Phenacoccus Manihoti Research Articles

Analysis of the Distribution Pattern of Phenacoccus manihoti in China under Climate Change Based on the Biomod2 Model.

The changing global climate has significantly impacted the spread of plant pests. The cassava mealybug (Phenacoccus manihoti) is among the most dangerous quarantine pests affecting cassavas worldwide, causing substantial losses in agricultural production and food security across several regions. Although China is currently free of the cassava mealybug, its proximity to affected countries and extensive trade with these regions necessitate a detailed understanding of the pest's distribution pattern and dynamic ecological niche changes. Using the Biomod2 model, we selected two historical climate scenarios and two future climate scenarios (SSP1-2.6 and SSP5-8.5) to investigate the distribution patterns, potential habitats, distribution centers, and dynamic ecological niches of cassava mealybugs in China. Key environmental variables influencing the distribution were identified, including bio4, bio8, bio12, bio18, and bio19. The potential habitat of cassava mealybugs is mainly located in several provinces in southern China. In the future, the suitable habitat is projected to expand slightly under the influence of climate change, maintaining the overall trend, but the distribution center of suitable areas will shift northward. Dynamic ecological niche prediction results indicate the potential for further expansion; however, the ecological niches may be unequal and dissimilar in the invaded areas. The predictions could serve as a valuable reference for early warning systems and management strategies to control the introduction of cassava mealybugs.

Effects of biopesticides on the management of Myzus persicae Sulzer and Phenacoccus manihoti

Aphids (Myzus persicae Sulzer) and mealybugs (Phenacoccus manihoti) are two economically important pests affecting agricultural crops in Guyana. The principal mode of control is the application of synthetic insecticides, which can be prejudicial on the environment and human health. Alternatively, these pests can be controlled using plant extracts with insecticidal and repellent properties. This article highlights the effects of three plant extracts obtained from locally cultivated crops in Guyana. Gas chromatography-mass spectrometry analysis was performed to identify the chemical compounds present in each extract with high insecticidal activity against aphids and mealy bugs revealing the presence of 8, 15, and 7 chemical compounds with “eucalyptol” common to all extracts. Laboratory bioassays were conducted under environmental conditions to determine the efficacy of methanol extracts obtained from Zingiber officinale rhizome, Mentha viridis, and Jatropha curcas leaves in controlling M. persicae Sulzer and P. manihoti using the leaf dip method. Results obtained indicated that the three plant extracts were significantly (p < 0.05) toxic to M. persicae Sulzer and P. manihoti after 48 h exposure.

A simple PCR‐based method for detecting Anagyrus lopezi (Hymenoptera: Encyrtidae) and Prochiloneurus pulchellus (Hymenoptera: Encyrtidae), primary and hyper parasitoids of the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae)

AbstractEstimating parasitism rates in the field is essential for developing and evaluating biocontrol strategies using parasitoids. In this study, we developed a simple polymerase chain reaction (PCR)‐based method for detecting parasitism of the cassava mealybug Phenacoccus manihoti Matile‐Ferrero (Hemiptera: Pseudococcidae) by the primary parasitoid Anagyrus lopezi De Santis (Hymenoptera: Encyrtidae) and its hyperparasitoid Prochiloneurus pulchellus Silvestri (Hymenoptera: Encyrtidae). Primers were designed to amplify partial cytochrome c oxidase subunit I genes of each species, and their sensitivity was evaluated with mealybugs that had been parasitized by A. lopezi 0, 3, and 6 days earlier, and mummified mealybugs containing A. lopezi pupae that had been parasitized by P. pulchellus 0, 3, 6, 9, and 12 days earlier. The detection rate of parasitism by A. lopezi was 100% for all ages of A. lopezi. The detection rate of parasitism by P. pulchellus ranged from 94.1% to 100%, depending on its developmental stage. For P. pulchellus, template DNA was diluted 10 times before PCR because PCR with the original concentration showed low detection rates, presumably due to the presence of PCR inhibitors. Overall, our primers can be considered sufficiently sensitive to be used for detecting each species.

Development of recombinase polymerase amplification-based colorimetric detection assay for rapid identification of invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero

Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is an economically important invasive cassava pest responsible for the massive devastation of cassava in Asia and African continent. Initially, identifying this invasive pest posed challenges because it closely resembled native mealybug species. Additionally, the traditional morphological identification process is labor-intensive and time-consuming. Detecting invasive pests at an early stage is crucial, hence development of a rapid detection assay is essential. In the current study, we have developed a simple, rapid, sensitive, and efficient molecular detection assay for P. manihoti based on Recombinase Polymerase Amplification (RPA). The primers for the RPA assay were designed using unique nucleic acid sequences of P. manihoti, and the protocol was standardized. Specificity test demonstrated that the RPA assay could amplify DNA of P. manihoti only, and no amplification was observed in six other mealybug species. The specificity of assay was confirmed using SYBR green-based colorimetric detection and gel electrophoresis where positive samples showed 195 bp amplicon size in P. manihoti samples. The assay successfully amplified P. manihoti DNA in thirty minutes at an annealing temperature of 41° C in a water bath and displayed a sensitivity of 72.5 picograms per microliter. The assay's simplicity, rapidity, and high sensitivity make it a valuable tool for detecting and monitoring P. manihoti in quarantine stations and facilitating in development of a portable diagnostic kit.

Susceptibility baselines for the invasive mealybugs Phenacoccus manihoti and Paracoccus marginatus (Hemiptera: Pseudococcidae) in cassava ecosystem against selected neonicotinoid insecticides

In recent years, an invasive cassava mealybug Phenacoccus manihoti has been threatening cassava cultivation alongside another invasive papaya mealybug Paracoccus marginatus which invaded the country more than a decade ago. In order to evaluate their responses against the commonly used neonicotinoid insecticides: thiamethoxam 25 WG and imidacloprid 17.8 SL, acute toxicity experiments to determine the susceptibility baselines in populations of two invasive mealybugs in the cassava agro-ecosystem, namely, cassava mealybug P. manihoti and papaya mealybug P. marginatus were performed upto 15 generations. A systemic uptake method was used for the bioassay. The LC50 values of thiamethoxam for F1 generation were 3.298 ppm whereas it was 1.066 ppm for F15 in cassava mealybug. The LC50 values of F1 generation were 2.014 ppm and that of F15 generation was 1.384 ppm when tested with imidacloprid. In the case of papaya mealybug, the LC50 values ranged from 6.138 ppm (F1) to 2.503 ppm (F15) for thiamethoxam and 7.457 ppm (F1) to 3.231 ppm (F15) for imidacloprid. All the susceptibility indices calculated were less than threefold. The rate of resistance development was negative in all cases showing that none of the tested populations harboured any resistance without insecticidal selection pressure. Tentative discriminating doses were fixed for both chemicals with the help of LC95 values obtained from the bioassay experiments, namely five ppm for both thiamethoxam and imidacloprid in the case of cassava mealybug and 10 ppm and 15 ppm, respectively, for thiamethoxam and imidacloprid in the case of papaya mealybug.

Generalist Predators Shape Biotic Resistance along a Tropical Island Chain.

Islands offer exclusive prisms for an experimental investigation of biodiversity x ecosystem function interplay. Given that species in upper trophic layers, e.g., arthropod predators, experience a comparative disadvantage on small, isolated islands, such settings can help to clarify how predation features within biotic resistance equations. Here, we use observational and manipulative studies on a chain of nine Indonesian islands to quantify predator-mediated biotic resistance against the cassava mealybug Phenacoccus manihoti (Homoptera: Pseudococcidae) and the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). Across island settings, a diverse set of generalist lacewing, spider and ladybeetle predators aggregates on P. manihoti infested plants, attaining max. (field-level) abundance levels of 1.0, 8.0 and 3.2 individuals per plant, respectively. Though biotic resistance-as imperfectly defined by a predator/prey ratio index-exhibits no inter-island differences, P. manihoti population regulation is primarily provided through an introduced monophagous parasitoid. Meanwhile, resident predators, such as soil-dwelling ants, inflict apparent mortality rates up to 100% for various S. frugiperda life stages, which translates into a 13- to 800-fold lower S. frugiperda survivorship on small versus large islands. While biotic resistance against S. frugiperda is ubiquitous along the island chain, its magnitude differs between island contexts, seasons and ecological realms, i.e., plant canopy vs. soil surface. Hence, under our experimental context, generalist predators determine biotic resistance and exert important levels of mortality even in biodiversity-poor settings. Given the rapid pace of biodiversity loss and alien species accumulation globally, their active conservation in farmland settings (e.g., through pesticide phasedown) is pivotal to ensuring the overall resilience of production ecosystems.

Intraguild predation of Phenacoccus manihoti parasitoid Anagyrus lopezi by two mealybug predators, Cryptolaemus montrouzieri and Plesiochrysa ramburi

Anagyrus lopezi is a specialist parasitoid was introduced to Indonesia in 2014 to control cassava mealybug, Phenacoccus manihoti. Plesiochrysa ramburi and Cryptolaemus montrouzieri are generalist predator insects associated with the mealybug. Intraguild predation is a crucial competition in an insect community. The study objective was to investigate interference of both predators on healthy mealybug (unparasitized) or parasitized mealybug by A. lopezi (mealybug which containing parasitoid larvae 1-, 3-, 8-, and 14-day old). Experiments were carried out in a non-choice test (served only one unparasitized or parasitized mealybug of a specific parasitoid age) and choice test (unparasitized and parasitized mealybug of a specific parasitoid age together) in laboratory under controlled environmental conditions. Both of predators species able to fed on both unparasitized and parasitized mealybugs of three different age (1-, 3-, and 8- day-old), but both predators discriminated against mealybug were parasitized 14-day old (hardened mummies). Interaction between parasitoid of A. lopezi and both predators showed antagonistic interaction type. We recommended A. lopezi should be released in field at the beginning of the time when the population of the mealybug is still low and could be continued with the predators release when the mealybug population is high.

Induction of leaf curling in cassava plants by the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae)

Induction of leaf curling in cassava plants by the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae)

Parasitoid of cassava mealybug, Anagyrus lopezi (Hymenoptera: Encyrtidae): Mummy size, adult emergence, sex ratio, and parasitization level

Abstract. Naimah F, Sartiami D, Maryana N, Anwar R, Pudjianto. 2023. Parasitoid of cassava mealybug, Anagyrus lopezi (Hymenoptera: Encyrtidae): mummy size, adult emergence, sex ratio, and parasitization level. Biodiversitas 24: 1629-1634. The presence of Anagyrus lopezi as a natural enemy can reduce the population of Phenacoccus manihoti. This parasitoid was introduced from Thailand to Indonesia in 2014 to control cassava mealybugs. This research aims to determine the mummy length and width, adult emergence time, sex ratio, and parasitization level. This study was conducted in July-November 2022, while parasitoids and mealybugs were obtained from Bogor, Indonesia. The size of mummies was measured under Dino-light digital microscope; the emergence time was counted for 24 hours within six days, and the sex ratio of parasitoids was calculated based on the number of males and females emergence. The parasitization level was observed from four female parasitoids at 120, 160, and 200 of host population densities. The study showed the length and width of female mummies (n: 100) were 0.71 mm and 1.64, while the length and width of male mummies (n: 100) were shorter than female with 1.00 mm and 2.18 mm. The peak time of adult emergence is A. lopezi, i.e., during the daytime at 09:01-12:00 AM and 03:01-06:00 PM. The sex ratio of parasitoids from the field and laboratory was 1:0.49, 1:1.05, and 1:1.09, respectively. The one-way ANOVA and Tukey's test at a 5% significance level showed that the host population density of 120 nymphs was significantly different from other densities, with a parasitization level of 66.7%.

Range of host plants, spatial distribution, and insect predator of Phenacoccus manihoti (Hemiptera: Pseudococcidae) as an emerging pest of cassava plants in Bali, Indonesia

Abstract. Supartha IW, Widaningsih D, Susila IW, Yudha IKW, Utama IWEK, Wiradana PA. 2022. Range of host plants, spatial distribution, and insect predator of Phenacoccus manihoti (Hemiptera: Pseudococcidae) as an emerging pest of cassava plants in Bali. Biodiversitas 23: 3022-3030. The cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) is a very destructive pest in cassava farming in Indonesia. The insect has already made its way into Indonesia, where it has attacked cassava plants with indications of a bunchy top, which may cause plant death. The objectives of this study were to 1) discover and identify an invasive pest of cassava mealybug pest, P. manihoti, that attacks cassava plants in Bali; 2) map the distribution and abundance of these pest species populations on cassava plants in Bali; 3) describe the structure of the pest population in cassava plantations in Bali; 4) identify the dominant factors that influence the population structure of P. manihoti in Bali, and 5) evaluate the predator fauna in regulating the population. The findings revealed that the mealybug species that attacked cassava in Bali was P. manihoti, an exotic species that had never been published earlier. With a high population abundance, the pest has spread far and effectively overall in regencies/cities in Bali Province. In all regency/city regions, the population structure of P. manihoti was dominated by age groups of instar-1 and two nymphs, with the exception of the Buleleng Regency, which was dominated by age groups of nymphs instar 3 and 4. The nature of polyphagy and cosmopolite features that are readily adaptable to the environment and host plant variables, farming pattern, temperature and rainfall factors were the key factors impacting the population structure of P. manihoti in the field. Cryptolaemus montrouzieri, Chrysoperla carnea, and Scymnus sp. were discovered to have a role in managing P. manihoti populations in the field. The predator fauna community is structurally diverse, abundant, and has a low dominance. Cryptolaemus montrouzieri was the most dominant of the three producer species in the field. These results indicate that there is a positive potential shown by predatory mealybugs in the field and can be used as an initial model by related parties in formulating policies related to controlling insect pests of cassava plants.

Efficacy of the extract from pongam (Pongamia pinnata) leaves against the cassava pink mealybug (Phenacoccus manihoti Matile-Ferrero) under laboratory conditions

The cassava pink mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), a native of South America, have been one of the most serious pests of cassava (Manihot esculenta Crantz) in the world. Conventional control of this pest is dependent on synthetic chemical insecticides. This study was carried out at Entomology Laboratory, Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Vietnam during 2020 - 2021 to determine the efficacy of leaf extract from Progamia pinnata against the cassava pink mealybug. The efficacy of pongam leaf extract was more efficacious against the first instar than the second instar of P. manihoti, and was according to the evaluation time. After ten days treatment, the efficacy of the leaf extract against first and second instars of P. manihoti was 100% and 50.0, 73.3, 66.7% at concentrations of 2.0, 1.8 and 1.4%, respectively. Therefore, pongam leaf extract can be recommended for protection of the cassava pink mealybug.

The Fungus Metarhizium sp. BCC 4849 Is an Effective and Safe Mycoinsecticide for the Management of Spider Mites and Other Insect Pests.

Simple SummaryThe spider mite is a destructive pest of various crops during warm and dry conditions in tropical countries, including Thailand. The pest is difficult to control despite synthetic acaricide use. In the field, insect populations gradually develop resistance to synthetic pesticides over long-term use. The use of entomopathogenic fungi is more human- and environmentally friendly. We searched and identified a potential fungal isolate from a culture collection, focusing on the genus Metarhizium. Metarhizium sp. BCC 4849 not only controls the spider mite but also plays a significant role as a natural regulator of other insect pests. Here, we investigated its infection process on the mite, optimized a conidial formulation for extended shelf life, and conducted toxicological assays in animals to assess its biosafety in humans. The fungal genome has been sequenced. The genomic data indicated that oxidoreduction proteins; zinc-, heme-, and iron-binding proteins; and transmembrane transporters are abundant in the genome.Five isolates of Metarhizium sp. were evaluated for their pathogenicity against the spider mite (Tetranychus truncatus Ehara) (Acari: Tetranychidae) and Metarhizium sp. BCC 4849 resulted in the highest mortality (82%) on the 5th day post-inoculation (DPI). Subsequent insect bioassay data indicated similar high virulence against five other insects: African red mites (Eutetranychus africanus Tucker) (Acari: Tetranychidae), bean aphid (Aphis craccivora Koch) (Hemiptera: Aphididae), cassava mealybug (Phenacoccus manihoti Matile-Ferrero) (Hemiptera: Pseudococcidae), sweet potato weevil (Cylas formicarius Fabricius) (Coleoptera: Brentidae), and oriental fruit fly (Bactrocera dorsalis Hendel) (Diptera: Tephritidae), at mortalities of 92–99%, on 3rd–6th DPI, and in laboratory conditions. The pathogenicity assay against E. africanus in hemp plants under greenhouse conditions indicated 85–100% insect mortality on 10th DPI using the fungus alone or in combination with synthetic acaricide. Genome sequencing of Metarhizium sp. BCC 4849 revealed the high abundance of proteins associated with zinc-, heme-, and iron-binding; oxidation-reduction; and transmembrane transport, implicating its versatile mode of interaction with the environment and adaptation to various ion homeostasis. The light and scanning electron microscopy indicated that at 24 h post inoculation (PI), adhesion and appressorial formation occurred, notably near the setae. Most infected mites had stopped moving and started dying by 48–72 h PI. Elongated hyphal bodies and oval blastospores were detected in the legs. At 96–120 h PI or longer, dense mycelia and conidial mass had colonized the interior and exterior of dead mites, primarily at the bottom than the upper part. The shelf-life study also indicated that conidial formulation combined with an oxygen-moisture absorber markedly enhanced the viability and germination after storage at 35 °C for four months. The fungus was tested as safe for humans and animals, according to our toxicological assays.

Assessing adverse impact of the native biological control disruptors in the colonies of the recent invasive pest Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae) in India

New challenges appear with every biological invasion and presses need to probe their ecological interactions. In the comprehensive yet complicated food web associated with the niche of the recently invaded cassava mealybug (CMB) Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), there was a multitrophic interaction structured vertically as well as horizontally. Altogether 45 species: thirty four species of insects from six orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Neuroptera) and eleven species of spiders (Araneae) were grouped under four trophic levels into 11 guilds. The analysis of trophic guild structure and interaction indicated that many indigenous parasitoid species, which qualified to be placed under the fourth trophic level, actively parasitized the potential native predators of cassava mealybug (CMB) and thereby negatively impacted the natural biological control of CMB. Most of these resident hyperparasitoid species were recorded for the first time, to be associated directly or indirectly with CMB. The species diversity at fourth trophic level could be viewed as a bioindicator and one of the most important determinant factors on the success rate of any biological control program. No indigenous primary parasitoids were documented on CMB from any of the sites sampled. In the absence of any indigenous parasitoids and high level of parasitization of the potential CMB predators, the long-term and indirect ecosystem risks will be significant until the introduction and establishment of the proven classical biological control agent, Anagyrus lopezi (De Santis) (Encyrtidae: Hymenoptera) from other countries. • First comprehensive study involving multitrophic interactions in the niche of invasive pest Phenacoccus manihoti. • Many indigenous parasitoid species actively parasitized the potential native predators of CMB. • Negatively impact on the natural biological control of CMB. • No indigenous primary parasitoids documented. • We assess the long-term and indirect ecosystem risks due to CMB and spread to other countries.

Peroxidase and polyphenol oxidase activity in cassava genotypes infested with Phenacoccus manihoti

AbstractThe cassava mealybug, Phenacoccus manihoti (Matile‐Ferrero) (Hemiptera: Pseudococcidae), has become an important pest with major potential to damage cassava, Manihot esculenta Crantz (Euphorbiaceae), around the world. To find new sources of plant resistance, the development of P. manihoti on 18 cassava genotypes was evaluated (duration of embryonic, nymphal, egg–adult, pre‐oviposition, and oviposition periods, longevity, and fecundity), and the defense‐related peroxidase (POD) and polyphenol oxidase (PPO) activities in the leaves were measured. The fecundity of P. manihoti was the parameter most affected by the cassava genotype that the insect was fed. POD activity was negatively correlated with the intrinsic rate of increase (rm) of P. manihoti. PPO activity was negatively correlated with insect fecundity, net reproductive rate (R0), and rm and positively correlated with population doubling time. According to hierarchical groupings of the genotypes tested, three genotypes were resistant to P. manihoti, five were moderately resistant, nine were susceptible, and one was highly susceptible. This information could aid future genetic breeding programs, leading to development of more resistant commercial cassava varieties which could be used in integrated pest management systems.

Diversity of Predators Associated with the Mealybug Complex in Cassava Growing Districts of Tamil Nadu, India

An extensive survey was carried to study the diversity of predators associated with the mealybug complex in the cassava growing districts viz., Salem, Namakkal, Erode, Tiruppur and Coimbatore of Tamil Nadu, India from January to September, 2021. The survey revealed the dominance of Phenacoccus manihoti Matile-Ferrero 1977 (Hemiptera: Pseudococcidae) than other mealybug species in all the surveyed districts. The incidence of P. manihoti ranged from 12 to 90 per cent while Paracoccus marginatus Williams and Granara de Willink 1992 (Hemiptera: Pseudococcidae) incidence was found to be between 8 and 54 per cent. The incidence of Ferrisia virgata Cockerell 1893 (Hemiptera: Pseudococcidae) was found to be very low (8-16%) compared to other mealybug species. Association of total predators with P. manihoti were found to be maximum (30.87%) followed by the total predators with P. marginatus (6.49%) whereas 0.53 per cent of total predators associated with F. virgata. The fourteen different predators viz., Cryptolaemus montrouzieri Mulsant 1853 (Coleoptera: Coccinellidae), Menocheilus sexmaculatus Fabricius 1781 (Coleoptera: Coccinellidae), Anegleis cardoni Weise 1892 (Coleoptera: Coccinellidae), Hyperaspis maindroni Sicard 1929 (Coleoptera: Coccinellidae), Brumoides suturalis Fabricius 1798 (Coleoptera: Coccinellidae), Scymnus spp. (Coleoptera: Coccinellidae), Chrysoperla spp. (Neuroptera: Chrysopidae), Mallada spp. (Neuroptera: Chrysopidae), Spalgis epeus Westwood 1851 (Lepidoptera: Lycaenidae), Geocoris spp. (Hemiptera: Geocoridae), Cardiastethus spp. (Hemiptera: Anthocoridae), Diadiplosis spp. (Diptera: Cecidomyiidae), Oxyopes spp. (Araneae: Oxyopidae) and Argiope spp. (Araneae: Araneidae) were found to associated with the mealybug species viz.,P. manihoti, P. marginatus and F. virgata. Among the predators of the mealybug complex, the most relative abundant species were H. maindroni (11.74%) associated with P. manihoti and C. montrouzieri (6.49%) associated with P. marginatus followed by S. epeus (0.67%) associated with F. virgata. The diversity of predators assessed through Simpson’s Index of Diversity, Shannon-Wiener, Pielou’s Evenness and Margalef indices revealed highest species diversity, species richness and species evenness in Namakkal district.

Uji Pemangsaan dan Tanggap Fungsional Predator Chysoperla carnea Stephens (Neuroptera: Crysopidae) Terhadap Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae)

Predation and Functional Response Test of Predator Chysoperla carnea Stephens (Neuroptera: Crysopidae) Against Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). This study aims to evaluate the predatory capacity of C. carnea by measuring the rate of searching capacity and handling-time of one prey and its functional response to the population density of P. manihoti. The research was conducted at the Integrated Pest Management Laboratory (IPMLab), Faculty of Agriculture, Udayana University. The study was conducted from February to May 2019. Testing of functional responses used a randomized block design with 5 treatments (3, 6, 9, 12, 15 nymphs-3) each of which was repeated 10 times. The results showed that the prey searching-capacity when the population was low (3 nymphs-3) took longer (10.37 minutes), while when the population was high it took a short time (6.23 minutes). The length of time for handling one prey in the low population was 6.08 minutes, while in the high population it was 5.48 minutes. Predator C. carnea has a tpe-2 functional response to an increase in the population of P. manihoti nymphs with the equation Y = 4.32x / 1 + 1.973x (R2 = 0.980). The rate of predation increases sharply when the population of low increases, and decreases when the increase of prey population increases. C. carnea has the potential to be developed as a control agent for P. manihoti.

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Farmers' knowledge, attitudes and practices towards management of cassava pests and diseases in forest transition and Guinea savannah agro-ecological zones of Ghana.

Background: Cassava is a major staple root crop in Ghana, which serves as a food security and an income generating crop for farming families. In spite of its importance, the crop is plagued with biotic factors such as pests and diseases, resulting in yield and income reductions. Methods: Farmers' knowledge, attitudes and practices towards cassava pest and disease management were investigated. A mixed research questionnaire was used to collect both qualitative and quantitative data from 94 cassava farm households across two major cassava growing agro-ecologies. Results: Using descriptive statistics, parametric and non-parametric analysis, our study revealed that farmers' knowledge on cassava pests was high but low for diseases. Whiteflies ( Bemisia tabaci Gennadius), grasshoppers ( Zonocerus variegatus), aphids ( Aphis gossypii Glover), mealybugs ( Phenacoccus manihoti), termites ( Isoptera), and grasscutters ( Thryonomys swinderianus) were perceived as the most common damaging pests. Farmers' descriptions showed that disease pathogens attacked foliar tissues, stem and root tissues and caused leaf dropping and die back. Cassava mosaic disease and root rot were the most common diseases; however, disease descriptions suggested the incidence of viral, bacterial and fungal diseases. Some of the farmers observed mixed symptoms on their farms. The results also showed that only 25.5% cultivated improved varieties. Management actions applied included field sanitation practices and pesticide application. The effectiveness level of the control actions was rated moderately effective. Conclusions: The analysis showed heterogeneity in personal and farm level characteristics of respondents across the two agro-ecologies, but agro-ecologies were independent of the management practices employed. There is a need to improve farmers' access to improved disease-free planting materials through efficient dissemination pathways and increase farmers' knowledge on cassava pests, diseases and integrated management through publfic awareness creation and capacity building by extension agents and research institutions. Continued government investment is needed to achieve sustainable outcomes.

Farmers’ knowledge, attitudes and practices towards management of cassava pests and diseases in forest transition and Guinea savannah agro-ecological zones of Ghana

Background: Cassava is a major staple root crop in Ghana, which serves as a food security and an income generating crop for farming families. In spite of its importance, the crop is plagued with biotic factors such as pests and diseases, resulting in yield and income reductions. Methods: Farmers’ knowledge, attitudes and practices towards cassava pest and disease management were investigated. A mixed research questionnaire was used to collect both qualitative and quantitative data from 94 cassava farm households across two major cassava growing agro-ecologies. Results: Using descriptive statistics, parametric and non-parametric analysis, our study revealed that farmers’ knowledge on cassava pests was high but low for diseases. Whiteflies ( Bemisia tabaci Gennadius), grasshoppers ( Zonocerus variegatus), aphids ( Aphis gossypii Glover), mealybugs ( Phenacoccus manihoti), termites ( Isoptera), and grasscutters ( Thryonomys swinderianus) were perceived as the most common damaging pests. Farmers’ descriptions showed that disease pathogens attacked foliar tissues, stem and root tissues and caused leaf dropping and die back. Cassava mosaic disease and root rot were the most common diseases; however, disease descriptions suggested the incidence of viral, bacterial and fungal diseases. Some of the farmers observed mixed symptoms on their farms. The results also showed that only 25.5% cultivated improved varieties. Management actions applied included field sanitation practices and pesticide application. The effectiveness level of the control actions was rated moderately effective. Conclusions: The analysis showed heterogeneity in personal and farm level characteristics of respondents across the two agro-ecologies, but agro-ecologies were independent of the management practices employed. There is a need to improve farmers’ access to improved disease-free planting materials through efficient dissemination pathways and increase farmers’ knowledge on cassava pests, diseases and integrated management through publfic awareness creation and capacity building by extension agents and research institutions. Continued government investment is needed to achieve sustainable outcomes.

Record of coccinellid predator, Hyperaspis maindroni Sicard (Coleoptera: Coccinellidae) on invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae)

The cassava mealybug, Phenacoccus manihoti Matile-Ferrero is one of the most serious pests of cassava worldwide, which got recently introduced into India (traced in Kerala) as a potential invasive pest. Studies were carried out to record the incidence of mealybug, P. manihoti and its natural enemies on different varieties of cassava in Namakkal dt. of Tamil Nadu during June 2020. The observations were taken in the field in situ as well in the collected mealybug infested twigs in the laboratory. Results revealed that all the three surveyed cassava varieties viz. , Mulluvadi, Thailand white and Shree Atulya were found severely infested with cassava mealybug. A huge number of coccinellid beetles were collected from the P. manihoti colonies, which were identified as Hyperaspis maindroni Sicard, 1929 (Coccinellidae:Coccinellinae:Hyperaspidini). Molecular characterization of both grub and adult beetle of H. maindroni was carried out to confirm its identity.