Efficacy of LED-enhanced blue sticky traps combined with the synthetic lure Lurem-TR for trapping of western flower thrips (<Emphasis Type="Italic">Frankliniella occidentalis</Emphasis>)

Pest monitoring is an important tool for successful integrated pest management programmes. Blue sticky traps are important for monitoring western flower thrips, Frankliniella occidentalis, in greenhouses. However, blue sticky traps have three major weak points: (1) efficacy depends on reflection of light, which varies in intensity with fluctuating light conditions (season, diurnal rhythmic pattern), (2) they reflect broad wavelength pattern not optimally matching with maximum sensitivity of WFT photoreceptors, and (3) they offer no olfactory cues which are important for thrips orientation. This study explored the most attractive wavelength range for WFT using broad range of narrow-bandwidth light-emitting diodes (LEDs) in order to improve the attractiveness of blue sticky traps. Subsequently, trapping efficacy of the most attractive blue LED in combination with blue sticky trap and addition of an attractive lure (Lurem-TR) was evaluated in flight cages under greenhouse conditions. Release-capture studies revealed that LEDs with peak emission of 445 nm were clearly more effective than conventional blue sticky traps. In choice experiments, up to 2.7-fold and in no-choice experiment up to 2.1-fold more WFT were captured by LED-blue sticky traps compared to conventional reflecting blue sticky traps. Lurem-TR improved the performance of blue sticky traps and LED-blue sticky traps 2.3-fold and 2.0-fold, respectively, as compared to those without Lurem-TR. The addition of LEDs and kairomone lure to blue sticky traps seems promising for improving WFT trapping, specifically at low population densities especially during early infestation. However, these results should be further validated under more complex, large field conditions.     

On parasites and predators of Cleoninae weevils (Col. Curculionidae) in Ukrainian steppe

The data on natural enemies of 19 species of Cleoninae (generaCleonis, Chromoderus, Cyphocleonus, Rhinocyllus, Lixus, Larinus) are given. They were parasitized by Ichneumonidae, Braconidae (Hymenoptera), Erythraeidae (Acariformes) and fungi. Weevils fell victim of ants (Formicidae), beetles (Tenebrionidae, Elateridae, Scarabaeidae) and probablyOrius bugs (Anthocoridae).

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Zusammenfassung Es werden Beobachtungen von 56 Stellen der Ukrainischen Steppe mitgeteilt über natürliche Feinde von 19 Rüsselkäfer-(Cleoninae-) Arten der GattungenCleomis, Chromoderus, Cyphocleonus, Rhinocyllus, Lixus undLarinus. Die Rüsselkäfer und ihre Stadien werden vor allem von Ichneumonidae, Braconidae (Hymenoptera), Erythraeidae (Acariformes) und Pilzen angegriffen. Des weiteren werden sie auch zu Opfern von Ameisen (Formicidae), Käfern (Coleoptera) und wahrscheinlich Wanzen (Orius spp., Anthocoridae).

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With one table     

Container characteristics influence Pinus pinea seedling development in the nursery and field

The growth and development of Pinus pinea seedlings grown in different containers was followed through one growing season in the nursery and 3 years following outplanting in the field. The variables studied in the nursery were height, diameter, biomass of shoots and roots, nutrient uptake and root density. The measured field variables, height and diameter increment and survival, were correlated with the nursery variables. Container volume had the greatest influence on plant morphology. Containers with larger rooting volume had seedlings with larger height and diameter, greater nutrient content, and better field performance. Growing density was correlated with seedling morphology and nutrient concentration in the nursery. Among the variables that influenced container volume, the diameter of the container was the most important, while the depth of the container had a minor influence on seedling morphology.The best indicator of seedling development in the nursery was the ratio of container depth to container diameter, and the optimum ratio was 4. All containers produced seedlings with some root spiralling, including those containers with ribs. There was no relationship between either the number of spiralling roots or the angle of spiralling and container characteristics. Furthermore, root spiralling did not influence seedling performance following outplanting. Root density (root biomass/cm³) was inversely correlated with container volume but there was no correlation with either depth or growing density. The largest plants were produced with container volumes of 300–400 cm³, depth/diameter ratios of 4, and growing densities of 200–300 seedlings/m². These growing conditions will result in larger Pinus pinea seedlings coming out of the nursery, which will increase growth following outplanting.     

中国园林蓟马天敌的初步研究

对全国 2 5个省 (市、区 )的 2 8个大中城市园林蓟马天敌种类进行了初步调查研究 ,鉴定出我国园林蓟马天敌 90种 ,列表说明了天敌分布及捕食和寄生对象。     

Effect of ground cover management on Thysanoptera (thrips) in clementine mandarin orchards

Conservation biological control by means of ground cover offers an interesting alternative to chemical control. A complex of Thysanoptera (thrips) species inhabits citrus, some of which are considered pests. This study investigated the effect of ground cover management on thrips species composition, distribution, and seasonal abundance in four commercial clementine mandarin (Citrus clementina Tanaka) orchards. Three soil management systems were compared: resident vegetation, Festuca arundinacea Schreber (Poales: Poaceae), and bare soil. Cover management affected thrips species diversity and abundance. Two of the main species causing fruit damage in Spanish citrus, Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman, were abundant in the resident ground cover. However, their abundance was strongly depressed in the F. arundinacea cover. The resident vegetation cover could provide a range of suitable host plants supporting populations of potential thrips pest species beyond the citrus blooming period. The F. arundinacea cover, which hosted Poaceae-specific thrips species, could also provide alternative food sources for Phytoseiidae mites. These predatory mites could reduce populations of potential thrips and other citrus pests below economic injury level. Our results confirm the suitability of F. arundinacea as a cover crop for clementine mandarins.     

Compatibility of foliage-dwelling predatory mites and mycoinsecticides,and their combined efficacy against western flower thrips <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis>

Foliage-dwelling predatory mites and foliar applications of mycoinsecticides are commonly used in biological control programs for Western flower thrips. A laboratory study was designed to examine the compatibility of two foliage-dwelling predatory mites with two commercially available mycoinsecticides, followed by a greenhouse study to assess their combined efficacy against Western flower thrips, with a view to their concurrent use in an integrated strategy. The following commercially available biocontrol agents were evaluated: the predatory mites, Neoseiulus cucumeris (Oudemans) and Amblyseius swirskii (Athias-Henriot); and entomopathogenic fungi, Metarhizium anisopliae (Metschnikoff) Sorokin (now classified as Metarhizium brunneum) strain F52 and Beauveria bassiana (Balsamo) GHA strain. Mortality caused by the mycoinsecticides ranged from 0 to 15.98% in the laboratory studies. In the greenhouse, the relative efficacy of predatory mite slow-release breeding sachets, Met52 EC spray, and a combined application was determined. Under high pest pressure, Met52 EC-alone was not as effective as N. cucumeris-alone or the combination treatment over 8 weeks. Neoseiulus cucumeris-alone provided better control of thrips than Met52 EC, but in a mixed infestation of thrips and two-spotted spider mites, the combination treatment worked best overall; the spider mites were effectively suppressed by Met52 EC. Under low pest pressure in the experiment with A. swirskii, use of Met52 EC or A. swirskii sachets effectively suppressed thrips population growth; moreover, the combination treatment completely eliminated both thrips and spider mites.     

Tannins and mimosine in Leucaena genotypes and their relations to Leucaena resistance against Leucaena Psyllid and Onion thrips

The study was conducted throughout two seasons (2013 and 2014) at Xmatkuil farm at Merida, Yucatan, Mexico, to determine the relationships and the interactions between chemical compositions of condensed tannins and mimosine and their effects on the susceptibility of four Leucaena genotypes: Cunningham and K636 (L. leucocephala), and Nativa and KX2 (L. leucocephala × L. pallida) to the infestation of the most destructive insect pests; Leucaena Psyllids, Heteropsylla cubana Crawford, 1914 (Homoptera: Psyllidae), and Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae). Mimosine showed insignificant effect on the population of both pests. However, tannins exhibited a significant effect for Psyllid population on Nativa and K636, and highly significant effect on thrips for the same respective genotypes. The insignificant relationships of tannin effect were found for Cunningham and KX2 to the population fluctuations of Psyllid and Thrips.     

When the ground cover brings guests: is <Emphasis Type="Italic">Anaphothrips obscurus</Emphasis> a friend or a foe for the biological control of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> in clementines?

Biological control of Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementines, can be improved in this crop with the establishment of a ground cover of Festuca arundinacea Schreber (Poaceae). This cover houses an abundant and diverse community of predatory Phytoseiidae mites including Euseius stipulatus (Athias-Henriot), Neoseiulus barkeri Hughes, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot and a dense population of the grass thrips Anaphothrips obscurus Müller (Thysanoptera: Thripidae) throughout the year. The aim of this study was to determine whether the presence of this thrips species could be related to the improvement in the biological control of T. urticae. Therefore, the capacity of the abovementioned phytoseiids to feed and reproduce on A. obscurus and their feeding preferences when T. urticae and A. obscurus were simultaneously offered, were analyzed. The results show that E. stipulatus, N. barkeri and N. californicus have a type II functional response when offered A. obscurus nymphs, whereas P. persimilis barely feeds on this thrips species. Furthermore, N. barkeri and N. californicus can reproduce feeding only on thrips. Regarding prey preference, the Tetranychus spp.-specialist P. persimilis preferably preyed on T. urticae, the generalists N. barkeri and E. stipulatus preferred A. obscurus, and the selective predator of tetranychid mites N. californicus showed no preference. Therefore, we hypothesize that the enhanced biological control of T. urticae observed could be related to A. obscurus becoming an alternative prey for non-specialist phytoseiids, without altering the control exerted by the T. urticae-specialist P. persimilis and likely reducing intraguild predation.     

Oviposition preference,larval distribution and impact of the swede midge, <Emphasis Type="Italic">Contarinia nasturtii</Emphasis>, on growth and yield of canola

The swede midge (Contarinia nasturtii) has become a significant economic pest of canola (Brassica napus L.) in Ontario and an emergent pest in the Prairie provinces. Determining yield impacts of swede midge damage and the growth stage(s) at which canola is most vulnerable or attractive to swede midge will contribute to the development of pest management recommendations throughout the growth of the crop. In four experiments, canola plants were exposed to specific densities of adult swede midge and measures of oviposition, damage and yield were collected. There was a significant positive relationship between female density and total oviposition per plant with a very high capacity for larval numbers on canola; up to ~ 4000. Given a choice of four growth stages, approximately 85% of oviposition occurred on seven-leaf and early bud canola. Given no choice, the high total oviposition on 3-leaf and flowering stages suggests that swede midge will oviposit on less favorable canola growth stages, if no others are present. Damage sustained on primary racemes remained relatively constant over time. However, damage ratings on secondary and tertiary racemes decreased over time in the highest treatment densities, suggesting compensation by the plant. All yield measures, except seed weight per pod, significantly decreased with increasing female density on primary and/or secondary racemes. A density of ~ 0.6 females per plant resulted in 10% reductions in the number of pods and seed weight produced on primary racemes. These results support recommendations for insecticide applications at, or just prior to, the early bud stage.     

Effect of GCSC-BtA biocide on population dynamics of cabbage pests and their natural enemies from fields in southeastern China

The present paper deals with the effect of the biocide GCSC-BtA on population dynamics of cabbage pests, i.?e., Plutella xylostella (L.) (Lep., Plutellidae), Brevicoryne brassicae (L.) (Hom., Aphididae), Liriomyza sativae Blanch. (Dip., Agromyzidae), Phyllotreta vittata Fabric. (Col., Chrysomelidae) and their natural enemies, i.?e., Apanteles plutellae Kurdj. (Hym., Braconidae), Erigonidium graminicola (Sundv.) (Araneida, Linyphiidae), Coccinella septempunctata L. (Col., Coccinellidae), in common head cabbage (Brassica oleracea var. capitata) fields in the southeastern China. The experiments were conducted at the experimental farm of Fujian Academy of Agricultural Sciences, Fuzhou, PR China in April?–?June, 2001. The results showed that, at the end of sampling, the pest populations of P. xylostella, B. brassicae and P. vittata reached averages of 39.7, 68.3 and 6.2 ind. / 30 plants in the plot treated with GCSC-BtA, which were about 1.5, 11 and 0.7 times lower than those treated with methomyl, respectively. In contrast, the natural enemy populations were, on average, 23.5 ind./30 plants for A. plutellae, 24.6 ind./30 plants for E. graminicol and 12.2 ind./30 plants for C. septempunctata in the plot treated with GCSC-BtA, about 6, 5 and 3 times higher than for those treated with methomyl, respectively. The GCSC-BtA biocide demonstrated greater effectiveness in controlling the cabbage pests, e.?g., P. xylostella, B. brassicae and P. vittata, having final decreasing ratios of 83.60, 97.05 and 53.67?% compared to 57.63, 64.89 and 30.88?% with the methomyl insecticide. However, it was less toxic to natural enemies, e.?g., A. plutellae, E. graminicola and C. septempunctata, final decreasing ratios being 47.68, 17.84, 27.81?%, than methomyl, with 90.94, 80.80, 74.55?%, in comparison to the populations in the control plots, respectively. So, because of the low toxicity of GCSC-BtA to the natural enemies, it is recommended that, on one hand, its application should be carried out after mass migration of the pests to the fields, on the other hand, the alternative agent GCSC-BtA should be used with the aim of minimizing the harmfulness to the natural enemies in the whole program of integrated pest management in cabbage fields.     

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Low-input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here, we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low-input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life cycle of the pest and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4–37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood and with semi-natural woody habitat in the surrounding landscape and decreased with tree distance to orchard edge and apple bloom level. Thus, the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their life cycle: seven parasitoid species attacked immature weevils (6.4–81.5%), while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31–44%). We conclude that the effective biological control of A. pomorum can be achieved in low-input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.     

High resolution temporal variation in wood properties in irrigated and nonirrigated Eucalyptus globulus

? Environmental determinants of wood properties variation were examined in Eucalyptus globulus, a globally important hardwood plantation species, in southern Tasmania, Australia.

? Radial variation in wood properties, measured with the SilviScan system, were re-scaled from distance to time abscissa using stem radial growth data measured with dendrometers. With this re-scaled data it was possible to evaluate how water availability and temperature affected wood density, microfibril angle (MFA) and fibre and vessel transverse dimensions in irrigated and non-irrigated trees.

? Wood density, fibre radial diameter and MFA were sensitive to water availability. Wood density increased and fibre radial diameter decreased in response to reduced water availability. When high water availability was maintained, wood density was negatively correlated with temperature. Together, temperature and soil matric potential explained about 60% of temporal variation in wood density variation. In contrast MFA was not related to temperature but decreased with increasing water stress. Slower growing trees also had lower MFA than faster growing trees. Slower growing trees had a larger number of vessels per unit area of wood than faster growing trees within this even aged stand. However, vessel radius to the 4th power was significantly higher in faster growing trees than in slower growing trees.

? Overall, E. globulus wood properties were sensitive to temporal changes in environmental conditions (particularly water availability) and associated growth rates. The data provided support for the hypothesis that growth rates are hydraulically mediated.

     

Demography and life history of Geonoma orbignyana: An understory palm used as foliage in Colombia

Geonoma orbignyana is a common understory palm, whose leaves are used as foliage in Colombia. This palm has been used for more than 30 years; but there is no information about its life history or conservation status. Our objective was to characterize the life history of this palm and population dynamics of a natural population as a first step to assess the effect of leaf harvesting. More than 1600 palms were monitored from June 1999 to March 2000; we measured growth, mortality, and reproductive success. Population dynamics were evaluated using a Lefkovitch matrix model, and elasticity analysis. Results indicate that G. orbignyana grows at a rate of 1.98 ± 0.047 leaves/year, the palm has a long lifespan, and growth and reproduction are related to light conditions in the forest. The density of this palm is high (108–311 palms/100 m²), which is explained in part by its capacity to continue growing after damage, and to respond to the frequent gap formation in the forest. The population is growing (λ = 1.074, CI = [1.046–1.099]). Survival transitions account for 77% of population growth, a value that is higher compared to other understory plants. Because of the high density, the recovery capacity of these palms, and the correlations found between individual and population performances with forest dynamics, we hypothesize that G. orbignyana behaves as an opportunistic species taking advantage of forest gaps. This palm is a promising non-timber forest product (NTFP) with a high profile for further exploitation, although we recommend that harvesting regimens should consider time of recovery and forest dynamics. Without these considerations mortality could increase in all classes, which will compromise population persistence. Further studies should accurately estimate the recovery time after defoliation as well as to characterize forest dynamics identifying its most important features for population growth.     

Distribution of Aeolothrips intermedius Bagnall (Thysanoptera: Aeolothripidae) and its potential prey Thysanoptera species on different cultivated host plants

The results of the monitoring of Thysanoptera species on cultivated plants in Slovenia (2000–2001), Croatia (1994–1996), and Serbia and Montenegro (1988–2003) are presented in this study. The aim of the investigation was to study the host plant distribution of the predator Aeolothrips intermedius Bagnall and its potential prey. Banded thrips were found on 30 different host plant species belonging to 16 botanical families, always in mixed populations with phytophagous or facultative phytophagous insects (including 18 Thysanoptera species). On the vegetative parts of the cultivated plants, banded thrips were found less numerous in spite of the massive population of some harmful thrips species. This indicates highly important role of pollen as alternative food for Aeolothrips intermedius.     

Ein Beitrag zur Prognose der Populationsentwicklung von Mäusen in Forstkulturen

In the years 1976–1981 the density of mice and voles was estimated by snaptrapping in 65 cultivations in different woodland areas in Bavaria. The trapping procedure was repeated at the same places after 3 and 6 months. All the trapped specimens were frozen in the field and later dissected in the lab. 21 different parameters of population structure and of morpho-physiological condition of the animals were compared with the development of the density of each species in the different areas. All together 1447 redbacked voles (Clethrionomys glareolus), 869 common voles (Microtus agrestis) and 873 yellownecked field mice (Apodemus flavicollis) were taken into the analysis. It was observed that the fertility resp. the weight of testes was significantly correlated with the change of density of all three species. In all cases also the percentage of pregnant females and the percentage of embryoes related to the total number of trapped specimens, was positively correlated with the development of density. It is suggested that these correlations can help to forecast the development of population density of mice and voles in forest plantations.     

The scale Nemolecanium graniformis (Wunn) (Homoptera: Coccidae) in Greece

The phenology and natural enemies of Nemolecanium graniformis (Wunn) (Homoptera: Coccidae) in infesting Abies cephalonica, were studied in Greece during 1998?–?1999. This oviparous species develops one generation per year in Central Greece (Attica) and overwinters as 2^nd instar nymph. Young adult females appear by the end of July, and the first instar nymphs by the middle of August. By the middle of October, the whole population of the scale is recorded as 2^nd instar nymphs. The parasitoids Coccophagus lycimnia (Walker), Coccophagus Westwood sp., Aphycoides Mercet sp. and the predator Exochomus quadripustulatus L. (Coleoptera: Coccinellidae), were observed as natural enemies of the scale. The average fecundity of N. graniformis was 188.4 eggs.     

Crop damage by nematodes in improved-fallow fields in western Kenya

The rotation of leguminous shrubs and crops is being tested on farms and recommended as a means of improving soil fertility and increasing crop yield in eastern and southern Africa, including western Kenya. However, this improved fallow practice may also increase the nematode population in the soil. An experiment was conducted to monitor the effects of plant-parasitic nematodes on crops after improved fallow. Soil was collected from a maize (Zea mays L.)/bean (Phaseolus vulgaris L.) field, a natural fallow, a Crotalaria (Crotalaria grahamiana Wight & Arn.) fallow, a Tephrosia (Tephrosia vogelii Hook. f.) fallow and a Crotalaria — Tephrosia mixed fallow and used to fill plastic pots placed in a shade. Three successive crop cycles of 2 months were tested in these pots using maize and beans, the most important staple foods in western Kenya. In the first cycle, beans grew poorly on the Tephrosia and Crotalaria — Tephrosia soil due to the high incidence of root knot nematodes, Meloidogyne spp., while maize did not suffer any loss. Although the populations of root knot nematodes reduced drastically in the second and third cycles, both maize and beans experienced heavy losses on the soil under improved fallow probably due to the spiral nematodes, Scutellonema spp., which became dominant in the nematode communities. Despite the use of fertilisers (N, P, K), both crops became highly sensitive to spiral nematodes in the third cycle because of the degradation of the soil physical properties. The study showed that the benefits of improved fallows in terms of crop production may be limited by the high number of plant-parasitic nematodes they help develop in the process.This revised version was published online in November 2005 with corrections to the Cover Date.     

Phytosociology,structure and dynamics of Pinus roxburghii associations from Northern Pakistan

We investigated the phytosociology, structure and dynamics of Pinus roxburghii in 40 stands in northern areas of Pakistan by using cluster analysis （Ward’s agglomerative clustering） and ordination （Non-metric Multidimensional Scaling）. Cluster analysis revealed three major groups associated with specific environmental characteristics： （1） P. roxburghii （2） Pinus-Quercus baloot and （3） Pinus-Olea ferruginea community types. NMS-ordination showed the major gradient as an amalgam of elevation （r2=0.441, p＆lt;0.01） and slope （r2=0.391, p＆lt;0.05） as the two topographic factors correlated with species distribution. The first ordination axis also showed positive correlation with soil variables like pH and electrical conductivity, suggesting that soil chemistry was related to topographic characteristics and probably acted as a secondary gradient. We also examined size class distributions, age structures and growth rates of the three communities in order to describe community development and dynamics. Total tree density was 14700 plants/ha, with P. roxburghii having a relative density of 82%to 100%. Density of juve-nile and total density and basal area of the subordinate tree species were low. The low density of trees in the smallest diameter size-class sug-gested that the recruitment of small P. roxburghii plants into the adult population may be lower than the required replacement rate for the stands. Pooled size-class distributions for the species showed a multimo-dal pattern with some regeneration gaps. Browsing, heavy logging and＆amp;nbsp;other anthropogenic activities were the overriding factors responsible for the poor recruitment of P. roxburghii. We concluded from the age struc-ture that the forests were characterized by the dominance of young trees. Growth rate analysis revealed that P. roxburghii was the fastest growing species among the conifers species in Pakistan. In view of its relatively fast growth and longevity, P. roxburghii seems to be a suitable choice for short-t     

Yields of Green Grams and Pigeonpeas under Smallholder Conditions in Machakos County,Kenya

Green grams and pigeonpeas have multiple benefits to the rural poor as food security, fodder for livestock and fuel for small-scale farmers, despite low smallholder yields in Kenya. However, little is known about the factors between different farmers that influence the yields of green grams and pigeonpeas. The objectives of this study therefore were to describe and compare how the groups of farmers in agro-ecological zones (AEZs) LM 4 and LM 5 differ by their yields of green grams and pigeonpeas and to estimate the parameters of the variables which explain the yields. Data collection was through a well-structured questionnaire, administered to 364 respondents, selected through a multi-stage sampling technique. Each AEZ had an equal sample size (182 respondents). One-way analysis of variance (ANOVA) and multiple linear regression were used during data analysis. The ANOVA results showed that the mean of the green gram yields in AEZs LM 4 and LM 5 was 19.90 and 173.67 kg ha^?1 while the mean of the pigeonpea yields was 109.26 and 34.01 kg ha^?1, respectively. The multiple linear regression model results showed that the green gram yields were positively related to the use of improved seed (p?=?0.001), cultivated farm sizes (p?=?0.011), green gram crop intensity (p?=?0.005), oxcart (p?=?0.003) and agro-ecological zone (p?=?0.000). The farmer differences in the use of improved seed were found to be significantly and positively related to the yields of pigeonpeas (p?=?0.057), while the sizes of the cultivated farms (p?=?0.057) and the agro-ecological zones (p?=?0.000) showed inverse relationships (IRs). Based on the given research evidence, it was therefore concluded that the groups of farmers in AEZs LM 4 and LM 5 have different yields of green grams and pigeonpeas and there are factor gaps in productivity.     

Different population performances of <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Thrips hawaiiensis</Emphasis> on flowers of two horticultural plants

Gardenia jasminoides and Rosa chinensis are economically important horticultural plants in China. Frankliniella occidentalis and Thrips hawaiiensis are serious coexisting pests that previously demonstrated opposite population trends on G. jasminoides and R. chinensis flowers. To further study the different performances between F. occidentalis and T. hawaiiensis, we investigated their population dynamics in the field (for 5 years) and their life history characteristics on the two flowers in the laboratory. In the field, the density of F. occidentalis was lower than that of T. hawaiiensis on G. jasminoides but was higher than that of T. hawaiiensis on R. chinensis. Under laboratory conditions, F. occidentalis showed significantly slower development, and lower survival and fecundity levels than T. hawaiiensis on G. jasminoides, but the opposite was true on R. chinensis. Significant differences in the net reproductive rate (R ₀) between F. occidentalis and T. hawaiiensis were observed, with respective values of 38.66 ± 2.85 and 47.91 ± 2.70 on G. jasminoides, and 55.64 ± 2.15 and 32.45 ± 2.16 on R. chinensis. The intrinsic rates of increase (r _m ) of F. occidentalis and T. hawaiiensis were 0.156 ± 0.008 and 0.198 ± 0.007, respectively, on G. jasminoides, and 0.172 ± 0.003 and 0.165 ± 0.002, respectively, on R. chinensis. Thus, the performances of both thrips with respect to population size in the laboratory were in accordance with those in the field, suggesting that the innate capacity for insect population increases may directly impact their population dynamics in fields. Thus, the population performance of different thrips species on flowers is species-dependent, which could be exploited in thrips control programs by breeding pest-resistant cultivars.