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M Tertuliano - One of the best experts on this subject based on the ideXlab platform.
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seasonal changes in secondary compounds in the phloem sap of cassava in relation to plant genotype and infestation by Phenacoccus manihoti homoptera pseudococcidae
Bulletin of Entomological Research, 1994Co-Authors: Paulandre Calatayud, M TertulianoAbstract:A previous study on the population dynamics of the cassava mealybug, Phenacoccus manihoti (Matile-Ferrero), on cassava has shown that populations increase during the dry season. The aim of the present studies was to determine whether these important changes in the pest population observed throughout the seasons in the field in the Congo, could be correlated with seasonal variations in the level of secondary compounds in the phloem, implicated in cassava plant resistance to P. manihoti. Our results showed that cassava was in drought stress conditions during the dry season (foliar area decreased). The combination of infestation and dry stress factors was clearly visible during the dry season. In fact, the decrease in leaf water potential together with infestation by P. manihoti was clearly observed at the end of the rainy season and during the dry season. The levels of the secondary compounds, rutin (an unfavourable substance to P. manihoti) decreased in the less resistant genotype, and cyanide (a phagostimulant substance) increased in each genotype in the dry season. These results may partially explain the important population changes in P. manihoti during the seasons.
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influence of secondary compounds in the phloem sap of cassava on expression of antibiosis towards the mealybug Phenacoccus manihoti
Entomologia Experimentalis Et Applicata, 1994Co-Authors: Paulandre Calatayud, Yvan Rahbe, Bernard Delobel, F Khuonghuu, M TertulianoAbstract:Identification and assay of cyanogenic and phenolic compounds in phloem sap of cassava (Manihot esculenta Crantz, Euphorbiaceae) and in honeydew of the cassava mealybug Phenacoccus manihoti Matt. Ferr. (Homoptera, Pseudococcidae) were realised. Cyanogenic glucosides and three flavonoid glycosides (rutin, kaempferol glycoside-1 and kaempferol glycoside2) were found to be translocated in cassava phloem sap and consumed by the mealybug. Differences in profiles of secondary compounds of phloem sap and honeydew samples, characterised mainly by the appearance of free cyanide and of a free flavonoid, suggest the metabolic processing of at least some of the ingested compounds. The relationship between foliar concentrations of these different compounds and expression of the antibiotic resistance of cassava towards €? manihoti was also investigated in 7 varieties of cassava and in the 'faux-caoutchouc' hybrid. Infestation by mealybug was followed by a clear increase in levels of both rutin and kaempferol glycoside2, while no modification in cyanide contents was noted. The best rank correlation between antibiotic resistance (measured by the intrinsic rate of increase r,) and secondary compounds analyzed is observed with rutin contents of infested plants (p=-0.73; p=0.05). The possible implication of this compound in the biochemical mechanisms accompanying cassava defence reaction to mealybug attack is discussed.
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antixenotic and antibiotic components of resistance to the cassava mealybug Phenacoccus manihoti homoptera pseudococcidae in various host plants
International Journal of Tropical Insect Science, 1993Co-Authors: M Tertuliano, S DossougbeteAbstract:Antixenotic and antibiotic components of resistance to the cassava mealybug, Phenacoccus manihoti Matt. Ferr, were evaluated in different varieties of cassava (Manihot esculenta Crantz), in Poinsettia (Euphorbia pulcherrima Wild), Talinum (Talinum triangulare Jack) and Fauxcaoutchouc (hybrid of M. esculenta and M. glaziovii Mull. Arg.). Resistance, was estimated in the field on 25 varieties of cassava by means of varietal screening. Although we were unable to identify varieties of cassava totally resistant to P. manihoti, there was evidence of partial resistances. Thus the Incoza variety is the most resistant, followed by the Moudouma and Zanaga varieties. On the other hand we found very susceptible varieties, such as Dikonda, Kataoli, 3M8 and 1M20. Laboratory evaluations of the antibiotic component of resistance, made by estimating the intrinsic capacity for increase rc, showed that the host-plants have a considerable effect on the multiplying capacity of the mealybug. Indeed rc ranges from 0.038 (Poinsettia) to 0.160 (Ganfo cassava variety), i.e. a ratio of 1 to 4 between the two extreme values. If the cassava varieties alone are considered, the percentage of maximum variation is 20% between the Incoza (rc = 0.133) and Ganfo (rc = 0.160) varieties. The Incoza cassava variety is the most resistant, in terms of both antixenosis and antibiosis. Classification of the other cassava varieties, from the most to the least resistant, differs according to the resistant component under consideration. Poinsettia and Talinum both have a very strong antixenotic component, but their antibiotic component differs (rc = 0.038 and 0.150 respectively). Our results suggest that the resistance mechanisms of the host-plants of P. manihoti intervening in the fixation of the pest (antixenosis), are different from those acting on the development of the mealybug (antibiosis). We established significant correlations between the size of the mealybugs and their demographic characteristics for all the plants studied: the duration of the prereproductive period is shorter and the net reproduction rate is higher when the mealybugs are large-sized. These results are discussed in the context of an integrated monitoring programme.
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tolerance of different host plants to the cassava mealybug Phenacoccus manihoti matile ferrero homoptera pseudococcidae
International Journal of Pest Management, 1993Co-Authors: M TertulianoAbstract:Abstract The tolerance of seven varieties of cassava (Manihot esculenta Crantz), Poinsettia (Euphorbia pulcherrima Wild.), Talinum (Talinum triangulare Jacq.) and Faux‐caoutchouc (a hybrid of M. esculenta and M. glaziovii Mull. Arg.) to the cassava mealybug Phenacoccus manihoti Matt. Ferr., was measured in the laboratory, by quantifying morphological and physiological changes in the growth of plants infested with P. manihoti. A 2‐month infestation by 100 mealybugs decreased the total leaf area and the leaf area ratio F but did not modify total dry weight, relative growth rate R or net assimilation rate E of plants studied. The decrease in leaf area was extremely variable and depended on plant species and variety. The effect of infestation on dry weight of different plant organs was not homogeneous, suggesting that translocation of nutrients made during photosynthesis was modified. In cassava the decrease in leaf area, without significant change in leaf dry weight, appeared to be due to physiological chang...
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interaction entre la cochenille du manioc Phenacoccus manihoti et ses differentes plantes hotes etude de la teneur de la seve en acide amine et en sucre
Entomologia Experimentalis Et Applicata, 1992Co-Authors: M TertulianoAbstract:Resume L'analyse (acides amines et sucres) d'extrait de feuille, de 5 varietes de manioc (Manihot esculenta), du Faux caoutchouc (Hybride de M. esculenta × M. glaziovii), du Poinsettia (Euphorbia pulcherrina) et du Talinum (Talinum triangularae), caracterises par differents degres de resistance par antibiose a la cochenille du manioc (Phenacoccus manihoti (Mat. Ferr.)) (Homoptera: Pseudococcidae), a ete realisee sur des extraits obtenus par centrifugation du materiel foliaire. Les teneurs en acides amines, tres differentes d'une plante a l'autre, apparaissent aussi importantes entre les varietes de l'espece manioc qu'entre les differentes especes vegetales avec respectivement un rapport de variation de 4, 5 et 5, 5. De měme, les teneurs en sucres (exprimees en equivalent saccharose), sont tres differentes d'une plante a l'autre avec un rapport de variation de 1 a 33 entre les deux extrěmes, si l'on ne considere que l'espece M. esculenta, il n'est plus que de 3, 5. Des differences dans les proportions relatives des acides amines libres d'extrait de feuille sont observees aussi bien entre les varietes de manioc qu'entre les especes vegetales. Cependant pour toutes les plantes etudiees l'acide glutamique, la glutamine, l'ethanolamine, et l'alanine representent pres de 50% des acides amines de l'extrait de feuille; l'acide aspartique, l'asparagine et la serine pres de 20% tandis que la tyrosine, la methionine, l'isoleucine, la leucine et la lysine sont presents en tres faibles pourcentages. Le degre de resistance a la cochenille du manioc des differentes plantes-hotes n'a pu ětre relie, ni a la teneur de leur extrait de feuille en acides amines et en sucres, ni a leur composition relative en acides amines. Il n'a pu ětre non plus relie au rapport Sucres/Acides aminees. Nos resultats suggerent que des caracteristiques biochimiques autres que celles etudiees dans ce travail interviennent dans les mecanismes de resistance vis-a-vis de la cochenille du manioc.
R. Souissi - One of the best experts on this subject based on the ideXlab platform.
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influence of the host plant of the cassava mealybug Phenacoccus manihoti hemiptera pseudococcidae on biological characteristics of its parasitoid apoanagyrus lopezi hymenoptera encyrtidae
Bulletin of Entomological Research, 1998Co-Authors: R. SouissiAbstract:The influence of the host plant of the cassava mealybug, Phenacoccus manihoti Matile Ferrero on the encyrtid parasitoid Apoanagyrus lopezi De Santis was studied in the laboratory. Four different host plants were used: two cultivars of cassava, Manihot esculenta (Euphorbiaceae), cv. Incoza and cv. MM79; Faux caoutchouc, a hybrid of M. esculenta × M glaziovii; and talinum Talinum triangularae (Portulacaceae), a common weed in cassava fields. Plants were selected for different levels of antibiotic resistance to P. manihoti. Mealybug mortality due to host feeding by the adult parasitoid and the percentage of mealybugs parasitized were significantly lower when mealybugs were reared on the Manihot cultivars and hybrid than when reared on talinum. However, the encapsulation rate was significantly lower in P. manihoti reared on talinum. The highest percentage parasitism and the lowest rate of emergence were recorded on cv. Incoza, the most resistant Manihot cultivar. The sex ratio did not vary significantly with the host plant used. The total developmental time and size of male and female progeny of A. lopezi differed significantly between P. manihoti reared on different host plants. Among Manihot plants, parasitoid size was positively correlated with development time and negatively with plant resistance. Results suggest that the parasitoid, A. lopezi, might perform better if cassava cultivars were selected for their strong antixenosis but low antibiotic characteristics.
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tritrophic interactions between host plants the cassava mealybug Phenacoccus manihoti matile ferrero horn pseudococcidae and its parasitoid apoanagyrus lopezi de santis hym encyrtidae
Journal of Applied Entomology, 1998Co-Authors: R. Souissi, J P NenonAbstract:: The influence of the host plant on the parsitism of third instar Phenacoccus manihoti Matile-Ferrero by Apoanagyrus (Epidinocarsis) lopezi De Santis, was investigated under laboratory conditions. Four different host plants were used: two cassava varieties (Incoza and Zanaga, Manihot esculenta Crantz, Euphorbiaceae), the Faux caoutchouc (FC) (a hybrid of M. esculenta and Manihot glaziovii, Euphorbiaceae) and Talinum (Talinum triangularae Jack., Portulacaceae). The percentage of parasitism of P. manihoti by A. lopezi varied significantly between host plants and was 1.5 to 1.8 higher on Talinum than on the plants of the Manihot genus. The parasitism on Incoza did not differ from the one on Zanaga but was significantly higher than that on FC. The percentage of mummified hosts also differed among the four plants and was lower on FC (80.5%) than on the others. A significantly lower percentage of emerged parasitoids (69.5%) was recorded with the Incoza variety, which was the most resistant cassava plant. The total mealybug mortality due to parasitoid activity was significantly higher on Talinum than on the others. The results for the Manihot plants suggest that the probability of achieving successful augmentative biological control will be greater on the plants of the M. esculenta species despite lower A. lopezi survival on Incoza due to its high level of antibiosis resistance. Talinum would be a better host plant for a mass rearing of the host and the parasitoid in the laboratory.
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Comparative life table statistics of Apoanagyrus lopezi reared on the cassava mealybug Phenacoccus manihoti fed on four host plants
Entomologia Experimentalis et Applicata, 1997Co-Authors: R. SouissiAbstract:The demographic statistics of Apoanagyrus lopezi De Santis (Hymenoptera: Encyrtidae) were studied in the laboratory on its host, the cassava mealybug Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae), reared on four host plants characterized by different levels of antibiotic resistance to the mealybug: two cassava varieties, Incoza and Zanaga (Manihot esculenta Crantz: Euphorbiaceae), the faux-caoutchouc (hybrid of M. esculenta × M. glaziovii Muel. Arg.) and Talinum (Talinum triangulare Jack:Portulacaceae). Total and daily mean fecundities of female parasitoids were strongly influenced by the host plant but there was no link with antibiotic resistance. The mean duration of the oviposition period was also significantly modified by the host plant and was again not correlated to the level of antibiotic resistance. Net reproduction rates of female parasitoids were nearly 2 times higher on hosts fed on Zanaga and Talinum than on Incoza and Faux-caoutchouc, and were not related to the total fecundities. The generation time was significantly longer on Faux-caoutchouc than on the other three plants. The intrinsic rate of increase varied significantly with host plants and was higher on Talinum and Zanaga than on Incoza and Faux-caoutchouc. With the varieties of cassava, Incoza and Zanaga, it was observed that antibiosis had a significant negative effect on the survival of A. lopezi, which would influence the effectiveness of the parasitoid.
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effect of host plants on fecundity and development of apoanagyrus lopezi an endoparasitoid of the cassava mealybug Phenacoccus manihoti
Entomologia Experimentalis Et Applicata, 1997Co-Authors: R. SouissiAbstract:Apoanagyrus (Epidinocarsis) lopezi (De Santis) (Hymenoptera: Encyrtidae) is a solitary parasitoid indigenous to South America, that was introduced to subsaharan Africa in 1981 as a biological control agent against the cassava mealybug Phenacoccus manihoti Matile-Ferrero (Hemiptera; Pseudococcidae), a pest of cassava, Manihot esculenta Crantz, (Euphorbiaceae). These cassava-mealybug and mealybug-parasitoid systems have been studied extensively, both in the laboratory and under field conditions (Fabres, 1981; Lohr et al., 1988; Le Ru & Tertuliano, 1993). Laboratory evaluations of cassava antibiosis resistance,made by estimating the intrinsic capacity for increase rc, showed that the host plant has an important effect on the multiplying capacity of the mealybug (Tertuliano et al., 1993). Data are still lacking on tritrophic aspects of cassava mealybugs and there is no information on interactions between resistant cassava cultivars and A. lopezi. We conducted laboratory experiments to investigate the influence of four host plants previously characterized by different resistance levels of antibiosis to P. manihoti on the oviposition pattern, longevity, fecundity, survival and development time of A. lopezi. These are five important qualities of a parasitoid that influence its efficiency.
Aunu Rauf - One of the best experts on this subject based on the ideXlab platform.
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influence of host stage on oviposition development and sex ratio of anagyrus lopezi de santis hymenoptera encyrtidae a parasitoid of the cassava mealybug Phenacoccus manihoti matile ferrero 1 hemiptera pseudococcidae
Jurnal Hama dan Penyakit Tumbuhan Tropika, 2020Co-Authors: Evie Adriani, Aunu Rauf, Pudjianto PudjiantoAbstract:Influence of host stage on oviposition, development, and sex ratio of Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae),a parasitoid of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). The parasitoidAnagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced from Thailand into Indonesia in early 2014 to controlthe invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). Because of the need toproduce large numbers of high-quality females, research was conducted in the laboratory to determine host stage preferencefor A. lopezi on different instars of P. manihoti. Individual female wasps were exposed to first, second, third instar nymphs,and pre-reproductive adult mealybugs. In the no-choice test, the frequency of parasitized hosts and the number of eggs laidper host was significantly higher in second and third instar nymphs as well as adult mealybugs compared to first instarnymphs. In the two-choice test, third instars nymphs and adult mealybugs were the most preferred host for oviposition.Immature development of parasitoids was faster and the ratio of female to male parasitoids was higher following ovipositionin second and third instar nymphs and pre-reproductive adult hosts, compared to the first instar nymphs. Our findingsindicate that the use of pre-reproductive adults as hosts in a mass-rearing program would be the most productive and fastestway to produce A. lopezi populations with a female-biased sex ratio. Field release of parasitoids should be conducted whenthe host’s third instar nymph is the most abundant because the period during which preferred and suitable host stages areavailable would be the longest.
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geographic distribution of the invasive mealybug Phenacoccus manihoti and its introduced parasitoid anagyrus lopezi in parts of indonesia
Biodiversitas, 2019Co-Authors: Muhammad Zainal Fanani, Aunu Rauf, Nina Maryana, Ali Nurmansyah, Dadan HindayanaAbstract:Abstract. Fanani Z. M., Rauf A, Maryana N, Nurmansyah A, Hindayana D. 2019. Geographic distribution of the invasive mealybug Phenacoccus manihoti and its introduced parasitoid Anagyrus lopezi in parts of Indonesia. Biodiversitas 20: 3751-3757. Cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is an invasive pest detected for the first time in Indonesia in 2010. An exotic parasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced and released in 2014 to control the pest. Study was conducted with the objective to determine the geographic distribution of P. manihoti and spread of A. lopezi. Field surveys were conducted on cassava fields in various locations in Lampung, Java, and Nusa Tenggara. Our studies showed that P. manihoti was found to be widely distributed in Lampung, Banten, West Java, Central Java, East Java, West Nusa Tenggara and East Nusa Tenggara. In each location visited, symptoms of P. manihoti infestation as indicated by internode distortion and bunchy top were prominent. Three years following release, parasitoid A. lopezi has established and spread into several cassava growing areas, except East Nusa Tenggara. Parasitism rates varied from 1.50% in West Nusa Tenggara up to 59.18% in East Java. Logistic regression revealed that probability of severe damage by the cassava mealybug was significantly (P<0.05) increased with the increasing abundance of ants.
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genetic variation among the geographic population of cassava mealybug Phenacoccus manihoti hemiptera pseudococcidae in indonesia inferred from mitochondrial coi gene sequence
Biodiversitas, 2019Co-Authors: Nopriawansyah Nopriawansyah, Aunu Rauf, Ali Nurmansyah, Yayi Munara Kusumah, Yonny KoesmaryonoAbstract:Abstract. Nopriawansyah N, Rauf A, Kusumah YM, Nurmansyah A, Koesmaryono Y. 2019. Genetic variation among the geographic population of Cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) in Indonesia inferred from mitochondrial COI gene sequence. Biodiversitas 20: 2685-2692. Cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae) is an invasive pest native to South America. Research was conducted with the objective to study genetic variation of cassava mealybug from different geographic areas in Indonesia. Thirty-six samples of cassava mealybugs were collected from eight different population locations. Genomic DNA was extracted from individual specimens of P. manihoti using gSYNC DNA Extraction Kit from Geneaid Lot No. FB221707. PCR amplification using primary CO1 gene showed the target position as long as 518 bp. Analysis of homology from eight populations revealed eight haplotypes in Indonesia with different variable sites. Genetic distance analysis was done by calculating base pair differences in each population. The percentage of genetic distance between populations was 0.0000% -0.00409%. The results of the analyst using the Kimura-2 parameter showed that the population was divided into 2 clusters. The highest haplotype (Hd) diversity value was 0.8333, while the lowest was zero (Hd = 0). The highest nucleotide diversity (?) was 0.00225 and the lowest was 0.000000. The genetic distance and nucleotide diversity were low because P. manihoti was thelytoky parthenogenesis.
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kutu putih singkong Phenacoccus manihoti matile ferrero hemiptera pseudococcidae persebaran geografi di pulau jawa dan rintisan pengendalian hayati
JURNAL HAMA DAN PENYAKIT TUMBUHAN TROPIKA, 2017Co-Authors: Budi Abduchalek, Aunu RaufAbstract:Cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae): Geographic distribution in Java and initiation of biological control. Cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Psedococcidae), is a recently introduced pest in Indonesia. Parasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was imported to control the pest. Studies were conducted to determine geographic distribution of P. manihoti throughout Java, and to evaluate the potential of the parasitoid as a biological control agent. Geographic distribution of the pest was determined through field survey, whereas evaluation of the parasitoid was studied through cage experiment and field release. Our survey revealed that the cassava mealybug has spread throughout Java. Heavy infestations caused shortened and distorted stems, complete defoliation, and stunted growth. In cages containing only mealybugs, all cassava plants (100%) died after two months. Whereas in cages containing both mealybugs and three pairs of parasitoid, rate of parasitization was 25% and plant mortality 20%. Parasitoids released in the field were able to survive, reproduce, and establish under Bogor climatic condition. These might indicate that parasitoid A. lopezi is a potential natural enemy to be used in biological control program of the cassava mealybug.
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Laju enkapsulasi parasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) oleh kutu putih singkong Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae)
Perhimpunan Entomologi Indonesia, 2017Co-Authors: Evie Adriani, Aunu Rauf, Pudjianto PudjiantoAbstract:Parasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced into Indonesia in early 2014 to control the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). The objective of study was to determine encapsulation rate of parasitoid A. lopezi by various host instars of P. manihoti. Observation of encapsulation rate was made by exposing a single mated female of parasitoid on mealybug nymph-1, -2, -3, and adult in a plastic cage for 24 h. Mealybugs then were dissected and number of parasitoid eggs laid and those encapsulated were counted. Study revealed that rate of aggregate encapsulation was highest (8.4%) by adults, followed by nymph-3 (5.8%), nymph-2 (3.1%), and nymph-1 (1.1%). Rate of effective encapsulation by adults was 2.0%, whereas by nymphs about 1.0%. The low rate of encapsulation is believed not to reduce the effectiveness of parasitoid A. lopezi in the biological control of cassava mealybug P. manihoti in Indonesia.
Neuenschwander P. - One of the best experts on this subject based on the ideXlab platform.
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Biological control of the cassava mealybug, Phenacoccus manihoti (Hom., Pseudococcidae), by Epidinocarsis lopezi (Hym., Encyrtidae) in Malawi
'Informa UK Limited', 2019Co-Authors: Neuenschwander P., Borowka R., Phiri G., Hammans H., Nyirenda S., Kapeya E.h., Gadabu A.Abstract:From 1985 to 1989 five large scale surveys were made to document the spread of the cassava mealybug (CM) Phenacoccus manihoti Matile‐Ferrero (Hom., Pseudococcidae) and the releases and successful establishment of its exotic parasitoid Epidinocarsis lopezi (De Santis) (Hym., Encyrtidae) through most cassava‐growing areas of Malawi. In a multiple regression analysis involving 29 meteorological, agronomic and plant variables from 476 fields, the duration of E. lopezi's presence was the major factor influencing CM population densities. In the first year the CM was recorded in a particular place, 25% of all tips had more than 100 CM. Wherever E. lopezi had been present for two years or more, CM populations were reduced on average seven times and tips infested with more than 100 CM became rare (1%). In parallel, damage on cassava tips stabilized at a low level. Similarly, along Lake Malawi, 84.9% of all tips had more than 10 CM in 1986; this value stabilized at 3.3%‐4.0% in 1988–1989. Indigenous coccinellids were often abundant in the first year of the CM infestation, but their populations collapsed later, while the frequency of fields with E. lopezi increased. In 1987, farmers abandoned 28.4% of all fields where E. lopezi was just introduced as compared with 2.7% where the parasitoid had been present for two years or more. Overall, satisfactory control was achieved by E. lopezi in all but a few fields concentrated on extremely poor soils characterized by sand dune vegetation. The socioeconomic implications of this ongoing and apparently successful biological control program are discussed
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Impact assessment of the biological control of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), by the introduced parasitoid Epidinocarsis lopezi (De Santis) (Hymenoptera: Encyrtidae)
2017Co-Authors: Neuenschwander P., Hammond W. N. O., Gutierrez A. P., Cudjoe A. R., Adjakloe R., Baumgärtner J. U., Regev U.Abstract:The impact of Phenacoccus manihoti Matile-Ferrero on growth and tuber yield of cassava, and the results of its biological control by the exotic parasitoid Epidinocarsis lopezi (De Santis) were investigated in a survey of 60 farmers' fields in Ghana and Ivory Coast over an area of 180 000 km2 of the savana and forest ecosystems. Twenty-nine variables associated with plant growth, agronomic and environmental factors, and insect populations were recorded. Densities of P. manihoti were closely correlated with stunting of the cassava shoot tips and, less so, with the rate of stunting early in the growing season. With increasing mealybug infestations, average harvest indices declined and populations of E. lopezi and of indigenous coccinellids increased, but parasitoids were found at lower host levels than were predators. The length of time E. lopezi had been present in an area was the most important factor influencing mealybug densities. Thus, P. manihoti populations were significantly lower where E. lopezi had been present for more than half the planting season than in areas where E. lopezi was lacking or had been only recently introduced. A significant proportion of the farmers in the savanna zone, where P. manihoti populations were much higher than in the forest zone, had observed this decline due to E. lopezi. Tuber yield losses due to P. manihoti in the absence of E. lopezi were tentatively estimated at 463 g/plant in the savanna zone. No significant effect was found in the forest region. When E. lopezi was present, average P. manihoti damage scores were reduced significantly, both in the savanna and forest regions. The increase in yields was 228g/plant or about 2.48 t/ha in the savanna regio
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Measuring host finding capacity and arrestment of natural enemies of the cassava mealbug, Phenacoccus manihoti, in the field
1995Co-Authors: Neuenschwander P., Ajuonu O.Abstract:In uninfested fields, 80 cassava tips were artificially infested with 0, 1, 2, 4, 8, 16, 32, or 64 third instars, and 20 or 100 eggs of cassava mealybug, Phenacoccus manihoti Matile‐Ferrero (Hom., Pseudococcidae). Another 80 uninfested tips served as a control. Tips were arranged in a circle of 28 m diameter, in the centre of which the following exotic natural enemies of P. manihoti were released: Apoanagyrus (Epidinocarsis) lopezi De Santis and A. diversicornis (Howard) (Hym., Encyrtidae), Hyperaspis notata (Mulsant) and Diomus hennesseyi Fürsch (Col., Coccinellidae), and others. This experiment was repeated six times. During the 4–14 days following release, all experimental tips were inspected at two‐hour intervals during each day and the presence of exotic as well as indigenous natural enemies, like Exochomus troberti Mulsant (Col., Coccinellidae), ants and spiders was noted. The experiment was repeated six times measured the aggregative response by the natural enemies to different host densities, achieved through host attractance and arrestment. All exotic natural enemies, except the males of Apoanagyrus spp., were fast attracted to the host colonies. As compared to the control tips, they concentrated on the infested tips about 50‐fold for the two Apoanagyrus spp. and 10 to 20‐fold for the exotic coccinellids. By contrast, non‐coevolved indigenous coccinellids, as well as generalist predators like ants and spiders were attracted to the infested tips only 2 to 5‐fold. A. lopezi responded best to different host densities, followed by A. diversicornis and the coccinellids, followed by ants and spiders. None of the parasitoids or predators was particularly attracted to egg masses. These results correspond closely to the known efficiencies of these natural enemies, A. lopezi standing out among all candidates. The results of such aggregation studies are compared with those of life‐table studies.Peer Revie
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Biological control of the cassava mealybug, Phenacoccus manihoti (Homoptera: Pseudococcidae), in Zambia
1994Co-Authors: Chakupurakal J., Markham R.h., Neuenschwander P., Sakala M., Malambo C., Mulwanda D., Banda E., Chalabesa A., Bird T., Haug T.m.Abstract:Surveys were carried out in Zambia twice yearly from 1986 to 1990, to assess the impact of a biological control campaign against the cassava mealybug (CM), Phenacoccus manihoti Mat.-Ferr., throughout the infested area. From 1984 onward, the exotic parasitoid Epidinocarsis lopezi (De Santis) (Hym., Encyrtidae) and some exotic coccinellid predators were released on 54 occasions along the spreading front of CM infestation. E. lopezi established in every release site, spread, and covered the entire infested area, but the exotic coccinellids did not establish. Between 1986 and 1990, CM populations declined on average 5.8 times. In a multiple regression analysis involving meteorological, agronomic, plant, and entomological variables, from a total of 4804 cassava fields, nine variables had a significant influence on the CM population density, which in turn was the main factor influencing tip damage scores. The duration of E. lopezi′s presence in an area was the most important factor: in the year the CM was recorded for the first time in a particular district, more than 20% of all cassava fields had an average of 10 or more CM/tip (a few having as many as 1000). This percentage was gradually reduced to 0% in Year 5. The condition of the plant, its age, rainfall, and water retention capacity of the soil were also important. Where CM populations were lower, damage by the cassava green mite, Mononychellus tanajoa (Bondar) (Acari, Tetranychidae), appeared more severe. The frequency of ants increased with the CM population density. In conclusion, biological control of the CM in Zambia was successful.Peer Revie
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Interference by ants in biological control of the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) in Ghana
1993Co-Authors: Cudjoe A., Neuenschwander P., Copland M.Abstract:In surveys of cassava fields in the coastal savanna and rain forest zones of Ghana, eight species of ants, mostly in the genera Camponotus, Crematogaster and Pheidole (Hymenoptera: Formicidae), were found attending cassava mealybug, Phenacoccus manihoti Matile-Ferrero. Ant densities were much higher in the rain forest than in the savanna and, in most zones, positively correlated to mealybug population densities. Pheidole megacephala (Fabricius) was the only species more abundant in the interior of fields, whereas the other species preferred the edges of fields or, like Camponotus spp., did not respond to edge effects. Weediness of the fields did not clearly influence the presence of ants. Crematogaster sp. and P. megacephala spent most of the time on cassava tips, where they built carton tents. Ants of the three genera reduced parasitism rates by the exotic Epidinocarsis lopezi (De Santis) (Hymenoptera: Encyrtidae) to half, compared to the rates observed on mealybug colonies of equal size that were not attended. Hyperparasitism by Prochiloneurus insolitus (Alam) (Hymenoptera: Encyrtidae) and Chartocerus hyalipennis Hayat (Hymenoptera: Signiphoridae) and predation by the indigenous Exochomus troberti Mulsant (Coleoptera: Coccinellidae) were similarly reduced. Where ants were excluded experimentally by insectcide barriers, parasitism was 32%, compared to only 10% in the control, and predator densities were reduced three-fold. In a 24 h experiment, Pheidole megacephala was observed to remove about half the E. troberti larvae; Crematogaster sp. and Camponotus spp. were less efficient. The results show the locally strong interference of ants with biological control of the cassava mealybug. Despite this interference, mealybug populations in the rain forest were judged to be below damaging levels.Peer Revie
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Interference by ants in biological control of the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) in Ghana.
Bulletin of Entomological Research, 1993Co-Authors: A. R. Cudjoe, Peter Neuenschwander, Michael J.w. CoplandAbstract:AbstractIn surveys of cassava fields in the coastal savanna and rain forest zones of Ghana, eight species of ants, mostly in the genera Camponotus, Crematogaster and Pheidole (Hymenoptera: Formicidae), were found attending cassava mealybug, Phenacoccus manihoti Matile-Ferrero. Ant densities were much higher in the rain forest than in the savanna and, in most zones, positively correlated to mealybug population densities. Pheidole megacephala (Fabricius) was the only species more abundant in the interior of fields, whereas the other species preferred the edges of fields or, like Camponotus spp., did not respond to edge effects. Weediness of the fields did not clearly influence the presence of ants. Crematogaster sp. and P. megacephala spent most of the time on cassava tips, where they built carton tents. Ants of the three genera reduced parasitism rates by the exotic Epidinocarsis lopezi (De Santis) (Hymenoptera: Encyrtidae) to half, compared to the rates observed on mealybug colonies of equal size that were not attended. Hyperparasitism by Prochiloneurus insolitus (Alam) (Hymenoptera: Encyrtidae) and Chartocerus hyalipennis Hayat (Hymenoptera: Signiphoridae) and predation by the indigenous Exochomus troberti Mulsant (Coleoptera: Coccinellidae) were similarly reduced. Where ants were excluded experimentally by insectcide barriers, parasitism was 32%, compared to only 10% in the control, and predator densities were reduced three-fold. In a 24 h experiment, Pheidole megacephala was observed to remove about half the E. troberti larvae; Crematogaster sp. and Camponotus spp. were less efficient. The results show the locally strong interference of ants with biological control of the cassava mealybug. Despite this interference, mealybug populations in the rain forest were judged to be below damaging levels.
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Experimental determination of the efficiency of indigenous and exotic natural enemies of the cassava mealybug, Phenacoccus manihoti Mat.-Ferr. (Hom., Pseudococcidae), in Ghana
Journal of Applied Entomology, 1992Co-Authors: A. R. Cudjoe, Peter Neuenschwander, Michael J.w. CoplandAbstract:Abstract The efficiency of natural enemies, especially the exotic parasitoid Epidinocarsis lopezi (De Santis) and the indigenous predator Exochomus troberti Mulsant, in reducing populations of the cassava mealybug (CM), Phenacoccus manihoti Mat.-Ferr., was studied through exclusion experiments. In the physical exclusion experiment lasting 52 days, CM numbers on tips in open sleeves, where access by natural enemies was allowed, were on average 43 times lower than on infested tips enclosed by a sleeve cage. In comparison to the situation in closed sleeve cages with CM only, host densities were reduced by only 3.9 and 1.4 times, where E. lopezi and coccinellid larvae, respectively, had been added. In the chemical exclusion experiment, mealybug numbers increased continuously up to the end of the experiment, after nine weeks, reaching 694 CM per group of 10 tips treated with insecticide, as compared to between 11.5 and 19.6 CM on the same unit of plants sprayed with water. Zusammenfassung Experimentelle Bestimmung der Wirksamkeit von einheimischen und exotischen naturlichen Feinden der Maniokschmierlaus Phenacoccus manihoti Mat.-Ferr. (Hom., Pseudococcidae) in Ghana Die Wirksamkeit der naturlichen Feinde, im Besonderen des Parasitoiden Epidinocarsis lopezi (De Santis) und des einheimischen Raubers Exochomus troberti Mulsant, zur Bekampfung der Maniokschmierlaus Phenacoccus manihoti Mat.-Ferr. wurde in Ausschlusexperimenten untersucht. Im physikalischen Ausschlusverfahren waren die Schmierlausdichten nach 52 Tagen in offenen Kafigen, welche Zugang der naturlichen Feinde erlaubten, 43 mal niedriger als auf Schmierlaus-befallenen Triebspitzen in geschlossenen Kafigen. Im Vergleich zu solch geschlossenen Kafigen waren die Wirtsdichten in Kafigen mit eingeschlossenen E. lopezi oder Coccinelliden-Larven nur 3.9, respektive 1.4 mal vermindert. Im chemischen Ausschlusverfahren stiegen die Schmierlauszahlen bis zum Ende des Versuches nach neun Wochen an und erreichten eine mittlere Dichte von 694 Schmierlausen pro Zehnergruppe von insektizid-behandelten Maniokstengeln, wahrend die Wirtsdichten auf mit Wasser behandelten Pflanzen zwischen 11.5 und 19.6 Schmierlausen pro Pflanzengruppe schwankten.