Ferrisia Virgata Research Articles

Host specificity and comparative foraging behaviour of Aenasius vexans and Acerophagus coccois, two endo‐parasitoids of the cassava mealybug

AbstractTwo encyrtid parasitoids, Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) and Acerophagus coccois Smith (Hymenoptera: Encyrtidae), were compared for their degree of dietary specialisation and the impact this has on their foraging strategies. Both parasitoid species are significant for biological control of the cassava mealybug, Phenacoccus herreni, Cox & Williams (Homoptera: Sternorrhyncha) a major Latin American pest of cassava, Manihot esculenta Crantz, an important root crop. Host acceptance and parasitism were analysed in seven mealybug species (with different levels of polyphagy) occurring in and around cassava fields. Results demonstrate that, in this ecosystem, An. vexans is a specialist for P. herreni while Ac. coccois is a generalist on the first and second trophic level. Of the seven mealybug species, P. herreni and P. madeirensis Green were the most acceptable hosts for Ac. coccois, followed by Ferrisia virgata Cockerell. Ac. coccois did not accept the other four mealybug species.The foraging and oviposition behaviour of individual parasitoids was observed in bioassays with cassava leaves infested by P. herreni. The two species used different strategies to locate their host. Aenasius vexans spent significantly more time walking and standing on an infested leaf and examined a host longer than did Ac. coccois. Acerophagus coccois, in contrast, spent more time for oviposition. As a consequence An. vexans parasitised more hosts in a given time than did Ac. coccois. Because the rate of offspring production of the two species did not differ, we conclude that the gregarious Ac. coccois's strategy to deposit several eggs at once might compensate for its relatively low number of ovipostitions, compared with the solitary An. vexans. These findings suggest that, given the advantages and limitations of each species, a multi‐species approach to biological control of P. herreni may yield best results.

Preliminary Test on Insecticidal Effect of Physic Nut (Jatropha curcas Linn.) Extract Against the Eggplant Mealy Bug (Ferrisia virgata)

The toxicity of different concentrations of Jatropha curcas Linn. extracts were evaluated -against the eggplant mealy bug, Ferrisia virgata. One hundred percent (100%) mortality of F. virgata was attained 54 hours after application in all treatments with J. curcas. A mixture of 2 ml extract plus 50 ml distilled water showed significantly highest insect mortality 6, 12, and 18 h after treatment. Changes in color from whitish to yellowish and eventually to dark brown; shrinkage of the body; and straightening of the legs were some of the observable postmortem characteristics of mealy bugs after treatment with the extracts.

Trophic influences on survival, development and reproduction of Hyperaspis notata (Col., Coccinellidae)

AbstractThe coccinellid, Hyperaspis notata Mulsant, is associated with the mealybugs Phenacoccus manihoti Mat.‐Ferr. and P. herreni Williams, on cassava in southern Brazil and the highlands of Colombia. Brought to Africa to help control the accidentally introduced P. manihoti, its range of target prey and plant food sources as well as its performance under conditions of food scarcity were investigated in the laboratory. H. notata showed a moderately narrow food spectrum which should allow survival in periods when P. manihoti is scarce without threatening a broad range of insects species: H. notata survived, completed larval development and reproduced on P. madeirensis (Green) and Ferrisia virgata (Cockerell), which are alternate prey species of the family Pseudococcidae and occur abundantly in cassava fields and on ornamental plants in southern Benin. By contrast, development was not possible on less related taxa of the Sternorrhyncha, namely on Aphis craccivora Koch which occur on cowpea often intercropped with cassava and on the spiralling white fly Aleurodicus dispersus Russel infesting cassava, and many other food crops and ornamental plants. These alternate food sources allowed survival of the larvae and adults for a limited period only and neither moulting nor egg production were observed. Cassava pollen was unsuitable as a food source since it did not allow larvae to develop, females to oviposit, nor did it extend longevity of larvae and adults. Honey prolonged the life span of adults without allowing egg production, and is thus a suitable food substitute for adult H. notata during shipment to release destinations. The coccinellid larvae completed their development to the adult stage when fed from a range of ad libitum supply (consuming up to 6 mg per day) of cassava mealybugs to a minimal daily amount of 1 mg (consuming only ∽0.8 mg per day). Females even laid eggs when fed with a minimal amount of 1.2 mg per couple and day. Larvae of the Colombian strain gained more weight before pupation, and the tolerance of larvae and adults to starving was more marked than in the Brazilian strain.

Arthropods Associated with Bromelia hemisphaerica (Bromeliales: Bromeliaceae) in Morelos, Mexico

A survey was conducted of the arthropod fauna associated with Bromelia hemisphaerica Lamarck (Bromeliaceae) at Yautepec, Morelos, Mexico. In this survey, conducted from January to September 1989, 40.3 percent of the species represented in the collections were predatory, belonging to the orders Araneae, Acarina (Parasitiformes and Acariformes), Hemiptera, Coleoptera and Hymenoptera. Herbivorous species accounted for 16.4 percent of the total species collected. Among these were Ferrisia virgata (Cockerell) and Dysmicoccus brevipes (Cockerell), which might become pests when these plants are cultivated in monoculture.

Population growth patterns forPhenacoccus manihotiMat‐Ferr on cassava in Sierra Leone

Abstract The population growth pattern of the cassava mealybug Phenacoccus manihoti Mat‐Ferr was studied over two population cycles of the pest in Freetown, Sierra Leone. The numbers and rate of dispersal of the insect were higher and the damage it produced more severe in the dry season than in the rainy season. During the rainy season the mealybug population consisted mainly of adults. Even though rain is an important known abiotic natural control factor for the pest the decline in the insect's numbers started before the rainy season. This was attributed to reduction in the carrying capacity of the habitat. The indigenous natural enemies adopted the pest as a food source but did not control its population growth. The other mealybugs observed on the crop, P. madeirensis (Green) and Ferrisia virgata (Cockerell) were economically insignificant.

Contact toxicity of different pesticides to the encyrtid parasitoids,Aenasius advenaandBlepyrus insularisof the striped mealybug,Ferrisia virgata

Abstract The encyrtids Aenasius advena Comp. and Blepyrus insularis (Cam.) are the key parasitoids of the striped mealybug Ferrisia virgata (Ckll.) in many countries. Adult parasitoids were exposed to the guava leaves treated with 13 insecticides and 18 acaricides/fungicides. Diazion (0.05%) was found to be non‐toxic to A. advena and least toxic to B. insularis. The other chemicals such as endosulfan (0.07%), phosalone (0.07%) and dichlorvos (0.20%) showed lesser toxic residual activity while chlorpyriphos (0.05%), carbaryl (0.10%) and fenthion (0.10%) had shown significantly higher residual activity to both the parasitoids. The fungicides, except triademifon, proved harmless to A. advena and B. insularis. It is hoped that the results would help to plan the pest management programme in crops where F. virgata is problematic.

The impact of the predator, Cryptolaemus Montrouzieri Mulsant, on pesticide-resistant populations of the striped mealybug, Ferrisia virgata (Ckll.) on guava in India

The striped mealybug, Ferrista virgata (Ckll.) has become a very serious pest of guava in India. Since the insecticides are ineffective, an attempt was made to suppress F. virgata with an introduced coccinellid, Cryptolaemus montrouzieri Mulsant C. montrouzieri and other local natural enemies especially Aenasius advena Comp. and Scymnus coccivora Ayyar effectively controlled F. virgata in guava orchards.

Effect of substrata and age of Menochilus sexmaculata (Fabr.) (Coleoptera: Coccinellidae) on its oviposition.

Adults of Menochilus sexmaculata (Fabr.) reared on the striped mealybug, Ferrisia virgata (Cockerell) showed no particular preference to different substrata Viz ., jar surface, tissue paper or potato as indicated by the percentage of egg-laying which was 36.51, 36.23 and 29.10, respectively. However, when fed on aphids [ Lipaphis erysimi (Kalt.) and Aphis gossypit Glover] it preferred to lay maximum eggs (71.75%) on cotton twigs. Rearing of M. sexmaculata either on mealybug using tissue paper or aphids with cotton twigs as substrata upto 4th week (Productive age) may be adopted as 73.44-81.47 % eggs with 91.35-100.00 % hatching are obtained In this period. Thereafter, adults may be discarded In order to save laboratory host.

Preliminary Studies on Cryptolaemus montrouzieri Muls. Against the White-Tailed Mealybug Ferrisia virgata (Cockerell) Infesting Tobacco Plants

On an average 2-3 grubs and adults of the cocdnellid predator, Cryptolaemus montrouzieri Muls. per tobacco plant controlled the mealybug, Ferrisia virgata (Cockerell) successfully under glasshouse conditions in a period of a month. The population of vectors viz . aphid, Myzus persicae (Sulz.) and white fly Bemisia tabaci (Gennadius) remained undisturbed on the same plants infested with F. virgata probably due to the host-specific nature of the predator.

The assessment of mealybugs (Pseudococcidae) and other Homoptera on mature cocoa trees in Ghana

AbstractThe numbers of mealybugs and other Homoptera on 96 cocoa trees in Ghana were assessed by examining four branches from each tree. The trees were then felled and examined in detail. Ten species of mealybugs, eight other coccoids, an aphid and a psyllid were recorded. Ninety–five of the trees were infested with mealybugs, 66, 90 and 69 trees, respectively, with Planococcoides njalensis (Laing), Planococcus citri (Risso) and Phenacoccus hargreavesi (Laing). Stictococcus sjostedti Ckll., a species of Gascardia near G. zonata (Newst.) and Mesohomotoma tessmanni (Aulm.) were found on 70, 68 and 48 trees, respectively. The remaining 14 species were found on fewer than 48 trees. All species other than Pseudococcus calceolariae (Mask.) and Ferrisia virgata Ckll.) were most prevalent in the canopy. In the field, mealybug densities recorded on shoots underestimated true levels by an average of 95%. Branches were as effective as whole trees for detecting mealybugs, but less effective for other Homoptera. Branches were suitable sample units for estimating population densities of mealybugs, stictococcids and psyllids. All species of mealybug other than F. virgata infested vegetative buds. An average of 21.7% of buds on the youngest shoots were infested. Samples of buds can be used for detecting mealybug infestations.

Wax produced by dermal pores in three species of mealybug (Homoptera : Pseudococcidae)

The dermal pores and the characteristic forms of wax that they produce are examined in three species of mealybug, Ferrisia virgata, Phenacoccus manihoti and Planococcus citri (Homoptera : Pseudococcidae), and illustrated with scanning electron photomicrographs. The trilocular and quinquelocular pores covering the bodies of most instars produce curled filaments of wax which are also found on the surfaces of droplets of honeydew and ostiole exudate. Their primary function is probably to protect the mealybugs from contamination by their own honeydew and defensive exudates. The paired marginal cerarian setae are secretory and produce long wax rods which support tangled masses of trilocular pore wax. These lateral wax projections may protect the mealybugs from predators and aid in the spacing of individuals within the colony. Tubular ducts and multilocular disc pores respectively produce long hollow and shorter curled filaments which make up the ovisac and the male cocoon. Solid rods of wax produced by an unusual type of tubular duct in F. virgata have associated setae and a campaniform sensillum and probably have a sensory function. Adult males also have pores which produce filamentous wax, but these pores are of a different form from those of the other stages.

The relative abundance of the mealybug vectors (Hemiptera: Coccidae and Pseudococcidae) of Cocoa swollen shoot disease in Ghana

AbstractA census of the mealybug vectors of cocoa swollen shoot disease was made weekly on 238 Amazon cocoa trees at the Cocoa Research Institute, Tafo, Ghana, between 1971 and 1976. The six species encountered were ranked in descending order of abundance: Planococcoides njalensis (Laing), Planococcus citri (Risso), Phenacoccus hargreavesi (Laing), Ferrisia virgata (Ckll), Pseudococcus concavocerarii James, P. calceolariae (Mask.). Planococcoides njalensis occurred at a much higher density on infested trees than other species but was found on fewer trees than either Planococcus citri or Phenacoccus hargreavesi. Over 13-week periods the probability of finding a mealybug on a particular tree was 0·87 for Planococcus citri, 0·77 for Phenacoccus hargreavesi, 0·36 for F. virgata, 0·32 for Pseudococcus concavocerarii, 0·23 for Planococcoides njalensis and 0·05 for Pseudococcus calceolariae. The results suggest that the first four species are more mobile than Planococcoides njalensis and could be more important in the spread of disease than has previously been supposed.

Influence of Nutrition, Propagation Techniques, Light Intensity, and Insecticides on Episcia cupreata1

Abstract Experiments were designed to develop information on commercial production systems for Episcia cupreata (Hook.) Hanst. (flame violet) encompassing nutrition, propagation, light intensity, and insect pest management. A 200–250 ppm N and 150 ppm K solution applied at a rate of 50 ml/10-cm pot per week provided adequate nutritional requirements for these major elements. Propagation techniques involving combinations of rooted or unrooted plantlets 5–13 cm in canopy diameter provided crop turnover rates from 4 to 12 weeks for production in 10-cm pots. Optimum light intensity was established at 17–22 klx. Acephate and oxamyl eliminated mealybugs (Ferrisia virgata) on Episcia plants and were not phytotoxic to the foliage.

Transmission of cocoa viruses by mealybugs (Homoptera: Pseudococcidae)

Several mealybug species reacted positively towards light and high humidity. Planococcoides njalensis (Laing) had a thermopreferendum at 20-25°C. and 25-33° C. was optimum for reproduction with a partial fecundity of 92 nymphs per female. T ½ biol. of 32P in the species was 11.4—15.3 days. Food uptake from virus infected plants was positively related to the infectivity of P. njalensis with cocoa swollen shoot virus isolate 1A. Plant and mealybug radioactivity were positively correlated. Amount of honeydew excreted by the species and the radioactivity of the honeydew were positively correlated. Frequency distribution of 32P in P. njalensis after feeding on 32P-active seedlings or sucrose solution was similar. Radiation effects on infectivity of mealybugs were not detected at 30 µCi/ml of 32P in seedling culture solution. With CSSV 1A and P. njalensis, preliminary fasting increased the rate of settling down to feed, the food uptake and infectivity of mealybugs. Virus was transmitted more often from stems than leaves of source plants. Groups of seedlings of 29—54 days old were almost equally good sources of virus for mealybugs and availability varied more between individual source plants. Mealybugs removed their stylets from source plants in 240 seconds. The length of acquisition access time for maximum transmission was 48—72 hours. Virus was not acquired during short feeds of up to one hour. Virus was acquired from infected seedlings by mealybugs via a parafilm membrane. Acquisition of virus from liquid leaf extract was rare. Virus persisted in mealybugs up to 72—96 hours and loss of infectivity was exponential with a T 1/2 of 12—13 hours. Virus persisted in the mealybugs through postacquisition moulting. Mealybugs vere seemingly more efficient vectors after postacquisition feeding than fasting, Latent period of virus in the test plants was short and over 98 % of the test plants showed virus symptoms in three months. With different numbers of mealybugs on test plants during the inoculation feed, the infection rate was as expected. The use of mealybugs while testing virus resistant and tolerant cocoa is demonstrated. Location of feeding mealybugs on test beans did not influence the infection rate. Virus transmission by mealybugs was not affected by light or darkness. The food uptake was highest and virus was transmitted most often in 29—36°C. The transmission of CSSV isolate 1M or cocoa mottle leaf virus isolate 1C with P. njalensis as the vector, or CSSV 1A with Ferrisia virgata (Cockerell) was similar to that of CSSV 1A with P. njalensis as the vector. A formula is given to describe the increase of infectivity in mealybugs during acquisition feed.

Studies on Nephus regularis (Coleoptera: Coccinellidae) as a Predator of the Striped Mealybug in Madhya Pradesh (India)1

Observations on the life history of Nephus regularis Sicard, a predator on the striped mealybug, Ferrisia virgata (Cockerell), (Homoptera: Pseudococcidae) arc given and include data on the duration of developmental stages, mating behavior, longevity, role in the natural control of the host mealybug, seasonal activity, and distribution in India.

Calonectria rigidiuscula . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Calonectria rigidiuscula [Nectria rigidiuscula] . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Theobroma cacao and many other hosts represented by the following families: Anonaceae, Anacardiaceae, Apocynaceae, Bombacaceae, Euphorbiaceae, Gramineae, Leguminosae, Malvaceae, Meliaceae, Moraceae, Sterculiaceae, Tiliaceae . Also pathogenic on wound inoculation to hosts in the above and following additional families: Bignoniaceae and Ulmaceae (31: 232). DISEASES: Causing die-back and canker of branches associated with capsid injury, 'green-point' cushion gall of buds, and pod rot of cacao; panel decay of Hevea rubber associated with Pbytophthora spp. ; stem canker of robusta coffee associated with Xyleborus morstatta ; stem rot of durian; and blight of rice plants including grain. GEOGRAPHICAL DISTRIBUTION: Africa (Cameroons, Central African Republic, Congo, Ghana, Ivory Coast, Madagascar, Nigeria, Sierra Leone); North America [United States (Okla.)]; Central America and West Indies (British Guiana, Costa Rica, Grenada, Guatemala, Honduras, Panama, Trinidad); South America (Argentina, Colombia, Surinam, Venezuela); Asia (Ceylon, India, Indo-China, Java, Malaya, Philippines); Australasia & Oceania (New Caledonia, North Borneo, Tahiti). TRANSMISSION: By air-borne spores, either microconidia produced on recently infected tissue of injured, living stems, or macroconidia from sporodochia on recently dead stems, or ascospores from perithecia produced on long dead stems or cracks in bark (25: 548). The pathogen has been transmitted to cacao cotyledons by means of mealybugs ( Pseudococcus njalensis [Planococcoides njalensis] and Ferrisiana virgata [Ferrisia virgata] ) in the laboratory, but not elsewhere. Also a soil invader commonly recovered from previous sites of cacao (13: 128, 594) or coffee plantations (34: 179), and in grassland areas (33: 687); seed-borne on rice (32: 449).

VIRUS DISEASES OF CACAO IN WEST AFRICA

Thirteen species in the Coccoidea were tested as vectors of seventeen cacao viruses or virus strains; in addition to the vectors previously recorded, the following species transmitted some of the viruses: Paraputo ritchiei Laing, Phenacocctis sp. H 6418 (? sp.nov.) Pseudococcusbukobensis Laing, Ps. brevipes (Ckll.), Pseudococcus sp. near celt is Strickland, Pseudococcus sp. near gahani Green, Ps. longispinus T.‐T. and Pseudo‐coccus sp. near masakensis James. The viruses transmitted by Ps. longispinus were not usually transmitted by Ferrisia virgata (Ckll.), but there was no other virus‐vector specificity.

Insect Transmission of Cacao Virus Disease in Trinidad

Insect Transmission of Cacao Virus Disease in Trinidad