Biological Control of Anastrepha spp. (Diptera: Tephritidae) in Mango Orchards through Augmentative Releases of Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae)

Diachasmimorpha longicaudata (Ashmead) parasitoids were released by air on a weekly basis over 1600 ha of commercial mango orchards, backyard orchards, and patches of native vegetation, at a density of ca. 940 parasitoids/ha. Releases were made during 2 consecutive years, beginning at flower onset and lasting until the end of the production cycle. Two areas, 7 km apart, were compared. In one area parasitoids were released, whereas the other area was used as a control. During the 2nd year treatments were reversed. Fruit was sampled in commercial mango orchards and in backyard orchards to assess levels of parasitism in fruit fly larvae. Highly significant differences in percentage parasitism were found in release and control zones in backyard orchards. Furthermore, trapping results indicated that D. longicaudata releases were associated with ca. 2.7-fold suppression of Anastrepha spp. populations in backyard orchards. Results suggest that suppression might be affected by environmental conditions and by the parasitoid:fly ratio achieved. Anastrepha obliqua McQuart populations were suppressed more effectively by use of parasitoids than those of Anastrepha ludens Loew, perhaps due to the type of host fruits used by each species. Augmentative parasitoid releases in marginal areas surrounding commercial orchards (backyard orchards, wild vegetation) can substantially suppress fly populations. Through this approach, the number of flies that later move into commercial orchards can be significantly reduced. Such a strategy, when combined with sound orchard management schemes, can allow growers to produce clean fruit without the need to resort to the widespread use of insecticides.     

湿地生态系统土壤温度对气温的响应特征及对CO2排放的影响

通过2年的野外定位观测,研究了沼泽湿地土壤温度对气温变化的响应特征,以及土壤温度对沼泽湿地植物 土壤系统CO₂排放的影响,并对CO₂排放的季节性变化进行模拟计算.结果表明,随融冻作用开始,沼泽湿地土壤温度对气温变化的响应强度不断增大,根层土壤温度与气温间呈显著指数关系（R²=0.94,P<0.01）,但不同深度土壤温度对气温变化的响应强度存在一定的差异,表现为随土壤深度的增加,二者之间的相关系数变小,土壤温度对气温的响应强度减弱.沼泽湿地植物 土壤系统CO₂排放与根层土壤温度有关,二者呈显著指数相关关系（R²=0.84,P<0.01）,利用模型模拟计算出沼泽湿地2003年生长季植物 土壤系统CO₂排放通量平均值为664.5±213.9 mg·m^-2·h^-1,野外定位观测值为634.0±227.7 mg·m^-2·h^-1,二者之间差值不大,表明利用此方法可以对沼泽湿地生长季CO₂排放进行估算.     

The zoophilic fruitfly Phortica variegata: morphology, ecology and biological niche

Abstract.  Flies belonging to the subfamily Steganinae (Drosophilidae) display unusual zoophilic feeding habits at the adult and/or larval stage. Phortica variegata (Fallén) feeds on tears or eye liquid around the eyes of humans and carnivores. When feeding it is a potential vector of Thelazia callipaeda (Railliet and Henry) eyeworms. Adult and larval stages of this fly may be easily confused with other species belonging to the same genus, and little is known on the biology and ecology of P. variegata . In April–November 2005, a total of 969 P. variegata were collected in an area with a high prevalence of canine thelaziosis. The number of flies collected weekly was then related to climatic and environmental parameters (e.g. temperature, relative humidity and total rainfall) recorded daily at the collection site. The highest number of Phortica were collected during July–August. The sex ratio (number of males : females) rose from ∼ 0.5 during May–July, to ∼ 3.0 in August and 181 during September–October. Distributional data, representing 242 sites at which P. variegata has been collected in Europe, were analysed using a desktop implementation of the genetic algorithm for rule-set prediction (GARP) to model ecological requirements across Europe, as well as in Italy. P. variegata is shown to be mainly active at 20–25 °C and 50–75% RH. The ecological niche model suggests with a high degree of confidence that large areas of Europe are likely to represent suitable habitat for this species, mostly concentrated in central Europe. The results reported here contribute basic knowledge on the ecology and geographical distribution of P. variegata flies, which will be fundamental to gaining a better understanding of their role as vectors of human and animal pathogens.     

Habitat size, flora, and fauna: Interactions in a tidal saltwater marsh

Anthropogenic habitat fragmentation is increasingly problematic in both terrestrial and aquatic systems. Fragmentation reduces the size of habitat patches, so examining the effect of patch size on community structure can provide insight into the potential effects of fragmentation. In this study, we examined the effect of habitat size on the density of Spartina alterniflora shoots in tidal saltwater marshes, as well as on the two predominant macrofaunal species, the marsh periwinkle Littoraria irrorata and fiddler crabs Uca spp. We estimated the density of shoots in three different marsh habitats, (1) large island marshes, (2) small island marshes, and (3) large fringing marshes, in Indian Field Creek, York River, Chesapeake Bay. We manipulated shoot density in each of the marsh types to distinguish between the effects of marsh grass density and marsh type on crab and Littoraria densities in the system. We found significant differences in grass density among the three marsh types as well as significant species-specific effects of grass density, marsh type, and distance from edge on faunal abundance. Decreasing the shoot density resulted in a decrease in Littoraria density in the large marshes. Littoraria density increased with distance from edge in the small marshes and in the first 5 m of the fringing marshes, then decreased with distance from edge after 5 m in the fringing marshes. Shoot density had a negative effect on crabs in both the large and small marshes. These results suggest that fragmentation would have a negative effect on the community structure by lowering the densities of both the flora and fauna.     

泽蛙（蝌蚪）和蜘蛛对农药的敏感性与急性毒性分级

泽蛙和蜘蛛是稻田害虫的重要天敌。通过室内和田间毒性试验,发现它们对拟除虫菊酯、有机氯、沙蚕毒素及治螟磷等农药,特别是对拟除虫菊酯的纯活性异构体敏感．蝌蚪群体异质性比蜘蛛小,对农药更敏感．根据田间毒性试验,室内用４８小时的致死中浓度,田间用安全浓度和药量安全指数,可评价农药对它们的安全性,其急性毒性可分为剧毒、高毒、中等毒和低毒四级．     

草地螟寄生蝇与寄主间的关系及控害作用

草地螟寄生蝇是草地螟Loxotego stictialisL.的重要天敌,但其发生种类、控害作用尚不明确。通过室内饲养,结合历年田间调查对康保县草地螟寄生蝇种类、田间分布、寄生率及消长规律进行研究,结果表明康保县草地螟寄生蝇发生种类有5种。田间呈聚集分布,种群数量大,寄生率高,控害作用显著。对开展草地螟预测预报,保护利用天敌资源和综合治理提供了科学依据。     

LONG-TONGUED FLY POLLINATION AND EVOLUTION OF FLORAL SPUR LENGTH IN THE DISA DRACONIS COMPLEX (ORCHIDACEAE)

Field studies in South Africa showed that floral spur length in the Disa draconis complex (Orchidaceae) varies enormously between populations in the southern mountains (means = 32–38 mm), lowland sandplain (mean = 48 mm), and northern mountains (means = 57–72 mm). We tested the hypothesis that divergence in spur length has resulted from selection exerted through pollinator proboscis length. Short-spurred plants in several southern mountain populations, as well as long-spurred plants in one northern mountain population, were pollinated by a horsefly, Philoliche rostrata (Tabanidae), with a proboscis length that varied from 22 to 35 mm among sites. Long-spurred plants on the sandplain were pollinated by the tanglewing fly, Moegistorynchus longirostris (Nemestrinidae), which has a very long proboscis (mean = 57 mm). Selection apparently favors long spurs in sandplain plants, as artificial shortening of spurs resulted in a significant decline in pollen receipt and fruit set, although pollinaria removal was not significantly affected. Fruit set in the study populations was limited by pollen availability, which further suggests that selection on spur length occurs mainly through the female component of reproductive success.     

A comparison of the water balance characteristics of temperate and tropical fly pupae

Abstract Water balance characteristics of temperate zone fly pupae are compared with the characteristics of flies inhabiting the tropics. The flies, all of which were reared without diapause, had very similar equilibrium weights that were quite high (a_v 0.90-0.92), thus implying a limited capacity to absorb water from a subsaturated atmosphere. Likewise, the critical transition temperatures (CTT) were nearly the same for all the flies. Net transpiration rates at 20^oC are a function of size, but the rate is less size dependent as temperature increases. When water loss is examined across a broad temperature range, as described by activation energies, it is apparent that the tropical flies lose water at a greater rate than their temperate zone counterparts. Activation energy may be a good parameter to use in evaluating habitat preference and suitability for a species because it describes water loss as a function of temperature, and thus is likely to be a good indicator of the insect's response to the fluctuating temperatures that occur naturally.     

西藏地区有瓣蝇类记述(三)花蝇科七新种描述

本文报道采自西藏的有瓣蝇类7个新种,均属花蝇科。正模标本保存在中国科学院上海昆虫研究所。 银额泉种蝇Pegohylemyia argyrometopa,新种（图1—3） 雄:体长6毫米。复眼裸,额宽约为前单眼宽的2倍,间额黑,间额鬃1,下眶鬃7—8,侧额及侧颜黑色上具银白色粉被,侧颜宽为触角第三节宽的4/3倍,触角黑,第三节长为宽的2倍,芒具毳毛,最长毛与芒基宽相等,颊高为眼高的1/5,银白色粉被明显,上倾口缘鬃3行,下颚须黑,中喙具粉被,长为高的4倍,口上片与额齐,后头背区有小毛。