A new species of Bracon (Hymenoptera: Braconidae) parasitic on alien sweetpotato weevils in the south-west islands of Japan

A new species of braconid, Bracon yasudai Maeto et Uesato sp. nov., is described here from the south‐west islands of Japan. It is a solitary idiobiont ectoparasitoid of the larvae of the West Indian sweetpotato weevil, Euscepes postfasciatus (Curculionidae), and the sweetpotato weevil, Cylas formicarius (Brentidae), both feeding on Ipomoea batatas (L.) (Convolvulaceae). The percentage parasitism of the braconid on E. postfasciatus in the vines of I. batatas was 19.9–40.7% in the field. Bracon cylasovorus (Rohwer) reared from C. formicarius in the Philippines is also described.     

Mating system of Bracon hebetor (Hymenoptera: Braconidae)

Abstract.

• 1 We report on the mating system of a field population of the parasitic wasp, Bracon hebetor, on a corn pile infested by the Indian meal moth, Plodia interpunctella. We demonstrate that the mating system is based upon male scramble competition polygyny with male aggregations on high places on the corn.
• 2 The sex ratio among adults was greater than 80% males on the surface of the corn, whereas below the surface the sex ratio was less than 45%. Males actively courted females on the surface, but there were no aggressive interactions among males during courtship or mating.
• 3 Approximately 20% of the females found on the surface of the corn had no sperm in their spermathecae, regardless of age, but the numbers of unmated females decreased later during the day.
• 4 In laboratory studies we showed that females from this population oviposit a female biassed sex ratio, and that only 14% of females were mated before dispersing from their place of emergence.
• 5 Thus sib-mating is unlikely in this gregarious parasitoid. This outcrossing mating system probably arose because of severe inbreeding depression that B.hebetor suffers via a sex locus: diploids that are heterozygous at the sex locus develop into females, but homozygous diploids are male and are generally inviable. The female biassed sex ratio may have evolved in B. hebetor in response to males being the more expensive sex, females dispersing more frequently from the population than males, or a fraction of females remaining unmated in the population.

     

白蜡吉丁柄腹茧蜂的寄生和繁殖生物学

白蜡吉丁柄腹茧蜂Spathius agrili Yang是我国天津地区寄生白蜡窄吉丁幼虫的一种重要天敌。本研究通过林间调查并结合室内观察,测定了该寄生蜂在不同营养条件下的存活时间和不同时期的产卵量,调查了不同寄主大小对寄生蜂后代生长发育的影响,以及寄生蜂对不同深度树皮下的寄主利用情况。结果表明：不同营养条件下白蜡吉丁柄腹茧蜂的存活时间差异很大,补充20％蜂蜜水的成蜂存活时间明显延长,最长可达3个月。相同条件下雌蜂的存活时间比雄蜂略长。在补充营养的条件下,茧蜂的产卵时间最长可达8周,产卵的高蜂在羽化后第2周前后,平均每雌每周产卵量在整个产卵期内基本保持在8～12粒上下,没有大的波动。茧蜂低龄幼虫也可能分泌毒素主动攻击寄主,提高了寄生蜂后代的生存能力。寄主个体大,营养量也大,寄生其上的茧蜂幼虫成功完成发育的数量随之增加,表明寄主营养资源的多少直接影响到寄生蜂后代的生长发育和存活。白蜡吉丁柄腹茧蜂对1～6.5 mm树皮深度范围内的适龄寄主幼虫均能够寄生利用,约92％的被寄生白蜡窄吉丁幼虫个体分布于1～4 mm深度的树皮下,在3 mm厚的树皮下分布的数量最多。茧蜂数量与树皮深度大致上呈抛物线关系,理论上在树皮深度为3.97 mm处茧蜂分布数量最多。     

First record of the genus Wilkinsonellus (Hymenoptera,Braconidae, Microgastrinae) from Fiji with description of three new species

Wilkinsonellus Mason is a relatively small Pantropical genus of braconid parasitoid wasps within the subfamily Microgastrinae. Most of the currently described species are from the Palaeotropics; however, previous records were absent from Fiji. Here, the first three Wilkinsonellus species from Fiji are described: Wilkinsonellus corpustriacolor sp. n., Wilkinsonellus fijienis sp. n. and Wilkinsonellus nescalpura sp. n. The material was collected by Malaise traps set up in a quite variety of ecosystems (wet zone, dry zone and coastal forests) throughout the archipelago. With these records, Fiji represents the easternmost known distribution of the genus in the Indo-Pacific Region. A key to all of the currently known Wilkinsonellus species is included to facilitate species identification.     

Parasitism of the wheat stem sawfly (Hymenoptera: Cephidae) by Bracon cephi and B. lissogaster (Hymenoptera: Braconidae) in wheat fields bordering tilled and untilled fallow in Montana

We evaluated wheat stem sawfly, Cephus cinctus Norton, parasitism, infestation, and sawfly-cut stems in wheat fields bordering intensely tilled (no visible stubble residue), minimally tilled (>75% stubble residue visible), and untilled (chemical fallow, herbicide fallow management) summer fallow fields in north-central and south-central Montana. No difference in sawfly parasitism or sawfly-cut stems was found between fields bordering minimally tilled and fields bordering untilled summer fallow. Sawfly parasitism in fields bordering untilled summer fallow was greater than in fields bordering intensely tilled summer fallow at six of the eight sites examined. Sawfly-cut stems were greater in the field bordering intensely tilled fallow at four sites, with no difference in sawfly-cut stems between the intensely tilled and untilled field at the other four sites. Although it has never been reported, we have observed that many sawfly stubs are completely buried. Therefore, we measured the depth of sawfly stubs in four untilled fields in Broadwater County, MT. Two-thirds of the stubs were completely buried (206 of 300) with an average depth of 6 mm. Intensive tillage, which results in soil-covered stubble, is not an effective sawfly control practice, because sawflies typically overwinter below ground and upon emergence must dig to reach the soil surface. However, Bracon cephi (Gahan) and Bracon lissogaster Muesebeck overwinter above ground in stems and might be unable to dig to the soil surface if buried. The elimination of intensive tillage in favor of chemical fallow should result in greater sawfly parasitism over time. Producers replacing minimal tillage with chemical fallow should see no effect on sawfly parasitism.     

First record of Alysia alticola Ashmead (Hymenoptera: Braconidae) in the Neotropical region

Alysia alticola Ashmead, 1890, is recorded for the first time in central Argentina, reared from pig carcasses. This is also the first mention of the genus Alysia Latreille, 1804, in Argentina, which represents the southernmost record in the Neotropical region.     

Three new species of Sesioctonus Viereck (Hymenoptera, Braconidae, Agathidinae) from Peru

Three new species of Sesioctonus (Braconidae: Agathidinae) are described and illustrated, i.e., Sesioctonus huggerti, Sesioctonus wayquecha, and Sesioctonus bina. Two new Peruvian species records for Sesioctonus are reported: Sesioctonus longinoi and Sesioctonus diazi. A revised key to all known species of Sesioctonus is presented.     

橘小实蝇寄生蜂切割潜蝇茧蜂的人工繁殖技术

切割潜蝇茧蜂[Psyttalia incisi(S ilvestri)]是福建疫区寄生于橘小实蝇[Bactrocera dorsalis(Hendel)]幼虫—蛹期的重要本地寄生蜂。利用室内大量繁殖的橘小实蝇幼虫作为寄主,在室内条件下对其进行人工繁殖技术研究,并设计了人工繁蜂的质量控制和工艺流程。旨在将来提供足够数量的寄生蜂来满足田间放蜂的需要,尽早实现对橘小实蝇的持续、有效地治理。     

Finding of Torymus koreanus (Hymenoptera: Torymidae) attacking Dryocosmus kuriphilus (Hymenoptera: Cynipidae) in Japan

Torymus koreanus (Hymenoptera: Torymidae) was reared from galls of Dryocosmus kuriphilus (Hymenoptera: Cynipidae) for the first time in Japan. We here report morphological features and partial mtDNA sequencing data of T. koreanus. Torymus koreanus has several common characteristics with species of the cyaneus group defined by Zavada (2003 ). According to the key to species groups defined by Graham and Gijswijt (1998 ), it does not belong to any species group because of the entire posterior margin of metasomal tergum five.     

Parasitism on medfly by Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) in different guava cultivars

The parasitism efficiency of the Braconidae wasp, Diachasmimorpha longicaudata (Ashmead), was checked on four guava cultivars (Paluma, Sassaoca, Pedro Sato and Kumagai) infested with larvae of medfly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Five blocks of eight fruits, each with two fruits of each cultivar, were put inside C. capitata adult cages, during 2h for oviposition, and a week later, when the larvae inside guavas were developed, the fruits were exposed to parasitoids for 24h. The mean fruit weight, larvae mortality, number of pupae, percentage of medfly and parasitoid emergence were evaluated. There was not statistical difference among cultivars to weight, larvae mortality, number of pupae e emergence of medfly. The percentage of parasitism was higher in Pedro Sato cultivar (19.8%) compared with Kumagai cultivar (2.9%), but it was statistically similar to the other cultivars.     

The influence of humidity on emergence in Dacnusa sibirica Telenga (Hymenoptera: Braconidae)

The effects of four humidities (33, 55, 76 and 93% relative humidity) and four ages (0–1, 2–3, 4–5, 6–7 days) of parasitized Chromatomyia syngenesiae puparia on adult emergence in the leafminer parasitoid Dacnusa sibirica were examined in the laboratory. Parasitized puparia harvested at 0–1 days were susceptible to low humidities resulting in a significantly reduced parasitoid emergence. Aging of the puparia appeared to protect the developing parasitoid from low humidities. Increasing humidity produced a corresponding increase in the longevity of the adult parasitoid.     

Quality control of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) from different Brazilian bio-factories

The goal of this study was to evaluate the quality of Cotesia flavipes from different bio-factories as biological control agents. We evaluated biological characteristics of the parasitoids throughout their lifespan, and measured the body length and width, abdomen width, thorax width and width and length of the right forewing of female and male parasitoids. Our results showed that the number of males and pupal viability were similar among the bio-factories; the number of emerged females was greater in bio-factories I and II; the egg-pupa period and the pupal period were shorter in bio-factory IV; and a greater longevity was found in bio-factories II and III. Sex ratio (at approximately 60% females) was satisfactory (in terms of suitability for release) across all bio-factories. For morphometric measurements, the body, abdomen and wing widths were similar in males; however, thorax width was greater in the males from bio-factory I; bio-factory III produced females with the highest body length; bio-factory I produced females with the greatest abdomen width; bio-factories III and IV produced females with the greatest wing length. Among the bio-factories studied, bio-factory IV produced the best quality C. flavipes, with respect to the greatest number of parasitoids per pupal mass (a mean of 57% more parasitoids) in a satisfactory sex ratio, and with the shortest developmental time, which facilitates faster rearing in the laboratory. Studies such as this, which assess the quality of a mass-produced C. flavipes, are crucial for the continued use of this parasitoid in controlling Diatraea saccharalis in the field.     

Parasitism of Tuta absoluta (Lepidoptera, Gelechiidae) by Pseudapanteles dignus (Hymenoptera, Braconidae) under laboratory conditions

Laboratory studies were conducted to measure selected life history traits and the functional response of the parasitoid Pseudapanteles dignus (Muesebeck), a major enemy of Tuta absoluta (Meyrick) in tomato crops in South America. Newly mated P. dignus females were individually exposed to 10 host larvae in mines for 24 h. We determined developmental time from egg to pupal formation and pupal stage duration, female adult life span, fecundity, reproductive period, daily parasitism rate, and sex ratio of offspring. For the functional response experiment, treatments consisted of six host densities: 3, 5, 7, 10, 15, 20, or 30 larvae. The number and proportion of parasitized hosts were calculated for each density. The shape of the functional response curve was analyzed by logistic regression. P. dignus females attacked hosts daily, exhibiting modest lifetime fecundity (approximately 32 parasitized hosts per female) and a female-biased offspring sex ratio. Female adult life span was 36 d. P. dignus showed a type I functional response within the range of host densities tested. We observed that females detect and parasitize the host within a wide range of densities, including low densities. The functional response curve reached an asymptote at a mean density of six hosts per day and seemed not to be egg-limited. Percent parasitism was approximately 30%. The ecological implications of the results in relation to the potential of P. dignus for the biological control of T. absoluta in tomato are discussed.     

Factors governing host discrimination byOpius dimidiatus (Ashmead) (Hymenoptera: Braconidae)

The detection of, and response to, parasitized hosts by female parasitoids can involve a number of complex phenomena, including the ability of females to discriminate between unparasitized and parasitized hosts, the physiological state of females, and the nature and longevity of the cues they are detecting. The discriminatory ability of Opius dimidiatus,a solitary endoparasitoid of Liriomyza trifoliiwas examined. Experiments showed, first, that when presented with a choice of unparasitized hosts and hosts which they had previously parasitized, O. dimidiatusfemales could discriminate between them, both upon encounter (before probing) and after probing with the ovipositor. It was further demonstrated that the detection of parasitized hosts was time dependent: females could discriminate on the basis of antennal examination for up to 2.5 h after the first egg was laid. Postprobing discrimination lasted for up to 3.5 h. Some of the causal and evolutionary factors resulting in superparasitism are discussed.     

Dispersion patterns of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in citrus orchards in southeast Brazil

We studied the dispersion patterns of the exotic endoparasitoid, Diachasmimorpha longicaudata (Ahsmed) (Hymenoptera: Braconidae), in 1999 (summer) and in 2000 (winter) in a citrus orchard in southeast Brazil. Different population densities of D. longicaudata were released in the centre of the orchard, and their dispersion was determined by using yellow, sticky, rectangular traps, placed in various distances and heights around the release point. Our results suggest that during summer, climatic conditions did not affect dispersion. However, in winter, dispersion rates were positively affected by temperature, and negatively by rainfall. Both estimated dispersal distance and surface were higher in summer than in winter for all release densities. Dispersion peaked at 2000 parasitoids ha^?1 in summer and 8000 parasitoids ha^?1 in winter. The importance of our results for the biological control of fruit flies by augmented or innoculative releases of D. longicaudata in southeast Brazil is discussed.     

Diversity of Microgastrinae (Hymenoptera: Braconidae) in apple orchards of southern Quebec,Canada

This study reports the Microgastrinae (Hymenoptera: Braconidae) species collected from two blocks of apple trees from 1993 to 1994 in southern Quebec, Canada. The habitat management block (HMB) had companion flowering plants within the block, whereas the control had no flowering plants. Thirty-six Microgastrinae species were identified including three new records for Canada: Apanteles tischeriae Viereck, Cotesia crambi Weed, Diolcogaster bakeri Muesebeck. The number of microgastrine varied considerably between the two blocks and years. Species numbers were similar between the two blocks, but the Shannon diversity and Evenness similarity indices indicated that HMB had a more diverse and balanced population of Microgastrinae. Matching our microgastrine identifications with literature records showed that the wasps could potentially parasitize over one-third of the lepidopteran pests of apples and/or other lepidopteran species recorded within this agro-ecosystem. The inclusion of four Asteraceae companion plant species in the HMB enhanced the diversity of Microgastrinae.     

Density-dependent parasitism of cowpea aphid,Aphis craccivora by Lysiphlebus fabarum,Binodoxys acalephae,and Aphidius matricariae (Hymenoptera: Braconidae: Aphidiinae)

Biological control, as a major component of pest management strategies, uses natural biological agents to reduce pest populations. Studying the interaction among Aphis craccivora and its parasitoids including, Lysiphlebus fabarum, Binodoxys acalephae, and Aphidius matricariae in 2016 and 2017 in Tehran Parke-Shahr, showed positive, significant correlations in all cases between the densities of three parasitoid species and that of aphid nymphs and adults. The density of the parasitoids increased by increasing the density of the aphids. The parasitoids showed aggregative behavior in response to different densities of the host. There was a positive density-dependent correlation between the density of A. craccivora and rate of parasitism. Parasitism rates of nymphs and adult aphids by L. fabarum, B. acalephae, and A. matricariae increased or decreased along with decline or increase in the population of the aphid host. In 2016 spring, the highest rates of parasitism on aphid nymphs by L. fabarum, B. acalephae, and A. matricariae were 46.82, 23.09, and 17.16%, respectively. In 2017 spring, the highest rates of parasitism on aphid nymphs by L. fabarum, B. acalephae, and A. matricariae were 48.97, 21.77, and 15.06%, respectively. So, given the accordance between changes in aphid population and that of parasitoids, and parasitoids’ efficacy in Tehran’s polluted air, they can be used as biological agents in the management of A. craccivora population.     

Comparative selectivity of pesticides used in greenhouses,on the aphid parasitoid Aphidius colemani (Hymenoptera: Braconidae)

A series of bioassays were conducted under laboratory conditions to determine the relative toxicities of various pesticides (acetamiprid, cypermethrin, chlorantraniliprole and emamectin benzoate, Bacillus thuringiensis var. kurstaki and Helicoverpa armigera nucleopolyhedrovirus, copper oxychloride, iprodione, mandipropamid, a mixture of propamocarb?+?fluopicolide and mixture of fludioxonil?+?cyprodinil) on Aphidius colemani adults and mummies, as well as sublethal effects on female fecundity. Cypermethrin was highly toxic to pupa of A. colemani within host mummies. Acetamiprid, cypermethrin, emamectin benzoate, a mixture of propamocarb?+?fluopicolide and mixture of fludioxonil?+?cyprodinil were also highly toxic to A. colemani adults (92–100% mortality at 48?h post treatment). Mandipropamid, iprodione and copper oxycloride treatments significantly reduced fecundity of the female parasitoids. In contrast B. thuringiensis var. kurstaki, H. armigera nucleopolyhedrovirus and chlorantraniliprole were harmless (<30% mortality) to the parasitoid species tested according to International Organisation for Biological Control toxicity classification and are likely to be compatible with integrated pest management programmes.     

Multiple oviposition by Apoderus balteatus (Coleoptera, Attelabidae) is associated with larger leaves

ABSTRACT.

• 1 The female weevil of Apoderus balteatus Roelofs cuts the leaf near its base in order to make a leaf-roll‘cradle', in which one, two or three eggs are laid. Cuts are always located about 5 mm from the leaf base, independent of leaf size.
• 2 Larger leaves are made into larger cradles.
• 3 Weevils tend to lay more eggs in large cradles.
• 4 Eggs are laid through different holes and separated by leaf layers in the cradle. Cannibalism by larvae will be prevented by this isolated oviposition.
• 5 Multiple oviposition of this weevil allows larger leaves to be used by multiple larvae. It facilitates more efficient use of larger leaves and economizes on female effort in cradle formation.