Superparasitism in mass reared Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), a parasitoid of fruit flies (Diptera: Tephritidae)

Superparasitism frequency and its effects on the quality of mass-reared Diachasmimorpha longicaudata (Ashmead) parasitoids were investigated under laboratory conditions. Percentage of adult emergence, sex ratio, survival, fecundity and flight ability of adult parasitoids that emerged from Anastrepha ludens (Loew) pupae with different levels of superparasitism were determined. A high prevalence of superparasitism was observed. The number of scars per pupa, produced by insertion of the parasitoid ovipositor, ranged from 1 to 30, with an average (±SD) of 8.3 ± 6.2. Adult parasitoid emergence decreased as the level of superparasitism increased. However, the fraction of females rose with increasing superparasitism and the flight ability was lower in adults emerging from pupae with only one scar, compared with adults emerging from superparasitized hosts. Female longevity and fecundity were not affected by superparasitism. Our results support the hypothesis that superparasitism in D. longicaudata might be adaptive, since adults emerging from hosts with moderate levels of superparasitism showed the highest percentage of emergence and there were no significant differences in the other quality control parameters tested. Our findings are relevant to the mass rearing process, where the ratio of hosts to parasitoids can be optimized as well as the distribution of eggs deposited in host larvae. This contributes to efficient mass rearing methods for augmentative biological control programs.     

Olfactory response of three parasitoid species (Hymenoptera: Braconidae) to volatiles of guavas infested or not with fruit fly larvae (Diptera: Tephritidae)

The olfactory responses of the native parasitoids Doryctobracon areolatus (Szépligeti) and Asobara anastrephae (Muesebeck) and of the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) to guava (Psidium guajava L.) infested or not with fruit fly larvae were evaluated. D. areolatus and D. longicaudata females responded to the odors of uninfested rotting guavas, although D. areolatus was also attracted to fruits at the initial maturation (turning) stage. The females of these species recognized the volatiles of guavas containing Ceratitis capitata (Wied.) larvae. However, in bioassays involving fruits with larvae of different instars, D. longicaudata females were not able to separate between fruits containing C. capitata larvae at the initial instars and larvae at the third instar. In the evaluations of volatiles released by guavas containing C. capitata and Anastrepha fraterculus (Wied.) larvae, the D. longicaudata females were oriented toward the volatiles of fruits containing both host species, but differed significantly from volatiles of guavas containing C. capitata larvae. The D. areolatus females also showed responses to both species, although with a preference for volatiles of fruits containing A. fraterculus larvae. The A. anastrephae females were oriented toward the odors of fruits infested with both fruit fly species. In the shade house, D. longicaudata females were oriented to volatiles of rotting fruits containing larvae or not, but could not significantly differentiate between hosts. D. areolatus females were not attracted toward fruits on the ground in the shade house, regardless of host, suggesting that this parasitoid does not forage on fallen fruits.     

Natural establishment of a parasitoid complex on Bactrocera latifrons (Diptera: Tephritidae) in Hawaii

Bactrocera latifrons (Hendel) (Diptera: Tephritidae) is the most recent of four tephritid fruit fly species accidentally introduced into Hawaii. Although parasitoids have been released against other tephritid fruit fly species and have shown partial success in Hawaii, no parasitoids were released until 2004 to suppress populations of B. latifrons. The present study was conducted to document the parasitoid complex that has naturally established against B. latifrons in Hawaii and to assess whether there is a need for improving the biological control of this species. Based on ripe turkeyberry (Solanum torvum Sw) fruit collections over three consecutive years B. latifrons was the dominant tephritid fruit fly infestating turkeyberry at all four sites surveyed, across three major islands in Hawaii. The overall percentage parasitism of B. latifrons ranged from a low of 0.8% (Hana, Maui) to a high of 8.8% (Kahaluu, Oahu). Five primary parasitoid species were recovered from individually held B. latifrons puparia: Fopius arisanus (Sonan), Psyttalia incisi (Silvestri), Diachasmimorpha longicaudata (Ashmead), D. tryoni (Cameron), and Tetrastichus giffardianus Silvestri. F. arisanus was the predominant parasitoid at three of the four sites. Low levels of parasitism suggest that there is a need to improve biological control of B. latifrons, to minimize chances of this species causing economic impacts on crop production in Hawaii. We discuss the possibility of improving biological control of B. latifrons through augmentative releases of F. arisanus or introduction and release of specific and efficient new parasitoid species.     

Longevity of multiple species of tephritid (Diptera) fruit fly parasitoids (Hymenoptera: Braconidae: Opiinae) provided exotic and sympatric-fruit based diets

While adult parasitic Hymenoptera in general feed on floral and extrafloral nectars, hemipteran-honeydews and fluids from punctured hosts, Diachasmimorpha longicaudata (Ashmead), an Old World opiine braconid introduced to tropical/subtropical America for the biological control of Anastrepha spp. (Tephritidae), can survive on fruit juices as they seep from injured fruit. An ability to exploit fruit juice would allow such a parasitoid to efficiently forage for hosts and food sources simultaneously. Two New World opiines, Doryctobracon areolatus (Szepligeti) and Utetes anastrephae (Viereck), are also prominent Anastrepha parasitoids and are roughly sympatric. All three species were provided with: (1) pulp and juice diets derived from a highly domesticated Old World fruit (orange, Citrus sinensis L.) that is only recently sympatric with the Mexican flies and parasitoids and so offered little opportunity for the evolution of feeding-adaptations and (2) a less-domesticated New World fruit (guava, Psidium guajava L.), sympatric over evolutionary time with D. areolatus and U. anastrephae. Both sexes of D. longicaudata died when provided guava pulp or juice at a rate similar to a water-only control. D. areolatus and U. anastrephae, presumably adapted to the nutrient/chemical constituents of guava, also died at a similar rate. Survival of all three species on orange pulp and juice was greater than on water, and often equaled that obtained on a honey and water solution. In confirmatory experiments in Mexico, D. areolatus and U. anastrephae, as well as other tephritid parasitoids Doryctobracon crawfordi (Viereck) and Opius hirtus (Fisher), all died at a significantly higher rates when provided guava in comparison to a honey and water diet. Such a result is likely due to guavas being repellent, innutritious or toxic. D. longicaudata clearly consumed guava juice tagged with a colored dye. Dilutions of orange and guava juice resulted in shorter lifespans than dilutions of orange juice and water demonstrating that there while diluted orange juice provided nutrition the addition of guava created toxicity. Given the differences in fruit-food quality, adult opiine food sources would not be obtainable at all oviposition sites and in the case of guava, more additional sites and foraging for food than previously postulated may be required.     

The Diachasmimorpha longicaudata complex: Reproductive isolation and geometric patterns of the wing

Diachasmimorpha longicaudata is an endoparasitoid of Tephritid fruit fly larvae and is regarded as an important biocontrol agent. However, it is likely that under this specific name several biological species may be contained, the correct identification of which is essential for effective use in control programs. In this paper, three populations (DLA, DLB and DLBB) of D. longicaudata designated according to geography and/or natural hosts were reared in the same laboratory. They were tested for reproductive compatibility and characterized by morphometric analyzes. Forced-contact mating technique showed either complete lack of inter-population reproductive compatibility or the production of rare, sterile female offspring. The three populations, indistinguishable on the basis of morphological characters alone, were readily identified by the geometry of the wing. Results strongly suggest that the DLA, DLB and DLBB are distinct biological species, and highlight the usefulness of wing geometry to distinguish them.     

Seed dispersal curve of a Mediterranean myrmecochore: Influence of ant size and the distance to nests

Euphorbia characias is a Mediterranean spurge with a diplochorous dispersal system: after a ballistic dispersal that scatters the seeds, some ant species find and retrieve the seeds to their nest (myrmecochorous dispersal). The seed dispersal curve generated by ants in an abandoned field was described and partitioned according to ant size and to the distance to nest entrance from where seeds fell after ballistic dispersal. Both variables (ant size, distance to nest) affected dispersal distance. The seed dispersal curve showed a peak at short distance (median=1m) and a tail extending to 9.4m. The peak and the tail are explained differently. Short distances are usually generated by small ants (Pheidole pallidula and Tapinoma nigerrimum; 0.56±0.41m [n=48]) both from the nearest or farther nest entrances. The tail of the curve is generated disproportionately by big ants (Aphaenogaster senilis and Messor barbarus; 2.09±1.71m [n=61]) from farther nests. Seeds have a much greater probability (P=0.734) of being transported to nests which are not the nearest. This effect is largely due to transportation by big ants.     

Kin recognition in Bufo scaber tadpoles: ontogenetic changes and mechanism

Ontogenetic changes in kin-recognition behavior, effect of social environment on kin-recognition ability, and use of visual and chemical cues in kin recognition have been studied in tadpoles of Bufo scaber after rearing them with kin, in mixed groups, or in isolation from Gosner stage 12 (gastrula). By use of a rectangular choice tank the tadpoles were tested for their ability to choose between (a) familiar siblings and unfamiliar non-siblings, (b) unfamiliar siblings and familiar non-siblings, and (c) unfamiliar siblings and unfamiliar non-siblings. When tested without any stimulus groups in the end compartments of the tank, random distribution was observed for the tadpoles and no bias for the apparatus or the procedure. In the presence of kin and non-kin in the end compartments, significantly more tadpoles spent most of their time near kin (familiar or unfamiliar) rather than near non-kin during early larval stages, up to stage 37. After stage 37 (characterized by the differentiation of toes), test tadpoles showed no preference to associate with kin, suggesting an ontogenetic shift in the kin-recognition ability in B. scaber. In experiments involving selective blockade of visual or chemical cues the test tadpoles preferentially associated near their kin on the basis of chemical rather than visual cues. These findings suggest that familiarity with siblings is not necessary for kin recognition and that kin-recognition ability is not modified after exposure to non-kin by mixed rearing. The findings for B. scaber indicate a self referent phenotype matching mechanism of kin recognition which is predominantly aided by chemical rather than visual cues.     

Effect of Two Opiine Parasitoids (Hymenoptera: Braconidae) Introduced for Fruit Fly Control on a Native Hawaiian Tephritid,Trupanea dubautiae(Diptera: Tephritidae)

Diachasmimorpha longicaudata(Ashmead) andPsyttalia fletcheri(Silvestri) are opiine parasitoids introduced into Hawaii for control of the Oriental fruit fly,Bactrocera dorsalis(Hendel) and the melon fly,Bactrocera cucurbitae(Coquillett), respectively. Both species have recently been mass-reared and released for research in augmentative biocontrol programs. Laboratory and field sleeve cage experiments were conducted to investigate the potential impact of mass-producedD. longicaudataandP. fletcherion a native Hawaiian tephritid,Trupanea dubautiae(Bryan), infesting the flowerheads of the native composite shrubDubautia raillardioidesHillebrand. Gravid females ofD. longicaudataandP. fletcheriwere confined with bloomingD. raillardioidesflowerheads infested with late instarT. dubautiae.BothD. longicaudataandP. fletcherilacked positive oviposition responses toT. dubautiaelarvae in infested flowerheads and caused neither parasitism nor mortality to the flies. However, when larvae were removed from the flowerheads and presented in screened dishes containing artificial diet of the parasitoids' normal rearing hosts (B. dorsalisandB. cucurbitae), bothD. longicaudataandP. fletcherireadily oviposited in the test larvae. Oviposition byD. longicaudatadid not significantly affect the percentage pupation ofT. dubautiae,but did reduce the emergence of adult flies. Oviposition byP. fletcherisignificantly reduced both pupation and adult fly emergence. All progeny of both parasitoid species died as eggs or first-instar larvae. Results from our experiments demonstrate that biological control programs targeted against frugivorous tephritid pests byD. longicaudataandP. fletcherihave no harmful impact on flowerhead-infestingT. dubautiae.     

Effects of oil droplets by Pieris caterpillars against generalist and specialist carnivores

Pieris rapae larvae secrete small oil droplets from their dorsal setae, which adhere to objects that touch them. The function of the droplets was studied in terms of both generalist and specialist predators. We tested the function of the droplets against ants under laboratory and field conditions. In the laboratory observation, Formica japonica ants that touched the larvae with their antennae initiated antennal cleaning and did not prey on the larvae. In the field, predation pressure by ants on larvae with oil droplets was significantly lower than on larvae from which oil droplets were removed. Thus, we concluded that the droplets had a defensive function. By contrast, oviposition by Cotesia glomerata, the specialist parasitic wasp of P. rapae larvae, was not affected by the presence of oil droplets. Furthermore, the wasps exhibited searching behavior and oviposition behavior towards filter paper which had been impregnated with the droplets substance, suggesting that the oil functions as a host-searching cue and an oviposition stimulant for C. glomerata. According to these results, the functions of the droplets are discussed with regard to the prey–predator interaction.     

Spatio-temporal patterns of colony distribution in monodomous and polydomous species of North African desert ants,genus <Emphasis Type="Italic">Cataglyphis</Emphasis>

Summary Two monogynous species of North African desert ants belonging to the formicine genus Cataglyphis exhibit extremely different habitat preferences, population densities, and population structures. C. fortis is the only Cataglyphis species within the salt-pan flats of the Algerian and Tunisian chotts and sebkhas, whereas C. bicolor, alongside C. albicans and C. ruber, inhabits the nutritionally richer low-shrub semi-deserts surrounding the salt pans. We present a comparative study of the spatio-temporal patterns of colony distribution of the two monogynous species over periods of at least 5 (maximally 15) years. In C. fortis low population densities (0.5 kg body mass per km²) and, correspondingly, large inter-nest distances (40.6 m mean nearest neighbour nest distance) are correlated with absolute intra-annual and high inter-annual nest-site stability (more than 75% inter-annual survival rate) and a monodomous colony structure. In C. bicolor the population density is one hundred times higher (42 kg body mass per km², 9.1 m mean nearest neighbour nest distance), nest-site stability is extremely low in both intra-annual and inter-annual terms (67% intra-annual survival rate for 13-day periods; less than 5% inter-annual survival rate), and polydomy prevails. These marked differences in population structure are discussed with respect to adapted traits such as foraging range, running speed, and relative lengths of the legs.Received 8 August 2003; revised 27 November 2003; accepted 2 December 2003.     

Use of terrestrial chemical trails for nest orientation in an open nesting wasp, <Emphasis Type="Italic">Dolichovespula saxonica</Emphasis> F.

Summary The long-cheeked wasp Dolichovespula saxonica typically constructs exposed nests which can be reached by flying. Usually foragers do not walk on substrates in the close vicinity of the nests as cavity breeding wasps do (Steinmetz et al., 2002). Unexpectedly, when forced to walk outside the nest instead of flying in an artificial tunnel system, D. saxonica foragers lay a terrestrial trail and use it for orientation in the nest area in our experiments. 41% of the foragers followed the trail in a direction they were not accustomed to. We suggest that the foragers have employed the same orientation cues normally used for orientation in the close vicinity of the nest when approaching a free-hanging nest by flying, for example nest odour. Nest odour substances may have been transferred to the substrate as a trail as a consequence of foragers walking through the tunnels.Received 23 August 2002; revised 27 January 2003; accepted 30 April 2003.     

Response of Three Hymenopteran Parasitoids Introduced for Fruit Fly Control to a Gall-Forming Tephritid,Procecidochares alani(Diptera: Tephritidae)

The response of three larval–pupal parasitoids,Diachasmimorpha longicaudata(Ashmead),Diachasmimorpha tryoni(Cameron), andTetrastichus giffardianusSilvestri, to the Hamakua pamakani gall fly,Procecidochares alaniL., was determined in the laboratory. We also observed responses of these parasitoids to their normal rearing hosts,Bactrocera dorsalis(Hendel) andCeratitis capitata(Weidemann).D. tryonilanded on pamakani galls or on dishes containingP. alanilarvae as frequently as on dishes containingC. capitata.In contrast,D. longicaudataonly rarely landed on the galls.D. tryoniandD. longicaudataoviposited in galls in fewer than 1% of our observations.D. longicaudataprobedP. alanilarvae as frequently asB. dorsalislarvae, but no parasitoid offspring were observed.D. tryonioviposited more frequently inC. capitatathanP. alani.NoD. tryonideveloped inP. alanilarvae.T. giffardianuslanded on pamakani galls andP. alanilarvae more frequently than any other host substrate. In contrast,T. giffardianusentered galls with artificially opened windows one time in 10 observations. We observed 12% parasitism ofP. alanilarvae dissected from the galls and 20% of parasitismP. alaniin the windowed galls. We discuss the implications of our results for future augmentative or classical biological control studies.     

Change in movement and subdivision of Myrmica punctiventris (Hymenoptera, Formicidae) colonies in north temperate forests is related to a long-term shift in social organization

We assessed temporal and spatial patterns of nest site use in the cavity dwelling ant, Myrmica punctiventris in a well-studied temperate forest site in central New York State. We evaluated changes in nest site use by repeatedly censusing the ants inhabiting artificial nests (hollow dowels) for three consecutive growing seasons. We confirm a shift towards more polydomy in this population of M. punctiventris, first reported by DeHeer et al. (2001), but extend these findings by demonstrating that this shift has occurred gradually over several years. We are unable to determine if this polydomy is seasonal or year round. We explore various explanations for the occurrence of polydomy and suggest that long-term changes in sex allocation are indirectly driving the shift in nesting strategies. Received 15 July 2004; revised 11 April and 19 October 2005; accepted 25 October.     

Excavation and architecture of Argentine ant nests

We used x-ray computed tomography to study the elaboration of nest structures in small sand-filled nest boxes by Argentine ant (Linepithema humile) colonies composed of 10, 100, and 1000 workers. The pattern of nest growth was consistent with a process of density-dependent stimulation of excavation, which subsided as nests grew and the density of digging stimuli declined. Thus, nest excavation would be auto-regulating, and final nest size should be adjusted to colony size. We found that excavation rates and final nest sizes increased with colony size, but were not tenfold greater in 1000-worker colonies than in 100-worker colonies. In the largest colonies, the internal surface area scaled allometrically with volume, so that more surface was obtained relative to volume excavated as the nest grew. Although the gross features of Argentine ant nests, such as total size, seem explicable by a simple, self-organized regulatory process, other features of the nest architecture will require further investigation. Received 3 March 2005; revised 26 April 2005; accepted 3 May 2005.     

Postnatal remains of the foetal membranes affect growth and survival of wild European rabbit pups

During a long-term study on reproduction of the European rabbit (Oryctolagus cuniculus L.) that was carried out on a population living under semi-natural conditions, occasionally single pups per litter were discovered being stuck in remnants of the foetal membranes. Here we describe this so far unknown phenomenon, quantify the occurrence, and investigate the consequences for the individual growth rate and for survival. Furthermore, we tested if maternal social rank and age were correlated with the occurrence of this phenomenon. Pups comprising the described adherence of the foetal membranes had lower growth rates than their unaffected litter siblings, and usually died during the nestling period or short after emergence above ground. Our findings point out that there was an individual predisposition of the mother for having affected litters. However, an impact of maternal social rank or age on the occurrence of this feature in their offspring was not supported by our data. Nevertheless, a pathological background also has to be considered as a possible cause.     

白蚁巢来源链霉菌T12的分离鉴定及其抗菌活性代谢产物

[目的]探索黑翅土白蚁巢中链霉菌发酵产物的抗菌活性,并对其抗菌成分进行研究.[方法]通过牛津杯法测试菌株发酵液对4种致病菌的抗菌活性,筛选出活性菌株T12;利用分子生物学16S rRNA序列分析确定T12的分类地位;运用多种色谱方法从乙酸乙酯粗提物中分离纯化活性化合物,利用质谱和核磁共振谱鉴定其化学结构;结合滤纸片法测...     

海拔梯度变化对黄缘蜾蠃筑巢结构及相关生物学特性的影响

黄缘蜾蠃(Anterhynchium flavomarginatum)是一种以鳞翅目幼虫为食的独栖性捕食昆虫,在生态系统中提供了重要的生物防治功能。2018—2019年,在广东车八岭国家级自然保护区通过人工巢穴收集了不同海拔梯度下(332—1007 m)该蜂的筑巢巢管,系统研究了黄缘蜾蠃的筑巢特征(巢管内径、巢室长度、巢室数量)以及该蜂的子代雌雄数和体型大小随海拔梯度的变化趋势。结果表明：海拔主要影响的是黄缘蜾蠃对巢管内径大小的选择,以及对前庭长度的分配,同时,黄缘蜾蠃对巢管内径的选择可以影响到后代性别比,这种策略主要体现在亲本对雌性子代的投资,而不是雄性子代。研究结果表明黄缘蜾蠃在不同海拔梯度下可根据外界环境压力调整其营巢和生殖策略,以提高种群对环境的适应性。     

Object Depots in the Genus <Emphasis Type="Italic">Pogonomyrmex</Emphasis>: Exploring the “Who,” What,When, and Where

Harvester ants of the genus Pogonomyrmex collect and deposit many items on top of their nests. The depots of P. badius consist mostly of small charcoal fragments, while those of other species are primarily pebbles. Mature colonies can have hundreds of thousands of objects in their depot. In P. badius, the distributions of midden and charcoal about the mound are not completely overlapping, but are positively correlated in areas of overlap. Charcoal depots are isometric with colony size, but the amount of charcoal per colony size varies with season and site. The absence of the depot stimulates collection of nonfood objects. Recruitment to objects only occurs in the presence of food, and foragers choose objects based on size, but not color. An overview of current knowledge concerning depots in the genus indicates that depot formation is likely the ancestral state in the North American species. Furthermore, it is likely that selection is operating indirectly on these depots through selection on many dependent tasks.     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.