First record of Asian grey weevil (<Emphasis Type="Italic">Myllocerus undatus)</Emphasis> on coconut from Kerala,India

The occurrence of Asian grey weevil Myllocerus undatus (Curculionidae: Coleoptera) damaging coconut (Cocos nucifera L.) seedlings is reported for the first time from Kerala, India. A mild to moderate level of infestation damaging 5–10% leaf lamina of un-split leaves with a typical notching-like symptom along the leaf margins is noticed on the majority of the coconut seedlings belonging to different coconut varieties, viz., ‘Chowghat Orange Dwarf’, ‘Chowghat Green Dwarf’, ‘Malayan Green Dwarf’, ‘West Coast Tall’ and Dwarf x Tall hybrids. M. undatus has not been reported as a destructive pest on any of the crops from India and is considered to be a pest of quarantine significance. Adult weevils have a characteristic tri-spined hind femur and elytra strongly angled broader than the prothorax.     

First report of Encarsia cubensis Gahan (Hymenoptera: Aphelinidae) an exotic parasitoid on the Neotropical Whitefly Aleurotrachelus atratus Hempel (Hemiptera: Aleyrodidae) in India

The Neotropical palm infesting whitefly, Aleurotrachelus atratus Hempel (Hemiptera: Aleyrodidae) is a highly invasive pest that was reported during 2019 on coconut in India. In a short span of time, it spread rapidly across states of Karnataka, Tamil Nadu, Kerala and Andhra Pradesh on coconut, oil palm and many other ornamental palm plants. During the recent survey, the immature stages of A. atratus were found parasitized by an aphelinid parasitoid, Encarsia cubensis Gahan (Hymenoptera: Aphelinidae). These parasitoids were identified by their morphological characteristics and also characterized by DNA barcoding of adult parasitoids using partial (658 bp) mitochondrial cytochrome oxidase 1 (CO1) gene (GenBank accession number ON881119). This is the first report on occurrence of Encarsia cubensis as primary parasitoids on A. atratus in India and its natural parasitism ranged from (46–68%) on coconut across the different locations in Karnataka. It is believed that the parasitoid likely entered India along with A. atratus in India and constitutes a potential biological agent against A. atratus. It is expected that the E. cubensis population will become fully established, increase, spread and exert a significant impact on A. atratus population in India. Therefore, efforts may be made by growers and other stakeholders to increase the rate of natural parasitism through inundative, conservation and classical biological control approaches to reduce the pest population, crop damage and yield loss.

     

Report on the palm aphid, <Emphasis Type="Italic">Cerataphis brasiliensis</Emphasis> on ‘Kalparaksha’ coconut cultivar

Aggregations of palm aphid Cerataphis brasiliensis (Hempel) (Aphididae: Hemiptera) on the unfurled spindle leaf of ‘Kalparaksha’ variety of coconut, a selection from Malayan Green Dwarf, is reported for the first time. C. brasiliensis has not yet been observed from other coconut varieties, viz., West Coast Tall, Chowghat Orange Dwarf, Chowghat Green Dwarf, and Dwarf x Tall hybrids planted in the research farm of Central Plantation Crops Research Institute, Kayangulam, Kerala, India. Only the apterous form of the palm aphid was noticed in the semi-tall variety and a variety-induced emergence of C. brasiliensis is indicated under natural conditions. Due to the presence of two phoretic ant species, no natural predator was observed in the aphid colonies. Two sprays of dimethoate (0.05%) at an interval of 15–20 days were effective in suppression of the pest on Kalparaksha.     

Influence of abiotic factors on behaviour and adult emergence pattern of coconut white grub, <Emphasis Type="Italic">Leucopholis coneophora</Emphasis> Burmeister (Coleoptera: Scarabaeidae)

Leucopholis coneophora Burmeister is a subterranean pest associated with coconut based cropping systems in south India. Feeding damage causes yellowing of fronds and yield reduction. To develop appropriate IPM strategy a basic knowledge on insect behaviour is essential. Four years studies indicated that, adult emergence of L. coneophora was commenced with summer shower in April in Kerala. Delay in summer shower delayed the emergence. After a pause in May, the emergence resumed with the setting of south west monsoon in June. The beetles did not emerge during dry spells in between the rainy days, when the soil temperature (at 10 cm depth) was ≥34.5 °C. Emergence of the beetles started at an illuminance of 124.37?±?75.5 l in evening and remained active till 2?±?0.4 l with a maximum swarming at 32.6?±?15.1 l. Female emergence and mating occurred at 12.04?±?8.1 l. Female based sex pheromone mediated communication is evident. Strong competition among the males for mating with emerging female, which was evident by a wider operational sex ratio in the initial period (1:10.11) that narrowed down to 1:4.33 in later days. The beetles neither congregate on any host plant nor exhibit phototaxis. Number of beetles entrapped in light traps varied from 1.5–16.5% and hand picking is highly significant over light trapping. Hence hand picking of beetles daily in the evening for 2 weeks commencing from the onset of south west monsoon in Kerala, in Indian subcontinent is suggested as a tool in IPM.     

Insects and Mites

Abstract

During August 1986 when there was a build up of Parasa lepida Cramer on coconut in the study area in Kerala, India, many dead larvae were found on the underside of the leaves. A few of these cadavers which were suspected to be infected by a virus were collected. Pathogenicity tests proved positive. PIBs were negative to stain by Giemsa, and section of the polyhedra shows that the virions are rod shaped. The pathogen is a multiple embedded baculovirus.     

Discovery of a sooty mould scavenging beetle, <Emphasis Type="Italic">Leiochrinus nilgirianus</Emphasis> Kaszab (Coleoptera: Tenebrionidae) on coconut palms infested by the invasive rugose spiralling whitefly, <Emphasis Type="Italic">Aleurodicus rugioperculatus</Emphasis> Martin (Hemiptera: Aleyrodidae)

Scavenging action of Leiochrinus nilgirianus Kaszab (Coleoptera: Tenebrionidae) on sooty mould deposition on coconut palms due to heavy honeydew production by the invasive rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae), is reported for the first time from Kerala, India. Adult beetles, averaging 2.07?±?0.9 / leaflet, with a maximum of five beetles per leaflet, and immature stages were generally confined to the abaxial of the palm leaves during daytime, but were found feeding on sooty mould during morning hours in damp conditions. The specially aided adaptive leg features of L. nilgirianus with bristle-like hairs on the undersurface of tarsomeres probably aid in proper adhesion on sooty mould laden plant surface and well developed tarsal claws that perhaps assist swift movement on fungus-laden leaflets. On an average one adult beetle could clear 1–2 mm² sooty mould laden area in a period of one minute. In situ habitat conservation of L. nilgirianus would help to reduce the sooty mould at no cost in the most natural and eco-friendly manner avoiding chemical management options and other expensive methods.     

Invasion of rugose spiraling whitefly, <Emphasis Type="Italic">Aleurodicus rugioperculatus</Emphasis> Martin (Hemiptera: Aleyrodidae): a potential threat to coconut in India

The invasion and infestation of the Rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) on coconut palm (Cocos nucifera L.) (Arecales: Arecaceae) in India is reported for the first time from Indian as well as from Oriental region. The severity of its infestations and impact on coconut cultivation in India is discussed.     

Kerala wilt disease phytoplasma: Phylogenetic analysis and identification of a vector, Proutista moesta

Kerala wilt disease of coconut palm is a major threat of coconut production in Kerala caused by phytoplasma. The genomic DNA purified from the insect tissues of Proutista moesta (PM) and Stephanitis typica (ST) was subjected to PCR assay using the primer combination P1/P6, P1/P7 and P4/P7. The amplified products resolved a prominent band of 650 bp for the universal primer P4/P7 and no bands were noticed for the primer pairs P1/P6 and P1/P7 combination. Since P4/P7 amplifies the 16S–23S intergenic spacer region of 16SrRNA gene, the PCR product 650 bp of the insect PM indicate the phytoplasma DNA. The presence of 650 bp for the primer P4/P7 in the genomic DNA isolated from P. moesta indicates the vectoral ability of the insect. No sign of amplification was noticed in the case of ST for the three sets of primers suggesting the inability of this insect as vector. The amplified product 650 bp from the genomic DNA of KWD palms as well as the insect tissues of P. moesta was gel purified and sequenced. The sequential similarity of 650 bp of both KWD phytoplasma and the insect phytoplasma supports the transmission of phytoplasma through the vector PM. Moreover, the sequence of 650 bp was compared with other sequences of 26 coconut phytoplasmas so far reported internationally and a cladogram was prepared for determining the phylogenetic status. It is obvious from the cladogram that the KWD disease phytoplasma is evolutionarily closest to coconut phytoplasma of coconut lethal yellowing of Mexican palms within the group 16SrIV. Phylogenetically, KWD phytoplasma is grouped in the new subgroup 16SrIV-C subsequent to the groups 16SrIV-A and 16SrIV-B for Mexican coconut lethal yellowing and Tanzanian coconut lethal decline, respectively. The restriction enzyme analysis of the PCR product 650 bp using the enzymes AluI, BclI, HindIII and RsaI further supports the phytoplasmic nature of DNA. This data records the first finding of the vector of Kerala wilt disease by detecting KWD phytoplasma in insect tissue of PM by PCR based methods. Moreover, the study reveals the phylogenetic status of KWD phytoplasma compared to other coconut phytoplasmas internationally.     

Damage by Homalinotus depressus in commercial coconut palm crops in the Amazonian region of Brazil

The coconut palm (Cocos nucifera L., Arecaceae) has great economic and social importance for many industrial and non-industrial products. Pests can reduce its productivity and cause its death. In 2005, larvae and adults of a Curculionidae were observed damaging the floral stalk of coconut palms in commercial plantations in the municipality of Moju, Pará State, in the Brazilian Amazon. Insects were identified as the black coconut bunch weevil, Homalinotus depressus (L.) (Coleoptera: Curculionidae: Cholini). This is the first report of this pest damaging coconut palms in Brazil.     

First report of Maconellicoccus hirsutus Green infestation on Jatropha curcas saplings

In December 2009 and May 2010 an insect pest was observed on Jatropha curcas L. (Euphorbiaceae) saplings at the Biomass Farm Site, Banthara, of CSIR-National Botanical Research Institute, Lucknow, India. On the basis of morphology of the insect pest and symptoms caused on its host, it was identified as Maconellicoccus hirsutus (Green) (Homoptera: Coccoidae: Pseudococcidae) synonym Phenacoccus hirsutus Green. This is the first report of the occurrence of M. hirsutus infestation on J. curcas.     

Competitive interactions between Goniozus nephantidis and Bracon brevicornis,parasitoids of the coconut pest Opisina arenosella

Black-headed caterpillar, Opisina arenosella Walker (Lepidoptera: Crytophasidae) is an endemic, frequently outbreaking pest of coconut in India and Sri Lanka. It also occurs in Bangladesh and Myanmar. Two larval parasitoid wasps Goniozus nephantidis (Muesebeck) (Bethylidae) and Bracon brevicornis Wesmael (Braconidae), are widely employed, either singly or in combination, for the biological control of O. arenosella in India. The co-occurrence of G. nephantidis and B. brevicornis in the field indicates the potential for competitive interactions which may interfere with pest suppression. In order to study the outcome of competitive interactions between these parasitoids, host larvae were exposed to the parasitoid species either alone or in combination. Females of G. nephantidis and B. brevicornis did not discriminate between unparasitised hosts and hosts parasitised by the other species. Survival of G. nephantidis and B. brevicornis from eggs to adult eclosion was 89.6 and 81.8%, respectively, when larvae of O. arenosella were exposed to these parasitoids individually. When both species were released simultaneously, the survival of G. nephantidis was 86.8% and females of that species chased B. brevicornis females, attempting to bite and sting them. The mean percentage of progeny obtained was significantly higher for G. nephantidis than for B. brevicornis. G. nephantidis dominated due to its parental care behaviour producing 87.0% of progeny and a sex ratio (proportion of females) of 0.79, whereas B. brevicornis produced 84.0% progeny and a sex ratio of 0.36. Although parental care by G. nephantidis females serves to protect the progeny from intruders, it may be disadvantageous from the standpoint of pest suppression under field conditions especially, when the pest population density is high.     

Toxins from a symbiotic fungus, Leptographium qinlingensis associated with Dendroctonus armandi and their in vitro toxicities to Pinus armandi seedlings

Leptographium qinlingensis is an ophiostomatoid fungal pathogen associated with a forest pest Dendroctonus armandi, which causes enormous deaths of its host trees Pinus armandi. The objective of this research was to isolate and characterise some toxic metabolites from cultures of the pathogen. Three toxins, 6-methoxymethyleugenin (compound 1), maculosin (cyclo(L-Pro-L-Tyr), compound 5) and cerevisterol (compound 12), together with 11 other compounds, have been isolated from the ethyl acetate extracts of the cultures of L. qinlingensis by several chromatographic methods. Their structures were characterized on the basis of spectroscopic analyses including ESIMS, ¹H-NMR, and ¹³C-NMR, in comparison with those reported in the literature. Phytotoxic test showed that these three compounds were active in vitro against both aseptic Pinus armandi seedlings and field P. armandi seedlings. The present investigation demonstrated that three toxic metabolites including 6-methoxymethyleugenin, maculosin and cerevisterol, which were biosynthesized by L. qinlingensis isolated from the insect Dendroctonus armandi on Pinus armandi tree, could be phytotoxic to P. armandi seedlings.     

Review on exotic Bondar’s nesting whitefly,Paraleyrodes bondari Peracchi infestation on multiple cropping system

Between 2016 and 2020, seven new whitefly species were uncovered in the tropical Southern region of India, wrecking chaos among producers in certain invasive whitefly instances. The repercussions of climate change, improved free trade practices between countries, increased intercontinental migration, enhanced exim operations for planting supplies, etc., may have led to insect invasions. A limited number of invasive insect species only swelled to unmanageable proportions when entered into new geographic locations. Bondar’s Nesting Whitefly (BNW), Paraleyrodes bondari Peracchi (Hemiptera: Aleyrodidae), a native of Brazil to Honduras, was one such species. In May 2017, BNW noticed from the Indian Andaman and Nicobar islands, by December 2018 reached Indian mainland Kerala. Because of its co-existence with other whiteflies and cryptic appearance, BNW identification at immature stages can be challenging and may call for specific instruments and methods. Global analysis of BNW mitochondrial cytochrome oxidase (COI) indicated the presence of highly homogenous population. BNW is polyphagous, co-lives with other whiteflies and feeds by desapping from adaxial leaf surfaces of perennial and seasonal plants, crops, weeds etc., thus promoting sickliness. The land areas invaded and host plants exploited have increased within a short span from its introduction. BNW has no known parasitoids, and only non-specific predators utilize them. The presence of an intensive BNW population warrants frequent adoption of pest control practices. Even though insecticides bring down whiteflies, it is not the sole panacea. The information pertinent to BNW and its sustainable control is limited and scattered. These details mandate reviewing them concerning poly-crop systems practised in tropical ecosystems. This review discusses the possibilities of BNW becoming a significant pest of crops in tropical Indian mainlands and its management prospects.

     

Factors affecting cross protection of fusarium wilt of pigeon pea by soilborne nonpathogenic fungi

Preinoculation of pigeon pea (Cajanus cajan (L.) Millsp.) seedlings with soilborne fungi nonpathogenic to pigeon pea, namely,Fusarium oxysporum f.sp.niveum; F. oxysporum f.sp.ciceris; F. solani f.sp.pisi; andCephalosporium sacchari, before challenge inoculation with the pathogenFusarium udum, or simultaneous inoculation of the seedlings with nonpathogen and pathogen was effective in controlling wilt of pigeon pea to a great extent. Inoculation with the nonpathogens before the challenge inoculation was more effective than simultaneous inoculation and gave up to 81.6% protection. The higher the spore concentration of the nonpathogenic fungi, the better was the degree of protection. The shorter the period was (in the range of 2–7 days) between nonpathogen inoculation and challenge inoculation, the greater was the degree of protection. Injury to the roots resulted in a decrease of the effect. Maximum disease reduction was obtained when the seedlings were kept at 20-30°C before inoculation; at 5°C and also at 40°C, protection was much less.     

Role of hydrogen peroxide and antioxidative enzymes in Pinus tabulaeformis seedlings inoculated with Amanita vaginata and/or Rhizoctonia solani

The ectomycorrhizal fungus Amanita vaginata can control damping off (Rhizoctonia solani) and promote growth of Pinus tabulaeformis seedlings. The aim of this study was to investigate whether reactive oxygen species and antioxidative enzymes play a role in preventing damping off in ectomycorrhizal roots. Two months after P. tabulaeformis roots were inoculated with A. vaginata, the roots were inoculated with R. solani. During the early stages (2?C96?h) of R. solani infection, the quantity and localisation of hydrogen peroxide and the activities of superoxide dismutase and catalase were evaluated. A burst of hydrogen peroxide occurred in ectomycorrhizal roots and in non-ectomycorrhizal roots when attacked by R. solani. In ectomycorrhizal roots, hydrogen peroxide production peaked 12?h after R. solani inoculation, which coincided with an increase in the activity of superoxide dismutase and catalase, whereas in non-ectomycorrhizal roots, hydrogen peroxide production peaked 24?h after R. solani inoculation and did not coincide with changes in superoxide dismutase or catalase activity. The imbalanced activities of superoxide dismutase and catalase might cause excessive accumulation of hydrogen peroxide and consequent damage to cell walls. Electron microscopy revealed that there was a positive correlation between hydrogen peroxide levels and the number of amyloplasts, with seedlings inoculated with A. vaginata and/or R. solani showing higher levels. These results indicated that A. vaginata inoculation enhanced damping off resistance and stimulated seedling growth, which may be due to the activation of a burst of hydrogen peroxide and its scavenging enzymes and the production of biochemical substances such as amyloplasts.     

<Emphasis Type="Italic">Cylindrocarpon</Emphasis> species associated with apple tree roots in South Africa and their quantification using real-time PCR

Cylindrocarpon species are known to be a component of the pathogen/pest complex that incites apple replant disease. In South Africa, no information is available on apple associated Cylindrocarpon species and their pathogenicity. Therefore, these aspects were investigated. Among the isolates recovered from apple roots in South Africa, four species (C. destructans, C. liriodendri, C. macrodidymum and C. pauciseptatum) were identified using β-tubulin gene sequencing and phylogenetic analysis. This is the first report of C. liriodendri, C. macrodidymum and C. pauciseptatum on apple trees. Cylindrocarpon macrodidymum was the most prevalent. Isolates within each of the four species were pathogenic towards apple seedlings, but varied in their virulence. With a single exception, all isolates were able to induce lesion development on seedling roots. Only 57% of the isolates, which represented all four species, were able to cause a significant reduction in seedling weight and/or height. The greatest seedling growth reductions were caused by two isolates of C. destructans, and one isolate each of C. liriodendri and C. macrodidymum. A quantitative real-time polymerase chain reaction (qPCR) method was developed for simultaneous detection of all four Cylindrocarpon species. qPCR analyses of Cylindrocarpon from the roots of inoculated seedlings showed that the amount of Cylindrocarpon DNA in roots was not correlated to seedling growth reductions (weight and height) or root rot. The qPCR method is, however, very useful for the rapid identification of apple associated Cylindrocarpon species in roots. The technique may also hold potential for being indicative of Cylindrocarpon disease potential if rhizosphere soil rather than roots are used.     

Molecular and phenotypic characterization revealed six <Emphasis Type="Italic">Colletotrichum</Emphasis> species responsible for anthracnose disease of small cardamom in South India

Small cardamom (Elettaria cardamomum Maton) is extensively cultivated in the Western Ghats of South India either as a monocrop under the forest trees or as an intercrop along with arecanut and coffee plantations. Colletotrichum species responsible for severe outbreaks of anthracnose on small cardamom in South India are reported. Small cardamom anthracnose, popularly known as “Chenthal”, manifests itself on the foliage as yellowish lesions, which later coalesce to form large blighted areas. In advanced stages, the affected leaves dry up giving a burnt appearance to the plant. Twenty-five isolates of Colletotrichum were isolated from leaves of small cardamom in Karnataka, Kerala and Tamil Nadu states of India. The isolates were characterized through morphological studies and multilocus phylogenetic analysis (ITS, ACT, CHS-1, GAPDH, TUB2, CYLH3, GS and ApMat gene regions) to test whether different species are present and identified: C. karstii (2 isolates), C. gloeosporioides (1), C. siamense (7), C. syzygicola (6), Colletotrichum sp (5), and C. guajavae (4), as the cause of anthracnose on small cardamom for the first time. Pathogenicity of the six species was confirmed. To our knowledge, this is the first detailed study of Colletotrichum species which cause anthracnose diseases on small cardamom.