Localization of mating behavior of releasedBactrocera dorsalis flies on host fruit in an orchard

Oriental fruit flies,Bactrocera dorsalis, cultured in the laboratory for six generations, were released when 12–14 days old in an orchard of nonfruiting host trees that were furnished with either food and water, nonpunctured host fruit, punctured host fruit, or no resources. Nearly all flies of both sexes, all sexual behavior of males, and all mating pairs were observed on trees with fruit. Moreover, on trees with fruit, nearly all flies of both sexes, nearly all sexual behavior of males, and nearly all mating pairs occurred on the fruit itself rather than on the foliage or branches. In a subsequent test, both sexes were found to be strongly attracted to the odor of host fruit. For a polyphagous species of a tropical tephritid, these findings are the first to show a high level of male aggregation and a high amount of male sexual behavior on the fruit of host trees. Findings are discussed in relation to current knowledge of tephritid mating behavior. An additional quality-control test for laboratory cultured males used in the sterile insect technique of fly management is recommended.     

Thermal stress exposure of pupal oriental fruit fly has strong and trait-specific consequences in adult flies

Global climate change is projected to increase the incidence of heat waves, their magnitude and duration resulting in insects experiencing increasing environmental stress in both natural and managed ecosystems. While studies on insect thermal tolerance are rapidly increasing, variation across developmental or juvenile stress cross-stage effects within and across generations remain largely unexplored. Yet in holometabolous insects, heat stress at an early developmental stage may influence performance and survival during later stages. Here, we investigated the effects of pupal mild heat stress on the performance of laboratory-reared adult Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) measured as longevity, critical thermal maximum (CT_max), critical thermal minima (CT_min), heat knockdown time (HKDT) and chill coma recovery time (CCRT). Pupal heat stress significantly influenced performance of B. dorsalis adults resulting in impaired longevity and heat tolerance (CT_max and HKDT) in both sexes with improved and compromised cold tolerance (CT_min and CCRT) in females and males, respectively. These findings highlight the role of juvenile stages in mediating stress responses at adult stages. For B. dorsalis, pupal heat stress largely compromised thermal tolerance implying that the species has limited potential to shift its geographic range in heat prone areas. Significant benefits in cold tolerance in females following heat stress may help in improving survival in the cold in the short-term despite restricted activity to the same traits in males. This study suggests that basal heat tolerance and not short-term compensatory thermal plasticity following heat stress may have aided the recent invasion of B. dorsalis in African landscapes.     

柑橘大实蝇精巢、精泵和精泵内骨骼的生长发育状况

【目的】柑橘大实蝇是一种严重为害柑橘类果实的经济害虫。研究其精巢、精泵以及精泵内骨骼生长发育状况,有助于提高柑橘大实蝇人工繁殖效率以及其田间防治效果,为柑橘大实蝇的预测预报及防治提供理论基础。【方法】基于光学显微镜测量恒温和室温条件下柑橘大实蝇雄虫的精巢、精泵以及精泵内骨骼的长度和宽度,并建立其长度、宽度和指数的函数模型,比较恒温和室温2种饲养条件下其雄虫器官发育状况差异。【结果】无论是在恒温还是室温条件下饲养,随着柑橘大实蝇雄成虫日龄的增加,其精巢、精泵以及精泵内骨骼的长度、宽度和指数变化趋势均符合幂函数增长模型。在恒温和室温条件下,其雄虫的精巢宽度、精泵的长度和宽度以及指数、精泵内骨骼宽度均无明显差异。在室温条件下饲养的雄虫的精巢长度[(4.00±0.14) mm]及指数(3.40±0.14)、精泵内骨骼长度[(1.65±0.03) mm]及指数(1.84±0.08)均分别显著高于在恒温条件下饲养的雄虫的精巢长度[(3.75±0.13) mm]及指数(3.19±0.14)、精泵内骨骼长度[(1.61±0.03) mm]及指数(1.77±0.08)。【结论】变温(室温)比恒温更有利于柑橘大实蝇雄虫的精巢和精泵内骨骼的发育,并推荐使用精泵长度推断其雄虫日龄的方法。     

The transposable element mariner can excise in non-drosophilid insects

Plasmid-based excision assays performed in embryos of two non-drosophilid species using the mariner transposable element from Drosophila mauritiana resulted in empty excision sites identical to those observed after the excision of mariner from D. mauritiana chromosomes. In the presence of the autonomous mariner element Mos1, excision products were recovered from D. melanogaster, D. mauritiana and the blowfly Lucilia cuprina. When a hsp82 heat shock promoter-Mos1 construct was used to supply mariner transposase, excision products were also recovered from the Queensland fruitfly Bactrocera tryoni. Analysis of DNA sequences at empty excision sites led us to hypothesise that the mariner excision/repair process involves the formation of a heteroduplex at the excision breakpoint. The success of these assays suggests that they will provide a valuable tool for assessing the ability of mariner and mariner-like elements to function in non-drosophilid insects and for investigating the basic mechanisms of mariner excision and repair.     

Intercropping cucumber with amaranth (Amaranthus cruentus L.) to suppress populations of major insect pests of cucumber (Cucumis sativus L.)

A study was conducted in 2007 and 2008 to investigate the effectiveness of grain amaranth (Amaranthus cruentus L.) planted at different times in an amaranth/cucumber intercrop to reduce the density of cucumber insect pests. Cucumber varieties, Marketmore and hybrid F_1, were established from seed as a monocrop or intercropped with amaranth, and with amaranth established at two weeks before cucumber (2 WBC) on the same day as cucumber (SDC) or two weeks after cucumber (2 WAC). The population of cucumber beetles and fruit flies was lower with amaranth established 2 WBC and SDC than with 2 WAC. Populations of the insects were influenced by cropping system and time of introducing amaranth. Fruit damage by cucumber beetles and fruit flies was lower with 2 WBC and SDC than with 2 WAC. However, the damage was reduced in the intercrop compared with the monocropped cucumber. With SDC, the reduction was about 75 and 50% in 2007 and 2008, respectively. In intercrops and monocrops, cucumber fruit yield was influenced by the time of inter-cropping; in the mono- and inter-crop, the highest yield was with SDC. The highest land equivalent ratios for cucumber were 1.0 and 0.7 in 2007 and 2008, respectively, with SDC. Planting amaranth and cucumber on the same day (SDC) achieved effective control of cucumber insect pests.     

The effect of dietary restriction on longevity,fecundity, and antioxidant responses in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Recent studies in fruit flies have imposed dietary restriction (DR) by diluting yeast and have reported increased lifespan as the yeast-to-sugar ratio decreased. In this study, the effects of DR on the lifespan of Bactrocera dorsalis were investigated using constant-feeding diets with different yeast:sugar ratios and an intermittent-feeding diet in which flies ate every sixth day. Antioxidant enzyme activities and the malondialdehyde concentration were also measured in virgin females under constant-feeding DR protocols to investigate their relationships with lifespan. The results showed that B. dorsalis lifespan was significantly extended by DR, and carbohydrate-enriched diet may be important for lifespan-extension. Female flies lived significantly longer than males at all dietary levels under both feeding regimes, indicating no interaction between diet and sex in determining lifespan. Antioxidant enzyme activities increased with the amount of yeast increased in the diets (0–4.76%) between starvation and DR treatments, indicating that the antioxidants may have influences in determining lifespan in B. dorsalis under starvation and DR treatments. However, antioxidants cannot keep up with increased oxidative damage induced by the high yeast diet (25%). These results revealed that the extension of lifespan by DR is evolutionarily conserved in B. dorsalis and that yeast:sugar ratios significantly modulate lifespan in this species.     

Female‐borne cues affecting Psyttalia concolor (Hymenoptera: Braconidae) male behavior during courtship and mating

Knowledge of the mechanisms that regulate courtship and mating behavior in Psyttalia concolor (Szépligeti)–a koinobiont endophagous solitary parasitoid of the olive fruit fly, Bactrocera oleae (Rossi), and of other fruit flies–is essential to its mass rearing and management. Augmentative releases of P. concolor for olive fruit fly control started in the Mediterranean areas in the 1950s and still continue with limited success. We determined the influence of visual and chemical cues on courtship and mating behavior of this braconid and the possible effect of the mating status of males and females in the perception of these cues. Our results suggest that integration of visual and chemical stimuli are fundamental for mate location and courtship. Indeed, the optimal response of the male was achieved when physical and chemical cues were simultaneously presented and vision and olfaction worked synergistically.     

海南儋州地区橘小实蝇成虫数量动态

【背景】橘小实蝇是热带、亚热带水果的重要害虫,在海南发生严重。【方法】利用橘小实蝇性诱剂进行田间诱捕,以诱到的雄成虫为指标,通过定期调查,获得了海南儋州地区4种样地橘小实蝇成虫的种群动态,并进一步通过相关分析,研究了芒果园橘小实蝇种群动态与温度和降雨量的相关性。【结果】儋州地区橘小实蝇种群周年发生,冬季种群数量较低,夏季种群数量较高。橘小实蝇种群高峰期发生于6月,其中芒果园达327.6头,蔬菜地为182.8头,办公区为150.0头,植物园为209.6头。在芒果园中,随着温度的升高,橘小实蝇的种群数量呈指数增长,其相关系数R=0.799;而与降雨量的相关系数较低,为0.367。【结论与意义】本研究可为儋州地区制定橘小实蝇综合防治策略提供理论依据。