths, the PUFA components of WGO did not improve adult fruit fly performance. Taken with recent publications reporting that WGO in larval diets influences gene expression, we conclude that dietary WGO improves biological performance of adults through changes in tissue C18 PUFAs and gene expression.     

Host species and vegetable fruit suitability and preference by the parasitoid wasp Fopius arisanus

Parasitoids that oviposit in a concealed host inside a plant part need to be able to find both the plant and the host. Egg parasitoids of fruit‐infesting Tephritidae need to assess the oviposition site based both on the host egg and the infested fruit. Infestation by Tephritidae fruit flies threatens fruit and vegetable production. Management methods have been implemented including biological control, using Fopius arisanus Sonan (Hymenoptera: Braconidae). The parasitism by F. arisanus in three Tephritidae flies in vegetable fruits was investigated. Laboratory assays were conducted to assess the parasitoid's preference and survival. Zucchini, sweet pepper, and tomato were artificially infested with eggs of Bactrocera dorsalis Hendel, Ceratitis capitata Wiedemann, and Ceratitis cosyra Walker (all Diptera: Tephritidae), then exposed to mated naïve F. arisanus females in a 20:1 egg:parasitoid ratio. Parasitoid behavioral activities (resting, antennating, probing, ovipositing) were observed on the infested fruits. Parasitism rate was determined by dissection of fruit fly eggs under a stereomicroscope. Behavioral activities of F. arisanus differed between all the fruits when infested with B. dorsalis or C. cosyra eggs but differed only between some of the fruits when infested with C. capitata. Fopius arisanus preferred B. dorsalis over C. capitata and C. cosyra, with a parasitism rate 2× higher on B. dorsalis compared to the Ceratitis species. Preference for fruits was dependent on the infesting fruit fly. The emergence of F. arisanus was higher with B. dorsalis than with Ceratitis spp. Although B. dorsalis completed its development earlier than Ceratitis spp., host fly species did not affect the developmental time of F. arisanus. We discuss the significance of F. arisanus preference in relation to naturally occurring Tephritidae infestations. We also discuss whether some fruits might constitute a refuge for Tephritidae flies and whether this will affect the current biological control efforts against B. dorsalis.     

橘小实蝇与番石榴实蝇卵及蛹的种间竞争

【背景】实蝇的竞争可能发生在生活史的各个阶段,但未见卵和蛹的种间竞争的相关报道。【方法】将橘小实蝇与番石榴实蝇的卵及蛹按照相应的比例或龄期分别进行混合培养,分析2种实蝇的卵或蛹混合后的发育历期和存活率是否受到彼此影响。【结果】橘小实蝇与番石榴实蝇的卵同龄等量混合,对彼此卵的历期和孵化率无影响。当橘小实蝇和番石榴实蝇的蛹为新鲜蛹时,分别与比它们蛹龄大1 d的对方蛹混合,蛹的羽化率分别为(87.67±3.61)%和(84.33±2.56)%,显著小于对照,说明在此混合蛹处理中,后化蛹者的发育可能受到先化蛹者的抑制。【结论与意义】总体上,在卵和蛹期,橘小实蝇与番石榴实蝇未产生竞争作用;但不排除蛹期竞争的可能性,这种竞争可能存在于特定的蛹期。     

Cytoplasmic glutamine synthetase gene expression regulates larval development in Bactrocera dorsalis (Hendel)

In insects, glutamine synthetase (GS), a key enzyme in the synthesis of glutamine, has been reported to be associated with embryonic development, heat shock response, and fecundity regulation. However, little is known about the influence of GS on postembryonic development. In this study, we demonstrate that blocking the activity of GS in the oriental fruit fly (Bactrocera dorsalis) with use of a GS‐specific inhibitor (L‐methionine S‐sulfoximine), led to a significant delay in larval development, pupal weight loss, and inhibition of pupation. We further identify cloned and characterized two GS genes (BdGS‐c and BdGS‐m) from B. dorsalis. The two GS genes identified in B. dorsalis were predicted to be located in the cytosol (BdGS‐c) and mitochondria (BdGS‐m), and homology analysis indicated that both genes were similar to homologs from other Dipterans, such as Drosophila melanogaster and Aedes aegypti. BdGS‐c was highly expressed in the larval stages, suggesting that cytosolic GS plays a predominant role in larval development. Furthermore, RNA interference experiments against BdGS‐c, to specifically decrease the expression of cytosolic GS, resulted in delay in larval development as well as pupal weight loss. This study presents the prominent role played by BdGS‐c in regulating larval development and suggests that the observed effect could have been modulated through ecdysteroid synthesis, agreeing with the reduced expression of the halloween gene spook. Also, the direct effects of BdGS‐c silencing on B. dorsalis, such as larval lethality, delayed pupation, and late emergence, can be further exploited as novel insecticide target in the context of pest management.     

Wheat germ oil in larval diet influences gene expression in adult oriental fruit fly

Culture medium supplemented with wheat germ oil (WGO) causes physiological reactions, such as increased fecundity and mobility, in some insects. Although the impact of WGO on insect physiology is important, the mechanisms of these actions are poorly understood. In this paper, we test the hypothesis that the addition of WGO to medium developed for larval oriental fruit flies modulates gene expression in the corresponding adults. We separately reared larvae of Bactrocera dorsalis on diets lacking or supplemented with WGO, and analyzed for expressed proteins in the resulting adult males and females by 2D-electrophoresis. Analysis of the gels revealed significant changes in expression levels of >70 proteins, 64 of which were identified by mass spectrometric analysis on MALDI-TOF/TOF. Apparent changes in expression levels for 6 of these proteins were confirmed by quantitative real-time PCR, showing that the changes in mRNA expression were reflected in changes in protein expression. These findings support the hypothesis that one mechanism of WGO actions in insect nutrition is the modulation of gene expression.     

Attraction of wild‐like and colony‐reared Bactrocera cucurbitae (Diptera:Tephritidae) to cuelure in the field

The attraction of wild tephritids to semiochemical‐based lures is the ideal basis for trap network design in detection programmes, but in practice, mass‐reared colony insects are usually used to determine trap efficiency. For Bactrocera cucurbitae Coquillett, a lower response by wild males compared with colony‐derived individuals, usually used to estimate attraction parameters, could mean that the sensitivity of detection networks targeting this pest is reduced. We describe the results of mark–release–recapture experiments with wild‐ and colony‐derived B. cucurbitae males in a grid of cuelure‐baited traps within a macadamia nut orchard in Hawaii Island designed to quantify the attraction of cuelure to each fly type. For colony males, we estimate a 65% probability of capture at 27 m, intermediate with previous estimates on the attraction of methyl eugenol to Bactrocera dorsalis Hendel (36 m) and trimedlure to Ceratitis capitata Wiedemann (14 m) at the same site. Results suggest similar response over distance by wild‐derived B. cucurbitae compared with colony in the field, but there may be qualitative differences in response between wild and colony based on very low response of wild males in a standard bioassay of attraction. For both fly types, the estimates of attraction in the smaller of two grid sizes tested were lower than for the larger spacing, suggesting trap competition was a factor at an intertrap distance of 75 m. Dispersal patterns within the grid were generally to the south for the colony‐derived males and more variable for the wild‐derived males. In neither case was the direction of recapture correlated with the prevailing direction of the wind.     

Host specificity of the egg pupal parasitoid Fopius arisanus (Hymenoptera: Braconidae) in La Reunion

Fopius arisanus is a polyphagous parasitoid of Tephritidae, which has been recently introduced to La Réunion Island as part of a classical biological control programme. We carried out laboratory experiments to assess the host specificity of this parasitoid, initially reared on Bactrocera zonata, and then offered for parasitization the eight local tephritid pest species. Naive or experienced parasitoid females were given tephritid eggs in no choice tests. Fopius arisanus females parasitize all fly species but parasitism varies with host species. No adult wasps emerge from Bactrocera cucurbitae and the survival of this species is only slightly affected by parasitism. Dissections show that the late instars of this fly may eliminate the parasitoid by encapsulation. When developing on Ceratitis capitata, Ceratitis rosa, Dacus ciliatus, Dacus demmerezi, and Neoceratitis cyanescens, parasitoid survival rate ranges from 10 to 25%. Bactrocera zonata and Ceratitis catoirii are the best hosts, yielding parasitoid survival rates of more than 70% with no premature mortality. The egg-larval mortality of C. capitata, C. rosa, D. ciliatus, and N. cyanescens, and the pupal mortality of D. demmerezi, are significantly increased by parasitism. The size of emerging adults is affected by host species and is correlated to pupal weight. Bactrocera zonata would be a favorable host to support routine colonization of F. arisanus for mass production of this parasitoid.     

Acceptability and suitability of six fruit fly species (Diptera: Tephritidae) for Kenyan strains of Psyttalia concolor (Hymenoptera: Braconidae)

Host acceptability and suitability Psyttalia concolor (Szépligeti) is a koinobiont, larval parasitoid of tephritid fruit flies. Individuals of P. concolor were field-collected from coffee in the central highlands of Kenya, and cultured initially on Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann). They were then examined for their ability to oviposit in and develop on five other tephritid species that are pests in Kenya. In addition to the medfly, acceptability for oviposition and suitability for development were tested against the mango fruit fly, Ceratitis cosyra (Walker), the Natal fruit fly, Ceratitis rosa Karsch, Ceratitis fasciventris (Bezzi), Ceratitis anonae Graham and the melon fruit fly, Bactrocera cucurbitae (Coquillett). Ceratitis capitata and C. cosyra were accepted as hosts significantly more often than the other species. Superparasitism was recorded only from C. capitata and C. cosyra. Two days after oviposition, parasitoid eggs in C. fasciventris and B. cucurbitae were encapsulated, whereas those in C. rosa and C. anonae were encapsulated, and often melanized. Ceratitis capitata was the most suitable host for Kenyan populations of Psyttalia concolor in terms of progeny production, and proportion of female progeny.