Secondary Pests Research Articles

Construction and Selection of an Entomopathogenic Fungal Library From Soil Samples for Controlling Spodoptera litura

Chemical pesticides have been used for pest control for many decades, but they cause serious problems, including insecticide resistance, secondary pest resurgence, and negative environmental impacts. Therefore, sustainable alternatives to chemical pesticides are necessary for pest control. Entomopathogenic fungi (EPF) are natural epizootic pathogens of insects, and some of them have been used as microbial biocontrol agents. Herein, we attempted to construct an entomopathogenic fungal library (EFLib) via the “Tenebrio molitor pathogenicity-based fungal collection method (TmPC)” to select EPF for control of the serious agricultural pest Spodoptera litura. A total of 172 soil samples were collected in northern and central Taiwan for the EFLib construction. The isolation efficiency of TmPC was 64.02%. The EFLib consisted of 101 isolates and was designated as the National Chung Hsing University (NCHU) EFLib. Among these isolates, 26 showed high virulence (mortality = 100%) to T. molitor larvae. Based on the results of molecular identification, the highly virulent isolates belonged to seven genera, including Beauveria, Clonostachys, Fusarium, Cordyceps, Penicillium, Purpureocillium, and Metarhizium. To evaluate the potential of these isolates for Spodoptera litura control, 12 isolates were selected for pathogenicity screening against S. litura larvae. A total of six EPF isolates belonging to the genera Beauveria and Metarhizium showed rapid eradication of the S. litura larvae. To rank the potential of these fungal strains for pest management, the six isolates were subjected to thermotolerance and conidial production assays, and a novel effective conidia number (ECN) formula was applied. The results indicated that the ECN index of Beauveria australis (NCHU-113) was much higher than that of Metarhizium isolates. However, among the Metarhizium isolates, NCHU-95 showed the highest ECN index. Altogether, NCHU-69 and NCHU-113 should be further tested in field trials. To our knowledge, this is the first attempt to integrate pathogenicity or virulence and ECN data into EPF screening and ranking, providing a baseline for mass selection of potential EPF strains for further applications.

Selection for resistance to pyrethroids in the predator Orius laevigatus.

Insecticide resistance in the natural enemies of pest species is a very desirable trait. It allows better integration of biological control with the synthetic and natural compounds applied to manage certain pests, especially secondary pest outbreaks. Insecticide resistance in predatory insects has been documented for lady beetles and lacewings, but intriguingly no cases of field-evolved resistance have been noted in any heteropteran predator. In this work, we first explored the variation in susceptibility to pyrethroids in wild and commercial populations of Orius laevigatus (Fieber). Second, we exploited this genetic variation to artificially select a strain of O. laevigatus resistant to pyrethroids. We found significant variation [median lethal dose (LC50 ) 1.6-77.0 mg L-1 ] in susceptibility to pyrethroids in wild populations of the heteropteran predator O. laevigatus, with a baseline LC50 value of 14.6 mg L-1 . We successfully selected a strain of O. laevigatus highly resistant to pyrethroids (LC50 = 1059.9 mg L-1 ). In addition, such resistance was expressed in every instar, particularly in the last nymphal stages, increasing the resilience of the whole population present in the crop facing pyrethroid application. The level of resistance achieved may be sufficient to allow survival of adults and nymphs of O. laevigatus exposed to the maximum field rate of several pyrethroids and natural pyrethrins, widely used to control a number of pests in organic and integrated pest management crops. Therefore, this strain resistant to pyrethrins and pyrethroids would improve the resilience of biocontrol protocols, which is an urgent requirement for wider adoption of biological control. © 2021 Society of Chemical Industry.

The Use of Insecticides to Manage the Western Corn Rootworm, Diabrotica virgifera virgifera, LeConte: History, Field-Evolved Resistance, and Associated Mechanisms.

Simple SummaryThe structure of agricultural enterprises in the western United States Corn Belt (large irrigated monocultures, continuous planting of maize, strong aerial pesticide application and livestock industries) has led to a tradition of extensive insecticide use over time to manage the western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) a key insect pest of maize. Dvv damages maize roots, which can cause maize plant instability, reduced plant growth, and significant yield loss. Long-term insecticide use has contributed to Dvv becoming resistant to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. This paper reviews the historical and current use of insecticides in Dvv management programs and Dvv adaptation to insecticide use. Currently, insecticides have a reduced role in Dvv management programs but are still used as complementary tactics with other management approaches. Past history suggests that the probability of selecting for resistance to any future Dvv control technology will be high if it is not used within an integrated pest management framework with other tactics.The western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) is a significant insect pest of maize in the United States (U.S.). This paper reviews the history of insecticide use in Dvv management programs, Dvv adaptation to insecticides, i.e., field-evolved resistance and associated mechanisms of resistance, plus the current role of insecticides in the transgenic era. In the western U.S. Corn Belt where continuous maize is commonly grown in large irrigated monocultures, broadcast-applied soil or foliar insecticides have been extensively used over time to manage annual densities of Dvv and other secondary insect pests. This has contributed to the sequential occurrence of Dvv resistance evolution to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. Mechanisms of resistance are complex, but both oxidative and hydrolytic metabolism contribute to organophosphate, carbamate, and pyrethroid resistance facilitating cross-resistance between insecticide classes. History shows that Dvv insecticide resistance can evolve quickly and may persist in field populations even in the absence of selection. This suggests minimal fitness costs associated with Dvv resistance. In the transgenic era, insecticides function primarily as complementary tools with other Dvv management tactics to manage annual Dvv densities/crop injury and resistance over time.

Pengaruh Beberapa Tingkatan Suhu Ruang Terhadap Waktu Perkembangan Cryptolestes ferrugineus Stephens

Cryptolestes ferrugineus (Cucujidae: Laemophloeidae) is a postharvest secondary pest of rice and other food commodity products. The distribution of C. ferrugineus covers tropical or subtropical climates with high humidity. Temperature fluctuations that occur every day affect development C. ferrugineus . The development of the life phase of C. ferrugineus largely determines the amount of its population and its massive impact on the damage caused to storing material. This research was conducted to determine the effect of several levels of room temperature on the development time of C. ferrugineus . The room temperature used in this study was 20°C, 25°C, 30°C, 35°C, and 40°C and was repeated five times. The results showed that the shortest development time of the insect pest C. ferrugineus (26.75 days) occurred at a room temperature of 30°C with a humidity of 68% compared to other room temperatures. The slowest development time for C. ferrugineus occurs at 25°C (42.60 days). At room temperature 40°C eggs produced by adult female C. ferrugineus cannot develop into larvae, so the development C. ferrugineus at 40°C was cut off.

Using multilevel models to explore the impact of abiotic and biotic conditions on the efficacy of pirimiphos-methyl against Tenebrio molitor L.

In this study, we utilized a hierarchical multilevel modeling approach to test the hypothesis that the activity of the organophosphate insecticide pirimiphos-methyl against the cosmopolitan serious secondary pest of stored products, the yellow mealworm, Tenebrio molitor (Coleoptera: Tenebrionidae), is affected by temperature, relative humidity (RH), and developmental stage (adults, small larvae, large larvae). Our results showed that as temperature increased from 20 to 25°C, the observed mortality of T. molitor was significantly higher. Furthermore, mortality at 25 °C did not significantly differ from that of 30°C. An ultimate increase at 35°C resulted in the highest mortality rate of T. molitor. However, an increase of RH from 55 to 75% adversely affected the efficacy of pirimiphos-methyl. In our study, it is also shown that the insect developmental stage is a critical feature of pirimiphos-methyl efficacy. Tenebrio molitor adults exhibited significantly higher mortality than larvae. In addition, small larvae showed significantly higher mortality than large larvae. Thus, adult is the most susceptible developmental stage of T. molitor to pirimiphos-methyl treatment. Our results could be useful tools for the management of T. molitor by indicating the optimum combination of temperature and RH that favors the insecticidal treatment against this species. In addition, we expect that the percentage of developmental stages in a whole population of T. molitoraffects the insecticidal efficacy of pirimiphos-methyl.

Protection of organic cereals from insect and rodent pests in a warehouse by combined use of traps and sticky tapes

Several options of protection of organic cereals (winter and spring wheat, rye and maize) from insect and rodent pests, using a combination of traps (with or without pheromone/ attractant) and sticky tapes and no chemicals, were tested in a warehouse over the summerspring season of 2019/2020. Temperature in the warehouse was 14-29?C and humidity around 50%. The average grain moisture of winter and spring wheat and rye was 10-11%, while it was 12-14% in maize grain, and the average grain temperature of all cereals was 13-27?C. Regarding stored-product insect pests, five coleopteran, two moth and one Psocoptera species were detected, and the coleopterans predominated (98.5%) along with secondary pest insects (94.0%). Regarding rodents, only specimens of Mus musculus were found throughout the test period, their maximum monthly frequency being 72 (in January 2020). A combination of traps (with or without pheromones) and sticky tape barriers was found to provide an effective tool for trapping insects. Also, snap traps and trapping boxes for killing rodents, when used simultaneously with sticky tape barriers, were found to provide good protection of cereals from house mice. The pest control effect was also confirmed by collecting samples of organic cereal grain, which showed no significant presence of stored-product insects or grain damage (0.94% and 0.96% in spring wheat and rye, respectively) at the end of the test period. The results showed a great potential of combined application of traps and sticky tapes for protecting organic cereals in horizontal bulk storages, but the use of chemicals approved for organic food production would be required under extended storage periods.

Arthropod pests of pomegranate (Punica granatum L.) and their management

There are ninety one insects, six mites and one snail pest have been found feeding on pomegranate crop in India. Pomegranate pests cause severe damage to flowers, fruits, twigs and leaves by de sapping, biting and boring, which result in loss of quality of fruits and reduction in yield. In addition, the abuse of insecticides has led to secondary pests outbreak like pomegranate whitefly, (Siphoninus phillyreae Haliday), spiralling whitefly, (Aleurodicus dispersus Russell), mealy bug (Pseudococcus lilacinus Cockerell), thrips (Rhipiphorothrips cruentatus Hood, Scirtothrips dorsalis Hood, Anaphothrips oligochaetus Karny), aphid (Aphis punicae Passerini) and mites (Aceria granati Can. and Massal, Oligonychus punicae). The above reports confirmed that the commercially growing pomegranate farmers are facing a number of pest problems in their field, with no practical ecofriendly solutions. Further, in order to increase the production and productivity, farmers are growing pomegranate under high density planting. Since the introduction of high density planting in pomegranate is new, systematic study on the occurrence of pests is wanting. Hence, to address the problem of pests with ecosafe management practices was discussed in this review.

Distinct barcodes for the Cereal leaf beetles Oulema melanopus and Oulema duftschmidi (Coleoptera: Chrysomelidae), two syntopical sibling species

Oulema melanopus (Linnaeus, 1758) and Oulema duftschmidi (Redtenbacher, 1874) (Coleoptera: Chrysomelidae) are two native West Palaearctic species developing on various cultivated and wild grasses. Along with O. obscura they are considered to be secondary pests of cereal crops. However, local outbreaks have been recorded recently and their status as secondary pests may evolve, especially as the use of broad-spectrum insecticides is now greatly reduced. Oulema melanopus and O. duftschmidi are considered to be sibling species. They are morphologically very close and difficult to distinguish from each other, which makes it difficult to study them. We tested the reliability of the standard barcode fragment (COI) for distinguishing between these species. A total of 92 samples of the two species, covering the majority of their natural range, was sequenced for the barcode fragment and inter- and intraspecific genetic distances were estimated. Our results confirm those of Bezděk & Baselga (2015, Acta Entomol. Mus. Nat. Prag. 55: 273-304) in that this marker cannot differentiate between all the species of the Oulema melanopus complex, which in the Mediterranean basin contains several described and possibly some undescribed cryptic species. However, this marker may be useful in an agricultural context in areas where only O. melanopus and O. duftschmidi occur (such as in cereal crops in France) where it can be used to reliably and rapidly separate all stages of these two taxa and can therefore help in studying their ecology and dynamics.

Olive Production Threatened by a Resurgent Pest Liothrips oleae (Costa, 1857) (Thysanoptera: Phlaeothripidae) in Southern Italy.

Simple SummaryLiothrips oleae (Costa, 1857) (Thysanoptera: Phlaeothripidae) is widespread in the Mediterranean area, and in all regions, it is reputed to be a secondary pest in olive crops, mainly associated with damage to leaves and secondarily with damage to drupes, for which this thrips pest has a marginal impact on olive production. Taking into account the increase in the frequency of extreme damage by this species in Southern Italy in the last decade, this research aimed to elucidate the real impact (i.e., damage to leaves and drupes) by feeding thrips’ activity in olive orchards. Our results revealed that the impact of thrips was significant in all monitored olive orchards and the estimated damage level on drupes and leaves was higher in organic olive than in integrated olive management. A detailed morphological description of the Italian specimens and their molecular characterization are also provided.This study investigated a resurgence of Liothrips oleae Costa (Thysanoptera: Phlaeothripidae), an insect pest of olive crops, in a focal Southern Italian olive-producing area (Calabria Region). The young and adult olive thrips feed on the leaves and fruits of wild and cultivated olive trees, producing distortions, necrosis, and premature dropping of fruit. In our study, organic and integrated olive groves were compared for two years in order to establish the relationship between leaf and fruit damage among olive groves managed under different phytosanitary conditions. Sampling techniques were used in order to collect and count leaves and fruits (on plants and dropped premature drupes) presenting symptoms of thrips’ feeding activity. The impact of the thrips was significant in all orchards, and the estimated damage level on drupes and leaves was higher in organic olive management in each year. A morphological description of the adult females of the species is provided, and the first molecular characterization of the Calabrian olive thrips population was performed by using three different genetic regions (cytochrome c oxidase subunit I (COI), 28S ribosomal subunit (28S), and internal transcribed spacer 2 (ITS2)).

Toxicity of the Bt Protein Cry1Ac Expressed in Leaves of the Event of Transgenic Soybean Released in Paraguay Against Spodoptera cosmioides

Spodoptera cosmioides Walk (Lepidoptera: Noctuidae) is a polyphagous species, considered a secondary pest in soybean crop. The Intacta soybean (Bt soybean) event was released in Paraguay with Bt proteins which are supposed to be toxic for caterpillars. However, the effects of these proteins in the Spodoptera cosmioides biology still uncertainty. This study evaluated the biological activity of Bt soybean in S. cosmioides that were fed on Bt and non-Bt soybean leaves under laboratory conditions. The experiment was carried out at the Laboratory of Entomology; temperature 26±2 ºC; relative humidity: 60±10%; photoperiod: 14:00 h where 150 neonate larvae were used per treatment. The period and viability of each stage, the mortality of larval, number of eggs and neonate per couple, and the period of larvae to adult were the assessed variables. Higher mortality was observed in larvae fed with intact soybeans, but without statistical differences with non-Bt soybeans. For larval survival, period, number and total period, no statistical differences were verified. Higher percentage of fertility was observed in soybeans non-Bt but no statistical differences.

P.417 The emotional disturbances in young patients with type 1 diabetes using various methods of insulin therapy by four-dimensional symptom questionnaire

The southern green stink bug, Nezara viridula is a polyphagous pest of commercially important crops during both nymph and adult stages. This insect has recently transitioned from a secondary agricultural pest to one of primary concern. Novel management solutions are needed due to the limited effectiveness of current control strategies. We performed biochemical and transcriptomic analyses to characterize digestive enzymes in the salivary glands and along midgut tissues of N. viridula nymphs and adults fed on sweet corn. The digestive profiles were more distinct between midgut regions (M1 to M3) than between life stages. Aminopeptidase and chymotrypsin activities declined from the M1 (anterior) toward the M3 midgut region. Cysteine protease activity was higher in the M2 and M3 regions than in M1. Differences in sensitivity to chymotrypsin inhibitors between midgut regions suggest that distinct genes or isoforms are expressed in different regions of the gut. In nymphs, DNA and RNA degradation was higher in M1 than in M3. Adult nuclease activity was low across all midgut regions, but high in salivary glands. The differences in protease activities are reflected by transcriptomic data and functional enrichment of GO terms. Together, our results show that different regions of the digestive tract of N. viridula have specific and distinct digestive properties, and increase our understanding of the physiology of this organism.

Evaluation of Various Pest Management Modules Against Rice Yellow Stemborer, Scirphopaga incertulas (Walker) (Crambidae: Lepidoptera)

Background: Globally, rice yellow stem borer alone causes yield losses of 10 m t accounting for 50 per cent of all insecticides usage in the rice field farmers depend upon a plenty of insecticide applications, even though a lot of insecticide applications are not effectual (Sarwar et al., 2005). The over- reliance on use of chemicals to manage this pest had lead to numerous undesirable consequences like disrupting natural enemy complexes, secondary pest outbreaks, pest resurgence, development of insecticide resistance and environmental pollution. Keeping in view the deleterious effects of chemical pesticides, there is a need to evaluate alternate methods or integrated methods to manage the rice stem borer effectively without any menace to the ecological niche. Hence, a research trial was conducted to evaluate the efficacy of various pest management modules against rice stem borer in comparison to farmers practice and sole chemical control, besides in concern to yield and cost economics. Methods: The field efficacy of various pest management modules viz., non-chemical based, non-chemical + biorational methods, chemical-based, IPM module and farmers practice against rice yellow stem borer were evaluated during the wet season and dry seasons of 2016 and 2017. The experimental was laid in a net area of 10 m x 20 m each plot laid in Randomized Block Design which comprised of five treatments (modules) with four replications. The incidence of rice yellow stem borer (YSB) in various modules in terms of percent dead hearts (% DH) during tillering stage and percent white ears (%WE) during maturing stage were recorded. Result: It was evident from the pooled mean data that among various modules, the least per cent dead hearts (2.68 and 2.56% DH ) and white ears (2.79 and 2.31% WE) were registered in IPM based module followed by farmers practice (2.31 and 2.32% dead hearts and 3.92 and 4.77% white ears) and chemical-l based module (2.90 and 4.24% dead hearts and 5.59 and 5.18% white ears) as against highest incidence in non- chemical (13.78 and 13.7% dead hearts; 18.24 and 17.94% white ears) and non- chemical + bio rational (11.40 and 9.88% dead hearts; 13.09 and 11.25% white ears ) based modules during the wet season and dry season, respectively.

Hormesis in the Brown Citrus Aphid, Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae) Exposed to Sublethal Doses of Imidacloprid

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest that transmits phloem-limited, gram negative bacteria including ‘Candidatus’ liberibacter asiaticus (Clas), causing huanglongbing. Management of this pest relies primarily on insecticides, such as the neonicotinoid imidacloprid, that may affect secondary pests including the brown citrus aphid, Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae). Here, we report on direct toxicity and sublethal dose effects of imidacloprid on T. citricida nymphs and adults following direct contact and ingestion. We also examined transgenerational dose-response and hormetic effects following exposure of T. citricida to a sublethal concentration of imidacloprid. Toxicity of imidacloprid was similar for nymphs (0.6 ng per µL) and adults (1 ng per µL) at 72 h. Fecundity and finite rate of increase were greater for populations exposed to systemic and foliar treatments at a sublethal concentration (0.1 ng per µL) compared with untreated controls. Development times of first instar nymphs in the F1 generation and third instar nymphs in the F2 generation were significantly greater for individuals treated with the sublethal dose than an untreated control. Survival of second instar T. citricida on plants treated with a sublethal concentration also was significantly greater than controls. There also was a significant increase in fecundity of F1 and F2 individuals after sublethal treatment compared with controls. Our results indicated that a sublethal concentration of imidacloprid increased the reproductive performance and induced possible physiologically stimulative (hormetic) effects in T. citricida. Hormesis in secondary pests should be considered when developing a management program for pathogen vectors such as D. citri.

Dasineura oleae: morphological and physiological characterization following the midge attack on olive leaves

Dasineura oleae (Angelini, 1831) (Diptera: Cecidomyiidae), the gall agent of Olea europaea L. leaves, has always been considered just a secondary pest of the olive grove since it does not cause any direct damages on the olive fruits production. However, severe outbreaks were recently recorded in the Mediterranean Basin. Our result shed light on the potential alteration that D. oleae trophic action may trigger on leaf morphology and some physiological activities of olive leaves (O. europaea cv Frantoio), since they are strictly related with the photosynthates accumulation and olives production. Net photosynthesis and stomatal conductance were significantly lower just in infested leaves (P = 0.0038 and P = 0.0487, respectively), inducing to consider that the symptoms of suffering are limited to the attacked organs. Shoot elongation in control versus infested plants shows no difference between the two treatments. Polyphenols content was analyzed in tissues surrounding D. oleae galls, and no deficits were recorded compared to control leaves. Although lab trials reveal no dramatic effects on these physiological activities, further experiments are needed in order to relate physiological alteration in field and olive fruit production.

Bacteria Belonging to Pseudomonas typographi sp. nov. from the Bark Beetle Ips typographus Have Genomic Potential to Aid in the Host Ecology.

Simple SummaryEuropean Bark Beetle (Ips typographus) is a pest that affects dead and weakened spruce trees. Under certain environmental conditions, it has massive outbreaks, resulting in attacks of healthy trees, becoming a forest pest. It has been proposed that the bark beetle’s microbiome plays a key role in the insect’s ecology, providing nutrients, inhibiting pathogens, and degrading tree defense compounds, among other probable traits. During a study of bacterial associates from I. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. In this work, we aimed to reveal the taxonomic status of these bacterial strains and to sequence and annotate their genomes to mine possible traits related to a role within the bark beetle holobiont. Our study indicates that these bacteria constitute a new species for which the name of Pseudomonas typographi sp. nov. is proposed. Moreover, their genome analysis suggests different metabolic pathways possibly related to the beetle’s ecology. Finally, in vitro tests conclude the capability of these bacteria to inhibit beetle’s fungal pathogens. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens. These findings might be of interest in the development of integrated methods for pest control.European Bark Beetle Ips typographus is a secondary pest that affects dead and weakened spruce trees (Picea genus). Under certain environmental conditions, it has massive outbreaks, resulting in the attacks of healthy trees, becoming a forest pest. It has been proposed that the bark beetle’s microbiome plays a key role in the insect’s ecology, providing nutrients, inhibiting pathogens, and degrading tree defense compounds, among other probable traits yet to be discovered. During a study of bacterial associates from I. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. A polyphasic taxonomical approach showed that they belong to a new species for which the name Pseudomonas typographi sp nov. is proposed. Genome sequences show their potential to hydrolyze wood compounds and synthesize several vitamins; screening for enzymes production was verified using PNP substrates. Assays in Petri dishes confirmed cellulose and xylan hydrolysis. Moreover, the genomes harbor genes encoding chitinases and gene clusters involved in the synthesis of secondary metabolites with antimicrobial potential. In vitro tests confirmed the capability of the three P. typographi strains to inhibit several Ips beetles’ pathogenic fungi. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens.

Mite Pests of Southern Highbush Blueberry in Florida

Several mite species attack southern highbush blueberries (SHB), including the southern red mite (Oligonychus ilicis McGregor (Acari: Tetranychidae)), the false spider mite or flat mite (Brevipalpus yothersi Baker) and the blueberry bud mite (Acalitus vaccinii Keifer). The southern red mite is the key mite pest attacking blueberry plants in the southeastern US (Lopez and Liburd 2020). The false spider mite is a secondary leaf feeding mite pest that was reported attacking southern highbush blueberry in 2016 (Akyazi et al. 2017). This publication discusses southern red mites and flat mites on SHB in Florida, including life cycle, damage, and management practices.

INFECTIVITY OF BEAUVERIA BASSIANA (BALSAMO) AGAINST TRIBOLIUM CASTANEUM (COLEOPTERA: TENEBRIONIDAE)

Tribolium castaneum is a major pest in wheat flour but can attack other processed foodstuffs. Control of these pests can be done in various ways, one of them by biological control using entomopathogenic fungus Beauveria bassiana. This study aims to determine the infectivity of B. bassiana entomopathogenic fungus against T. castaneum populations in the laboratory. The experiment was completed with random preparations, each preparation was repeated three times. Imago T. castaneum was sprayed with a conidia suspension of B. bassiana at a density of 106 and 107 conidia/mL on three different storage media namely PDA, rice, and corn media. Mortality was calculated based on the percentage of imago that died of B. bassiana fungi. One week observation showed the mortality of T. castaneum after the application of B. bassiana fungus was 55.33% with 107 conidia/mL in corn media. The highest spore density was found in rice media with an average of 10.53 x 106 conidia/mL. Meanwhile, the value of the results showed LC50 of 2.11 x 107 conidia/mL and the fastest LT50 in corn media was 5.31 days

Frass produced by the primary pest Rhyzopertha dominica supports the population growth of the secondary stored product pests Oryzaephilus surinamensis, Tribolium castaneum, and T. confusum.

Primary pests such as Rhyzoperta dominica may increase the contents of dockage, dust, and frass in grain mass. Although it has been suggested that frass can affect the population growth of stored product pests and ecological interactions among primary and secondary pests in stored grain, this has not been validated experimentally. Therefore, this work experimentally tested the hypothesis that R. dominica wheat frass may support population increases in secondary pests such as Tribolium confusum, T. castaneum, and Oryzaephilus surinamensis for the first time. The effect of frass on secondary pest performance was compared with the effects of various physical qualities of wheat grain (i.e., intact grain kernels, grain fragments, flour, grain + frass) and an artificially enriched control diet (milled wheat kernels, oat flakes, and yeast). The results showed that the clean intact grain kernels did not support the population growth of any tested species, and the nutrient-rich control diet provided the best support. Frass was a significantly better food medium for O. surinamensis and T. castaneum than flour or cracked grain, while T. confusum performed equally well on flour and frass. Our results showed that in terms of food quality and suitability for the tested species, frass occupied an intermediate position between the optimized breeding diet and simple uniform cereal diets such as cracked grain or flour. The results suggest that (i) the wheat frass of primary pest R. dominica is a riskier food source for the development of the tested secondary pests than intact or cracked wheat grain or flour; (ii) frass has the potential to positively influence interspecific interactions between R. dominica and the tested secondary pests; and (iii) wheat grain should be cleaned if increases in R. dominica populations and/or accumulated frass are detected.

UPAYA MEMINIMALISIR DAMPAK LINGKUNGAN DARI PENGGUNAAN PESTISIDA DALAM PERTANIAN (DAMPAK LINGKUNGAN DAN PENANGGULANGANNYA)

Utilization of synthetic pesticide seems up to now remains to be one of the methods in controlling pest and plant disease because it plays a role in determining the quality and quantity of the crops. Improver of synthetic pesticide in agriculture can adversely affect the ecosystem such as water and soil pollution. The occurrence of pest resistance, the outbreak of secondary pest, the resurgence of pest, the death of predators, the residue of pesticide in food, and the pesticide residue that affects man's health. Although it has been widely known that pesticide has a bad impact on the environment, the use of pesticide is still needed in agricultural practice. Its use needs to pay attention to the concept of Integrated Pest Management in which the use of pesticide is only made when it is absolutely necessary, that is, when the population of pest increases and lies above one level of the pest population, the Economic Threshold (Untung, 1993). To know the safety level of pesticide, evaluation of toxicity of a pesticide is needed and it is commonly tested in the animal of high level. This is done in such a way that the toxicity and safety level of the pesticide can be known by farmers, users of pesticide, and the environment. Based on the information on the toxicity level, it is expected that the steps of environmental management can be taken to minimize the negative impact of pesticide. The effort of minimizing the negative impact of pesticide can be done in a variety of ways. For example, the direction was given to the users in terms of giving the dosage, application time, safe working procedure, choosing pesticide with the precise target, choosing a pesticide that can decompose easily, application target, a time before harvest, tool and exact application technique, keeping as small pollution as possible. In the future, it is hoped that the use of pesticide will decrease and will be more selective, and supported by new inventions in the technology of processing pesticide disposal and the technology of utilizing botanical pesticide which is all expected to be effective in overcoming the disturbance of pest and plant disease at the same time minimizing environmental degradation.

Cell Wall Lytic Enzymes And Their Role In Bacteriophages Infection

Use of chemical pesticides has been shown to have many negative side effects, such as insecticide resistance and resurgence, an outbreak of secondary pests and diseases, the disappearance of parasitoid and predator species as well as residual effects on food crops and on the environment. Over the past 60 years, both the number of agricultural toxins in the environment and incidence rates of toxin-related diseases has increased dramatically. The most effective way to combat this problem is through the use of natural predators. One of the best examples of this is the use of host-specific bacteriophages to control bacterial diseases. The mechanism of infection is a very interesting one. To break through the bacterial cell wall the bacteriophages must produce a range of lytic enzymes. This review will examine and discuss studies of these site-specific cell wall lytic enzymes and their roles in the infection of bacteriophages.