Key Pest Research Articles

Field releases of Trichogramma cacoeciae (Marchal, 1927) (Hymenoptera: Trichogrammatidae) against the codling moth, Cydia pomonella (Linnaeus, 1758) (Lepidoptera: Tortricidae)

The codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), is a key pest of apples in Tunisia and other countries around the world. Various management strategies have been applied to manage this pest including releases of parasitoids. Trichogramma wasps are known as efficient biocontrol agents tested against a large number of lepidopteran pests including C. pomonella. Two inundative releases of Trichogramma cacoeciae Marchal, at the rates of 25 000 and 50 000 parasitoids per ha, were performed when threshold was reached (2 to 3 adults per pheromone trap) in a commercial apple orchard, in 2018. Results indicated the occurrence of three flight peaks registered in the spring, summer and autumn of the growing season. The efficacy of the two release rates in reducing the infestation level of the population of the codling moth was proved herein. Average infestation level of fruits was significantly reduced after of the first release with reduction of about 27% for rate 1 and 22% for rate 2 compared to the untreated control (45%). Likewise, the average percentage of damaged apples was significantly reduced after the second release (23, 18.37 and 43.37 % respectively for the rate 1, rate 2 and the untreated control). The results showed the efficacy of T. cacoeciae parasitoids as efficient candidates to control C. pomonella.

Morphological and molecular characterization of Purpureocillium lilacinum along with its biopesticidal effect against fall armyworm (Spodoptera frugiperda) in Southern Taiwan

Abstract Background Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), a key agricultural pest, impacts a broad spectrum of crop species, such as cotton, maize, rice, sorghum, and a range of vegetables. Chemical pesticides and transgenic maize are commonly used to protect crops against this major pest. However, biological control offers a safer and more sustainable solution for long-term FAW management. Entomopathogenic fungi (EPF), a substitute for synthetic insecticides, have been proven to be an effective biocontrol agent for managing pest populations. The present study objective is to isolate and identify the EPF, Purpureocillium lilacinum from soil using morphological and molecular techniques and evaluate its pathogenicity against FAW eggs and various larval stages under different spore concentrations. Results The micro-morphological characteristics fluctuated in growth behavior, appearance, and color under diverse growth media and temperatures. Molecular analysis, which involved constructing a phylogenetic tree from ITS and TEF gene regions, confirmed that PT-02 was P. lilacinum. The pathogenicity of the fungus was tested on FAW eggs, neonates, and larvae at multiple concentrations (1 × 108, 1 × 107, and 1 × 106 spores/ml), resulting in variation mortality. The egg mortality rate at 1 × 108, 1 × 107, and 1 × 106 spores/ml was 98, 98 and 96%, respectively. The neonate mortality rate was 100%, while first and second instars larvae mortality ranged from 10–36% across three concentrations, seven days after treatment (DAT). The median lethal concentration (LC50) values of P. lilacinum PT-02 against FAW eggs, first and second instars, were 3.02 × 107, 1.38 × 108, and 2.56 × 108 spore/ml, respectively. Conclusions The findings revealed that the native strain of P. lilacinum exhibited strong virulence against FAW, suggesting its potential use as an effective biocontrol agent for managing field pest populations.

Impact of Key Insect Pests on Cowpea and their Relationship with Weather Parameters

Introduction: Cowpea (Vigna unguiculata L.) is a vital pulse crop with substantial nutritional value in India that faces production challenges due to various biotic and abiotic factors. Among the biotic factors that affects cowpea, pests such as Maruca vitrata and Riptortus pedestris significantly impact cowpea yields. This study aimed to evaluate the seasonal incidence of these pests and analyze their correlations with weather parameters in Thiruvananthapuram, Kerala. Methodology: Field observations were conducted over the cropping season to record pest populations across Standard Meteorological Weeks (SMWs). The population of the pod bugs and pod borers were taken from five plants. Statistical analyses were performed to identify correlations between pest incidence and key weather factors. Key Findings: The incidence of R. pedestris peaked in the 16th SMW, reaching 7.54 bugs per five plants. This pest displayed a significant positive correlation with maximum temperature (r = 0.637) and minimum temperature (r = 0.559) and a negative correlation with evening relative humidity (r =-0.480). Similarly, M. vitrata larval populations peaked during the same period at 2.65 larvae per five plants, showing a similar temperature-dependent correlation. Implications: The temperature-sensitive incidence patterns observed underscore the need for integrated pest management (IPM) strategies that address climatic factors to enhance cowpea sustainability. This data provides valuable insights for future pest forecasting and management efforts.

Density Relationship of the Assassin Bugs Sycanus falleni Stål and Sycanus croceovittatus Dohrn (Hemiptera: Reduviidae) and Principal Corn Pests (Noctuidae: Lepidoptera) in Hoa Binh Province, Vietnam

The group of assassin bugs including the Sycanus falleni and Sycanus croceovittatus species were such potential candidates for biocontrol of key pests (fall armyworm Spodoptera frugiperda, black cutworm Agrotis ypsilon, cotton bollworm Heliothis armigera Hübner, maize caterpillar Mythimna loreyi (Lepidoptera: Noctuidae)) on Corn biomass in Hoa Binh Province. Seven species of assassin bugs belonging to the family Reduviidae as S. falleni Stål, S. croceovittatus Dohrn, Coranus spiniscutis Reuter, Coranus fuscipennis Reuter, Polytoxus fuscovittatus (Stål), Endochus nigricornis Stål, Sphedanoletes pubinotum Reuter were recorded on the Corn biomass, of which S. falleni and S. croceovittatus were common. The relationship between the density of the group of assassin bugs and the density species S. falleni, S. croceovittatus had a close relationship with each other (R=0.81, R=0.72 respectively). The relationship between the density of the group of assassin bugs and the density of their prey (4 key pests) on the Corn biomass in the Winter crops and Summer-fall crops were a close relationship with each other (R2= 0.5166, R2= 0.7274 respectively). The relationship between the density of the species S. falleni, S. croceovittatus and the density of their prey (4 key pests) in the Winter crops, and the Summer fall crops were a close relationship with each other (R2 =0.7815, R2 =0.5396 respectively). However, these relationships were not closely related in the Spring-Summer crops and Winter-Spring crops.

Evaluation of IPM Module for the Management of Key Insect Pests in Chilli

Chilli is a crop cultivated in tropical and subtropical regions of India, and the crop is attacked by a multitude of pests at different crop stages. The present study revealed that field experiments were laid out with three treatments, viz., IPM module, farmer practice, and untreated control, at Kuttiyagoundanur village of Kolathur block of Salem District, Tamil Nadu. The results of the IPM capsule for the management practices of major pests and diseases, including viral diseases in chillies. The pre-treatment count on thrips/leaf was non-significant in all treatments, and it ranged from 7.20 to 8.40 thrips/leaf. Among the three treatments, farmers practice of chemical control recorded less infestation of 2.93 thrips/leaf, followed by the IPM module recording 3.60 thrips/leaf. Before adoption of treatment, the mite/leaf count was between 17.09 and 19.23 mite/leaf. The IPM module recorded less infestation of 5.32 mites/leaf, followed by farmers practice recording 12.90 mites/leaf. The pre-treatment count of Helicoverpa armigera larvae was between 3.20 and 3.72 larvae/plant. Among the treatments, chemical control recorded less infestation of fruit borer and fruit damage (0.17 larvae/plant) and 1.40 percent, followed by the IPM module, which is 1.17 larvae/plant and 4.91 percent. The leaf curl infection was low in farmers practices. 10.82 percent, followed by the IPM module recorded 15.26 percent. Maximum fruit yield of 11200 kg/ha with a comfortable B:C ratio of 2.96 was obtained in the IPM module, followed by farmer practice with a B:C ratio of 2.91.

Functional response and control potential of adult Arma chinensis on Colorado potato beetle in Xinjiang, China

AbstractPotato is an important food crop. The Colorado potato beetle (CPB) is its key pest. CPBs are now resistant to several chemical pesticides, making their control more difficult. The predatory insect, Arma chinensis, is a natural enemy of other plant pests. We studied the predation of adult A. chinensis on CPB eggs and young larvae under indoor controlled conditions and its control of CPB in cages under outdoor conditions. Adult A. chinensis effectively reduces CPB egg and larva populations, and its predatory functional response aligns with Holling’s Type II model. A. chinensis adults released within outdoor cages reduced CPB populations. Based on the predation behavior of the adults of A. chinensis to CPB eggs and young larvae, A. chinensis is an efficient and potential predator.

Assessment of Lepidopteran Pest Dynamics in Maize: Dominance of Spodoptera frugiperda and Implications for Targeted Management in Himachal Pradesh, India

Maize (Zea mays L.) plays a crucial role in the agricultural economy of India, particularly in Himachal Pradesh, where it serves as a vital crop for food, feed, and fodder. This study assessed the distribution, and relative abundance of lepidopteran pests infesting maize during the kharif, 2022-23 across two agro-climatic zones of Himachal Pradesh. Surveys identified five key lepidopteran pests: Spodoptera frugiperda, Chilo partellus, Mythimna separata, Agrotis ipsilon, and Euproctis spp. Among all, S. frugiperda is the only pest occurring among the major three crop stages of maize. The findings revealed that S. frugiperda was the most dominant pest, with relative abundance values of 19.57 per cent in Zone I and 18.94 per cent in Zone II during the seedling stage, increasing to 30.87 per cent and 30.40 per cent during the vegetative stage, respectively. In contrast, other pests like C. partellus, M. separata, A. ipsilon, and Euproctis spp. exhibited variable distribution patterns, with some showing limited occurrence. In conclusion, this study underscores the necessity for targeted pest management strategies to address dominant and subdominant lepidopteran pests in maize cultivation in Himachal Pradesh. The results offer valuable insights that can inform focused pest control efforts, with the potential to significantly enhance sustainable maize production, crop resilience and overall productivity in the region.

Transcriptome reanalysis and gene expression of 13 detoxification genes for avermectin and pyridaben resistance in Panonychus citri

Citrus red mites (P. citri) are key pests affecting citrus production worldwide due to pesticide resistance. The resistance mechanisms of ten pesticides are known, but a comprehensive study using transcriptome data is missing. This study employed deeptools, cuffdiff, rmats, bcftools and other software to examine gene expression variation, alternative splicing (AS), and mutations in mite resistance. The research highlighted that pesticides can regulate gene transcription, and red mites with resistance increase cytochrome P450, glutathione S-transferases, carboxylesterase, and acetylcholinesterase expression. Pyridaben also induces new AS events. Fluazinam-induced mites show mRNA splicing peaking earlier than transcription, both peaking at one day and returning to baseline after two days. AS profiles are similar in different mite populations with overlapping pesticide resistances. Lastly, specific mitochondrial SNPs in mites might mediate resistance against select pesticides.

Revealing pest patterns: A comparative spatial distribution analysis of insect threats in Kharif rice across the key agricultural regions in the Eastern India.

This study investigates the spatial distribution and aggregation patterns of major insect pests in Kharif rice fields during the 2023 growing season in Eastern India. The analysis focuses on key pests such as yellow stem borer (YSB), gall midge, green leaf hopper (GLH), and brown planthopper (BPH), as well as rice thrips, caseworm, whorl maggot, Gundhi bug, grasshopper, and leaf folder. Using statistical indices, this study aims to understand pest behavior across Standard Meteorological Weeks (SMWs) to better inform pest control strategies. The study reveals significant clustering and aggregation patterns among the pests. YSB exhibited variance-mean ratio (VMR) values between 1.14 (40th SMW) and 1.96 (31st SMW), with dispersion parameter (K) values ranging from 0.57 to 21.65, and a peak index of dispersion of 132.66 (43rd SMW). Similarly, gall midge showed VMR values from 6.19 to 10.48, whereas GLH and BPH recorded VMR ranges of 1.19 to 132.10 and 1.01 to 1.50, respectively. These spatial distribution trends were confirmed through values for Iwao's patchiness index and Taylor's power law, indicating strong pest aggregation in specific areas. The results underscore the need for region-specific integrated pest management strategies that take into account pest clustering and environmental factors influencing pest distribution. Although an S-curve pattern of infestation-showing gradual population increases, rapid peaks, and eventual decline-was observed, the primary focus remains spatial patterns, which are critical for optimizing pest management and improving rice crop sustainability in the region. © 2024 Society of Chemical Industry.

Urban Entomology: Navigating the Intersection of Pests and Human Environments

Urban entomology, a distinct discipline within entomology, focuses on pests in human environments, addressing a wide range of species from insects to vertebrates. First coined by A.H. Waters in 1884 and popularized by W. Ebeling's 1975 book, urban entomology gives an idea about arthropods' interactions with humans, pets and structures. As urbanization accelerates, with a projected 68% of the global population living in cities by 2050, understanding pest dynamics becomes increasingly critical. Factors like invasive species, pesticide resistance and public health concerns underscore the need for effective pest management strategies, emphasizing Integrated Pest Management (IPM) approaches. This review explores urban entomology's history, key pest groups and modern management challenges, while highlighting the industry's evolution in response to urbanization. It also discusses the roles of various stakeholders, including researchers, pest management professionals and regulatory bodies, in addressing urban pest issues. Ultimately, the review calls for collaborative efforts to enhance pest control practices, leveraging biological control methods and sustainable strategies to mitigate the impacts of urban pests on public health and infrastructure.

Toxicity and deterrence of pyroligneous extracts on Liriomyza sativae (Diptera: Agromyzidae)

Liriomyza sativa is a cosmopolitan and polyphagous insect, a key pest of crops such as tomato and melon. The inadequacy of insecticide application techniques has developed resistant populations. The objective of this research was to evaluate the toxicity, insecticidal activity and deterrence of pyroligneous extracts on the leafminer fly. The experiments were carried out under laboratory conditions of 25 ± 2°C and humidity of 60 ± 10%. For the toxicity test, solutions were prepared in different concentrations by diluting them in distilled water. Leaf discs containing L. sativae larvae were immersed in the solutions. For insecticidal activity and deterrence tests, jack bean plants were subjected to application of treatments using an airbrush, spraying 6 mL of the solutions on each plant. All extracts showed significant mortality for the larvae, with emphasis on the pyroligneous extract of coffee straw at 350ºC. The extracts did not interfere with the other developmental stages of the leafminer fly. The pyroligneous extract from the commercial company Agttec and the coffee straw extract at 600ºC were classified as attractive and the coffee straw extract at 350ºC as detergent. It is concluded that pyroligneous extracts can be used in the management of L. sativae.

Genetic basis of resistance to Cry1Ac in Rachiplusia nu (Lepidoptera: Noctuidae): inheritance mode, cross-resistance patterns and fitness cost.

Rachiplusia nu (Guenée) was historically a secondary soybean pest in Brazil, but a key soybean pest in Argentina. From 2021 onwards, injury caused by R. nu has been reported in soybean that expresses the Cry1Ac toxin from Bacillus thuringiensis (Berliner) in both countries. In this study, we selected resistant and susceptible strains of R. nu to Cry1Ac using Cry1Ac-containing leaf tissue and characterized the inheritance of resistance, cross-resistance patterns and fitness cost. Neonates of the Cry1Ac-resistant strain of R. nu were able to develop on Cry1Ac soybean leaves and emerge as fertile adults, while neonates from the susceptible and heterozygous strains did not survive beyond 10 days. The resistance ratio to Cry1Ac estimated in diet-overlay bioassays in the resistant strain was > 736.92-fold. The inheritance pattern of Cry1Ac resistance in R. nu was characterized as autosomal recessive and monogenic. The Cry1Ac-resistant strain of R. nu also exhibited high resistance to Cry1A.105 (resistance ratio > 159.87-fold), but negligible resistance to Cry2Ab2 (resistance ratio = 1.25-fold). Life history data showed that the resistance to Cry1Ac in R. nu is not associated with a substantial fitness cost. The inheritance pattern of Cry1Ac resistance in R. nu is autosomal recessive, monogenic and not associated with obvious fitness costs. Cross-resistance occurred between Cry1Ac and Cry1A.105 in R. nu but not between Cry1Ac and Cry2Ab2, indicating that Cry1A.105/Cry2Ab2/Cry1Ac soybean is a valuable tool to manage Cry1Ac resistance in R. nu. This is the first study reporting the genetic basis of Cry1Ac resistance in R. nu. © 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd.

Why is single-use plastic still in the conservation sector toolbox?

ABSTRACT Microplastic residue left in the environment from plastic chewcards in three pest mammal monitoring operations was estimated at an average of 15% of the starting weight. This finding highlight the issue of single-use plastics within New Zealand’s (NZ) conservation sector. A review of other research operations across NZ shows a significant number of plastic chewcards are deployed, potentially contributing to microplastic pollution in environmentally sensitive areas. Our research shows the need for sustainable alternatives to plastic chewcards in order to mitigate the environmental impact. Alongside an estimation of microplastic being left in the environment, we evaluated wood-pulp chewcards as a potential alternative to corflute chewcards, with results indicating wood-pulp cards maintain comparable interaction rates across key pest species. By identifying the environmental issues of microplastics in the environment and offering a potential alternative, we aim to open a dialogue about adopting more sustainable tools and practices in the NZ conservation sector.

Effects of saline-alkali stress on cotton growth and physiochemical expression with cascading effects on aphid abundance.

Environmental stresses, such as soil salinity or alkalinity, usually affect crop growth and secondary plant metabolism, with follow on effects on foliar-feeding insects. Nevertheless, the underlying mechanism of how saline-alkali stress affects the key cotton pest Aphis gossypii Glover is poorly understood. In this study, we first considered effects of three types of saline-alkali stress (i.e., salinity alone, alkalinity alone - both at different concentration - and their mixed effects) on cotton plants. We then measured impacts of stress on (1) above and below plant growth traits (e.g., plant height, leaf area, root volume), (2) levels of nutrients and secondary metabolites in cotton leaves, and (3) feeding behavior, life-table parameters, and population growth of A. gossypii. We then used a path analysis to evaluate cascading effects of changes in plant growth (due to stress) and changes in levels of nutrients or secondary metabolites on growth of individual cotton aphids and aphid populations. We found either salinity or alkalinity stresses significantly reduced cotton growth, increased the content of tannin, soluble sugars, and proline in the leaves, and suppressed aphid growth and development, (including longevity, fecundity, and intrinsic rate of increase) and aphid population growth. Alkalinity had stronger effects on these traits than did salinity. This work provides insights into the bottom-up interaction mechanism by which these environmental stresses mediate aphid infestation levels in the cotton agricultural ecosystem.

Evidence at the landscape level links high predator/pest ratios to biocontrol services against aphids

Compared with external environment interferences, the interaction between arthropod natural enemies and pests is the key inherent driver determining the strength of biocontrol services. However, the extent to which this effect can suppress pests is still inconclusive. We combined two complementary experiments to determine how variation in an assemblage of generalist arthropod predators modified the level of biocontrol services for suppression of a key aphid pest in cotton fields. Using generalized linear mixed effect models (GLMM) and path analysis, we clarified the causal relationship between predator/aphid ratios (PAR) and (1) the resulting biocontrol services index (BSI) and (2) the aphid population growth index (APGI) as seen in field predator exclusion trials. We also measured the effect of PAR on APGI in more commercial cotton fields. Our results, at landscape level, indicate that when PAR values increased one unit, BSI values improved 34.1 %, and reduced aphid population growth 28.3 % (the standardized effect coefficient in path analysis) during two weeks in field cage-exclusion trials. The effect of high predator/aphid ratios on reducing the aphid population growth rates was also significant in more commercial cotton fields, which were sampled over a longer time interval (4 weeks). Our study confirmed that there was a causal relationship between the natural enemy/pest ratio and the level of biological pest control services for predators and aphid population growth in crop fields. PAR values (predator/aphid ratios) can, therefore, be used to predict the level of biocontrol services in this context instead of relying on more labor-intensive cage exclusion studies.

Hemp regulates the fitness of corn earworm (Lepidoptera, Noctuidae) and its tachinid (Diptera) parasitoids.

Pest management on hemp is still in its infancy, and biological control options are limited. Helicoverpa zea (corn earworm) is one of the key pests of hemp cultivated outdoors, especially on cultivars grown for cannabinoids and grain. In a three-year study, we assessed the effect of diet on the performance of H. zea and its tachinid parasitoids. Parasitized (bearing fly eggs) and unparasitized (without eggs) H. zea larvae were fed on hemp flowers or an artificial diet. Five tachinid species parasitized H. zea larvae, but the most abundant species were Winthemia rufopicta (68.8%) and Lespesia aletiae (28.3%). Overall, 55.2% of H. zea larvae bearing tachinid eggs died, while the mortality of unparasitized larvae reached 24.7%. The success of tachinids increased by 2-fold when the host larvae were fed on an artificial diet. Our results demonstrated that high protein food (artificial diet), intensity of parasitism, and caterpillar size play a role in the fitness of both the herbivores (H. zea) and its tachinid parasitoids. These findings have important implications for understanding biological control mechanisms and open new insights into the impact of landscape variation on plant-herbivore-parasitoid interactions. This study contains supporting evidence that makes both Winthemia rufopicta and Lespesia aletiae excellent candidates for biological control programs against H. zea, a key pest of hemp in the United States.

Population Dynamics of Coffee Thrips (<i>Diarthrothrips coffeae</i>) (Thysanoptera: Thripidae) Using Sticky Traps with Different Essential Oils

Coffee (<i>Coffea arabica </i>L.) is one of the most traded commodities worldwide, and it is grown in about 80 coffee producing countries. Ethiopia is the origin of <i>coffea arabica</i> L which is grown in different production systems. Insect pests are one of the biotic factors that contribute to low yield and quality. Thrips are key insect pests in several coffee-producing regions in Southern Ethiopia. This study evaluated blue sticky traps treated with different essential oils to monitor the population dynamics of coffee thrips over three years. The experiment was conducted at the Awada sub center research site on established coffee plots, with six treatments and three replications. The results showed a significantly different in the number of coffee thrips populations per week, month and year. In the 2021 cropping season, the highest number of coffee thrips was caught on sage oil-treated sticky traps in the second week of trap installation (WK2=77.50). In the 2022 cropping season, the highest number of coffee thrips was caught on lavander oil-treated sticky traps in the third week of trap installation (WK3=1,100.33). In the 2023 cropping season, the highest number of coffee thrips was caught on lavander oil-treated sticky traps in the third week of trap installation (WK3=2,320.00). Thus, the blue sticky trap treated with lavender oil attracted a higher thrips population in 2022 and 2023 year. Therefore, lavander oil is a promising essential oil along with the blue sticky trap for monitoring coffee thrips populations.

Impact of leaf trichomes and stomatal density on the response of three soybean varieties to sucking pest infestation

Chemical pesticides disrupt local ecosystems, reduce populations of natural predators, and contribute to the evolution of pest resistance. Therefore, developing pest-resistant crop varieties is one of the most promising and environmentally friendly alternatives for pest control today. In the present study field experiments were conducted over two consecutive growing seasons in 2022 and 2023 to explore pest resistance among three soybean varieties viz. Crawford, Giza 111, and Giza 22. The research aimed to assess pest infestation resistance among these varieties, considering various leaf morphological factors. Four key pests were evaluated in the study viz. whiteflies (Bemisia tabaci Genn), spider mites (Tetranychus urticae Koc), aphids (Aphis gossypii Glover), and thrips (Thrips tabaci Lind)). The soybean varieties exhibited differences in susceptibility, and pest density varied across the two growing seasons. Crawford and Giza 111 demonstrated lower resistance, characterized by reduced leaf hair density and an increased number of stomata per leaflet. In contrast, Giza 22 was the most susceptible, featuring a higher density of trichomes and lower stomata density. In terms of field yield, Crawford produced the highest yield, followed by Giza 111, while Giza 22 yielded the least. The results of this study underscore the importance of selecting resistant plant varieties in future pest resistance improvement programs.

Study on the Effect of Foliar Fertilizers on the Growth and Yield of V108 Heat-Tolerant Cucumber Variety

This study evaluates the efficacy of various foliar fertilizers on the growth and yield of the heat-tolerant cucumber variety TV108. The experimental design included six different foliar fertilizers and a control, with applications made weekly at a concentration of 1 mL per liter of water. Results showed that all foliar treatments significantly enhanced plant height compared to the control. Among these, Treatment T4 (ATONIK foliar fertilizer) demonstrated the most pronounced effect, achieving a main stem height of 216.57 cm by the 70th day, which was significantly higher than other treatments and the control. Treatment T4 also excelled in increasing stem diameter, with a final measurement of 1.48 cm, and in promoting both male and female flower formation. The fruit set rate was highest in Treatment T4, reaching 28.67% on day 56 and maintaining at 8.67% by day 70. This treatment also proved most effective in reducing the incidence of key diseases and pests, including powdery mildew, white mold, green worms, and yellow beetles. Regarding yield, Treatment T4 produced the highest individual fruit yield (2.32 kg/plant), actual yield (33.8 tons/ha), and theoretical yield (84.91 tons/ha). Additionally, it enhanced fruit quality, as indicated by the largest fruit length (15.22 cm), diameter (4.13 cm), and the highest Brix value (3.50%). These results substantiate that Treatment T4 is the most effective foliar fertilizer for enhancing both growth and quality of heat-tolerant cucumbers under experimental conditions.

Population Dynamics and Environmental Correlates of Insect Pests in Watermelon, Citrullus lanatus (T.)

The study was conducted in Kandavara village, Chikkaballapur district, during 2021, investigated the insect pest complex affecting watermelon, Citrullus lanatus (T) following standard crop management practices but without any insecticidal interventions to assess the natural occurrence of insect pests. Weekly observations were made from February to April (2021) employing various sampling methods to monitor key pests, including leaf miners, thrips, whiteflies, fruit flies, leaf-eating caterpillars, and pumpkin beetles. The study revealed that leaf miners, Liriomyza trifolii (Frick) were the first to appear, peaking in the 11th Standard Meteorological Week (SMW) with 6.45 leaf mines per five leaves. Thrips, Thrips palmi Karny and whiteflies, Bemisia tabaci (Gennadius) emerged during the vegetative stage, showing a significant positive correlation with maximum temperature. Fruit flies, Zeugodacus cucurbitae (Coquillett) caused the most significant damage during the fruiting stage, with a peak incidence of 14.92 per cent in the 15th SMW. The study highlighted that higher temperature had a positive correlation with pest populations, while rainfall had a negative correlation reducing the pest activity. These findings emphasize the importance of precise timing in pest management interventions to minimize crop losses and enhance the sustainability and productivity of watermelon cultivation in India.