Spatial relationships between shearing stresses and pressure on the plantar skin surface during gait

Based on the hypothesis that diabetic foot lesions have a mechanical etiology, extensive efforts have sought to establish a relationship between ulcer occurrence and plantar pressure distribution. However, these factors are still not fully understood. The purpose of this study was to simultaneously record shear and pressure distributions in the heel and forefoot and to answer whether: (i) peak pressure and peak shear for anterior-posterior (AP) and medio-lateral (ML) occur at different locations, and if (ii) peak pressure is always centrally located between sites of maximum AP and ML shear stresses. A custom built system was used to collect shear and pressure data simultaneously on 11 subjects using the 2-step method. The peak pressure was found to be 362 kPa ± 106 in the heel and 527 kPa ± 123 in the forefoot. In addition, the average peak shear values were higher in the forefoot than in the heel. The greatest shear on the plantar surface of the forefoot occurred in the anterior direction (mean and std. dev.: 37.7 ± 7.6 kPa), whereas for the heel, peak shear the foot was in the posterior direction (21.2 ± 5 kPa). The results of this study suggest that the interactions of the shear forces caused greater "spreading" in the forefoot and greater tissue "dragging" in the heel. The results also showed that peak shear stresses do not occur at the same site or time as peak pressure. This may be an important factor in locating where skin breakdown occurs in patients at high-risk for ulceration.     

Development and validation of a kinematically-driven discrete element model of the patellofemoral joint

Quantifying the complex loads at the patellofemoral joint (PFJ) is vital to understanding the development of PFJ pain and osteoarthritis. Discrete element analysis (DEA) is a computationally efficient method to estimate cartilage contact stresses with potential application at the PFJ to better understand PFJ mechanics. The current study validated a DEA modeling framework driven by PFJ kinematics to predict experimentally-measured PFJ contact stress distributions. Two cadaveric knee specimens underwent quadriceps muscle [215 N] and joint compression [350 N] forces at ten discrete knee positions representing PFJ positions during early gait while measured PFJ kinematics were used to drive specimen-specific DEA models. DEA-computed contact stress and area were compared to experimentally-measured data. There was good agreement between computed and measured mean and peak stress across the specimens and positions (r = 0.63–0.85). DEA-computed mean stress was within an average of 12% (range: 1–47%) of the experimentally-measured mean stress while DEA-computed peak stress was within an average of 22% (range: 1–40%). Stress magnitudes were within the ranges measured (0.17–1.26 MPa computationally vs 0.12–1.13 MPa experimentally). DEA-computed areas overestimated measured areas (average error = 60%; range: 4–117%) with magnitudes ranging from 139 to 307 mm² computationally vs 74–194 mm² experimentally. DEA estimates of the ratio of lateral to medial patellofemoral stress distribution predicted the experimental data well (mean error = 15%) with minimal measurement bias. These results indicate that kinematically-driven DEA models can provide good estimates of relative changes in PFJ contact stress.     

Simple finite element models for use in the design of therapeutic footwear

Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to relieve or redistribute high plantar pressures in the region of the metatarsal heads. Few guidelines exist as to how these interventions should be designed and what effect such interventions actually have on the plantar pressure distribution. Finite element analysis has the potential to assist in the design process by refining a given intervention or identifying an optimal intervention without having to actually build and test each condition. However, complete and detailed foot models based on medical image segmentation have proven time consuming to build and computationally expensive to solve, hindering their utility in practice. Therefore, the goal of the current work was to determine if a simplified patient-specific model could be used to assist in the design of foot orthoses to reduce the plantar pressure in the metatarsal head region. The approach is illustrated by a case study of a diabetic patient experiencing high pressures and pain over the fifth metatarsal head. The simple foot model was initially calibrated by adjusting the individual loads on the metatarsals to approximate measured peak plantar pressure distributions in the barefoot condition to within 3%. This loading was used in various shod conditions to identify an effective orthosis. Model results for metatarsal pads were considerably higher than measured values but predictions for uniform surfaces were generally within 16% of measured values. The approach enabled virtual prototyping of the orthoses, identifying the most favorable approach to redistribute the patient’s plantar pressures.     

Effect of a Double Helical Spring Decompression Structure Backpack on the Lumbar Spine Biomechanics of School-Age Children: A Finite Element Study

Background: A children’s backpack is one of the important school supplies for school-age children. Long-term excessive weight can cause spinal deformity that cannot be reversed. This study compared a double helical spring decompression structure backpack (DHSB) with a traditional backpack (TB) to explore the optimization of decompression devices on upper body pressure. The finite element (FE) method was then used to explore the simulation of lumbar stress with different backpacks, in order to prove that DHSB can reduce the influence of backpack weight on lumbar vertebrae, avoid the occurrence of muscle discomfort and spinal deformity in children; Methods: 18 male children subjects (age: 12.5 ± 0.6 years; height: 145.5 ± 1.9 cm; bodyweight: 40.8 ± 3.1 kg) ran with DHSB and TB at a speed of 3.3 ± 0.2 m/s. Flexible pressure sensors were used to measure the pressure on the shoulder, back, and waist during running. The pressure data was then inputted into the FE model to simulate the effect of carrying different backpacks on the stress of the lumbar intervertebral disc (IVD); Result: There was a significant difference in shoulder and waist peak pressure between the DHSB and TB during the running posture. At a speed of 3.3 ± 0.2 m/s, the peak pressure of the shoulder and waist decreased. After finite element analysis, it was found that carrying DHSB on the back could effectively reduce the intervertebral disc pressure between L4-5 and L5-S1 by 27.9% and 34.1%, respectively; Conclusion: DHSB can effectively reduce the pressure on the shoulder and waist when children are running and can reduce the influence of backpacks on children’s posture to a certain extent. By finite element analysis, it is found that carrying DHSB can effectively reduce the stress of the lumbar intervertebral disc, and the damage to lumbar vertebrae is lower than with a TB.     

Abnormalities of low density lipoproteins in normolipidemic type II diabetic and nondiabetic patients with coronary artery disease.

The characteristics of low density lipoproteins (LDL) of ten non-insulin-dependent diabetic (NIDDM) and ten nondiabetic patients with coronary artery disease (CAD) were investigated and compared to LDL of ten NIDDM patients without CAD and ten healthy persons. All subjects had LDL cholesterol below 160 mg/dl and serum triglycerides below 200 mg/dl. The mean LDL particle size and particle distribution profiles were analyzed by using nondenaturing polyacrylamide gradient gel electrophoresis. The LDL composition and hydrated density distribution were investigated by using density gradient ultracentrifugation. Both NIDDM and nondiabetic CAD patients tended to have larger LDL particles than NIDDM patients without CAD and healthy subjects. The increase of LDL particle size of CAD patients was due to marked enrichment of triglycerides (TG) in their LDL. The percentage content of TG in LDL of NIDDM patients with CAD was 14.5% and in LDL of nondiabetic CAD patients 13.4% compared with 7.9% in LDL of NIDDM patients without CAD and 7.2% in normal-LDL (P less than 0.05 or less between either CAD group and NIDDM without CAD or normals). The LDL TG/apolipoprotein (apo) B weight ratio was significantly higher in both CAD groups compared with LDL of the two groups without CAD (0.70 and 0.68 vs. 0.38 and 0.34, respectively, P less than 0.05, P less than 0.05 and P less than 0.01, P less than 0.01). The LDL total lipid to apoB weight ratio was similar in all four groups. Consistent with this, the hydrated density distributions of LDL in the four groups were similar, the average peak densities being 1.0346 g/ml, 1.0331 g/ml, 1.0331 g/ml, and 1.0331 g/ml, respectively. The findings of this study demonstrate that normolipidemic patients with CAD may have marked abnormalities in th eir LDL composition and these anomalies are present in both diabetic and nondiabetic patients.     

Discrete element analysis is a valid method for computing joint contact stress in the hip before and after acetabular fracture

Evaluation of abnormalities in joint contact stress that develop after inaccurate reduction of an acetabular fracture may provide a potential means for predicting the risk of developing post-traumatic osteoarthritis. Discrete element analysis (DEA) is a computational technique for calculating intra-articular contact stress distributions in a fraction of the time required to obtain the same information using the more commonly employed finite element analysis technique. The goal of this work was to validate the accuracy of DEA-computed contact stress against physical measurements of contact stress made in cadaveric hips using Tekscan sensors. Four static loading tests in a variety of poses from heel-strike to toe-off were performed in two different cadaveric hip specimens with the acetabulum intact and again with an intentionally malreduced posterior wall acetabular fracture. DEA-computed contact stress was compared on a point-by-point basis to stress measured from the physical experiments. There was good agreement between computed and measured contact stress over the entire contact area (correlation coefficients ranged from 0.88 to 0.99). DEA-computed peak contact stress was within an average of 0.5 MPa (range 0.2–0.8 MPa) of the Tekscan peak stress for intact hips, and within an average of 0.6 MPa (range 0–1.6 MPa) for fractured cases. DEA-computed contact areas were within an average of 33% of the Tekscan-measured areas (range: 1.4–60%). These results indicate that the DEA methodology is a valid method for accurately estimating contact stress in both intact and fractured hips.     

Effects of<Emphasis Type="Italic">Nigella sativa</Emphasis> and human parathyroid hormone on bone mass and strength in diabetic rats

Osteoporosis is a major complication in patients with diabetes mellitus (DM), particularly in those with insulin dependency. Recently, many therapeutic effects ofNigella sativa L. (NS) extracts have been exhibited such as anti-inflammatory, antitumor, and antidiabetic with clinical and experimental studies. Mechanical strength in the femur and vertebrae increases with human parathyroid hormone (hPTH) treatment. The aim of the present study was to test the hypothesis that combined treatment with NS and hPTH is more effective than treatment with NS or hPTH alone in improving bone mass, connectivity, and biomechanical behavior using the finite element method (FEM) in insulin-dependent diabetic rats. In the mechanical analysis, five rat bones (control, diabetic diabetic NS treated, diabetic hPTH treated, and diabetic NS + hPTH treated) have been studied for bending analysis using the finite element analysis program ANSYS. Combined treatment of NS and hPTH was more effective on bone histomorphometry and mechanical strength than treatment with NS or hPTH alone for streptozotocin-induced diabetic osteopenia, which notably decreased bone volume.     

Modelling stress in the feeding apparatus of seahorses and pipefishes (Teleostei: Syngnathidae)

Seahorses and pipefishes are extremely fast suction feeders, and the fast strikes probably result in large and rapid pressure drops in the buccal cavity. These rapid drops in pressure imply heavy mechanical loading on the cranium; hence, the feeding apparatus is thought to experience high levels of stress. We used finite element analysis (FEA) to investigate where stress accumulates under strong suction pressure, and whether there is a difference in craniofacial stress distribution between long‐ and short‐snouted species. The expectation was that high stress levels would occur at the articulations and in the cartilaginous regions of the cranium, and that, given the same pressure, the skulls of long‐snouted species would exhibit lower stress levels than the skulls of short‐snouted species, as an evolutionary increase in snout length might have made these species structurally better adapted to deal with high suction pressures. The results partially support the first hypothesis: except for Dunckerocampus dactyliophorus, all models show peak stress concentrations at the articulations and cartilaginous regions. However, no simple relationship between snout length and the magnitudes of stress predicted by the FEA was found. In an attempt to explain this lack of a relationship, the methodology was evaluated by assessing the effect of hyoid position and model construction on the stress distribution. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 680–691.     

Finite element models of the thigh-buttock complex for assessing static sitting discomfort and pressure sore risk: a literature review

Being seated for long periods, while part of many leisure or occupational activities, can lead to discomfort, pain and sometimes health issues. The impact of prolonged sitting on the body has been widely studied in the literature, with a large number of human-body finite element models developed to simulate sitting and assess seat-induced discomfort or to investigate the biomechanical factors involved. Here, we review the finite element models developed to investigate sitting discomfort or risk of pressure sores. Our study examines finite element models from twenty-seven papers, seventeen dedicated to assessing seating discomfort and ten dedicated to investigating pressure ulcers caused by prolonged sitting. The models’ mesh composition and material properties are found to differ widely. These models share a lack of validation and generally make little allowance for anthropometric diversity.     

Image-based midsole insert design and the material effects on heel plantar pressure distribution during simulated walking loads

The primary objective of this paper is to study the use of medical image-based finite element (FE) modelling in subject-specific midsole design and optimisation for heel pressure reduction using a midsole plug under the calcaneus area (UCA). Plugs with different relative dimensions to the size of the calcaneus of the subject have been incorporated in the heel region of the midsole. The FE foot model was validated by comparing the numerically predicted plantar pressure with biomechanical tests conducted on the same subject. For each UCA midsole plug design, the effect of material properties and plug thicknesses on the plantar pressure distribution and peak pressure level during the heel strike phase of normal walking was systematically studied. The results showed that the UCA midsole insert could effectively modify the pressure distribution, and its effect is directly associated with the ratio of the plug dimension to the size of the calcaneus bone of the subject. A medium hardness plug with a size of 95% of the calcaneus has achieved the best performance for relieving the peak pressure in comparison with the pressure level for a solid midsole without a plug, whereas a smaller plug with a size of 65% of the calcaneus insert with a very soft material showed minimum beneficial effect for the pressure relief.     

Investigation of pediatric neck response and muscle activation in low-speed frontal impacts

Pediatric necks present different responses and injury patterns compared with those of adults in motor vehicle crashes (MVCs). To evaluate the effect of different muscle modeling methodologies, three muscle models were developed and simulated under low-speed frontal impact conditions with an average peak acceleration of 3g's. The muscle activation curve for the curve-guided model, the muscle segment was curved using guiding nodes, was further optimized based on experimental data. The pediatric neck model was also simulated under more severe frontal impact conditions with an average peak acceleration of 8g's. Simulation results revealed that the curve-guided model needed more muscle force than the straight-guided model, in which the muscle segment was straight with guiding nodes, and the curve-constrained model, in which the muscle segment was curved without guiding nodes and which imposes more constraints on the head and neck than the curve-guided model. The predicted head responses for the child finite element neck model were within or close to the experimental corridors of 3- and 8-g's frontal impacts. The neck injuries for a 10-year-old child commonly occurred at the interspinous ligament in the C7–T1 segment. The model could be used to analyze the responses and injuries of pediatric neck and head in low-speed frontal impacts.     

Prediction of peak pressure from clinical and radiological measurements in patients with diabetes

Background

Various structural and functional factors of foot function have been associated with high local plantar pressures. The therapist focuses on these features which are thought to be responsible for plantar ulceration in patients with diabetes. Risk assessment of the diabetic foot would be made easier if locally elevated plantar pressure could be indicated with a minimum set of clinical measures.

Methods

Ninety three patients were evaluated through vascular, orthopaedic, neurological and radiological assessment. A pressure platform was used to quantify the barefoot peak pressure for six forefoot regions: big toe (BT) and metatarsals one (MT-1) to five (MT-5). Stepwise regression modelling was performed to determine which set of the clinical and radiological measures explained most variability in local barefoot plantar peak pressure in each of the six forefoot regions. Comprehensive models were computed with independent variables from the clinical and radiological measurements. The difference between the actual plantar pressure and the predicted value was examined through Bland-Altman analysis.

Results

Forefoot pressures were significant higher in patients with neuropathy, compared to patients without neuropathy for the whole forefoot, the MT-1 region and the MT-5 region (respectively 138 kPa, 173 kPa and 88 kPa higher: mean difference). The clinical models explained up to 39 percent of the variance in local peak pressures. Callus formation and toe deformity were identified as relevant clinical predictors for all forefoot regions. Regression models with radiological variables explained about 26 percent of the variance in local peak pressures. For most regions the combination of clinical and radiological variables resulted in a higher explained variance. The Bland and Altman analysis showed a major discrepancy between the predicted and the actual peak pressure values.

Conclusion

At best, clinical and radiological measurements could only explain about 34 percent of the variance in local barefoot peak pressure in this population of diabetic patients. The prediction models constructed with linear regression are not useful in clinical practice because of considerable underestimation of high plantar pressure values. Identification of elevated plantar pressure without equipment for quantification of plantar pressure is inadequate. The use of quantitative plantar pressure measurement for diabetic foot screening is therefore advocated.     

Duration of Type I Diabetes Affects Glucagon and Glucose Responses to Insulin-Induced Hypoglycemia

The glucagon response to hypoglycemia, which fulfills a primary role toward restoring the plasma glucose level, is blunted or absent in most patients with type I diabetes. To identify predictive factors for this abnormality and for the capability of glycemic counterregulation, we investigated the relationship between the duration of diabetes and glucagon and glucose responses to insulin-induced hypoglycemia. In 18 type I diabetic patients with 1 through 28 years of disease who had no detectable autonomic neuropathy, individual glucagon increments after insulin hypoglycemia were inversely correlated with the duration of disease (r = -.53, P < .025). Patients with disease for ten or fewer years showed a glucagon rise that was lower than in controls but significantly higher than in patients with a duration of more than ten years. The plasma glucose rise after the nadir correlated with peak glucagon increments (r = .60, P < .01); eight of the nine patients with glycemic increments comparable to normals had had diabetes for ten years or less. Thus, having diabetes for more than ten years implied that not only were glucagon responses to insulin hypoglycemia severely compromised but also that the abrupt restoration of plasma glucose levels was impaired. These findings should be taken into account when establishing goals and modalities for tight metabolic control.     

Heel-shoe interactions and the durability of EVA foam running-shoe midsoles

A finite element analysis (FEA) was made of the stress distribution in the heelpad and a running shoe midsole, using heelpad properties deduced from published force-deflection data, and measured foam properties. The heelpad has a lower initial shear modulus than the foam (100 vs. 1050 kPa), but a higher bulk modulus. The heelpad is more non-linear, with a higher Ogden strain energy function exponent than the foam (30 vs. 4). Measurements of plantar pressure distribution in running shoes confirmed the FEA. The peak plantar pressure increased on average by 100% after 500 km run. Scanning electron microscopy shows that structural damage (wrinkling of faces and some holes) occurred in the foam after 750 km run. Fatigue of the foam reduces heelstrike cushioning, and is a possible cause of running injuries.     

Effects of anterior offsetting of humeral head component in posteriorly unstable total shoulder arthroplasty: Finite element modeling of cadaver specimens

A novel technique of “anterior offsetting” of the humeral head component to address posterior instability in total shoulder arthroplasty has been proposed, and its biomechanical benefits have been previously demonstrated experimentally. The present study sought to characterize the changes in joint mechanics associated with anterior offsetting with various amounts of glenoid retroversion using cadaver specimen-specific 3-dimensional finite element models. Specimen-specific computational finite element models were developed through importing digitized locations of six musculotendinous units of the rotator cuff and deltoid muscles based off three cadaveric shoulder specimens implanted with total shoulder arthroplasty in either anatomic or anterior humeral head offset. Additional glenoid retroversion angles (0°, 10°, 20°, and 30°) other than each specimen׳s actual retroversion were modeled. Contact area, contact force, peak pressure, center of pressure, and humeral head displacement were calculated at each offset and retroversion for statistical analysis. Anterior offsetting was associated with significant anterior shift of center of pressure and humeral head displacement upon muscle loading (p<0.05). Although statistically insignificant, anterior offsetting was associated with increased contact area and decreased peak pressure (p > 0.05). All study variables showed significant differences when compared between the 4 different glenoid retroversion angles (p < 0.05) except for total force (p < 0.05). The study finding suggests that the anterior offsetting technique may contribute to joint stability in posteriorly unstable shoulder arthroplasty and may reduce eccentric loading on glenoid components although the long term clinical results are yet to be investigated in future.     

Abnormal Glomerular Filtration Rate,Renal Plasma Flow,and Renal Protein Excretion in Recent and Short-term Diabetics

Glomerular filtration rate and renal plasma flow were simultaneously determined in comparable groups of 43 diabetics less than 40 years of age and with a duration of diabetes less than 10 years and 32 control subjects. The average glomerular filtration rate in the diabetic group was significantly higher than that in the control group (P <0·01). The average renal plasma flow in the diabetic group was found to be significantly lower than that in the control group (P <0·05). The filtration fraction in both male and female diabetics was significantly higher than in the male and female control groups (P <0·001). These changes were found to be present even in recent juvenile diabetics with disease of a duration of less than one year. No correlation was apparent between the average levels of serum growth hormone and glomerular filtration rate.The urinary protein excretion was determined in 36 diabetic and 38 healthy subjects comparable with regard to glomerular filtration rate. In the diabetic group there was a greater frequency of cases with higher protein excretion rates (P <0·02). The average protein excretion rate was increased even in diabetics with less than one year''s duration of the disease.The results of the changes in renal haemodynamics in subjects with recent and short-term diabetes are compatible with the presence of a constrictive state of the vas efferens leading to an increase in the filtration pressure. The increase in protein excretion rate may similarly be a consequence of this process or of an increase in the glomerular permeability with augmented molecular sieving of proteins or both.     

Development and validation of a computational model of the knee joint for the evaluation of surgical treatments for osteoarthritis

A three-dimensional (3D) knee joint computational model was developed and validated to predict knee joint contact forces and pressures for different degrees of malalignment. A 3D computational knee model was created from high-resolution radiological images to emulate passive sagittal rotation (full-extension to 65°-flexion) and weight acceptance. A cadaveric knee mounted on a six-degree-of-freedom robot was subjected to matching boundary and loading conditions. A ligament-tuning process minimised kinematic differences between the robotically loaded cadaver specimen and the finite element (FE) model. The model was validated by measured intra-articular force and pressure measurements. Percent full scale error between FE-predicted and in vitro-measured values in the medial and lateral compartments were 6.67% and 5.94%, respectively, for normalised peak pressure values, and 7.56% and 4.48%, respectively, for normalised force values. The knee model can accurately predict normalised intra-articular pressure and forces for different loading conditions and could be further developed for subject-specific surgical planning.     

Shear and pressure under the first ray in neuropathic diabetic patients: Implications for support of the longitudinal arch

ObjectiveTo assess dynamic arch support in diabetic patients at risk for Charcot neuroarthopathy whose arch index has not yet shown overt signs of foot collapse.MethodsTwo indirect measures of toe flexor activation (ratios: peak hallux pressure to peak metatarsal pressure – Ph/Pm; peak posterior hallux shear to peak posterior metatarsal shear – Sh/Sm) were obtained with a custom built system for measuring shear and pressure on the plantar surface of the foot during gait. In addition, the tendency of the longitudinal arch to flatten was measured by quantifying the difference in shear between the 1st metatarsal head and the heel (S_flatten) during the first half of the stance phase. Four stance phases from the same foot for 29 participants (16 control and 13 neuropathic diabetic) were assessed.ResultsThe peak load ratio under the hallux (Ph/Pm) was significantly higher in the control group (2.10±1.08 versus 1.13±0.74, p=0.033). Similarly, Sh/Sm was significantly higher in the control group (1.87±0.88 versus 0.88±0.45, p=0.004). The difference in anterior shear under the first metatarsal head and posterior shear under the lateral heel (S_flatten) was significantly higher in the diabetic group (p<0.01). Together these findings demonstrate reduced plantar flexor activity in the musculature responsible for maintaining the longitudinal arch.ConclusionsWith no significant difference in arch index between the two groups, but significant differences in Ph/Pm, Sh/Sm and S_flatten the collective results suggest there are changes in muscle activity that precede arch collapse.     

Subject-specific finite element modelling of the human foot complex during walking: sensitivity analysis of material properties,boundary and loading conditions

The objective of this study was to develop and validate a subject-specific framework for modelling the human foot. This was achieved by integrating medical image-based finite element modelling, individualised multi-body musculoskeletal modelling and 3D gait measurements. A 3D ankle–foot finite element model comprising all major foot structures was constructed based on MRI of one individual. A multi-body musculoskeletal model and 3D gait measurements for the same subject were used to define loading and boundary conditions. Sensitivity analyses were used to investigate the effects of key modelling parameters on model predictions. Prediction errors of average and peak plantar pressures were below 10% in all ten plantar regions at five key gait events with only one exception (lateral heel, in early stance, error of 14.44%). The sensitivity analyses results suggest that predictions of peak plantar pressures are moderately sensitive to material properties, ground reaction forces and muscle forces, and significantly sensitive to foot orientation. The maximum region-specific percentage change ratios (peak stress percentage change over parameter percentage change) were 1.935–2.258 for ground reaction forces, 1.528–2.727 for plantar flexor muscles and 4.84–11.37 for foot orientations. This strongly suggests that loading and boundary conditions need to be very carefully defined based on personalised measurement data.     

重庆地区柑桔大实蝇系统监测研究

柑桔大实蝇Bactrocera minax是柑桔类植物果实的重要害虫,以往对该虫的发生监测仅局限于通过果园诱集和室内外养蛹监测成虫的发生期。本研究综合应用室外养蛹、桔园系统调查、成虫诱集和蛆果解剖等技术手段,以期了解柑桔大实蝇的产卵进度、幼虫发育进度、蛆果落地进度、幼虫化蛹进度以及蛹的羽化进度。研究结果表明,重庆地区柑桔大实蝇产卵盛期为6月下旬-7月上旬,高峰期为6月下旬末-7月初;一龄、二龄和三龄幼虫的发生盛期分别为9月中旬-10月初、10月上旬-下旬和10月中旬-11月初;受害蛆果落地盛期为10月上旬-下旬,与二龄和三龄幼虫的发生盛期吻合;室外养蛹的成虫羽化盛期为5月上旬-中旬末,但果园成虫诱集的盛期为6月中旬-下旬,较室外养蛹的成虫发生盛期推迟30 d左右,对出现此种情况的原因作者做了初步分析。研究结果还表明,各虫态的累计发生进度均可用逻辑斯缔方程拟合,从而可计算出各虫态发生进度为16%、50%和84%的始盛期、高峰期和盛末期。研究结果对于柑桔大实蝇的发生期预测和防治具有重要指导意义。