Damaging Insect Pests Research Articles

Determinants of oilseed rape-service plant intercropping performance variability across a farmers’ fields network in Western Switzerland

The intercropping of winter oilseed rape with frost-sensitive service plants can provide a diversity of services including weed control and N supply for oilseed rape. This practice started to be adopted by farmers and has therefore become one of the most popular intercropping in Western Europe. However, in Switzerland, such intercropping leads to contrasting yields. The growth of service plants and the benefits they provide have also been found to be variable. The factors explaining these variabilities remain unclear. Our study aimed to better understand this variability under a temperate climate thanks to the regional agronomic diagnosis framework. In this study, we first investigated the main factors explaining this variability and then aimed to rank them to identify ways to better manage such intercropping systems. A network of 28 farmers’ fields planted with winter oilseed rape intercropped with service plant mixtures was studied. Farmers’ practices were diverse in terms of specific composition of the service plant mixture, pest management, and fertilization. We observed that the growth of oilseed rape and service plants in fall was highly variable. We determined that in late fall, the main drivers of the service plant mixture dry weight were specific composition of the mixture and precipitation. The introduction of buckwheat in the service plant mixture enhanced its late fall biomass. The oilseed rape grain yields ranged from 0.4 to 5.0 t ha−1 and were lower than that of the local reference in 75% of the fields. This was mainly explained by insect pest damage in spring due to a very limited use of insecticide in our field network combined with a lack of alternative pest management strategies. This work provides further elements to investigate the causes leading to the high variability we observed, together with the local observations that will benefit the farmers.

Inducible defense phytohormones in annual bluegrass (Poa annua) and creeping bentgrass (Agrostis stolonifera) in response to annual bluegrass weevil (Listronotus maculicollis) infestation.

The annual bluegrass weevil (Listronotus maculicollis) is the most damaging insect pest of short-mown turfgrass on golf courses in eastern North America. Listronotus maculicollis larvae cause limited visible damage as stem-borers (L1-3), compared to the crown-feeding (L4-5) developmental instars. Prolonged larval feeding results in discoloration and formation of irregular patches of dead turf, exposing soil on high-value playing surfaces (fairways, collars, tee boxes, and putting greens). Annual bluegrass (Poa annua) is highly susceptible to L. maculicollis compared to a tolerant alternate host plant, creeping bentgrass (Agrostis stolonifera). This study explored whether defense signaling phytohormones contribute to A. stolonifera tolerance in response to L. maculicollis. Concentrations (ng/g) of salicylic acid (SA), jasmonic acid (JA), jasmonic-isoleucine (JA-Ile), 12-oxophytodienoic acid (OPDA), and abscisic acid (ABA) were extracted from turfgrass (leaf, stem, and root) tissue samples as mean larval age reached 2nd (L2), 3rd (L3), and 4th (L4) instar. Poa annua infested with L. maculicollis larvae (L2-4) possessed significantly greater SA in above-ground tissues than A. stolonifera. Levels of constitutive JA, JA-Ile, OPDA, and ABA were significantly higher within non-infested A. stolonifera aboveground tissues compared to P. annua. Inducible defense phytohormones may play a role in P. annua susceptibility to L. maculicollis but are unlikely to provide tolerance in A. stolonifera. Additional studies in turfgrass breeding, particularly focusing on cultivar selection for increased constitutive JA content, could provide a non-chemical alternative management strategy for L. maculicollis for turfgrass managers.

Response of sod webworm Chrysoteuchia topiaria Zeller (Lepidoptera: Crambidae) to endophyte infection and mycotoxin profiles of cool‐season turfgrass species grown for seed in Oregon

AbstractThe subterranean sod webworm, also known as cranberry girdler (Chrysoteuchia topiaria), is one of the most damaging insect pests in cool‐season grass grown for seed crops in Oregon. Chemical control options are limited and require irrigation or rainfall for adequate insecticide incorporation to control C. topiaria larvae. Epichloë endophytes associated with cool‐season turfgrass species and their mycotoxin profiles are well‐documented in offering plant protection against invertebrates; these fungi may offer sustainable pest management tools. Our objectives were to characterize endophyte‐mediated resistance to C. topiaria in 19 commercially available cultivars of tall fescue, perennial ryegrass, and fine fescue grown for seed in Oregon. Endophyte status (presence and viability) of fungal endophytes and their mycotoxin profiles were measured using polymerase chain reaction, and liquid chromatography‐tandem mass spectrometry, respectively. No‐choice assays were conducted in the laboratory to measure the impact of endophyte status on C. topiaria larvae in two separate no‐choice experiments. Our results suggested that increased mortality of C. topiaria larvae (R2 = 0.8526, Experiment 1; R2 = 0.6628, Experiment 2) in tall fescue cultivars was most influenced by total peramine and ergot alkaloid, and total ergoline concentrations in Experiment 1 and 2, respectively. However, no significant effect on insect mortality was found in the perennial ryegrass and fine fescue cultivars included in this study. Overall, these findings suggest a viable grass–endophyte association can be utilized as a sustainable alternative to foliar insecticides for C. topiaria management in tall fescue seed crops.

Insecticidal Efficacy of Diatomaceous Earth and Botanical Powders against Pulse Beetle, Callosobruchus analis F. in Stored Mung Bean (Vigna radiata L.)

The pulse beetle is the most damaging insect pest of legumes causing huge economic losses. The experiment was conducted to find out the insecticidal effects of diatomaceous earth (DE) combined with three botanical powders in three different combinations of 25% plant powder with 75% DE, 50% plant powder with 50% DE and 75% plant powder with 25% DE. The results indicated that the least number of adult beetles settled on grains treated with T9 (75% GP + 25% DE and T3 (75% NP + 25% DE) whereas maximum number of adult beetles settled in T4 (25% TP + 75% DE). After 168 hours, all the treatments showed significant mortality (100%) of adult beetles compared to control (43%). All the treatments reduced the number of eggs (3.60 to 6.80 eggs per 20 grains) in comparison to control (17.00). The maximum (28.80) days to adult emergence were documented in T9 whereas; minimum (21.40) days were recorded in untreated grains. Among all the treatments, T9: showed minimum emergence (36.40) of adult beetles whereas; the maximum (125.20) adults emerged in control. The lowest grain damage (5.50%) was observed in T9 as related to the maximum grain damage (28.96%) in the untreated control. The minimum weight loss (3.49%) was recorded in T9. The maximum weight loss (21.08%) was recorded in untreated grains. The use of diatomaceous earth in combination with garlic powder is recommended for the management of pulse beetle under storage conditions.

Influence of Lygus-Traited Cotton Technology on Performance of Commonly Used Inecticides for Tarnished Plant Bug Management Prior to Bloom

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is the most economically damaging insect pest of cotton, Gossypium hirsutum L., production in the Mid-South region of the U.S. In Mississippi alone, tarnished plant bug caused approximately $270 in losses per hectare and accounted for nearly 70,000 lost bales per annum during 2021 and 2022. Insecticide use is the foundation of integrated pest management strategies for control of tarnished plant bug in the Mid-South. Prior to bloom, acephate, imidacloprid, and sulfoxaflor are commonly used insecticides for tarnished plant bug management. Research was conducted in the Mississippi Delta region with commonly used insecticides prior to bloom to evaluate their performance in non-ThryvOnTM and ThryvOn cotton varieties. Research suggests that imidacloprid has a limited fit in non-ThryvOn cotton production. However, these data indicate that the additional mode of action provided by ThryvOn cotton could extend the longevity of imidacloprid, along with other commonly used insecticides in Mid-South cotton production.

Vertical and temporal flight patterns of coffee berry borer (Coleoptera: Curculionidae) in Hawaii.

Coffee berry borer (Hypothenemus hampei Ferrari) (Coleoptera: Curculionidae) is the most damaging insect pest of coffee worldwide, causing significant losses in coffee yields and quality. Knowledge of vertical and temporal flight patterns in coffee berry borer could be used to optimize spray timing and precision targeting of areas within the coffee tree, which may be more susceptible. In the present study, we estimated the vertical distribution of coffee berry borer females using traps set at 1-m intervals up to 5 m in height. We also quantified coffee berry borer infestation in the low, mid, and high canopy and documented fruit availability. Temporal flight patterns were estimated using timer traps, and correlation analyses were conducted to determine the relationship between the timing of daily flight and weather variables. Across the 4 study sites, we observed that 77%-84% of the trap catch was at 1 m, 11%-20% was at 2 m, and 1%-4% was at 3-5 m in height. Fruit infestation was significantly higher in the low branches (35%) relative to the high branches (17%). Flight height remained the same year-round, regardless of fruit availability. Coffee berry borer flew in low numbers during the day and night but peaked from 12 to 4 PM. Daily flight was positively correlated with an increase in air temperature and wind speed and negatively correlated with relative humidity. Findings from this study suggest that pesticide sprays should target low- to mid-level branches at 1-2 m in height and aim to be conducted in the early afternoon when coffee berry borer are actively flying and most vulnerable to chemical controls.

The Effects of Transplanting Date on Management of Tobacco Insect Pests. Min review

The main review purpose this paper provides updated information on the effect of different transplanting dates on the infestation of tobacco insect pets were carried out at different location by different Scholars. The results revealed that different trials conducted in different agro ecological zone indicated that damage was higher and green leaves yield decrease were in late transplanted tobacco. While, the damage was gradually decrease and green leaves yield increase in early transplanted tobacco. Numerous species of insect pests of tobacco affect the crop in the field, in the greenhouse, and in storage. The effect tobacco insect pests reduced green leaf yield, quality and damage roots, leaves, buds parts of plants and others transmit several important tobacco disease pathogens. As management systems for flue-cured tobacco (Nicotiana tabacum L.) used different transplanting date were compared to evaluate their influence on insect pests’ damage, leaves yield and quality of flue-cured tobacco. The results indicated that early transplanted significantly increase leaf yield, growth parameters and decrease insect pest damage incidence. The study indicated that transplanted has pronounced positive effect on management of tobacco insect pests and growth of tobacco.

Screening of Common Bean Genotypes for Their Resistance to Bean Stem Maggot (Ophiomyia Spp.) in Ethiopia

Common bean production in Africa faces various constraints, including biotic and abiotic stress. Among biotic stresses, bean stem maggots (BSM) (Ophiomyia spp.) are the most damaging insect pests of common beans in central and sub-Saharan Africa, especially under poor soils and dry conditions. Various control measures are available for bean stem maggots; however, there is insufficient information regarding the resistance of common bean genotypes to this pest. The present study aimed to identify sources of resistance to BSM in two groups of genotypes, namely red mottled and sugar bean, at Negelle Arsi and Shalla in Ethiopia during 2016 and 2017. A total of 111 genotypes with 56 belonging to the red mottled group and 55 to the sugar bean group were assessed for their resistance levels in open fields with a history of BSM infestation following randomized complete block design with three replications. In the 2016 assessment, 23 genotypes exhibited significantly lower numbers of dead seedlings and damage scores in both bean groups and locations. The results for the second year (2017) indicated that four genotypes from the red mottled group (DAB-365, DAB-398, DAB-449, and DAB-331) and four from sugar beans (DAB-500, DAB-512, DAB-483, and DAB-54) were moderately resistant to BSM in both locations. The combined findings from the 2016 and 2017 cropping seasons revealed that DAB-500, DAB-512, DAB-483, and DAB-541 from the red mottled group, and DAB-365, DAB-398, DAB-449, and DAB-331 from the sugar bean group, exhibited resistance to BSM at both locations. Therefore, based on the aforementioned information, these eight genotypes from both groups are recommended as potential sources of resistance to bean stem maggots for further common bean breeding purposes.

Plant–herbivore–natural enemy trophic webs in date palm agro-ecosystems

Understanding the composition and dynamics of ecological communities is challenging because of the large number of organisms present and their numerous interactions. Among agricultural systems, intercropping considerably increases the complexity of communities compared to monocultures and alternative host plants can influence insect pest damage. Using literature records, we construct and analyse connectance trophic webs of date palm (Phoenix dactylifera) agro-ecosystems, including and excluding intercrops. Estimates of connectance (community complexity) are relatively low and little affected by consideration of intercrops. Plant–herbivore overlap is relatively high, suggesting that herbivores are typically not specialists. Herbivore–natural enemy overlap is greater when intercrops are considered, suggesting that diffuse apparent competition regulates pest populations. We pay particular attention to how trophic web structure might affect Batrachedra amydraula (Lesser date moth), an important economic pest. Records indicate it having 15 species of natural enemies and sharing 9 of these with other herbivores; these may maintain populations of natural enemies when the moth is seasonally rare, contributing to pest suppression. The estimated potential for apparent competition between the lesser date moth and other herbivores is higher when intercrops are considered. The consequent expectation of less severe infestations in plantations that are intercropped compared to monocultures matches empirically derived reports. Further, comparing results obtained from the literature on one country (Oman) and from 15 Middle Eastern countries, we find that community metric estimates are relatively little affected by the geographical scale considered. Overall, our results suggest that literature-based trophic web construction can provide an efficient and robust alternative, or in addition, to direct empirical methodologies and that the presence of intercrops will contribute to major pest suppression via indirect apparent competition.

Recent outbreaks of the spruce bark beetle Ips typographus in the UK: Discovery, management, and implications

The eight-toothed spruce bark-beetle Ips typographus is the most damaging insect pest of Norway spruce in Europe, and it poses a serious risk to spruce in other countries where it is not currently present but might be introduced. The beetle is not native to the UK and before 2018 it had not been found established anywhere within the country. In November 2018, however, several adult Ips typographus were found in a billet trap set up as part of annual surveys that the UK carries out to monitor for this and other quarantine bark beetle pests. The finding of adult beetles in the billet trap, a few miles south of Ashford in Kent, led to the discovery of a breeding population in an adjacent woodland. Delimiting surveys to 1 km and further surveys to 50 km showed that the infestation was confined to a single stand of Norway spruce. The stand was felled in January and February 2019, and the material destroyed, and beetles emerging on the site were trapped out using pheromone traps, billet piles and trap trees. These prompt actions eradicated the breeding population, but small numbers of adult Ips typographus continued to be caught on the outbreak site in 2020 and 2021. These captures, and numerous adult Ips typographus caught in pheromone traps set up across the region in response to the outbreak, indicate that incursions of adult Ips typographus are occurring on a regular basis, most likely from source populations in northern France and Belgium. The arrival of adult Ips typographus over a wide area and the potential for further outbreaks represents a continuing threat to spruce woodlands in south-east England, and has important implications for surveillance and monitoring and the management of spruce in this part of the UK.

Reducing insecticide use in winter oilseed rape by in-field to landscape-scale agroecological pest management

Reducing insect pest damage in field crops while minimizing insecticide use poses a significant challenge for farmers in Europe. Initiated in 2019, the six-year territorial project R2D2 aimed to explore the effectiveness of an agroecological crop protection approach in the context of widespread resistance of winter oilseed rape (WOSR) autumn beetles to pyrethroid insecticides. Over an area of 1371 hectares, ten farmers collectively developed a generative experimentation based on modifying cultural practices and implementing conservation biological control to gradually phase out insecticide use. Two years later, these farmers had made significant shifts in their pest management strategies by implementing a coordinated array of pest control measures from the field to the landscape level. These changes led to a complete cessation of systematic insecticide applications on WOSR and a 37% reduction in the insecticide Treatment Frequency Index (TFI) for this crop. Despite these promising outcomes, the total TFI across all crops, as assessed at the territorial level, remained unchanged. One of the main reasons for this is the increase in aerial insecticide applications on winter barley following the ban on neonicotinoids, as well as on spring pea to combat rising pea beetle pressures across the territory. For these two crops, effective alternatives to insecticides must be identified. More time is needed to instigate fundamental changes in farming systems and to enhance natural pest regulation through conservation biological control. Farmers’ support strategy should focus on identifying and overcoming barriers to the implementation of transformative systems.

Socioeconomic Conditions of Apple Growers in Marpha, Mustang District

Socio-economic condition of the farmers plays a crucial role in agriculture. Apple is one of the key fruits with potential to generate income and employment in the high mountain districts of western Nepal. The objective of the study has to analyze the socioeconomic status of apple grower in Marpha of Mustang district. A total of 145 households have been sampled out of 235 households by using simple random sampling technique and interviewed with a semi-structured questionnaire to obtain data regarding socioeconomic condition, production, marketing channels, cost and apple price from apple growers as well as secondary sources of data obtained from the District Agriculture Development Office and Temperate Horticulture Development Center, Marpha, Mustang with other published and unpublished documents. The study concluded that socioeconomic conditions of marginal farmers have significantly improved during the last three decades because of apple farming. Seasonal road and poor marketing infrastructure, underprivileged technical knowledge, unavailability of inputs in time, insect pest damage and lack of storage facilities, price disparity and low quantity of production have been noticed major production and marketing problems in the study area.

Progress in developing and deploying drought-tolerant and insect-pest resistant climate-resilient droughtTEGO® and TELA® maize varieties

Currently, drought stress and associated insect-pest damage pose a huge threat to food and nutrition security for over 300 million people in Africa who depend on maize as their main food source. Recurrent drought events cause an annual 17 to 25 percent yield loss of maize in Africa [1]. Compounding the impact of drought, is the ravaging effect of insect-pests infestation on maize production, especially for pests whose population pressure is highly triggered under dry conditions. The crop under weakened conditions created by drought stress and pest effect further becomes constrained biologically and physiologically, thus limiting the crop’s ability to use already limited water and nutrients from the soil. The major insect pests of maize in Africa are fall armyworm (FAW, Spodoptera frugiperda) and various stem borer species (Spotted stem borer (Chilo partellus), African stem borer (Busseola fusca), and the pink stemborer (Sesamia Calamistis). For instance, in Kenya alone, an average of 13 percent or 400,000 tons of maize is lost to stem borer, which is equivalent to the annual maize imports, valued at USD 90 million [2]. The FAW, a transboundary pest, first observed in the continent in 2016, is a maize pandemic that if not controlled adequately, could potentially destroy up to 20 million metric tons of maize annually, enough to feed 100 million people in Africa [3].

Economic Analysis of Main Season and Off-season Vegetable Production: A Case Study in Dhading District, Nepal

This survey research was conducted in Benighat Rorang Rural Municipality of Dhading district of Nepal in 2022. Main objective of the study was to analyze the profitability of main season and off-season production of selected vegetables in Dhading district. Multistage sampling technique was used to select 60 respondents (commercial vegetable farmers) who were interviewed face-to-face administering a semi-structured questionnaire to collect primary data. Though the average cost of production of cauliflower and tomato in off-season was higher than in main season, net incomes from these crops in off-season were higher than in main season (p<0.01). Benefit-cost ratios of cauliflower and tomato in main season (2.09 and 1.13 respectively) were lower than in off-season (2.78 and 1.47 respectively). Results indicated that growing vegetables in off-season is more profitable than in main season. The major problems perceived by the commercial vegetable farmers in the study area were high fluctuation in market price of vegetables followed by disease and insect pest damage. Study suggests that off-season vegetable production can be used as better alternative for income generation taking advantage of premium price. Government support to off-season vegetable production could make this business more profitable and sustainable.

The Prospect of Hydrolytic Enzymes from Bacillus Species in the Biological Control of Pests and Diseases in Forest and Fruit Tree Production.

Plant diseases and insect pest damage cause tremendous losses in forestry and fruit tree production. Even though chemical pesticides have been effective in the control of plant diseases and insect pests for several decades, they are increasingly becoming undesirable due to their toxic residues that affect human life, animals, and the environment, as well as the growing challenge of pesticide resistance. In this study, we review the potential of hydrolytic enzymes from Bacillus species such as chitinases, β-1,3-glucanases, proteases, lipases, amylases, and cellulases in the biological control of phytopathogens and insect pests, which could be a more sustainable alternative to chemical pesticides. This study highlights the application potential of the hydrolytic enzymes from different Bacillus sp. as effective biocontrol alternatives against phytopathogens/insect pests through the degradation of cell wall/insect cuticles, which are mainly composed of structural polysaccharides like chitins, β-glucans, glycoproteins, and lipids. This study demonstrates the prospects for applying hydrolytic enzymes from Bacillus sp. as effective biopesticides in forest and fruit tree production, their mode of biocidal activity and dual antimicrobial/insecticidal potential, which indicates a great prospect for the simultaneous biocontrol of pests/diseases. Further research should focus on optimizing the production of hydrolytic enzymes, and the antimicrobial/insecticidal synergism of different Bacillus sp. which could facilitate the simultaneous biocontrol of pests and diseases in forest and fruit tree production.

Papaya Mealybug in Kenya: Identification, Management, and Future Outlook

Abstract Papaya mealybug, Paracoccus marginatus is the most important and damaging insect pest species attacking papaya in Kenya. In addition, it feeds on various crops, fruits, and ornamental plants, most of which are of high economic value in Kenya’s agricultural sector such as chilli pepper, mango, citrus, cassava, avocado, and coffee. The mealybugs cause damage by inserting their stylets into fruits, leaves, and stems, directly feeding on the plant’s vascular system and depleting the sap. Consequently, this leads to chlorosis, plant stunting, leaf deformation, and, if left uncontrolled, leads to eventual plant death. The control of papaya mealybug on Kenyan farms has primarily depended on the application of chemical pesticides and the implementation of cultural practices, but the effectiveness of these methods has been widely reported as inadequate and burdensome. Biological control using a parasitoid Acerophagus papayae offers an alternative and sustainable option for the management of papaya mealybug and simultaneously safeguards the native biodiversity threatened by excessive pesticide use. This case study provides insights into the identification, distribution, impacts, and existing management strategies of papaya mealybug in Kenya. Additionally, it emphasizes ongoing and future research endeavours aimed at enhancing papaya mealybug management techniques. Information © The Authors 2023

Lignocellulosic Composition Not Associated with Stem Borer Resistance in Select Louisiana Sugarcane Cultivars

The two most economically damaging insect pests of sugarcane in Louisiana are the sugarcane borer (SCB) and the newly invasive Mexican rice borer (MRB), both of which can be managed in part with cultivar resistance. High stalk fiber levels is a well-documented aspect of stem borer resistance but is inversely correlated with recoverable sugar levels. However, lignocellulosic components such as hemicellulose, cellulose, and lignin are associated with resistance to other borer species in poaceous crops, potentially indicating mechanisms that may provide resistance without substantial trade-offs in yield. The goal of this study was to determine whether lignocellulosic composition varied among four cultivars—HoCP 85-845, HoCP 04-838, Ho 07-613, and HoCP 00-950—selected based on known variation in SCB and MRB resistance and total fiber content. We estimated lignocellulosic composition as well as Brix throughout the growing season and the total stalk fiber and recoverable sugar content at harvest for both plant cane and first ratoon crop years. We found that the Brix content throughout the growing season, as well as total fiber and sugar content at harvest, were significantly associated with the cultivar, aligning with previously documented trends in borer resistance (i.e., higher Brix and lower total fiber indicate a more susceptible cultivar). While lignocellulosic composition during the growing season was not associated with cultivar or resistance to either borer species, it was significantly impacted by sampling month and crop year. These data indicate the potential influence of alternative resistance mechanisms and interactions with abiotic conditions.

Evaluating the impact of cultivar selection on carrot weevil (Coleoptera: Curculionidae) damage and foliar insect pest assemblages in carrot.

Knowledge of specialty crop cultivars with resistance against insect pests is limited, and this may serve as a barrier to implementing host-plant resistance as part of an integrated pest management strategy. Carrot (Daucus carota L.) (Apiaels: Apiaceae)is a valuable specialty crop with a diversity of insect pests and cultivars that differ in physical and chemical qualities that influence insect pest preferences. To investigate the role of cultivar as a tool to reduce insect pest damage, we evaluated 7 carrot cultivars in replicated laboratory and field trials in IN and OH, USA in 2021. During June and July, we documented oviposition and feeding damage by the carrot weevil (Listronotus oregonenesis LeConte) (Coleoptera: Curculionidae) and used faunistic analysis to measure the abundance and diversity of foliar insect assemblages on each cultivar. We found no significant differences in oviposition and root damage across cultivars in the field, with mean cumulative egg scars ranging from 1.83 ± 1.40 in "Red Core Chantenay" to 5.17 ± 2.62 in "Cosmic Purple". However, there was a positive correlation between the cumulative number of egg scars and number of trichomes on petioles. Similarly, no-choice laboratory bioassays revealed no significant differences in mean cumulative egg scars, ranging from 5.00 ± 1.15 in "Red Core Chantenay" to 10.63 ± 1.02 in "Danvers 126". Predominant insect pests differed across cultivars, but Cicadellidae was common across all cultivars. Interestingly, only 1 beneficial insect family, Pteromalidae, was predominant across cultivars. This research highlights the impact of cultivar selection on the diversity and damage potential of insect pests in carrot production.

Predicting the impact of climate change on the potential distribution of the invasive tomato pinworm Phthorimaea absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Phthorimaea absoluta (Meyrick) (= Tuta absoluta) (Lepidoptera: Gelechiidae), is the most damaging insect pest threatening the production of tomato and other solanaceous vegetables in many countries. In this study, we predicted the risk of establishment and number of generations for P. absoluta in the current and future climatic conditions under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) of the years 2050 and 2070 using insect life cycle modelling (ILCYM) software. We used a temperature-dependent phenology model to project three risk indices viz., establishment risk index (ERI), generation index (GI), and activity index (AI) based on temperature data. The model projected large suitable areas for P. absoluta establishment in the Southern hemisphere under current and future climatic scenarios, compared to the Northern part. However, the risk of P. absoluta is expected to increase in Europe, USA, Southern Africa, and some parts of Asia in the future. Under current conditions, P. absoluta can complete between 6 and 16 generations per year in suitable areas. However, an increase in GI between 1 and 3 per year is projected for most parts of the world in the future, with an increase in AI between 1 and 4. Our results provide information on the risk of establishment of P. absoluta which could guide decision-makers to develop control strategies adapted for specific agro-ecological zones.

SOWING TIME OPTIMIZATION FOR INSECT PEST MANAGEMENT AND ENHANCED CROP YIELD IN COTTON

Sowing time has a significant role in minimizing insect pest damage by disrupting synchronization between host plant and insect life cycle. The effect of different times of sowing viz. April, May and June designated as early, intermediate and late was determined on the ability of four cotton genotypes (NIA-30, NIA-88, NIA-98 and Sadori) to resist sucking insect pests and bollworms. Cotton genotypes were sown on the 15th of each month. The results showed that the planting time had pronounced effect on the infestation of insect pests. April sown cotton had a higher infestation of jassid compared to May and June sown cotton. The occurrence of thrips was recorded highest in the May sowing followed by April. Infestation of whiteflies and spotted bollworm was negligible on all the genotypes and were below the economic threshold levels during the entire period of observation. Furthermore, April sown cotton showed the higher infestation of spotted and pink bollworms. Among the tested genotypes in different sowing times, they exhibited similarity in insect pest abundance, except for jassid population which significantly differed in May sown genotypes. Concerning yield, April sowing yielded the most at 2107.7 kg/ha, followed by May (1917.6 kg/ha) and June (801.7 kg/ha). Notably, NIA-88 followed by Sadori consistently yielded the highest across all sowing times compared to the other two genotypes. This study indicates that sowing of cotton varieties in April is recommended for achieving higher yields.