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Symptoms on cassava due to cassava mealybug damage. a, Severely infested twig; b, Dried twig; c, Drying of leaves and shoot tip; d, Cassava plant with bunchy top appearance; e, Cassava plant with no tuber formation; f, Stunted cassava plants in the field.
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Increased globalization and trade have made India a target for entry of many new alien species. One such unintentional recent introduction is the deadly cassava mealybug (CMB), Phenacoccus manihoti Matile-Ferrero (Hemipera: Pseudococcidae) on cassava crop. Cassava is an important industrial crop with significant export revenue generation in additio...
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Context 1
... pinkish oval mealybugs were commonly noticed on tender shoots, and at the under surface of the top leaves. Due to extreme sucking of plant sap by the mealybug, symptoms such as drying of leaves, distortion of stem, clumping of leaves, shortening of internodes and bunchy top were observed in highly infested and unsprayed fields (Figure 2). The per cent infested plants in the sampled villages varied from 7.0 to 86.7, whereas the bunchy top symptoms appeared on up to 74.3% of the infested plants in certain locations especially in Edappadi, Senthamangalam and Namagiripettai blocks of Salem and Namakkal districts. ...
Citations
... CMB directly sucks sap from cassava stems, petioles and young leaves, injuring the plant in the process and indirectly stimulate growth of sooty molds via its toxic saliva (Fig. 1d) (Barilli et al., 2014;Nweke 2009). Heavy infestations ( Fig. 1b and c) cause plant stunting, terminal shoot distortion, leaf curling, withering, wilting and abscission, stem deformation or rosetting, bunchy top appearance, dieback and weakening of stems, reduced root systems and plants with no tuber formation (CABI 2021;Parsa et al., 2012;Sampathkumar et al., 2021;Nweke 2009;Graziosi et al., 2016;Calatayud and Le Rü 2006). As CMB feeds, honeydew is released and falls onto the leaves where it is colonized by sooty mould fungi blocking photosynthetic surfaces which results in weakening of plants (Herren and Neuenschwander 1991;CABI 2021;Parsa et al., 2012). ...
Cassava is a tuberous root crop that can maintain food and nutrition security, improve family and household incomes and minimize the adverse effects of climate change especially in sub-Saharan Africa (SSA). According to projections, cassava will probably be adaptable to stressors associated with current climatic changes, with ex-
pected improved production in SSA. Despite this positive outlook, the crop will still be more susceptible to arthropod pests including thrips, weevils, hornworms, whiteflies, stem borers, mealybugs, lacebugs, mites, grasshoppers among others that cause direct and indirect damage lowering its yield. A plethora of strategies ranging from monitoring, prevention, cultural, phytosanitation, use of insecticides, biological, clean seeds sys-
tems and host-plant resistance as well as a combination of two or more of these approaches through integrated pest management have been deployed to control these arthropod pests. This article review recent data on the damaging effects of these pests on cassava productivity and control strategies deployed in SSA to mitigate their impacts. Further, the review explores other management approaches that could be adopted for cassava pests’ management in SSA. The herein consolidated information will benefit cassava farmers, scientists, breeders, policy makers and other stakeholders involved in cassava value chain for improved and sustainable cassava production in SSA.
... This transboundary pest was reported for the first time in India in the year 2020 (Joshi et al., 2020). Ever since its entry, the insect has been reported in all major cassava-growing areas of the country (Sampathkumar et al., 2021). Yield loss of about 80% has been reported from cassava fields infested by this mealybug (Nwanze, 1982). ...
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.
... Mealybugs were collected from Rasipuram and Kalkurichi of Namakkal district, Vennandur of Salem District and Madathukulam of Thiruppur district.Under stereo zoom binocular microscope (LEICA M205C), observation was made on colour, presence or absence of posterior and lateral filaments and presence or absence of wax coating on the cuticle, which are the key characters for the field level identification of mealybug species (Sunil Joshi et al.,2021). At field level, the typical symptom of bunchy top was documented. ...
... Kaydan and Gullan (2012) detailed that the genus Ferrisia can easily be distinguished from other taxa of mealybugs with the presence of dark dorsal areas because of absence of wax. F. virgata in cassava was reported by Sunil Joshi et al. (2021). ...
... Mani et al. (2013) described that P. jackbeardsleyi is characterzed with thin filaments around the body and caudal pair of one-half length of body. Sunil Joshi et al. (2021) narrated the filaments of P. Jackbeardsleyi which is in accordance with the present study. ...
Cassava (Manihot esculenta Crantz) is an important tuber crop grown
for food, feed and beverages. Because of its ability to grow on soil of low
organic content and produce high yield, it is considered a food security
crop in African countries. Now it became the industrial crop since it is raw
material for the production of starch, energy and live stock feed. In Tamil
Nadu, it is grown in Salem, Namakkal, Erode, Cuddalore, Dharmapuri and
Kanyakumari districts, both in irrigated and rainfed condition. Recently,
the major constraint in cassava production are mealybug damage. The
invasive mealybug species, Phenococcus manihoti Matile-Ferrero
(Pseudococcidae) was first reported from Salem district and its
occurrence was found associated with other species of mealybug. The
nymphs and adult of mealybugs were collected from farmer”s field in
Namakkal, Salem and Tiruppur district and morphological characters
were observed to identify the key characters of mealybug species. Among
the specimens collected, the species identified with colour, wax coating
and body filaments were Ferrisia virgata, Pseudococcus jackbeardsleyi
and P. manihoti. P. manihoti differentiated from the other species with its
distinct symptom of distortion of leaves at tip (Bunchy top) and extensive
honey dew secretion.
... Under classical biological control, examples of pest suppression with imported natural enemies include the parasitoid, Acerophagous papayae against papaya mealy bug, Paracoccus marginatus (2010); parasitoid, Quadrastichus mendeli against eucalyptus gall wasp, Leptocybe invasa (2018); parasitoid, Encarsia guadeloupae against coconut rugose spiraling whitefly, Aleurodicus rugioperculatus (2019). The latest introduction has been the parasitoid Anagyrus lopezi from Benin for the control of cassava mealy bug in Tamil Nadu and Kerala during 2021 (Sampathkumar et al., 2021). ...
Insect pests, diseases, nematodes and weeds constitute major biotic stresses in crop production systems inflicting 15 to 25% or more yield losses. Adverse effects of pesticides can be countered through adoption of integrated pest management (IPM), which emphasizes harmonious use of safer and environment friendly methods of pest suppression. IPM works on the premise that all pest population levels are not injurious to crops. It is a knowledge intensive decision based activity and requires tools and techniques for its execution. IPM algorithm involves crop loss assessment, pest risk analysis, development of pest surveillance and forewarning methodology and decision support tools for harmonious integration of management tactics within the framework of Integrated Crop Management system. IPM modules for various field crops are based upon integration of resistant cultivars, cultural, mechanical and physical methods, natural enemies, biopesticides and pesticides to suppress pest population without jeopardizing the environment. Various organizations addressing the issue of plant health management need to converge in a mission mode to disseminate IPM throughout the country. This review covers the latest developments in these areas of IPM with main reference to India.
... Incursions of alien invasive insect pests have been a regular phenomenon in India, even though a robust regulatory mechanism is in place. A tentative list of major introduced and established pests is mentioned in (Sushil, 2015(Sushil, , 2016(Sushil, , 2018(Sushil, & 2021Shashank et al., 2015, Chakravarthy et al., 2017Sharanabasappa et al., 2018;Sundararaj & Selvaraj 2017;Shylesha et al., 2018;Josephrajkumar et al., 2019;Chandrikamohan et al., 2019;Joshi et al. 2020;Sampathkumar et al., 2021). ...
In the increasing globalisation era, movement of goods and planting materials between countries being carried out at ease, are potential factors of introduction of invasive alien insects, diseases, and weeds in India. Infested fruits carried by international travellers, cargo / sea shipments of wood logs, food trade, and accidental introduction through air travels were the potential ways of entry of invasive alien insects into any country. The entry of alien invasive pest causes huge economic damage by way of direct crop loss. In addition, the panic situation to save the crops results in indiscriminate use of chemical insecticides that is harmful to applicator, farmer and consumer. Frequent application of insecticides leads to reduction in natural enemies and pollinators there by having an adverse impact on the ecosystem. The present paper critically reviewes the existing plant quarantine regulations in India, recent invasive and migratory insect pest problems and way forwards to safeguard Indian Agriculture.
... All the stages viz., eggs, nymphs and adults cause curling of the leaves at growing tip of the plant leading to formation of bunchy tops and adventitious buds on almost all the internodes. Heavy population resulted in the leaf drying and entire defoliation (Sampath et al., 2021). ...
The agricultural sector of India is under risk from numerous possible bioweapons, primarily invasive pest species. Exotic, introduced, alien, non-indigenous or non-native species that have been unintentionally or purposefully introduced by humans from one area to another are considered invasive pest species. Due to trade liberalisation and greater intercontinental travel by people, the invasion of invasive insects has grown globally. So far, 34 different invasive insect pests of horticultural crops are recorded in India. The valuable natural agricultural systems that support us and the biodiversity are both suffering severe harm from these animals. The damage to nature and the environment is frequently irreparable and direct and indirect health repercussions are becoming more significant. The exact monitory values of the losses caused by these invasive pests on horticultural crops are not properly known. By having a fundamental understanding of invasive pest species and fostering international collaboration through the sharing of knowledge about invasive pests and their natural enemies, the introduction of new pest species in a new area can be minimised. India will be safe from such invasive pests due to strict import rules, international trade and commerce cooperation, early detection and taxonomic identification at entry points.
... It is established in parts of Kerala and Tamil Nadu; some cassava-growing regions of Tamil Nadu witnessed serious outbreaks in 2020-21 (ref. 3). Several mealybug species occur on cassava and mixed infestations of multiple species are common. ...
... In India, effective biological control agents are only available for use against papaya mealybug. Cassava mealybug has no major natural enemies in India at present and efforts are in progress to introduce an exotic parasitoid, Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) for its management 3 . ...
Phenacoccus manihoti Matile-Ferrero (Hemiptera: Coc-comorpha: Pseudococcidae), one of the most serious pests of cassava worldwide, was recently introduced to India. Surveillance, early detection and mapping of its distribution in cassava-growing areas are essential to prevent it from spreading further. Several species of mealybug are known to infest cassava in India; their authoritative identification normally requires preparation of slide mounts, which is a highly skilled and time-consuming process. A simple method is described here for screening alcohol-preserved samples of mixed-species infestations for cassava mealybug.
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
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 programme. 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.
