Economic Thresholds of Western Flower Thrips (Thysanoptera: Thripidae) for Unripe Red Pepper in Greenhouse

This study was conducted to develop economic thresholds of western flower thrips (Frankliniella occidentalis Pergande) for unripe red pepper in greenhouses. To investigate the relationship between the density of thrips and resulting damages, experimental plots with five treatments (0, 4, 16, 48, 96 adults per plot) as initial release densities were established at the National Institute of Agricultural Science and Technology, Suwon, Korea, in 2004. Western flower thrips density was monitored using flower samplings and yellow sticky trap (8×13 cm) counts. Western flower thrips density was directly related to increased numbers of damaged fruits and reduced fruit yield. The number of marketable fruits produced decreased as the thrips densities increased. The major damage to pepper fruits caused by thrips was cosmetic scars that resulted from immature feeding. When flower samples or yellow trap caches were used to determine the density of thrips, which were collected on a previous sampling date, thrips densities were determined to be related to the percentage of fruits that were damaged, and a significant relationship was found for the flower samples (y = 0.3219x + 1.0792, r² = 0.8640 and for trap catches (y = 11.9209 log(x) −2.158, r² = 0.8306). The economically-tolerable ratio of damaged fruits based on control cost and market values under current greenhouse cultivation was estimated as 3.4 to 8.0%. Economic thresholds of western flower thrips ranged from 0.7 to 2.1 adults or nymphs per flower, and 2.3 to 5.7 adults per four-day sticky card count.     

Odour-baited traps influence thrips capture in proximal unbaited traps in the field

Two field experiments examined the distance over which an attractant odour of a volatile chemical could influence thrips capture in proximal traps that were without the odour. In each experiment a star‐shaped array of water traps consisted of a centre trap with or without an odour surrounded by odourless traps at 0.5, 1, 2, 5, and 10 m in eight equally spaced radial arms 45° apart. Experiments ran for 47 h (centre trap: ethyl nicotinate) or 7 h (centre trap: ethyl isonicotinate). Each had four replicates. With ethyl nicotinate, more thrips were trapped in the centre‐baited traps than in the unbaited centre traps (63×, 7×, 98× and 200× for total thrips, Thrips tabaci Lindeman ♀, and Thrips obscuratus Crawford ♀and ♂, respectively) (Thysanoptera: Thripidae). More total thrips and T. tabaci♀ were trapped in the centre traps baited with ethyl isonicotinate than in unbaited centre traps (21× for both). For ethyl nicotinate, numbers of T. obscuratus in unbaited traps downwind from the baited centre trap declined by 50% within 0.4 m (♀) and 2 m (♂) and by 95% within 3 m (both ♀ and ♂) based on model predictions. For ethyl isonicotinate, numbers of T. tabaci in unbaited traps downwind from the baited centre trap declined by 50% within 1.3 m and by 95% within 10 m based on model predictions. Wind direction was an important factor in the degree and direction of thrips capture with the highest thrips capture downwind from the centre trap with odour. There was no increase in numbers of T. tabaci in any traps without odour in the ethyl nicotinate‐centred array. Differences in trapping patterns between thrips species and odours indicated that there were thrips species–odour specific interactions. Experiments examining differences between traps with and without a thrips attractant odour need to be designed very carefully to ensure meaningful results especially in enclosed and/or low‐wind indoor situations.     

Variety,mulch and stage of inoculation effects on incidence of tomato spotted wilt virus disease in cucumber (Cucumis sativus L.)

Abstract

Tomato spotted wilt virus (TSWV) vectored by thrips is one of the major diseases affecting cucumber yield. Control of thrips is an underlying factor in its management. A study was conducted to determine the effect of time of inoculation, variety and mulch on disease incidence. Four varieties were inoculated with TSWV at cotyledon, 3 – 4 leaf and flower bud stages in a RCBD experiment replicated four times in a greenhouse. In the field, a 2×8 factorial design where two cucumber varieties were raised on seven types of mulches (red, yellow, silver, clear, black, white, and straw) with unmulched plots as controls was used. Variety Marketer was more tolerant to the disease compared to other varieties. Most varieties were generally tolerant to TSWV at cotyledonous but susceptible at 3 – 4 leaf and flower bud stages. Silver and clear mulches significantly suppressed thrip populations, yield and quality under field conditions.     

Selenium Level Surveillance for the Year 2007 of Keshan Disease in Endemic Areas and Analysis on Surveillance Results Between 2003 and 2007

Selenium deficiency is widely accepted as a fundamental cause of Keshan disease (KD). In the present study, the selenium levels of hair and food samples of KD in some endemic areas were measured; the prevalence and incidence of KD for the year 2007 in these areas were surveyed. The results for KD surveillance from 2003 to 2007 were analyzed. The selenium level was measured fluorometrically. In 2007, a total of 19,280 residents were surveyed in 15 provinces. The prevalence and incidence of KD were 3.0% and 4.9‰, respectively. In KD and control subjects, the mean levels of hair selenium were respectively 0.3223 mg/kg and 0.4466 mg/kg. The mean level of staple food selenium was 0.0227?±?0.0144 mg/kg. During the 5 years, the selenium content in hair was always kept at a normal level within inhabitants of KD-endemic areas, but that in staple food was always kept at a lower level. These results indicate that the pathogenic factor has not been drastically eliminated even with the increasing selenium level of internal environment and is still continually damaging public health of KD in endemic areas. Since KD is still a serious threat to public health in its endemic areas, it is of great importance to pay attention to the prevention and control of this disease.     

Spatiotemporal Dynamics of Zucchini Squash Lethal Chlorosis and its Relationship with the Frankliniella zucchini Population

Lethal chlorosis of cucurbits, caused by the tospovirus Zucchini lethal chlorosis virus (ZLCV), is an important disease in the Brazilian zucchini squash crop. The virus is transmitted by the thrips Frankliniella zucchini. Progress of the disease in time and space was studied in zucchini squash experimental fields to better understand disease epidemiology. Nine independent experiments were carried out between December 2006 and September 2010. The effects of the disease were assessed every 2–7 days, depending on the experiment. The thrips population was monitored in five of these experiments. For disease progress over time, four models (exponential, monomolecular, logistic and Gompertz) were tested. Disease progress in space analysis included both the index of dispersion and Taylor's power law. The monomolecular model was the best fit to the disease incidence data, and spatial analysis indicated aggregated diseased plants at the end of the season in most experiments. A correlation was detected between the number of collected thrips and the incidence of zucchini squash lethal chlorosis. The results indicate that the thrips population significantly contributed to the primary spread of disease incidence. We propose that disease management should focus mainly on the elimination of the source of the inoculum.     

Trace element concentration and arsenic speciation in the well water of a Taiwan area with endemic Blackfoot disease

Blackfoot disease is a peripheral vascular disease resulting in gangrene of the lower extremities. Although extensive epidemiological study has implicated high arsenic content in artesian well water in the endemic area, there is more to learn about the etiology of the disease. In this study, effort is paid on multielement determination and arsenic speciation in order to find out whether the trace element concentration pattern in well water in the Blackfoot disease endemic area is different from those of two control areas. Experimental results indicate that the concentrations of Fe, P, Na, and Ba in well water in the Blackfoot disease endemic area are found to be significantly higher than those of the controls, but they are still below the drinking water standard. The total arsenic in well water in the endemic area (671±149 ppb) is much higher than that of one normal control area of Hsin-Chu (<0.7 ppb), but is a similar level as that of other control areas of I-Lan (653±71 ppb) where no Blackfoot disease has ever been found. It was also found that the insoluble arsenic in the endemic area (21.9 ppb) is much higher than that in two control areas (≤1.8 ppb), and the concentration ratio between As(III) and As(V) species in the endemic area (2.6) is much lower than that in one of the control areas, where the total arsenic is also high (14.7). The possible connection of Blackfoot disease with trace elements, arsenic species, and possibly other as yet undefined environmental factors in the artesian well water, is discussed.     

Identification of the areas of endemism (AOEs) of the genus Acantholimon (Plumbaginaceae) in Iran

Abstract

This study was conducted to identify areas of endemism for Acantholimon species using parsimony analysis of endemicity (PAE) and to detect endemic species richness of the genus in the region. The results obtained from the two methods used in this study were used in determining the priorities for the conservation of Acantholimon species in Iran. The distribution database of 62 endemic species belonging to this genus was formed by 1250 georeferenced observations in Iran. The study area was divided into 1?×1? grids of operative geographical units (OGUs) and the species?×?area matrix including presence/absence data was created. The endemic species richness was calculated using circular neighborhood with a radius of 50?km in 10?×?10?km² raster cells using DIVA-GIS software. The results of PAE analysis have shown four areas of endemism (AOEs) in Iran. AOE1: including Alborz and Zagros mountains, the mountains of central Iran. AOE2 and AOE3 are located in Khorassan subregion and AOE4 contains parts of western Iran. The map of endemic species richness indicated that the highest number of endemic species occurs in central Alborz region as well as Kerman, Chahar-Mahal and Bakhtiari, and Isfahan provinces.     

Visually and olfactorily enhanced attractive devices for thrips management

‘Lure-and-infect’ is an insect pest management strategy with high potential but so far there are few examples of its application. Using traps as surrogates for auto-dissemination devices, we tested the attractiveness to naturally occurring thrips (Thysanoptera: Thripidae) of three trap types differing in colour and structure, with and without the thrips lure methyl isonicotinate (MI), and sticky plate traps as a control. The aim was to find more effective traps that could be further developed into devices for auto-dissemination and lure-and-infect of thrips. The number of thrips captured varied substantially with trap type and the presence of the MI lure. We found a high visual response to a sticky ‘white ruffle’ trap (i.e., a 30-cm-long cylindrical outline of folded fabric), compared to a commonly used blue sticky plate trap (Bug-scan) as the control. This effect was seen both in a greenhouse with roses (Rosa spp.), where we encountered western flower thrips, Frankliniella occidentalis (Pergande), and in a grass field, where we encountered onion thrips, Thrips tabaci Lindeman, and New Zealand flower thrips, Thrips obscuratus (Crawford). In the absence of MI, the white ruffle trap caught 7–22× more thrips than the control Bug-scan trap. A similarly designed blue ruffle trap and a modified Lynfield trap caught lower thrips numbers than the white ruffle and the control Bug-scan traps. Presence of MI substantially increased the captures of T. tabaci in all three trap types in the field (2.5–18×). In the greenhouse, without MI the white ruffle trap caught 3.5–14× more thrips than the Bug-scan, blue ruffle, or modified Lynfield traps. Presence of MI increased the captures of F. occidentalis males and females in the Lynfield and blue ruffle traps (1.4–2.8×), but not in the white ruffle trap in the greenhouse (ca. 1.1×). The importance of visual and olfactory factors for the design of effective auto-dissemination and lure-and-infect strategies for thrips management is discussed.     

Effects of manipulating spray-application parameters on efficacy of the entomopathogenic fungus Beauveria bassiana against western flower thrips,Frankliniella occidentalis,infesting greenhouse impatiens crops

The effects of various spray application parameters on the efficacy of a clay-based wettable powder formulation of Beauveria bassiana strain GHA conidia against western flower thrips, Frankliniella occidentalis, were evaluated in a series of greenhouse tests. With the aim of optimizing spray application methods to maximize biopesticide efficacy, a series of independent experiments was conducted that varied four spray parameters: application interval, rate, volume, and spray-program timing. Impatiens crops infested with western flower thrips were treated with (1) multiple sprays at the rate of 5×10¹³ conidia in 935 L aqueous carrier ha^?1 applied at 3-, 5-, and 7-day intervals, (2) weekly sprays at rates of 5×10¹³, 1×10¹⁴, and 2.0×10¹⁴ conidia in 935 L carrier ha^?1, (3) weekly sprays at a rate of 2.0×10¹⁴ conidia in volumes of 935, 1870, and 3740 L water ha^?1, and (4) multiple sprays at the rate of 2.0×10¹⁴ conidia in 3740 L carrier ha^?1 applied at 5-day intervals in spray programs initiated before versus after the onset of flowering. Pollen-bearing impatiens flowers were sampled twice weekly to estimate thrips population density, and adult female and second-instar thrips were collected 24 h post application for determination of acquired dose (conidia/insect). Numbers of conidia inoculated onto thrips increased with increasing spray frequency and volume. Dose was unexpectedly not directly correlated with application rate when volume was held constant, suggesting that thrips avoided concentrated spray residues. Statistically significant thrips population reductions relative to controls were achieved only when three to four sprays were applied at the highest label rate in the highest volume at < 7-day intervals. Applications against thrips infesting young, preflowering impatiens crops were not consistently more effective than applications in older crops. The most effective treatment programs reduced pest populations by 30–40% compared to untreated controls; this slowed, but did not stop, the growth of pest populations. Results indicate that use of fungi for thrips management will require integration with other control agents.     

Interacting Virus Abundance and Transmission Intensity Underlie Tomato Spotted Wilt Virus Incidence: An Example Weather-Based Model for Cultivated Tobacco

Through a modeling approach, we investigated weather factors that affect the summer incidence of Tomato spotted wilt virus (TSWV), a virus vectored exclusively by thrips, in cultivated tobacco. Aspects of thrips and plant biology that affect disease spread were treated as functions of weather, leading to a model of disease incidence informed by thrips and plant biology, and dependent on weather input variables. We found that disease incidence during the summer was influenced by weather affecting thrips activity during the preceding year, especially during a time when thrips transmit TSWV to and from the plant hosts that constitute the virus’ natural reservoir. We identified an interaction between spring precipitation and earlier weather affecting thrips, relating this to virus abundance and transmission intensity as interacting factors affecting disease incidence. Throughout, weather is the basic driver of epidemiology in the system, and our findings allowed us to detect associations between atypically high- or low-incidence years and the local climatic deviations from normal weather patterns, brought about by El Niño Southern Oscillation transitions.     

Effects of tomato spotted wilt virus (TSWV) isolates, host plants, and temperature on survival, size, and development time of Frankliniella fusca

The effects of different isolates of the tomato spotted wilt tospovirus (TSWV), host plants, and temperatures on Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), the most important vector of TSWV in North Carolina, were measured in the laboratory. Thrips were reared at either 18.3, 23.9, or 29.4 °C until adult eclosion on excised leaves of Datura stramonium L. or Emilia sonchifolia (L.). Plants were either infected with the TSWV isolates CFL or RG2, or left uninfected (control). The results revealed a positive relationship between larval survival and temperature, regardless of host plant or TSWV isolate. Both survival to adult and percentage transmission of TSWV by F. fusca were significantly affected by the interaction between host plant and TSWV isolate. The consequence of this interaction was that the cohort‐based percentage transmission from infected E. sonchifolia plants for CFL was 1.3‐fold greater than that of RG2, whereas the percentage transmission from infected D. stramonium plants for RG2 was twice that of CFL. Both host plant and TSWV isolates showed significant effects on thrips development time to adult and head capsule width of adult thrips, as well as on the incidence of thrips infection with TSWV. The infection status of these thrips was determined by ELISA for the NSs viral protein. Infected thrips reared on infected host foliage took longer to develop to adult and were smaller than non‐infected thrips which had also been reared on infected host foliage, demonstrating a direct effect of the TSWV on thrips. However, non‐infected thrips reared on non‐infected leaves took longer to develop than non‐infected thrips reared on infected leaves, suggesting an effect of the plant tissue on thrips. In addition, adult thrips reared on TSWV‐infected D. stramonium at 29.4 °C developed smaller head capsules than thrips developing on infected foliage at lower temperatures and on non‐infected leaves of D. stramonium or E. sonchifolia. Both TSWV isolates and host plants differentially affected females more than males. In conclusion, both the infection of thrips by TSWV and TSWV‐mediated changes in host plant quality were found to have significant biological effects on F. fusca.     

BIODIVERSITY RESEARCH: Geographical linkages between threats and imperilment in freshwater fish in the Mediterranean Basin

Aim The level of imperilment of mediterranean freshwater fish is among the highest recorded for any group of organisms evaluated to date. Here, we describe the geographical patterns in the incidence of threats affecting mediterranean freshwater fish and test whether the effects of specific threats are spatially related to the degree of imperilment of fish faunas. Location The Mediterranean Basin Biome. Methods From the IUCN Red List, we recorded the six main threats to 232 endemic freshwater fish species. We used data on fish distributions from IUCN to characterize the spatial patterns in the incidence of threats (as percentage of species affected) through multivariate statistics. We studied the relationships between threat incidence and two estimators of imperilment (proportion of species threatened and an index of extinction risk) at two spatial scales (10 × 10 km and basins) using partial least squares regressions (PLSR) that incorporated the effects of species richness and mean range size. Results The main axis of variation in the incidence of threats to freshwater fish split areas mainly affected by invasive species from those areas where species are threatened by pollution and agriculture. Wherever invasive species and water extraction were predominant threats, fish assemblages consistently tended to be more imperilled. Main conclusions As far as we know, this is the first large‐scale analysis on the spatial relationships between the incidence of threats and level of imperilment of any taxonomic group. Our results highlight the primary role of invasive species and water extraction as drivers of native fish declines in the Mediterranean Basin. Large‐scale patterns described here should be generated by local‐scale impacts of both threats on fish biodiversity, widely reported in Mediterranean areas. Because all the species under concern are endemic, control of invasive species and reducing overexploitation of freshwater resources should be conservation priorities for mediterranean freshwater systems.     

Speciation, Distribution, and Bioavailability of Soil Selenium in the Tibetan Plateau Kashin–Beck Disease Area—A Case Study in Songpan County, Sichuan Province, China

To clarify the relationship between the soil selenium distribution and its bioavailability with the distribution of Kashin–Beck disease (KBD) endemic areas on the eastern edge of the Tibetan Plateau, samples of natural soil (0–20 cm), cultivated topsoil, and main crops of the region (highland barley) were collected at different altitudes according to topographical and geomorphological features in both KBD and non-KBD areas of Songpan County. These samples were used for determination and analysis of total selenium content in soil and highland barley and available selenium that can be absorbed and utilized by plants. The results showed that the average total selenium content of natural and cultivated topsoil in KBD areas was lower than that in non-KBD areas (natural soil, P?=?0.061; cultivated soil, P?=?0.002), which is in agreement with the geographical distributions of selenium in other KBD-affected areas. However, the total soil selenium content exhibits certain micro-spatial distribution features, namely, the total selenium content in some endemic areas was significantly higher than that of non-KBD areas. This result was contrary to the general distribution that total selenium content in a KBD-affected area is lower than that in a non-KBD area. We further studied the extraction rate and content of soil selenium in six different fractions. The results indicated that the content and extraction rate of available selenium in KBD-affected areas were significantly lower than those in non-KBD areas. There is a distinct positive correlation between plant-available selenium and highland barley selenium (r?=?0.875, P?=?0.001) and a distinct negative correlation with altitude (r?=??0.801, P?=?0.010). Therefore, in KBD endemic areas, the selenium content in crops decreases as the available selenium content in soil decreases and is closely related to the geographical environment features (such as altitude and precipitation). These results suggest that the soil available selenium and ecological features are important factors that restrict the dietary selenium flux for residents in KBD endemic areas of the Tibetan Plateau, providing a theoretical and experimental basis for implementing agricultural measures to regulate the ecological cycle of the selenium flux in the KBD endemic area.     

The importance of avocado (Persea americana Mill.) fruits anthracnose and factors influencing the disease in Mana district,south-western Ethiopia

Anthracnose disease surveys were conducted in 25 farmers’ orchards, wholesaler and retailer shops in south-west Ethiopia. In addition, harvesting and postharvest practices, and storage conditions influencing disease development were studied with observation and questionnaire. The assessment results indicated significant variation among farmers’ orchards with the highest incidence (84.0 ± 16.7%) and severity index (26.0 ± 5.4%). Anthracnose damage of fruit was higher at retailers (76.7 ± 20.8%) than in the wholesalers shop (56.7 ± 32.5%). The total number of isolates identified was 249 and Colletotrichum gloeosporioides was the predominant pathogen proved by pathogenecity test. Among the major factors, harvesting avocado fruits with children (88%) and climbing on the tree (72%) resulted in fruit dropping that caused substantial injury and bruise. Generally, anthracnose caused by C. gloeosporioides of avocado fruit was prevalent in producer orchards that aggravated by traditional harvest and postharvest practices coupled to inadequate transportation and storage facilities at wholesaler and retailer shops with subsequent decay and loss of avocado fruits.     

The impact of irrigation frequency on population density of thrips, Thrips tabaci Rom (Thripidae, Thysanoptera) and yield of onion in E1 Rahad, Sudan

Vegetable farmers of the El Rahad Scheme (a newly developed scheme situated between latitude 13°31′–14°25′ north and longitude 33°31–34°32′ east) used to extend irrigation frequency for onion production as they believed it would hamper and suppress thrips incidence. Thrips, T. tabaci, is the only major insect pest of onion in the El Rahad Scheme and the influence of irrigation intervals on the population density of the pest and on onion yield was not quantified. Irrigation is a factor in the development of crop pests and the levels of the pest population are related to the commencement of irrigation. The effect of irrigation frequency on the development of onion thrips and yield was investigated and the response was found to be a significant increase in the population density of the pests from February to March with shorter irrigation frequency. A steady increase of thrips population was noted from February and March and a sharp decline was recorded in April during both the 1992/93 and 1993/94 seasons. At wider irrigation intervals, levels of the pest population were significantly less from February to March during both seasons. Total bulb yield and average bulb weight were significantly higher at shorter irrigation frequencies when compared with extended frequencies. The same pattern of results existed throughout the course of the experiment.     

桑蓟马在桑树中空间分布的研究

桑蓟马Pseudodendrothrips mori是桑树的一种主要害虫。它的寄生直接影响供桑叶的质量和产量。我们通过泰勒幂法则和Morisita的散度指标对桑树蓟马在植株和桑园内的空间分布进行检验,结果显示:P.mori种群在植株内和桑园里的分布都存在局部化。桑树中蓟马的分布在树内显示出幼虫蓟马位于低层(从上面叶子起5-10层),但成虫更喜欢上层(从上面叶子起1-5层)。同一植株叶子的不同方向上蓟马密度没有出现明显变化。桑园内蓟马主要分布在桑园东部、南部和北部的植株上,中部,西部植株上的蓟马密度较低。P.mori的成虫和幼虫在叶子上的分布呈现明显聚集化。     

Failure costs associated with mastitis in smallholder dairy farms keeping Holstein Friesian × Zebu crossbreed cows

Mastitis is a costly disease and in many areas of the world, these costs have been quantified to support farmers in their decision making with regard to prevention of mastitis. Although for subsaharan circumstances estimates have been made for the costs of subclinical mastitis (SCM), farm-specific cost estimations comprising both clinical mastitis (CM) and SCM are lacking. In this paper, we quantified failure costs of both CM and SCM on 150 Ethiopian market-oriented dairy farms keeping Holstein Friesian × Zebu breed cows. Data about CM were collected by face-to-face interviews and the prevalence of SCM was estimated for each farm using the California mastitis test. All other relevant information needed to calculate the failure costs, such as the consequences of mastitis and price levels, was collected during the farm visits, except for the parameter for milk production losses due to SCM, which was based on literature estimates and subjected to sensitivity analyses. The average total failure costs of mastitis was estimated to be 4 765 Ethiopian Birr (ETB) (1 ETB = 0.0449 USD) per farm per year of which SCM contributed 54% of the costs. The average total failure costs per lactating cow per farm per year were 1 961 ETB, with a large variation between farms (range 0 to 35 084 ETB). This large variation in failure costs between farms was mainly driven by variation in incidence of CM and prevalence of SCM. Milk production losses made the largest contribution (80%), whereas culling contributed 13% to 17% to the total failure costs. In our estimates, costs of veterinary services, drugs, discarded milk and labour made a minor contribution to the total failure costs of mastitis. Relative to the income of dairy farmers in North Western Ethiopia; the total failure costs of mastitis are high. In general, Ethiopian farmers are aware of the negative consequences of CM, but creating awareness of the high costs of SCM and showing large variation between farmers may be instrumental in motivating farmers to also take preventive measures for SCM.     

Tactics for management of thrips (Thysanoptera: Thripidae) and tomato spotted wilt virus in tomato

Four studies were conducted in Georgia during spring 1999, 2000, 2001, and 2002 to evaluate various management tactics for reducing thrips and thrips-vectored tomato spotted wilt virus (TSWV) in tomato and their interactions relative to fruit yield. Populations of thrips vectors of TSWV, Frankliniella occidentalis (Pergande) and Frankliniella fusca (Hinds), were determined using flower and sticky trap samples. The management practices evaluated were host plant resistance, insecticide treatments, and silver or metallic reflective mulch. Averaged over all tests, the TSWV-resistant tomato 'BHN444' on silver mulch treatment had the largest effect in terms of reducing thrips and spotted wilt and increasing marketable yield. Of the insecticide treatments tested, the imidacloprid soil treatment followed by early applications of a thrips-effective foliar insecticide treatment provided significant increase in yield over other treatments. Tomato yield was negatively correlated with the number of F. fusca and percentage of TSWV incidence. F. occidentalis per blossom was positively correlated with percentage of TSWV incidence, but not with yield. No significant interactions were observed between cultivar reflective mulch main plot treatments and insecticide subplot treatments; thus, treatment seemed to be additive in reducing the economic impact of thrips-vectored TSWV. Control tactics that manage thrips early in the growing season significantly increased tomato yield in years when the incidence of TSWV was high (>17%).     

Heliothis zea larval mortality time from topical and per os dosages of Nomuraea rileyi conidia

Heliothis zea larval mortality time was established for topical applications and per os (feeding) with fungal conidia of Nomuraea rileyi. The 6-to 7-day-old larvae received per os dosages ranging from 6 × 10⁶ to 9 × 10⁹ and a topical dosage of ca. 1 × 10⁹. These spore loads initiated fungal infections in larvae resulting in 1.5–100% accumulated mortality during the 30-day testing periods. The data indicated that regardless of the larval treatment method (topical or per os), or conidial dosage rates, the larval mortality time was never shorter than 5 days post-treatment, nor longer than 22 days. The highest percentage of larval deaths occurred from 7 to 9 days with a maximum mortality at 8 days.     

西双版纳地区不同植被亚型蚁科昆虫群落研究

研究了西双版纳地区１６各被亚型蚂蚁的特有种、优势种、物种多样性指数、均匀度指数、优势度指数和相似性系数。所采蚂蚁分隶于８亚科６６属２２０种。雨季的季节性十麻蚂蚁物种多样性指数最大,为２．９０８;旱季的茶园中多样性指数最小,为０．１１４。以山地雨林和季风常绿阔叶林蚂蚁物各组成相似性系数最大,为０．３５６;以温暖性叶阔叶林和茶园相似性系数最小,为０．０１７。１６种植被亚型均有特有种,其中半常绿季雨林特