Physical Restraint or Stimulation? The Function(s) of the Modified Front Legs of Male Archisepsis diversiformis (Diptera, Sepsidae)

Four hypotheses that could explain the elaborate species-specific morphology of the clasping organs on the front legs of male Archisepsis diversiformis flies were tested: direct male–male combat, mechanical fit, male–female conflict of interests, and male stimulation of the female. Experimental modification of the shape of the male clasper and of the female wing base where the male clasped the female both strongly reduced the chances that a mount would result in copulation. This reduction was not predicted by the male–male combat hypothesis but was predicted by the others. Males in the field did nave to fight other males to remain mounted on females, as expected by the male–male combat hypothesis. Reduced male copulatory success was not due to inferior male ability to grasp and hold onto the female's wings, as predicted by the mechanical fit and male–female conflict hypotheses but to a reduction in the likelihood that the female would allow intromission, as predicted by the stimulation hypothesis. By a process of elimination, and in combination with data from a previous morphological study, the data support the hypothesis that the species-specific aspects of grasping organs in these flies function to stimulate females. Further behavioral data will be needed to test alternative possibilities.     

Genetic differentiation in diapause response along a latitudinal cline in European yellow dung fly populations

Abstract.  1. Seasonality is a prime selective factor expected to result in local adaptation of life cycles and dormancy. Genetic differentiation in diapause response was investigated along a European latitudinal cline in the dung fly Scathophaga stercoraria (Diptera: Scathophagidae). Such differentiation may be mediated by additive or dominance genetic and/or maternal effects, which need to be distinguished.
2. Replicate sibships from five European populations (Lugano, Switzerland: 46.00°N; Zurich, Switzerland: 47.37°N; Oxford, U.K.: 51.75°N; Lund, Sweden: 55.70°N; Reykjavik, Iceland: 64.15°N) were raised in a common laboratory environment known to induce pupal winter diapause (12 °C and 12 h light), revealing a genetic latitudinal cline in both the proportion of individuals entering diapause and diapause duration in response to winter length estimated from weather data.
3. Populations from the extremes of the cline (Lugano and Reykjavik) were further reciprocally crossed to investigate the underlying genetics. This experiment revealed evidence for diapause induction at 12 °C being dominant (i.e. not merely additive) and clearly rejected maternal effects as the primary source of this between-population variation.     

Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis

Abstract. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v . 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.     

Persistent courtship reduces male and female longevity in captive tsetse flies Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

Where males can increase their mating success by harassing femalesuntil they accept copulation, harassing tactics can be expectedto evolve to a point where they have costs to the longevityof both sexes. By experimentally manipulating the sex ratioin captive groups of tsetse flies Glossina morsitans morsitans,we demonstrated that the longevity of females declines wheresex ratios are biased toward males, while the longevity of malesdeclines where the sex ratio is biased toward females. Neitherirradiation of males nor prevention of copulation by blockingor damaging the external male genitalia increased the longevityof females caged with them, suggesting that female longevitywas reduced by the physical aspects of male harassment ratherthan by components of the ejaculate     

Management of Fruit Flies (Diptera: Tephritidae) of the Most Perishable Fruits

We investigated to minimize the dependency on the use of chemicals and thus develop safe and environmental friendly control program for the most perishable fruits i.e., apple,‘ber’, guava and mango. Our findings on the composition of fruit fly species reveal that Bactrocera dorsalis was dominant on apple (33.96% existence), Corpomya incompleta on‘ber’(51.91% existence) and Bactrocera zonata on guava (49.62% existence) and mango (74.66% existence). The correlation between population and infestation percentage was non‐significant in apple orchards, whereas positive and highly significant in between population and infestation, as well as on the cumulative basis in‘ber’, guava and mango orchards during 1998‐1999. Hoeing, baiting and methyl eugenol were statistically equal resulting about 77% decrease in infestation. The maximum control of 91.68% was observed where all four‐control operations including Dipterex® were integrated together. Weather factors, when computed together, had maximum effect on population fluctuation and infestation with rainfall contributing the major role. For guava fruits, the months of August (14.06A individuals/trap/day) and September (13.81A individuals/trap/day) were important, resulting in maximum infestation percentage of 10.76 to 14.74%, respectively.     

New species of subgenus Tipula (Sivatipula) from China,with redescription of T. (S.) parvauricula and a key to all known species of the Oriental Region (Diptera,Tipulidae, Tipula)

Species of Tipula (Sivatipula) biprocessa sp. n. from Guangxi, China is described and illustrated as new in the subgenus Tipula (Sivatipula) Alexander, 1964. Tipula (Sivatipula) parvauricula Alexander, 1941 is redescribed and illustrated based on additional morphological characters. Semen pump of this subgenus is discussed. A key to all described species in this group is compiled.     

The Function of Hitchhiking Behavior in the Leaf‐cutting Ant Atta cephalotes1

In some leaf‐cutting ant species, minim workers ride on the fragments of leaves as they are carried back to the nest from the cutting site. There is convincing evidence that these “hitchhikers” can protect the leaf carriers from attack by phorid (Diptera: Phoridae) parasitoids, but we consider the possibility of other functions for the hitchhiking behavior. It has been hypothesized that the hitchhikers (1) feed on leaf sap from the edges of the cut leaves; (2) ride back to the nest to save energy; (3) get caught on the fragments as they are cut, and hitchhike because they cannot (or will not) get off; and (4) begin the process of preparing the leaf to enter the fungal gardens in the nest, perhaps by removing microbial contaminants. We observed hitchhikers of Atta cephalotes in 14 nests at the La Selva Biological Station in Costa Rica. There was no difference in the proportion of leaf carriers with hitchhikers between day and night. Because the nests we observed were largely nocturnal, more than 90 percent of the hitchhiking occurred at night. The phorid parasitoids are usually considered to be diurnal, so the preponderance of nocturnal hitchhiking suggests other functions in addition to parasitoid defense. Hitchhikers spent more time in the defensive head‐up posture during the day, but spent more time in the head‐down posture at night. The head‐down posture may indicate cleaning or other leaf preparation. The hitchhikers were never observed feeding on sap. Hitchhikers frequently got onto and off of the fragments, and so they were not “marooned.” Few hitchhikers rode all the way back to the nest and were often moving on the leaf fragment; these observations make the energy conservation hypothesis less likely, although we cannot reject it. We conclude that parasitoid defense is an important function of hitchhiking but also that there are probably other functions when parasitoids are absent. Based on available data, the most likely possibility is preparation of the leaf fragment before it enters the nest.     

用“增强子陷阱”技术构造并筛选果蝇UAS/GAL4系统中GAL4新品系及脑基因表达图谱数据库的开发

"增强子陷阱"技术是建立果蝇脑全基因组表达图谱及其数据库的重要方法.筛选获得新特异表达的GAL4品系,可为进一步研究果蝇脑神经在学习记忆功能提供强有力的基因工具.通过"增强子陷阱"技术来获得果蝇突变体,并与报告转基因果蝇(UAS-EGFP)杂交,用荧光显微镜观察成年果蝇脑内荧光分布,从而获得该突变体的脑基因表达图谱,在此基础上利用JavaScript来建立果蝇脑全基因组表达数据库.目前获得基因突变体果蝇2 677种,大部分在果蝇脑中有表达,其中在果蝇嗅觉学习记忆相关脑区蘑菇体表达的基因有368个,且有部分基因特异地表达在某些传导通路上.这些果蝇基因突变体库及其表达图谱为进一步研究各基因的功能及作为遗传工具来研究各脑区结构和功能提供极大方便.     

Biology of Bactrocera carambolae (Diptera: Tephritidae) on four hosts

Bactrocera carambolae is a quarantine pest found in Brazil, restricted to the states of Amapá, Pará and Roraima. This fruit fly can potentially cause extensive socioeconomic and environmental damage in the country, if it disperse into areas where fruit is grown for exporting. The objective of this work was to study the biology of B. carambolae on fruits of Averrhoa carambola L. (Oxalidaceae), Psidium guajava L. (Myrtaceae), Spondias mombin L. (Anacardiaceae) and Eugenia stipitata McVaugh (Myrtaceae). The following parameters were investigated: duration of egg-larva, pupal, egg-adult, pre-oviposition, oviposition and post-oviposition periods, pupal weight and viability, sex ratio, fecundity, fertility and longevity. All parameters except pupal weight, oviposition and post-oviposition period, egg fertility and sex ratio were influenced by the host plant on which the larvae were reared. The carambola fruit fly completes its development on all those hosts studied here, with the highest fecundities on A. carambola and P. guajava.