Sesamia Inferens Research Articles

Relative Abundance and Field Efficacy of Insecticides and Bio-control Agents Against Stem Borer Species in Rice (Oryza sativa L.)

Background: In India, out of the total loss incurred by different insect pests of paddy, 25 to 30 per cent damage is done by stem borer alone. Many conventional insecticides though have been evaluated against stem borers, yet, most of the chemicals have failed to provide adequate control. Hence, the present study aimed to evaluate the efficacy of some newer molecules of insecticides and bio-control agents.Methods: Field trials were conducted to record the seasonal incidence and to evaluate the efficacy of insecticides and bio-control agents against the stem borer species in rice during Kharif and Rabi. Result: Field experiments revealed that during Kharif 2018, chlorantraniliprole 18.5 SC was highly effective with 92.98 and 91.24 per cent reduction of stem borer infestation over control at vegetative and reproductive stages, respectively and recorded a high yield of 5720 kg/ha followed by spinetoram 11.7 SC with 83.16 and 80.82 per cent reduction of stem borer over control at vegetative and reproductive stages, respectively. During Rabi 2019, spinetoram 11.7 SC was highly effective with 92.36 and 93.73 per cent reduction of stem borer infestation over control at vegetative and reproductive stages respectively and recorded a high yield of 4570 kg/ ha, followed by chlorantraniliprole 18.5 SC with 84.60 and 91.48 per cent reduction of stem borer at vegetative and reproductive stages, respectively. The difference in the efficacy of insecticides during Khaif, 2018 and Rabi, 2019, might be due to shift in the species occurrence of stem borer, with a dominant occurrence of yellow stem borer (80.61%) in Kharif 2018 and pink stem borer (70.00%) in Rabi, 2019. The bio-control agent Trichogramma japonicum exerted minimum reduction of stem borer with a low grain yield of 3946.6 kg/ha.

Screening of Rice Varieties for Resistance to Major Insect Pests

Rice is attacked by several insect pests and of these the stem borers Scirpophaga incertulas (Walker), S. innotata (Walker), Sesamia inferens (Walker), leaf folder Cnaphalocrocis medinalis (Guenee) and plant hoppers viz. brown plant hopper Nilaparvata lugens (Stal), white backed plant hopper, Sogatella furcifera (Horvath) are the most destructive. This study was carried out at the PAU Regional Station, Gurdaspur during kharif seasons of 2017 and 2018 to evaluate performance of varieties viz. PR 121, PR 122, PR 123, PR 124, Pusa 44, PR 126, PR 115, PR 114 and HKR 127 against these pests. The incidence of stem borers, leaf folder and of plant hoppers/ hill were observed at 40, 60, 80 and 100 days after transplanting. It was observed that rice varieties PR 126, PR 115 were the least preferred whereas Pusa 44 was found highly preferred by these major insect pests.

Evaluation of Insecticides Against Pink Stem Borer Sesamia Inferens (Walker) Infesting Durum Wheat

Field experiment was carried out at the Agricultural Research Station, Anand Agricultural University, Arnej during November 2017 to February 2018 to evaluate the efficacy of nine insecticides against the pink stem borer Sesamia inferens (Walker) infesting durum wheat. Spraying of chlorantraniliprole 18.5SC @ 0.006% was found significantly superior over other insecticides with maximum grain as well as straw yield (16.42 and 23.93 qt/ ha, respectively). Maximum ICBR was registered with seed treatment of chlorpyriphos 20EC (1:20.83) followed by chlorantraniliprole 18.5SC (1:10.46) and spraying of spinosad 45SC (1:9.52).

Species Richness of Leaf Roller and Stem Borers (Lepidoptera) Associated with Different Paddy Growth and First Documentation of Its DNA Barcode

Leaf folder and stem borer are pest moths (Lepidoptera) of paddy crop and caused serious damage and significant rice yield loss. The richness, abundance, and diversity of the pest moths were calculated in one paddy planting season and sampled from a model conventional paddy field, located on the west coast of Peninsular Malaysia (Sabak Bernam, Selangor). The adult and immature stages of moths associated with paddy plants have been sampled using active sampling namely sweep net and stem cross-cutting. A total of 189 individuals belonging to five species under two families (Crambidae and Noctuidae) were recorded. Overall, the richness (R’), diversity (H’), and evenness (E’) index of lepidopteran species were 0.76, 1.51, and 0.90, respectively. The richness and species abundance throughout the paddy stages were discussed. The DNA barcode of five collected species using cytochrome oxidase subunit 1 (CO1) viz. Cnaphalocrocis medinalis (Guenée) (leaf folder), Scirpophaga incertulas (Walker), Chilo auricilius Dudgeon, Sesamia inferens (Walker), and Parapoynx stagnalis (Zeller) (stem borers) were presented. This study’s outcomes are very important as the initial stage for conservation purposes, especially in managing the strategy in handling the pest species populations in the paddy field.

Establishment of Beauveria bassiana isolates as endophytes in rice cultivars and their biocontrol efficacy against rice stem borer, Sesamia calamistis

Possible endophytic colonisation of rice cultivar parts (leaves, stem and roots) by Beauveria bassiana isolates and their potential as biocontrol agents against Sesamia calamistis Hampson (African pink stem borer) were investigated. Five promising B. bassiana isolates were evaluated for their endophytic colonisation, the effectiveness of the inoculation methods and the efficacy of the isolates as biocontrol agents against S. calamistis. The plant part colonised is often dependent on the inoculation method. Colonisation of plant parts was assessed at 30 and 60 days after seed inoculation and foliar spray. For the pathogenicity activity, third instar larvae of S. calamistis were fed with rice stems that were previously inoculated with endophytic isolates of B. bassiana. Both inoculation methods led to the colonisation of the rice cultivar tissues, but were affected by the interactions of cultivars x isolates x inoculation methods. The colonisation of the cultivar plant parts varied over time (30- and 60-day intervals), and was affected by the inoculation method used. For both inoculation methods, highly significant differences were observed in the roots and the leaves over time (p=0.0001). However, with seed treatment, there was no significant difference in levels of colonisation in stems by the isolates x time (p=0.32). The B. bassiana isolates were pathogenic on the third instar larvae of S. calamistis, causing mortalities of more than 50% at 28 days after treatment. However, the virulence of the isolates varied. According to the isolates and the inoculation methods, B. bassiana formed an endophytic relationship with rice plants, and produced various mortality rates.
 Significance:
 
 Beauveria bassiana could be a potential biocontrol agent of rice stem borer, S. calamistis as there is no report of endophytic isolates of B. bassiana for the control of rice borers.
 Currently there is no commercially registered biocontrol agent against rice borers; hence further studies into B. bassiana could lead to the registration and commercialisation of B. bassiana as a bio-pesticide for rice stem borers.

An Overview of the Bionomics, Host Plant Resistance and Molecular Perspectives of Sesamia inferens Walker in Cereals and Millets

There is an urgent need to enhance agricultural production as well as productivity to meet the food demand of the growing population, estimated to be 10 billion by 2050, using a holistic and sustainable approach. The daily food sources for almost three-fourth of the global population, cereals and millets, are prone to several biotic factors and abiotic pressures. In particular, cereals and millet cultivation are limited by the polyphagous pink stem borer, Sesamia inferens Walker (Lepidoptera:Noctuidae) gaining national importance, since its larvae and pupae are concealed within the stem, none of the management measures have been found effective in controlling the menace. However, host plant resistance (HPR) is a reasonable and ecologically safe method wherein resistance mechanisms of crops could lower the stem borer infestation. The foremost challenge in understanding the mechanism would be to detecting the genes of interest in the crop using novel biotechnological approaches. The fundamental criterion for developing insect-resistant lines relies on recognizing the mechanism of plant resistance. The entire life cycle of this group of borers is completed or hidden within the stem, posing a hurdle in their management. Thus, molecular markers and Quantitative Trait Locus (QTL) mapping offer a more efficient approach to entomologists and plant breeders wherein they can work with traits like QTLs for stem borer resistance. In this review, an attempt has been made to provide an extensive summary of the host range and crop losses due to this borer, besides its taxonomic position, geographic distribution, bionomics, genetics of resistance, and molecular perspectives.

Management strategies for pink stem borer, Sesamia inferens Walker (Noctuidae: Lepidoptera) infesting barnyard millet, Echinochloa frumentacea Link using botanicals

Barnyard millet also known as kudhiraivaali is known for its high nutrient content. Barnyard millet is being cultivated mostly as rainfed crop and it is ravaged by several pests. Of which, pink stem borer causes dead heart and white ear symptoms by boring into stem and peduncle region causing heavy economic loss. Hence, the present study was conducted for the management of pink stem borer, Sesamia inferens in barnyard millet with botanicals. The treatments were neem oil 3%, pongamia oil 3%, mahua oil 3%, citrus peel oil 3%, Vitex negundo leaf extract 5%, sweet flag rhizome extract 3% and neem seed kernel extract 5%. The above treatments were applied two times during the year 2020 at Central farm, Agricultural College and Research Institute, Madurai. Among the treatments, neem oil 3% (62.01%) was found to be the most effective followed by citrus peel oil 3% (60.74%), pongamia oil 3% (57.94%), mahua oil 3% (56.87%), Vitex negundo leaf extract 5% (54.72%) and neem seed kernel extract 5% (51.73%). Among all treatments sweet flag rhizome extract (50.22%) was found to be the least effective. With regard to yield, the neem oil 3% recorded the highest yield (7.34 q/ha) over control with the cost benefit ratio of 1:1.74 and sweet flag rhizome extract 3% was the least performing treatment with 11.50% increase in yield over control with the cost benefit ratio of 1:1.45.

POPULATION DYNAMICS OF MAJOR PHOTOTATICS INSECT PESTS OF AGRICULTURE ECOSYSTEM THROUGH LIGHT TRAP

This study was conducted to monitor the population dynamics of major insect pest of agriculture ecosystem through light trap at the agriculture farm of GAASC ,Baitadi,during the winter of 2018.The main aim of this study was to determine the status of phototatics insects pest of the farm locality.. Light trap with a 100Watt filament bulb was installed at the site at college boundary, vegetable field and wheat field for trapping purpose. The observation was done every day and data was weekly record their status and occurrences. Overall nine insect species were observed and among them click beetle(Agriotes spp.) population was observed maximum compared to other species.Insects occurrence in vegetable field is dominated by click beetle followed by moths(Pieris canidia)and cabbage semi looper(Trichoplusia spp).The total 289 of 6 different species were found from vegetable fields. Trap installed on Agronomy farm contributes clickbeetle (Agriotes spp.)The most followed by Greenleaf hopper(Nephotettix spp)., Pink borer(Chilo partellus), wasp(Vespa spp.) and grasshopper(Hieroglyphus banian),total 152 of 5 different species were found until 15 week of monitoring. Similarly, trap installed in open field obtained total 176 out of which 68 were click beetle (Agriotes spp.),47 pink borer (Chilo partellus),40 moths (Pieris canidia) and 21 wasps (Vespa spp.).

Pest and Diseases Control Using Synthetic and Botanical Pesticides on Several Wheat Varieties

The research was carried out to find out the effect of wheat varieties and types of pesticide to control the naturally occurred pests and diseases. The research was designed in a split plot experiment with three replications. The main plot was 3 botanical pesticides (eugenol+eugenol acetate+caryophillene, azadirachtin, citronellal) and 1 synthetic pesticide (dimehypo 550 g/l) and 1 control (distilled water). The subplot was 4 wheat varieties (Guri 1, Guri 3, Guri 4, and Guri 6). Twice application of botanical pesticides was carried out at 30 and 60 days after planting (DAP). Results showed that in both vegetative and generative stage, two main pests were found, namely: Atherigona sp. and stem borer Sesamia inferens. Shoot fly incidence occured before the application of pesticide treatments. The percentage of incidence ranged from 10.33% at Guri 1 to 35.00% at Guri 6. No interaction among the applied treatments was observed on the average percentage of stem borer incidence on both growth stages. The visibly found disease was leaf blotch disease caused by Bipolaris sorokiniana. All evaluated varieties were very susceptible to leaf blotch. The harvestable grain yield was very low due to the attacks of shoot fly, stem borer and also high incidence of leaf blotch.

Impact of integrated pest management (IPM) module on major insect-pests of wheat and their natural enemies in North-western plains of India

In order to sustain the wheat production in North-western plains of India, a study was conducted to test the integrated pest management (IPM) module with commonly used farmer’s practices for the management of insect pests during 2017-18 and 2018-19. It was observed that aphid population was significantly lower in IPM plot (2.48-2.60 aphids/tiller) as compared to farmer’s practices (13.93-16.46 aphids/tiller) at peak period of their activity. At the same time, the population of coccinellids predators was significantly higher in IPM plots (6.80 beetle/m2) as compared to non-IPM plots (1.26 beetles/m2) during 2017-18. The termite damage ranged from 2.48-2.96 per cent in farmer's practices while it was only 0.20-0.80 per cent in IPM fields. Similarly, greater pink stem borer (PSB) damage was recorded in farmer's practices (0.96-2.48 per cent) as compared to IPM fields (0.46-0.68 per cent). The incidence of brown wheat mite (BWM) was recorded on maturing wheat and it was 2-5 fold higher in farmer's practice (11.73-31.53 mites/10 cm2) as compared to IPM plots (4.20- 5.00 mites/10 cm2). Approximately 9 per cent increase in grain yield resulted in additional income of Rs. 9291/ha in IPM plot. Seed treatment, yellow sticky trap based monitoring of aphids and need based application of insecticide resulted in better control of insect. Doi.org/10.25174/2582-2675/2020/100185

Low-temperature derived temporal change in the vertical distribution of Sesamia inferens larvae in winter, with links to its latitudinal distribution.

To escape or alleviate low temperatures in winter, insects have evolved many behavioral and physiological strategies. The purple stem borer, Sesamia inferens (Walker) is currently reported to be expanding their northern distributions and causing damage to summer maize in Xinxiang, China. However, their method of coping with the lower temperature in the new northern breeding area in winter is largely unknown. This paper investigates the overwinter site of S. inferens, and identifies the cold hardiness of larvae collected from a new breeding area in winter and explores a potential distribution based on low temperature threshold and on species distribution model MaxEnt. The results show that the overwintering location of the S. inferens population is more likely to be underground with increasing latitude and the population gradually moved down the corn stalk and drilled completely underground in later winter (February) in the north. The cold hardiness test shows the species is a moderate freeze-tolerant one, and Supercooling Points (SCP), Freezing Points (FP) and the incidence of mortality during the middle of winter (January, SCP: -7.653, FP: -6.596) were significantly lower than early winter (October) or late winter (March). Distribution in the new expansion area was predicted and the survival probability area was below N 35° for the Air Lower Lethal Temperature (ALLT50) and below N 40° for the Underground Lower Lethal Temperature (ULLT50). The suitable habitat areas for S. inferens with MaxEnt were also below N 40°. This study suggests the overwinter strategies of S. inferens have led to the colonization of up to a five degree more northerly overwintering latitude.

Exogenous Application of Different Silicon Sources and Potassium Reduces Pink Stem Borer Damage and Improves Photosynthesis, Yield and Related Parameters in Wheat

Silicon (Si) and potassium are known to impart tolerance against numerous biotic stresses in crop plants. A study was conducted to determine the effect of diatomaceous earth (DE), a soil-applied Si source and soluble silicic acid, a foliar applied Si source at two levels of potassium for their efficacy against pink stem borer (PSB) incidence and damage in wheat under field conditions for two seasons. The effect of these Si sources and potassium levels on photosynthesis, yield, and related parameters were also studied. Soil application of DE @ 300 kg ha−1 significantly decreased the PSB incidence with the lowest percent white ear damage and recorded the highest grain yield of 3.31 t ha−1. Both soil and foliar applied Si sources along with potassium @ 36 kg ha−1 significantly enhanced the net photosynthesis rate, stomatal conductance, water use efficiency, intercellular CO2 concentration, spike length, spike weight, number of grains per spike, 1000 grains weight and significantly decreased the transpiration rate in contrast to untreated control (no Si application) and insecticidal check. Soil applied Si sources significantly enhanced plant-available Si content in soil solution and thereby Si content in stem tissues of wheat plants in contrast to foliar-applied Si sources. Maximum Benefit: Cost ratio (2.03) was recorded with soil application of DE @ 150 kg ha−1 which was more than recommended insecticidal check (1.74). Both Si sources proved significantly superior to insecticidal check in managing PSB in wheat under field conditions and improved photosynthesis, yield and related parameters, which can be integrated with other practices for sustainable, eco-friendly management of PSB in wheat.

Impacts of plant spacing and nitrogen fertiliser on incidences and density of spotted and African pink stem borers in Tanzania

Nitrogen fertilisation and plant spacing hold potential for the integrated management of rice insect pests. Field experiments were conducted in Kilombero, Tanzania to evaluate the effects of plant spacing and nitrogenous fertiliser on incidences and density of spotted and African pink stem borers. A 3 × 4 × 4 factorial experiment was used in a randomized complete block design with three replications. Treatments included application of urea fertiliser at four levels (0, 40, 80, and 160 kg N ha−1) and spacing at four levels (10 cm × 10 cm, 15 cm × 15 cm, 20 cm × 20 cm, and 25 cm × 25 cm). Nitrogen significantly increased dead hearts by 4.8%, white heads by 2.8% and stem borer larvae density from 0 to 5.6 larvae/m2. Decreasing the planting density significantly increased dead hearts by 4.7%, white heads by 2.7% and stem borer larvae density from 0 to 5.4 larvae/m2. The interaction of nitrogen fertiliser rates and plant spacing did not affect stem borer incidences nor larvae density, but did influence the rice yield.

Silicon amendment induces synergistic plant defense mechanism against pink stem borer (Sesamia inferens Walker.) in finger millet (Eleusine coracana Gaertn.)

Silicon (Si) uptake and accumulation in plants can mitigate various biotic stresses through enhanced plant resistance against wide range of herbivores. But the role of silicon in defense molecular mechanism still remains to be elucidated in finger millet. In the present study, we identified three silicon transporter genes viz. EcLsi1, EcLsi2, and EcLsi6 involved in silicon uptake mechanism. In addition, the study also identified and characterized ten different Si transporters genes from finger millet through transcriptome assembly. The phylogenetic study revealed that EcLsi1 and EcLsi6 are homologs while EcLsi2 and EcLsi3 form another pair of homologs. EcLsi1 and EcLsi6 belong to family of NIP2s (Nod26-like major intrinsic protein), bona fide silicon transporters, whereas EcLsi2 and EcLsi3, an efflux Si transporter, belong to an uncharacterized anion transporter family having a significant identity with putative arsB transporter proteins. Further, the phylogenetic and topology analysis suggest that EcLsi1 and EcLsi2 co-evolved during evolution while, EcLsi2 and EcLsi3 are evolved from either EcLsi1 and/or EcLsi6 by fusion or duplication event. Moreover, these silicon transporters are predicted to be localized in plasma membrane, but their structural differences indicate that they might have differences in their silicon uptake ability. Silicon amendment induces the synergistic defense mechanism by significantly increasing the transcript level of silicon transporter genes (EcLsi1, EcLsi2 and EcLsi6) as well as defense hormone regulating genes (EcSAM, EcPAL and EcLOX) at 72 hpi (hours of post infestation) in both stem and roots compared to non-silicon treated plants against pink stem borer in finger millet plants. This study will help to understand the molecular defense mechanism for developing strategies for insect pest management.

Overview of the use of biocontrol agents in the control of Indonesian sugarcane borers

Sugarcane-borers complex in Indonesia consists of a shoot borer (Scirpophaga excerptalis) and four stem borers (Chilo sacchariphagus, C. auricilius, Sesamia inferens and Tetramoera schistaceana). Control of these borers is carried out biologically through the release of egg parasitoid Trichogramma spp. There are four species of mass-produced egg parasitoids and are used in the borer control program, namely Trichogramma japonicum, T. chilonis, T. nanum, and T. minutum. During this time, to measure the level of effectiveness of egg parasitoid releases was through the level of stalk damage. The effectiveness of the release of egg parasitoid should be measured through the mortality rate of borer eggs or parasitization level by the parasitoid. The observations in sugar cane plantations with release and without release of the Trichogramma spp. showed that releases of T. japonicum and T. chilonis were not effective in causing borer egg mortality. The level of parasitization of the borers’ eggs in both plantations was not significantly different, and the parasitization of sugarcane borer eggs was observed mostly due to natural egg parasitoid species, such as Tetrastichus sp., Telenomus sp., and T. chilonis. Biological control of the sugarcane borer complex by mass release of egg parasitoid needs to be reviewed.

Diallel analysis for yield and component traits in maize (Zea mays) under infestation and non-infestation with pink stem borer (Sesamia cretica)

A half diallel cross between nine yellow inbred lines of maize (Zea mays L.) was evaluated under two environments, viz. borer artificial infestation conditions and normal conditions in RCBD with three replications in 2015 to estimate general and specific combining ability effects and identify superior genotypes resistant to Sesamia cretica. Highly significant cross mean squares were detected for all the studied traits indicating the wide diversity in the parental materials used in this study. General and specific combining ability (GCA and SCA) were significant for all the studied traits except SCA for number of rows/ear in normal condition revealing that both additive and non-additive gene effects were involved in determining the performance of the single cross progeny. The parental inbred line P6, P8 and P9 can be considered as good combiners for grain yield and some of its component traits under infestation and non-infestation conditions as well as the combined over them. Six crosses (P1×P6, P1×P7, P2×P4, P3×P5, P5×P7, and P8×P9) selected based on desirable SCA effects also had high mean performance for grain yield and out-yielded the check hybrid SC 166. Therefore, these crosses could be utilized for future breeding work as well as for direct release after confirming the stability of their performance across different environments. The information from this study may be useful for researchers who would like to develop high yielding hybrids of maize tolerant to borer attack.

The effect of temperature and CO2 on the development of pink stem borer on maize

Pink Stem Borer, Sesamia inferens Walker (Lepidoptera: Noctuidae) incidence has increased on graminaceous crops in the north-western plains of India during recent years. To understand the effect of climate change on the northward spread of the pest, studies on the growth and development of S. inferens on maize (Zea mays L.) were planned with combinations of temperature and CO2. The combinations were 27: 22 °C and 375 ppm of CO2, 32: 26 °C and 375 ppm of CO2, 27: 22 °C and 450 ppm of CO2 and 32: 26 °C and 450 ppm of CO2. Various developmental parameters of S. inferens were analyzed using analysis of variance for the main effects of temperature and CO2 and their interactions. At elevated temperature, the growth of egg, larval and pupal stages were faster and the developmental period decreased by 30.9%. At elevated CO2, the larval and pupal development delayed and there was 5.7% increase in developmental period. Both temperature and CO2 individually and in combination significantly influenced adult longevity. Adult longevity reduced 24.9% and 21.7% in male and female, respectively at elevated temperature. Whereas, at elevated CO2, adult longevity increased 7.6% in male and 6.8% in female, respectively. The fecundity was positively influenced (+10.8%) by elevated temperature and negatively (−14.4%) by elevated CO2. The effects of temperature and CO2 on the development of pink stem borer were opposite, with temperature being positive and predominant in influencing the biology of S. inferens. So, it is probable that the faster development of S. inferens on maize in the warm climate might slightly get mitigated by the adverse effect of elevated CO2. The overall effect of rapid development of pest population and damage on maize on large area basis needs to be further investigated.

A New Northern Distribution Record of the Purple Stem Borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae) in China

A New Northern Distribution Record of the Purple Stem Borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae) in China

The Effects of the Essential Oils Isolated from Four Ecotypes of Cumin (Cuminum cyminum L.) on the Blood Cells of the Pink Stem Borer, Sesamia cretica Ledere (Lepidoptera: Noctuidae)

In this research, the effects of essential oils isolated from four ecotypes of cumin (Cuminum cyminum L.) Northern-Khorasan (NS), Fars (FS), Kerman (KK), and Kerman (KR) were evaluated on the 4th instar larvae of pink stem borer, Sesamia cretica Lederer. The essential oils were extracted from seeds and the chemical composition was assessed via Gas Chromatography-Mass Spectrometry (GC-MS). Cuminaldehyde (43.599-55.939%), γ-terpinene (13.134-21.750%), m-cymene (8.349-16.935%), s-pinene (6.320-14.130%), and α-phellandrene (2.137-4.742%) were the main components of the essential oils. Four types of blood cells: prohaemocytes, plasmatocyte, granulocyte, and oenocytoid were identified in the haemolymph of the 4th instar larvae of S. cretica. The decreasing haemocyte counts were found to be significant in the different ecotypes of C. cyminum essential oil. The utilized concentrations and specified times had significant effects on the reductions of the mentioned cell numbers. The fewest number of cells for all ecotypes was measured after 48 h. The highest decline in the total haemocyte count was related to the concentration of 8000 ppm in NS ecotype. The lowest LC50 value was observed in KR ecotype. Based on the results of the present study, the essential oils isolated from the different ecotypes of C. cyminum showed to be promising candidates for S. cretica management.

A Review of Rain-Fed Wheat Production Constraints in Zambia

Wheat (Triticum aestivum L.) is an important food crop in Zambia. It is the second most widely grown cereal crop after maize. However, its production and productivity during summer rain season is limited by socio-economic, abiotic and biotic constraints. The socio-economic factors limiting high wheat yield are high cost of inputs, lack of improved rain-fed wheat seed, lack of affordable loans, lack of access to market information and poor mechanization. The abiotic constraints on the other hand include drought, high temperature and aluminium toxicity. Biotic constraints affecting rain-fed wheat production include various weeds, pests (aphids, grass hoppers, pink stalk borers and termites) and diseases (powderly mildew, loose smut, leaf rust, fusarium head blight and spot blotch). Termites being the most serious and destructive pest of rain-fed wheat. Spot blotch is the most devastating and widely distributed among the diseases causing high yield losses of between 7-100% followed by fusarium head blight. This review paper, looks at the factors that limit the production and productivity of rain-fed wheat among small holder farmers in Zambia.