Characteristics of summer diapause in the onion maggot,Delia antiqua (Diptera: Anthomyiidae)

Characteristics of summer diapause in the onion maggot, Delia antiqua, were clarified by laboratory experiments. Temperature was the primary factor for the induction of summer diapause in this species. The critical temperature for diapause induction was approximately 24 degrees C, regardless of the photoperiod. At 23 degrees C, the development of the diapausing pupae was arrested the day after pupariation, when about 7% of the total pupal development had occurred in terms of total effective temperature (degree-days). The most sensitive period for temperature with regard to diapause induction was estimated to be between pupariation and "pupation" (i.e., evagination of the head in cyclorrhaphous flies). Completion of diapause occurred at a wide range of temperatures (4-25 degrees C): The optimal temperature was approximately 16 degrees C, at which temperature only five days were required for diapause completion. The characteristics of summer diapause in D. antiqua are discussed in comparison with those of summer dormancy in a congener D. radicum and those of winter diapause in D. antiqua.     

Nonwoven fiber barriers for control of cabbage maggot and onion maggot (Diptera: Anthomyiidae).

We investigated the use of nonwoven fiber barriers for control of cabbage maggot, Delia radicum (L.), and onion maggot, D. antiqua (Meigen). The barriers consist of arrangements of minute fibers loosely intertwined in "web" form. Results from a greenhouse experiment showed that manually applied graphite fibers placed at the base of broccoli plants reduced the number of D. radicum eggs by 64-98%, and that efficacy increased with greater fiber density. Using a melt extrusion process, we devised a method for on-site creation of nonwoven fibers of ethylene vinyl acetate (EVA). In field trials with broccoli and onion plants, EVA fibers significantly reduced the number of cabbage and onion maggots infesting plants. Fiber barriers provided comparable control to standard insecticide applications. The addition of blue, yellow, red, or black pigments, as well as optical brighteners that absorb UV light did not enhance fiber efficacy. Incorporation of capsaicin olfactory repellent to EVA also did not enhance fiber efficacy. Nonwoven fiber barriers may offer an alternative to insecticides for control of cabbage maggot and onion maggot and possibly other insect pests. Additional research is needed to improve the application process and to identify economically feasible and biodegradable compounds for fibers.     

Orientation behavior of newly hatched larvae of the cabbage maggot,Delia radicum (L.) (Diptera: Anthomyiidae), to volatile plant metabolites

Newly hatched larvae of the cabbage maggot, Delia radicum(L.), responded to various olfactory stimuli from their host plants and oriented themselves by the concentration gradients of these stimuli. Allyl and ethyl isothiocyanate (NCS), characteristic metabolites of host Brassicaceae, elicited positive taxis, but at a higher concentrations were repellent. Benzyl NCS was neutral; only at the highest concentration was it slightly repellent. Phenyl, cyclohexyl, and butyl NCS were repellent in the highest amounts used. Volatile compounds emanating prevailingly from surface parts of plants were both attractive (hexanol, hexanal, cis-3-hexen-1-ol, linalool) and repellent (hexylacetate, cis-3-hexenylacetate, benzaldehyde, myrcene, terpinene, -pinene, limonene). While the attractiveness was associated with NCS group and with unsaturated and saturated alcohols and aldehydes with an optimal sixcarbon chain length, the repellency was probably caused by a cyclized carbon chain and an acetate group. The activity of a compound was strongly influenced by its concentration.     

Crop sequence effects on root maggot (Diptera: Anthomyiidae: Delia spp.) infestations in canola

Strong market demand for canola, Brassica napus L., has prompted some western Canadian producers to increase the frequency of this crop in rotations with other crop species, but the impact of this practice on canola insect pests has not been determined. Here, we investigate 12 cropping sequences involving canola over a 3-yr period (2008-2010 inclusive) at five locations across western Canada. Cropping sequences varied from continuous production of two herbicide-tolerant canola varieties, to production in two of 3 yr, to canola production in one of the 3 yr. Treatments analyzed were the frequency and timing of canola within the rotational sequence. Damage by larvae of root maggots (Diptera: Anthomyiidae: Delia spp.) to canola taproots increased as the study progressed, particularly in 2010 after canola had been grown continuously for 3 yr. Yield declined with continuous canola production, and differences were greatest in 2010. At mean canola crop prices for 2010, the yield reduction from continuous production amounted to economic losses of approximately Can$282-$377/ha. Crop quality, in terms of oil and protein concentrations of harvested seed, was affected more by crop variety than cropping sequence. Crop sequence effects for root maggot damage, yield, and seed quality were relatively stable in the presence of environmental (location) variation. Results of our study suggest that continuous canola production could be unsustainable over the long-term even though market forces currently provide incentive for this practice.     

Onion maggot (Diptera: Anthomyiidae) resistance to chlorpyrifos in New York onion fields

A larval immersion bioassay was developed to identify susceptibility of onion maggot, Delia antiqua (Meigen) (Diptera: Anthomyiidae), to chlorpyrifos and to determine whether this assay could be used to predict control in onion fields. Laboratory colonies were established from larvae collected in New York onion fields during 2003 and 2004, providing us with test insects to use in bioassays. The larval assay effectively determined susceptibility of D. antiqua to chlorpyrifos, and results were congruent with an adult bioassay. However, use of similar-aged larvae (4 d old) in the assays was critical because larvae became more tolerant to chlorpyrifos as they aged. In a field survey, six of the 13 populations had LC50 values above the recommended field rate of 3,600 ppm (range 4,031-6,869). Over two successive seasons in the same field, susceptibility of D. antiqua to chlorpyrifos decreased in two of three fields (by 45 and 42%) and remained the same in another field, indicating that resistance is not predictable from year to year. Based on the relationship between damage in the field and LC50 values from 11 of the populations mentioned above, all five populations that had LC50 values above the field rate caused unacceptable levels of damage, whereas five of six populations that had LC50 values below the field rate did not cause serious damage.     

Delaying onion planting to control onion maggot (Diptera: Anthomyiidae): efficacy and underlying mechanisms

Onion maggot, Delia antiqua (Meigen) (Diptera: Anthomyiidae), is an important pest of onion, Allium cepa L., in northern temperate areas, especially in the Great Lakes region of North America Management of D. antiqua relies on insecticide use at planting, but insecticide resistance can cause control failures that threaten the long-term viability of this strategy. Delaying the time onions are planted was investigated as an alternative management approach for D. antiqua and the ecological and behavioral mechanisms underlying host age and insect relationships were examined in laboratory and field experiments. Delaying onion planting by two to four weeks reduced damage to onions by 35 and 90%, respectively. Onions planted later emerged later and this reduced the period overwintered flies had to oviposit on the plants. Moreover, flies tended to lay few to no eggs on these young, late-planted onions. As anticipated, D. antiqua laid 4-8 times more eggs on older onions than on young onions, and older onions were more resilient to injury caused by D. antiqua neonates compared with younger onions. However, the resiliency to maggot attack lessened as the density of D. antiqua increased from 2 to 10 eggs per plant, which probably explains why greater levels of maggot damage are typically observed in early onion plantings compared with later plantings. Delaying onion planting until mid-May reduced D. antiqua damage without jeopardizing the period required to produce marketable yield, but this cultural tactic must be combined with other management strategies to prevent economic loss.     

Laboratory evaluation of entomopathogenic fungi against larvae and adults of onion maggot (Diptera: Anthomyiidae)

Laboratory experiments were done to measure the susceptibility of larvae and adults of the onion maggot, Delia antiqua (Meigen) (Diptera: Muscidae: Anthomyiidae) to 27 isolates of entomopathogenic fungi from four genera [Beauveria Vuillemin, Lecanicillium (Petch) Zare & W. Gams, Metarhizium Sorokin, and Paecilomyces Bainier]. A novel bioassay was developed for D. antiqua larvae by using a diet based on mixed vegetable powder. When evaluated in a virulence screen, the fungal isolates caused less mortality of D. antiqua larvae than adults. Only three isolates caused > 50% mortality of larvae, whereas 12 isolates caused > 50% mortality of adults. Fungal species was a statistically significant factor affecting the mortality of larvae but not of adults. The fungal isolates causing the most mortality of larvae tended to belong to Metarhizium anisopliae (Metschnikoff) Sorokin. Two M. anisopliae isolates (389.93 and 392.93) were evaluated in dose-response bioassays. The median lethal concentrations of the isolates against larvae were 6.1 x 10(7) conidia ml(-1) for isolate 389.93 and 7.6 x 10(7) conidia ml(-1) for isolate 392.93. The emergence of adult flies from pupae was reduced at high concentrations of conidia (3.0 x 10(8) and 1.0 x 10(8) conidia ml(-1)). The median lethal concentrations of the isolates against adults were 1.7 x 10(7) and 4.0 x 10(7) conidia ml(-1), respectively. Some of the fungal isolates examined may have potential as biological control agents of larvae of D. antiqua and related species.     

Identifying sources and mechanisms of resistance in crucifers for control of cabbage maggot (Diptera: Anthomyiidae)

The cabbage maggot, Delia radicum (L.) is an important insect pest of eruciferous crops in upstate New York. This species causes considerable damage to seedlings and young plants by feeding on roots and stems, resulting in plant stand loss and yield loss. Five crucifer accessions (Brassica oleracea variety italica L.,'Green Comet'; B. oleracea L.,'Rapid Cycling' [Crucifer Genetics Cooperative 3-1 ]; B. oleracea variety botrytis L., a standard cauliflower cultivar'Amazing'; B. carinata L.; and Sinapis alba L., 'Cornell Alt 543') were evaluated to identify sources and mechanisms of resistance for D. radicum. Of the accessions tested, S. alba Cornell Alt 543 demonstrated reduced oviposition by D. radicum, reduced weights and survivorship of larvae, pupae or adults, and reduced damage to plants. Thus, S. alba Cornell Alt 543 could be a potential source for resistance to be bred into cruciferous crops for control of D. radicum.     

Strongwellsea castrans (Phycomycetes: Entomophthoraceae), a fungal parasite of the adult cabbage maggot,Hylemya brassicae (Diptera: Anthomyiidae)

Strongwellsea castrans is a parasite of the adult cabbage maggot, Hylemya brassicae, in Canada. Laboratory cultures of H. brassicae became infected when exposed to infected, field-collected flies. Infected flies lived a maximum of 5–7 days after the appearance of the characteristic abdominal hole through which the conidia are discharged. Attempts to culture the fungus on artificial media were not successful. Under field conditions, infection rate varied considerably within a season and between years; a high rate of infection was associated with a high relative humidity and possibly a comparatively low temperature.     

云南省花蝇科三新种(双翅目:花蝇科)

记述采自云南省花蝇科3新种,即：①分布于云南省禄劝的范氏草种蝇Phorbia fani sp.nov.,该种近似于四川产的峨眉草种蝇Phorbia omeishanensis Fan,1982,但新种雄性具1根上眶鬃;前中鬃1对,肩后鬃1：2,无后背侧片鬃;第5腹板侧叶的内缘具4行小刚毛,侧尾叶侧面观其中部宽大,后面观其端部较直等不同于已知种。②分布于土产兰坪冷山的冷山须泉蝇Pegoplata lengshanensis sp.nov.,该种雄性主要特征近似于,河南须泉蝇Pegoplata henanensis(Ge et Fan,1982）,但新种具间额鬃,侧颜为触角宽的2／3,芒具长纤毛,最长芒毛为触角宽的2／5（约为芒基的2倍）,后头背区裸;盾片具3条棕色粉被条;后股有1列后腹鬃;阳茎端部圆形,不向两侧呈角状延伸等不同。③分布于云南省泸水片马的云南泉蝇Pegomya yunnanensis sp.nov.,该种近似日本泉蝇Pegomya japonica Suwa,1974,但新种雄笥前中鬃呈2列体毛状,腹侧片鬃1＋3;中胫无后腹鬃,后胫后背鬃2;第5腹板侧叶侧面观较细长,侧尾叶后面观较宽,侧面观其端部前缘稍弯曲,前、后阳基侧突的形状不同。模式标本保存于沈阳师范大学昆虫研究所。     

Modification of female onion fly,Delia antiqua (Meigen), reproductive behavior by male paragonial gland extracts (Diptera: Anthomyiidae)

Egg depositional rates of onion flies, Delia antiqua(Meigen), injected thoracically with extracts of male paragonial glands were identical (14.5 eggs/female/ day) to those of normally mated females. Moreover, when continuously exposed to males, extract-injected females refused to mate and produced unfertilized eggs for the duration of the > 15- day experiment. For this normally monocoitic dipteran, <1 male equiv of paragonial secretion completely reproduced the ovipositional responses characteristic of normal mating, and this effect required no involvement of the genitalia or genital chamber. We suggest that the receptor for the active chemical (s) (sex peptide?) would be an excellent target for biorational insect control by sterilization. Moreover, these primer sex pheromones might play an important role in insect reproductive isolation and evolution.     

葱蝇非滞育、 冬滞育和夏滞育蛹发育和形态特征比较

昆虫非滞育、 冬滞育和夏滞育蛹具有不同的生理和发育过程。本研究以葱蝇Delia antiqua作为模式种, 以黑腹果蝇Drosophila melanogaster蛹的发育形态特征和命名为参照, 用解剖、 拍照、 长度测量和图像处理等方法系统地比较研究了非滞育、 冬滞育和夏滞育蛹的发育历期和形态变化, 重点在头外翻和滞育相关发育和形态特征, 目的在于弄清非滞育、 冬滞育和夏滞育蛹发育和形态特征差异, 为滞育发育阶段的识别、 滞育分子机理研究奠定形态学基础。冬滞育蛹的滞育前期、 滞育期和滞育后期分别为4, 85和27 d, 夏滞育蛹的滞育前期、 滞育期和滞育后期分别为2, 8和22 d。从化蛹至头外翻完成为滞育前期, 头外翻完成约10 h内复眼中央游离脂肪体可见。头外翻的完成是滞育发生的前提, 非滞育、 夏滞育和冬滞育蛹头外翻发生在化蛹后的48, 36和83 h, 在头外翻过程中发育形态没有差异。头外翻的过程为： 首先, 头囊和胸部附肢从胸腔外翻, 头部形态出现; 然后, 腹部肌肉继续收缩, 将血淋巴和脂肪体推进头部及胸部附肢。葱蝇蛹在完成蛹期有效积温约15%时进入冬滞育或夏滞育。在滞育期, 蛹的形态一直停留在复眼中央游离脂肪体可见这一形态时期, 且冬滞育和夏滞育的蛹在形态上没有区别。在体长、 体宽和体重上, 冬滞育蛹最大, 夏滞育蛹次之, 非滞育蛹最小。在滞育后期, 在黄色体出现期间, 非滞育蛹的马氏管清楚可见, 呈绿色, 而滞育蛹的马氏管几乎不可见。本研究为认知昆虫滞育生理、 从发育历期和形态上推断滞育发育进程提供了依据。     

The spatial distribution of the wheat-bulb fly,Leptohylemyia coarctata (fall.) (Diptera: Anthomyiidae)

The spatial distribution of the eggs, larvae, pupae and adults of the wheat-bulb fly was investigated by fitting 42 sets of data comprising 1334 samples to the Poisson and negative binomial distributions, and by using the power law (S²=am^b). In general, the tests indicated that all stages were aggregated and fitted the negative binomial model.     

葱蝇海藻糖-6-磷酸合成酶基因的克隆、序列分析及滞育相关表达

海藻糖-6-磷酸合成酶（trehalose-6-phosphate synthase, TPS）是昆虫海藻糖合成途径中的关键酶之一。本研究通过对葱蝇Delia antiqua海藻糖-6-磷酸合成酶基因的克隆、 序列分析及滞育相关表达的分析, 旨在证明该基因在能源合成以及抵御高温和低温环境方面发挥重要作用, 为进一步弄清葱蝇滞育分子机制提供理论依据。根据葱蝇抑制消减杂交文库中的EST序列信息, 设计特异性引物, 并通过RACE技术克隆了葱蝇海藻糖-6-磷酸合成酶基因全长cDNA, 命名为DaTPS1 （GenBank登录号： JX681124）, 其全长为2 904 bp, 开放阅读框2 448 bp, 编码815个氨基酸, 推测其相对分子质量为91.2 kD, 等电点为5.96。生物信息学分析表明, 该基因编码的氨基酸序列具有两个保守结构域, 与其他物种TPS具有较高的同源性, 其中和黑腹果蝇Drosophila melanogaster亲缘关系最近, 氨基酸序列一致性为92.1%; 其蛋白质三维结构有15条大的α螺旋和11股反向平行的β链折叠。RT-PCR分析表明, DaTPS1在葱蝇非滞育、 夏滞育和冬滞育期蛹中都有表达, 但是非滞育期各时期表达量基本没有变化, 而在夏滞育和冬滞育蛹的滞育前期表达量较高, 滞育保持期表达量较低, 滞育期后期表达量又有所升高。推断在葱蝇蛹夏滞育和冬滞育期前期, TPS1开始催化合成较多的海藻糖以提高滞育期抵御不良环境的能力, 滞育保持期蛹的新陈代谢降低, 所需能量较少, 所以TPS1处于低水平表达状态, 而滞育期结束后, 蛹生长发育逐渐恢复, 所需能量有所增加, TPS1的表达量再次升高。本研究对揭示昆虫TPS在能量代谢通路中的作用及昆虫滞育的分子机理具有一定的科学意义。     

Courtship behavior and discrimination between potential mates by maleDelia antiqua (Diptera: Anthomyiidae)

The repertoire of courtship behaviors of male onion maggots,Delia antiqua (Meigen), in a laboratory bioassay chamber, was analyzed by direct observation and by video recordings, in conjunction with a multichannel event recorder. Seven courtship behaviors were categorized: inspection from the substrate, aerial inspection, contact from the substrate, contact from the air, genital alignment, copulation, and male-male interaction. The frequency distribution of copulation bouts was best described by a Poisson distribution; peak mating activity occurred about 1 h into the bioassay. The duration in copulo, however, was extremely variable. On average, males spent 30 sin copulo (n=183); <30% of bouts were >50 s. The ability of males to discriminate between sexes, sexually immature and mature females, and between females ofD. antiqua and the cabbage maggot,Delia radicum (L.), was most pronounced in the elements of genital alignment and attempted copulation. The courtship and mating behavior inD. antiqua is consistent with a sequence that relies initially primarily on indiscriminate visual recognition of a potential mate, followed by species-and sex-specific semiochemical recognition upon contact.     

Relay cropping cauliflower with lettuce as a means to manage first-generation cabbage maggot (Diptera: Anthomyiidae) and minimize cauliflower yield loss

First-generation cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae), can cause extensive damage to newly transplanted brassica crops. This study investigated the use of relay cropping, a form of intercropping that involves overlapping two crops in the same field for a short period, as a means to 1) reduce first-generation D. radicum egg numbers by disrupting female host finding and 2) minimize yield loss by reducing the time that crops overlap. Because of the high incidence of two other Delia species, Delia platura (Meigen) and Delia florilega (Zetterstedt), treatment effects on these insects also were considered. In both years of the study (2003 and 2004), there were fewer D. radicum eggs collected from the base of cauliflower, Brassica oleracea variety botrytis, plants relay cropped with lettuce, Lactuca sativa L., than in monoculture. D. platura/D. florilega also laid fewer eggs on cauliflower in the relay crop than in monoculture in 2003, but in 2004 the opposite was true, there were more D. platura/D. florilega eggs laid on the relay-cropped cauliflower. After peak D. radicum oviposition, the lettuce was harvested. Cauliflower curd weights and diameters were comparable between treatments in both years. Plant loss because of D. platura/ D. florilega feeding in the 2004 relay-cropped plots resulted in reduced yields in these plots compared with the monoculture. Although further investigation is needed into the effects of relay cropping on other pests within this system, this is the first study to demonstrate that relay cropping can reduce egg laying by D. radicum at the scale studied while minimizing competition between component crops for key resources.     

The Linnaean Species of the Families Fanniidae, Anthomyiidae and Muscidae (Insecta: Diptera)

Linnaeus described eleven species in the genera Musca and Conops that are now placed in the Fanniidae, Anthomyiidae and Muscidae. A study is presented of the types and other material of these three families in his collection.