Pod Damage Research Articles

Yield Yield loss and economic threshold estimates for pod borer (Helicoverpa armigera) in late maturing pigeonpea (Cajanus cajan)

Pod borer [Helicoverpa armigera (Hubner)] is a major biotic constraint to global pigeonpea production. The farmers largely apply synthetic insecticides to control this pest in pigeonpea. The study was conducted to quantify yield losses and estimate economic thresholds for H. armigera. The late maturing cultivar, IPA-203 was infested with different larval densities to determine the insect density-yield loss relationships. The yield response was variable and grain yield declined with increasing larval density from 1–5/plant. Yield loss of 4.56 kg/ha was evident for each unit increase in larval population. Economic threshold estimates indicated that the control measures for pod borer in IPA 203 cultivar should be initiated at an insect density of ≈1 larva/2 plants or at 3% pod damage to avoid the economic crop losses. The damage potential and economic threshold estimates are prerequisite for integrated pest management and reducing production costs (Alves et al. 2017). Present results indicated that relatively low infestations of H. armigera can cause significant yield reduction in pigeonpea hence intensive monitoring and timely control measures are necessary. Based on present economic threshold estimates, the farmers could decide the timing and kind of control measures to be initiated against pod borer in late pigeonpea cultivars to avert the economic losses.

Effect of Packaging Material on Infestation Level in Stored Groundnut Pods

Groundnut crop is an important crop for farmers of the Saurashtra region of Gujarat State in India. Generally, farmers cultivate groundnut crop in the Kharif season. Storage of groundnut pods is associated with the problem of bruchid during storage in jute bags. To address this storage problem with groundnut pods, current research was carried out comparing performance of different packaging materials with their traditional storage system in jute bags. Seven different types of bags were used as packaging materials. The experiment was carried out for the year 2016-17 and 2017-18. The storage period was December-July. Pool data for two years were considered for determination of the effect of packaging material on storage of groundnut pods with respect to moisture content, germination percentage, pod damage due to infestation, pest population, and aflatoxin. Groundnut stored in cloth bag showed maximum variation in moisture content during the storage period (6.40% to 8.35%), maximum pest population of pupa (6.82 pupa/200 gm sample) and adult of bruchid beetle (3.14 adult/200 gm sample), pod damage due to infestation on number basis (61.13%) as well as weight basis (63.46%) whereas minimum variation was found in moisture content during the storage period (6.74% to 6.90%), maximum pest population of pupa (2.44 pupa/200 gm sample) and adult of bruchid beetle (1.51 adult/200 gm sample), pod damage due to infestation on number basis (18.24%) as well as weight basis (18.76%) in triple layer hermetic storage bag i.e., Purdue Improved Crop Storage (PICS) bags followed by closely woven net bag. The minimum germination percentage (69.22%) was found in cloth bag and it was the maximum (78.18%) in triple layer hermetic storage bag. Aflatoxin in the pods stored in triple layer hermetic storage bags was under limit. Results of this study will be helpful to select storage bags for storing groundnut pods.

Screening of Field Pea (Pisum sativum L.) Genotypes for their Susceptibility against Pod Borers

The present investigation on the varietal screening of 13 pea genotypes including a check was carried out at Agricultural Research Farm, RAK College of Agriculture, Sehore, M.P. during Rabi 2020-2021. The larval population of H. armigera was found to be minimum in Pant P 484 with 1.21 larvae/ plant, with a pod damage of 2.28%, and maximum in KPMR 942 with 2.01 larvae/ plant, with a pod damage of 12.82% which was found statistically at par with HFP 16-02 with 1.91 larvae/ plant (12.37% pod damage). The maximum population of L. boutiques was also recorded on KPMR 942 (2.22 larvae/ plant) with pod damage of 15.00% followed by HFP 16-02 (13.40%) while it was minimum in Pant P 484 (1.36 larvae/ plant) with 2.83% pod damage. The result on the yield was maximum in Pant P 484 with 2818 kg/ha and the minimum yield was recorded in KPMR 942 with 919 kg/ha during the crop period. Out of a total of 13 varieties tested for infestation by the pod borers, three varieties (Pant P 484, IPFD 20-03 and IPFD 12-02) were found to be highly resistant, two varieties (Pant P 480 and IPFD 11-05) were least susceptible, four varieties (Pant P 479, RNCP 14-13, IPFD 20-09 and IPFD 20-02) were considered to be moderately susceptible, and four varieties (KPMR 942, HFP 17-11, HFP 16-02 and IPFD 10-12) were reported to be highly susceptible. By identifying resistant genotypes, we can adopt more targeted and sustainable strategies to combat pod borers, reducing reliance on chemical pesticides and minimizing crop losses. These resistant genotypes could also serve as valuable genetic resources for future breeding programs aimed at developing improved cultivars with enhanced resistance and contribute to the broader field of integrated pest management in field pea cultivation.

<i>Bacillus thuringiensis</i> Isolates and their Cry Genes Toxic to Chickpea Pod Borer <i>Helicoverpa armigera</i> (Hubner) from Ethiopia

Helicoverpa armigera (Hubn) is one of the most destructive insect pests of chickpea in Ethiopia. For sustainable management of insect pests of food crops, Bacillus thuringiensis (Bt) is a widely used bioinsecticide. This study was aimed at exploring indigenous Bt isolates that harbour cry genes to control H. armigera. Ten indigenous Bt isolates were analyzed for their cry genes. Accordingly, all the indigenous Bt isolates were observed to harbour two or more cry genes. Statistically significant (p<0.05) variations were observed among Bt species in influencing larval incidence, pod damage (%) and grain yield (t/ ha). Three potential indigenous Bt isolates were identified with their respective cry genes that included KDL (cry2 + cry4), AUGHS-1 (cry1 + cry4), and AUSD-1 (cry1 + cry2 + cry4 + cry7, 8 + cry9). Indigenous Bt isolates exhibited a strong potential in the management of chickpea pod borer. Development of commercial bioinsecticide and other Bt technologies using B. thuringiensis from Ethiopian sources will be a new avenue to be addressed.

Bio efficacy of selected insecticides against pod fly, Melanagromyza obtusa (Malloch) in pigeonpea

In the present study, efficacy of selected insecticides was evaluated against pod fly, Melanagromyza obtuse (Malloch) over three consecutive years in pigeonpea cultivar, Rudreswara (WRG-65). The relative efficacy of nine insecticides was assessed in terms of pod fly population and pod damage. The insecticides were applied twice at 15 days interval, starting from pod formation stage. The results revealed that thiamethoxam 25WG at 0.4g/l + Jaggery @ 5g/l followed by flubendiamide 480 SC @ 0.3ml/l proved significantly superior by reducing pod fly population and pod damage by recording highest grain yield (1582 kg ha-1) and best Cost: Benefit ratio (1:2.39). The potential insecticides observed in this study may be used in rotation with other effective ones in order to avoid development of insecticide resistance in pod fly.

Evaluation of Medium Maturity Pigeonpea Genotypes for Resistance to Pod Borer Complex

The present investigation was conducted during Kharif 2022-23 at the experimental area of Department of Entomology, AICRP on Pigeonpea, Research cum Instructional Farm, IGKV, Raipur, (C.G.). The aim of the study was to screen the different pigeonpea genotypes against pod borer complex. The different pigeonpea genotypes were screened against pod borer complex which showed significant difference between tested genotypes on different parameters viz., percent pod damage and grain yield. Genotypes CG Arhar-2 (19 per cent), showed least affected by pod borers and RPS-15-50 (40.00 %) was found most affected by pod borers. The highest grain yield was observed in CG Arhar-2 (1927.78 kg/ha) and lowest grain yield was observed in RPS-15-21 (875 kg/ha)).

Role of Physical and Biochemical Characters in Groundnut Genotypes as a Basis of Resistance against Groundnut Bruchid, Caryedon serratus Olivier during Storage

Background: Groundnut bruchid (Caryedon serratus Olivier) is the most important stored grain insect pests of groundnut that significantly lowers the quality and market acceptance of the produce. The grub of this insect causes extensive damage to the kernels by boring into undamaged shell and feeds on seeds internally. Therefore, the present study is aimed at screening of the groundnut genotypes on the basis of their physical and biochemical characters which are responsible for imparting resistance against the bruchid pest. Methods: An experiment was conducted at the Department of seed science and technology, OUAT, Bhubaneswar during 2019-20 to study the physical and biochemical characters involved for resistance in stored groundnut genotypes against groundnut bruchid, C. serratus. Varietal screening study was conducted in twenty groundnut genotypes and their physical and biochemical characters were assessed in the laboratory. Result: Small pod size, less pod weight and more shell thickness attributed for resistance to C. serratus resulting in least percentage pod damage and weight loss. Similarly, groundnut genotypes with lower protein content and higher phenol, fiber and ash content conferred resistance against the test insect.

Genetic resources and genes/QTLs for gram pod borer (Helicoverpa armigera Hübner) resistance in chickpea from the Western Himalayas.

Helicoverpa armigera (also known as gram pod borer) is a serious threat to chickpea production in the world. A set of 173 chickpea genotypes were evaluated for H. armigera resistance, including mean larval population (MLP), percentage pod damage (PPD), and pest resistance (PR) for 2 consecutive years (year 2020 and 2021). The same core set was also genotyped with 50K AxiomCicerSNP Array. The trait data and 50,000 single nucleotide polymorphism genotypic data were used together to work out marker-trait associations (MTAs) using different genome-wide association studies models. For MLP, a total of 53 MTAs were identified, including 25 MTAs in year 2020 and 28 MTAs in year 2021. A set of three MTAs was found common in both environments. For PPD, two MTAs in year 2020 and five MTAs in year 2021 were identified. A set of two MTAs were common in both environments. Similarly, for PR, only two MTAs common in both environments were identified. Interestingly, a common MTA (Affx_123255526) on chromosome 2 (Ca2) was found to be associated with all the three component traits (MLP, PPD, and PR) of pod borer resistance in chickpea. Further, we report key genes that encode SCAMPs (that facilitates the secretion of defense-related molecules), quinone oxidoreductase (enables the production of reactive oxygen species that promotes diapause of gram pod borer), and NB-LRR proteins that have been implicated in plant defense against H. armigera. The resistant chickpea genotypes, MTAs, and key genes reported in the present study may prove useful in the future for developing pod borer-resistant chickpea varieties.

Seasonal Incidence of Spotted Pod Borer (Maruca vitrata F.) in Indian bean and Correlation with Meteorological Aspects

Aim: To study the population dynamics of spotted pod borer infesting Indian bean in relation to weather parameters Study Design: Field trail; Randomized Block Design. Place and Duration of Study: The study was conducted at College farm at Navsari Agricultural University during Rabi of 2022-23 and 2023-24. Methodology: 50 plants were randomly selected from the net plot area. The observations on the number of larvae per plant and per cent pod damage were counted. Results: The larval population, in year 2022-23 started from 51st SMW. The peak activity was observed in 4th SMW when 6.46 larvae/plant population was recorded which coincided with the peak flowering stage. During the second season (year 2023-24) also, the pest population started from 51st SMW with pest population of 0.8 larvae/plant. The peak pest population was observed on 4th SMW with 6.84 larvae/plant. The pod damage started from 2nd SMW with 10.05 per cent and gradually increased. The peak was recorded in 12th SMW, highest pod damage was observed with 55.89 per cent. Similar to previous year, the pod damage was recorded from 2nd SMW with 11.67 per cent and peak was seen in 8th SMW with 56.63 per cent damage. The correlation of number of larvae per plant with maximum (r=-0.63), minimum (r=-0.62), average temperature (r=-0.74) and average vapour pressure (r=-0.59) showed significantly negative correlation. During year 2023-24, minimum (r=-0.637) and average temperature (r=-0.610) showed significant negative correlation. In case of pod damage, it was revealed that maximum temperature (r=0.58) and bright sunshine hours (BSSH) (r=0.59) exhibited significant positive correlation with pod damage per cent, in year 2022-23. A similar trend was seen in year 2023-24 where, maximum temperature (r=0.692) and BSSH (r=0.787) showed significant positive correlation. Conclusion: Temperature and to some extent vapour pressure plays a significant role in the population fluctuation of spotted pod borer in Indian bean.

Native Bacillus thuringiensis isolates against the old-world bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in Ethiopia

ABSTRACT Chickpea ( Cicer arietinum L.) production in Ethiopia has been seriously constrained by the insect pest, Helicoverpa armigera. Insecticides have been used for decades to control this noxious pest. However, the restriction on chemical insecticides necessitates biological pest control alternatives. Therefore, the present study investigated the effectiveness of native Bacillus thuringiensis (Bt) isolates against Helicoverpa armigera 3rd instar larvae. The treatments consisted of Bt concentrations at the LD90 values, whereas the control plots were sprayed with distilled water and a commercial Bt. var. thuringiensis product. The results revealed statistically (p < 0.05) significant differences between the native Bt isolates and the control plots. Post 1st, pre 2nd and post 2nd Bt sprayed larval populations counted per plant ranged from 0.8 ± 0.3–3.1 ± 0.1, 0.6 ± 0.1–3.6 ± 0.0 and 0.5 ± 0.1–3.6 ± 0.4, respectively. Pod damage (%) and grain yield (t/ha) ranged between 9.7 ± 3.1 and 47.5 ± 9.5, 1.0 ± 0.0 and 2.6 ± 0.5, respectively compared to 47.5 ± 9.5% pod damage and 1.0 ± 0.0 (t/ha) grain yield from the control plots. These results indicate the potential of these bio-insecticides in the management of chickpea pod borer. Future research in Ethiopia should focus on additional collection, screening, characterisation, and testing in field trials.

Field screening and identification of biochemical indices of pod borer (Helicoverpa armigera) resistance in chickpea mutants.

Chickpea pod borer (CPB) (Helicoverpa armigera) is one of the major pests, causing significant yield losses. The objectives were to screen chickpea mutants for pod borer resistance/tolerance under field conditions and identification of biochemical markers of tolerance. Chickpea mutant CM216-A/15 had highest leaf (25 trichomes/mm2) and stem trichome density (17 trichomes/mm2) with least pod damage at Kallur Kot and highest pod weight per plant (22.8 ± 2.6g) at AZRI. Higher total phenolic contents (TPCs) and antioxidant capacity were detected in tolerant mutants, i.e., CM216-A/15 and CM664/15. TPC was positively associated with pod yield and had negative correlation with pod damage. Mutants CM216-A/15, CM664/15, and CM766/15 depicted the highest resilience to CPB, owing to higher hairiness, better antioxidant defense response, and lower levels of hydrolytic enzymes and sugars. Identified biochemical markers like TPC, total oxidant status, superoxide dismutase, and pigments can be used for screening of CPB-tolerant/resistant mutants.

Damage of Melanagromyza obtusa (Malloch) and Management Potential of Newer Insecticides in Pigeon Pea

Background: The pod fly, Melanagromyza obtusa (Malloch) is one of the major biotic constraints in increasing production and productivity of pigeonpea crop throughout the country and it causes up to 100 per cent losses in field condition. Injudicious use of pesticides against this destructive pest, further ignites the problem of resistance, resurgence and environmental and ecological imbalances. Methods: Experiments were conducted at Banda University of Agricultural and Technology, Banda during kharif, 2020 and 2021. To estimate the bio-efficacy of insecticides for the management of M. obtusa in pigeonpea the experiment was laid out in randomized block design (RBD) with eight treatments and three replications. Pod and grain damage were assessed and C:B ratio was calculated. Result: First appearance of pod fly was noticed in third standard week. Throughout cropping period highest pod damage was recorded in eighth standard week and lowest pod damage was recorded in twelfth standard week. Emamectin benzoate 5 SG @ 11g a.i./ha + Dimethoate 30 EC @ 300 g a.i./ha was the best treatment as it exhibited minimum pod damage and highest yield.

Population dynamics of pod pest complex of pigeonpea

A field experiment was conducted at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad, to study the population dynamics of pod pest complex of pigeonpea. The observations were recorded at fortnightly intervals starting from flower initiation stage upto the harvest of the crop. The peak activity of gram pod borer (3.63 larvae/plant), spotted pod borer (3.63 larvae/plant) and pod bugs (4.62 bugs/plant)was observed during 50th Standard Meteorological Week. The pod damage caused by Helicoverpa armigera (25.02%) and Maruca vitrata (16.77%) was also highest during 50th Standard Meteorological Week. The maximum pod damage by plume moth (12.02%) was noticed at 52nd Standard Meteorological Week. The 52nd Standard Meteorological Week witnessed highest pod fly population (10.80 maggots / 10 pods), per cent pod damage (27.75%), and per cent seed damage (17.51%).The correlation studies of incidence of pod pest to prevalent weather parameters revealed that, gram pod borer and the spotted pod borer were more prevalent as the minimum temperature rose, but pod fly and pod bugs population increased negatively. There was a negative correlation between the population of all pod pest, including gram pod borer, spotted pod borer, pod bugs and pod fly with maximum relative humidity, minimum relative humidity and rainfall.

Evaluation of different plant products against pod borer, Helicoverpa armigera (Hubner) infesting chickpea under certified organic farming system

Pest management under organic farming is a challenging task, wherein, ecofriendly approaches against insect pest were accomplished through the use of appropriate strategies which promotes manipulation and alteration of agro-ecosystem. In this view, an experiment was laid out in Randomized Block Design with JG-11, a chickpea variety sown during rabi of 2021-22 and 2022-23 at certified organic block (certified since 2006), Bio-Resource Farm, Institute of Organic Farming, University of Agricultural Sciences, Dharwad. The analysis of pooled data for two seasons revealed that, among various plant products evaluated the plots treated with NSKE @ 5% found superior with significantly least larval population of Helicoverpa armigera (0.72 larvae/m row), with minimum per cent defoliation (12.02%) as well as significantly lower pod damage (11.75%) which was followed by Vitex negundo @ 5%. Similarly, statistically higher chickpea yield was noticed under plots sprayed with NSKE @ 5% with (825.40 kg/ha) with B:C ratio (1.77) during 2021-22, and (788.36 kg/ha) with B:C ratio of (1.69) during 2022-23, compared to untreated check with 161.02 kg/ha and 195.77 kg/ha during 2021-22 and 2022-23, respectively. However, in comparison with inorganic check, organically treated plots documented, relatively higher population of major natural enemies of chickpea ecosystem such as Campoletis chlorideae and coccinellids which was on par with untreated control.

Assessment of Bioefficacy of Chilli Pepper Capsicum frutescens (L.) and its Intercropping on the Performance and Insect Pests Management of Bambara Groundnut (Vigna subterranea L.)

A study was conducted at the Yaba College of Technology Instructional and Research Farm in 2022 and 2023 wet and dry seasons to determine the bio-efficacy of chilli pepper, (Capsicum frutescens (L.)) and its intercropping on the growth, yield and insect pest management of Bambara groundnut (Vigna subterranea (L.)). The experiment was laid out in a 3×4 factorial experiment in Randomized Complete Block Design with 3 treatments (chilli pepper extract at 200l/ha, 250l/ha, and local control) at 3 replications in alternate intercropping, strip cropping, border cropping, and sole cropping arrangement. The chilli pepper aqueous extract at 200 l/ha and 250 l/ha sprayed on the Bambara groundnut plants were sprayed as scheduled from 10 am to 12 noon with the view of protecting it with aqueous extract of chilli pepper on 12 plots of 60 ridges. Data were collected on growth parameters of Bambara groundnut at 2, 4, and 6 weeks after planting, pest population, assessment of thrips and legume pod borer, assessment of both nymph and adult of legume pod borer and pod sucking bugs, pod density, pod damage, grain yield, yield loss and assessment of phytotoxicity signs using Analysis of Variance. Results showed that 250 l/ha aqueous extract treated plots reduced the number of insect pests including thrips (4.67±1.09), legume pod borer (1.76±0.35), legume pod borer nymph (1.08±0.10) adults of pod borers (1.18±0.11) and pod sucking bugs adult (3.33±1.09) in intercropping situation, followed by 200 l/ha respectively as compared to untreated plots (2.69±0.12). There was a significant difference (p &lt; 0.05) between the treated plots (9.08±0.62) and untreated plots (12.44±0.71) in terms of pod damage as well as increased grain yields (343.73±4.71) when compared to the untreated control (322.12±43). However, 250 l/ha causes higher phytotoxicity damage than 200 l/ha although it controlled pest population better than 200 l/ha. Alternate cropping proved to be superior to other cropping system with respect to grain yield (36.78±12.99), reduction in pest infestation (6.33±1.23) and reduction in yield loss (299.58±9.41) when compared to sole cropping of Bambara groundnut with respect to grain yield (100.24±12.99), reduction in pest infestation (15.33±1.23) and reduction in yield loss (395.27±9.41). The bio-pesticidal effect of chilli pepper on Bambara groundnut insects may be due to the presence of active ingredients present in chilli pepper including glycosides, tannin, terpenoides, flavonoids, saponin, reducing sugar, steroids, and resins. This result indicates the potential of using plant extract with insecticidal attributes for the protection of Bambara groundnut in low input agriculture practiced by limited resource farmers in developing countries.

Bio-efficacy of certain new insecticides against pod borer complex in pigeonpea (Cajanus cajan L.)

A study on evaluation of certain new insecticides against pod borer complex in pigeonpea was conducted at Regional Agricultural Research Station, Warangal for three consecutive years from Kharif 2019-20 to Kharif 2021 22 in medium maturity pigeonpea cultivar ‘Rudreswara’ (WRG-65). Seven treatments including untreated control were evaluated for their relative efficacy towards suppression of pod borer larval population and reduction of percent pod damage. The insecticide treatments along with untreated control were applied two times during the crop season viz., 50% flowering and pod formation stage. The results revealed that chlorantraniliprole 18.5 SC @ 0.3 ml/L followed by emamectin benzoate 5 SG proved significantly superior against gram pod borer (Helicoverpa armigera) and spotted pod borer (Maruca vitrata) with highest mean percent larval reduction and cumulative least percent pod damage (10.8 and 14.7%, respectively) over control. Further, chlorantraniliprole 18.5 SC followed by emamectin benzoate 5 SG @ 0.4 g/l recorded higher grain yields and best ICBR ratio (1:4.6; 1:4.5). Thus, the effective chemicals observed in the study could be used as basis for selection of label recommended insecticides for successful management of pod borers in pigeonpea.

Estimation of Yield Losses Caused by Insect Pests on Pigeon Pea (Cajanus cajan (L.) Millsp.)

Field experiment was carried out to estimate the yield losses in pigeon pea crop due to insect pests during kharif 2018-19, 2019-20 and 2020-21 at College of Agriculture, Navsari Agricultural University, Bharuch (Gujarat). Results revealed that avoidable yield loss due to insect pests in pigeon pea was recorded up to 38.48% when no plant protection measures are taken. Amongst different insect pests, the maximum damage was recorded due to pod borer, Helicoverpa armigera (34.90%) followed by pod sucking bugs, Clavigralla gibbosa (29.75%) and pod fly, Melanogromyza obtusa (23.64%). Pod damage due to spotted pod borer, Maruca vitrata and tur plume moth, Exelastis atomosa was recorded up to 14.09% and 5.60%, respectively.

A novel insecticide, isocycloseram, shows promise as an alternative to chlorpyrifos against a direct pest of peanut, Diabrotica undecimpunctata howardi (Coleoptera: Chrysomelidae).

Larvae of the southern corn rootworm (SCR) Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) are primary pests of peanut in the Virginia-Carolina region of the United States, and are relatively sporadic pests in southern states such as Georgia, Alabama, and Florida. Peanuts have strict quality standards which, when they are not met, can diminish crop value by more than 65%. Management of direct pests like SCR is therefore crucial to maintaining the economic viability of the crop. The soil-dwelling nature of SCR larvae complicates management due to difficulties associated with monitoring and predicting infestations. Nonchemical management options are limited in this system; preventative insecticide applications are the most reliable management strategy for at-risk fields. Chlorpyrifos was the standard product for larval SCR management in peanut until its registration was revoked in 2022, leaving no effective chemical management option for larvae. We tested a novel insecticide, isocycloseram, for its ability to reduce pod scarring, pod penetration, and non-SCR pod damage in field studies conducted in Suffolk, Virginia in 2020-2022. Overall injury was low in 2020 and 2022, and in 2022 there was not a significant effect of treatment. In 2021, 2 simulated chemigation applications of isocycloseram in July significantly reduced pod scarring and overall pod injury relative to chlorpyrifos and the untreated control. Our results suggest that isocycloseram may become an effective option for managing SCR in peanut, although more work is needed to understand the mechanisms by which it is effective as a soil-applied insecticide.

Pheromone traps and climate variations influence populations of Sahlbergella singularis (Hemiptera: Miridae) and associated damage of cocoa in Cameroon.

Knowledge of insect pest ecology and biology is important for maximizing crop protection and reducing crop losses. Currently, we lack an efficient control program for the cocoa mirid Sahlbergella singularis Haglund (Hemiptera: Miridae), the principal insect pest of cocoa in West and Central Africa. A 2-yr study was conducted in 11 plantations across Ayos and Konye, two of the largest cocoa growing areas of Cameroon. We evaluated the effects of mirid sex pheromone and climatic variations on mirid population dynamics and their associated cocoa damage. Sex pheromone traps caught 1.5-fold higher mirids in Ayos than in Konye, with more overall counts in 2015 than in 2016. Cocoa pod counts were also significantly higher in 2015 than in 2016 and were negatively correlated with temperature and relative humidity. In both localities, mirid populations and associated cocoa pod damage were suppressed in plantations where sex pheromone traps were used. Damage incidence was positively correlated with mirid counts, confirming that the cocoa pod is the preferential site for mirid feeding and reproduction. As such, damage incidence could be used as proxy for comparative mirid population level due to the mirid's cryptic habit. Of the recorded weather variables, only relative humidity was correlated (negatively) with damage severity. Our data on the relationships between damage caused by mirids and their population dynamics and sex pheromone trap catches suggest that an effective control strategy using mass trapping could be developed for mirid management in cocoa plantations.

Evaluation of newer insecticides against spotted pod borer and its pod damage in summer green gram

Evaluation of newer insecticides against spotted pod borer and its pod damage in summer green gram