The hemocytes of the mealybugs Phenacoccus manihoti and Planococcus citri (Insecta: Homoptera) and their role in capsule formation

1994 ◽  
Vol 72 (2) ◽  
pp. 252-258 ◽  
Author(s):  
Jacqueline Russo ◽  
Marie-Rose Allo ◽  
Jean-Pierre Nenon ◽  
Michel Brehélin
Keyword(s):  
Fat Body ◽  
Phenacoccus Manihoti ◽  
Planococcus Citri ◽  
Epidinocarsis Lopezi ◽  
Phenoloxidase Activity ◽  
Capsule Formation

Hemocytes of Phenacoccus manihoti and Planococcus citri were studied to determine general ultrastructure, phenoloxidase activity, and the presence or absence of a glycocalyx. Prohemocytes, oenocytoids, and granular hemocytes of types 1 (GH1), 2 (GH2), and 3 (GH3) were observed in P. manihoti. In P. citri we observed only GH2 and GH3 (macrophage-like cells). In addition to these hemocyte types, other cells that we believe to be fat-body cells were also observed free in the hemolymph. There was evidence of phenoloxidase activity in GH2 and GH3. The intensity of this reaction increased after parasitization of P. manihoti by the wasp Epidinocarsis lopezi. In most hemocyte types the glycocalyx was very little developed. In P. manihoti, lysis of hemocytes was observed in the vicinity of the parasitoid larva, leading to the formation of a capsule.

MELANIZATION OF EGGS AND LARVAE OF THE PARASITOID, EPIDINOCARSIS LOPEZI (DE SANTIS) (HYMENOPTERA: ENCYRTIDAE), BY THE CASSAVA MEALYBUG, PHENACOCCUS MANIHOTI MATILE-FERRERO (HOMOPTERA: PSEUDOCOCCIDAE)

1988 ◽  
Vol 120 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Daniel J. Sullivan ◽  
Peter Neuenschwander
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Control Agent ◽  
Phenacoccus Manihoti ◽  
Defense Reaction ◽  
Epidinocarsis Lopezi ◽  
Cassava Mealybug ◽  
Major Pest ◽  
Eggs And Larvae ◽  
Host Tissues

AbstractThe encyrtid wasp Epidinocarsis lopezi (De Santis) has been introduced into Africa as a biological control agent against the cassava mealybug Phenacoccus manihoti Matile-Ferrero. This host has a defense reaction against the immature parasitoid that involves encapsulation and melanization. Under laboratory conditions, 37.5% of once-stung cassava mealybugs had been parasitized, as indicated by eggs and larvae of the parasitoid in dissected hosts. Of these parasitized cassava mealybugs, 89.6% contained melanized particles (egg, partially melanized larva, internal host tissues, exoskeleton wound scars). Some of the parasitoid larvae were only partially melanized, and either freed themselves from the melanized capsule or else shed it at the next molt. By the 3rd day of their development only 12.5% were completely melanized. In cassava mealybugs with melanized host tissue but no living parasitoid, the survival of the host was not affected by the melanization. The mealybug itself sometimes shed black particles at the next molt and these were found attached to the cast skins. When superparasitized in the laboratory, 68.6% of twice-stung cassava mealybugs contained parasitoids. Mummies collected from a field experiment showed that melanization rates of mummies increased with increasing parasitization rates. Thus, melanization in the cassava mealybug was commonly triggered when E. lopezi oviposited, but this defense reaction was mostly ineffective, permitting the introduced parasitoid to be a successful biological control agent in Africa against the cassava mealybug, a major pest on this important food crop.

Biological control of the cassava mealybug, Phenacoccus manihoti by the exotic parasitoid Epidinocarsis lopezi in Africa

1988 ◽  
Vol 318 (1189) ◽  
pp. 319-333 ◽  
Keyword(s):  
Biological Control ◽  
Population Dynamics ◽  
South America ◽  
Reproductive Potential ◽  
Field Studies ◽  
Phenacoccus Manihoti ◽  
Epidinocarsis Lopezi ◽  
Southwestern Nigeria ◽  
Cassava Mealybug ◽  
Accidental Introduction

Since its accidental introduction into Africa, the cassava mealybug (CM) has spread to about 25 countries. The specific parasitoid Epidinocarsis lopezi , introduced from South America, its area of origin, into Nigeria in 1981, has since been released in more than 50 sites. By the end of 1986 it was established in 16 countries and more than 750 000 km 2 . In southwestern Nigeria, CM populations declined after two initial releases, and have since remained low. During the same period, populations of indigenous predators of CM , mainly coccinellids, have declined, as have indigenous hyperparasitoids on E. lopezi , because of scarcer hosts. Results from laboratory bionomic studies were incorporated into a simulation model. The model, field studies on population dynamics, and experiments excluding E. lopezi by physical or chemical means demonstrate its efficiency, despite its low reproductive potential.

Current immunity markers in insect ecological immunology: assumed trade-offs and methodological issues

2012 ◽  
Vol 103 (2) ◽  
pp. 127-139 ◽  
Author(s):  
M. Moreno-García ◽  
A. Córdoba-Aguilar ◽  
R. Condé ◽  
H. Lanz-Mendoza
Keyword(s):  
Nitric Oxide ◽  
Evolutionary Ecology ◽  
Nitric Oxide Production ◽  
Ecological Immunology ◽  
Methodological Issues ◽  
Phenoloxidase Activity ◽  
Capsule Formation ◽  
Trade Offs ◽  
Physiologically Based ◽  
Shed Light

AbstractThe field of ecological immunology currently relies on using a number of immune effectors or markers. These markers are usually used to infer ecological trade-offs (via conflicts in resource allocation), though physiological nature of these markers remains elusive. Here, we review markers frequently used in insect evolutionary ecology research: cuticle darkening, haemocyte density, nodule/capsule formation, phagocytosis and encapsulation/melanization via use of nylon filaments and beads, phenoloxidase activity, nitric oxide production, lysozyme and antimicrobial peptide production. We also provide physiologically based information that may shed light on the probable trade-offs inferred when these markers are used. In addition, we provide a number of methodological suggestions to improve immune marker assessment.

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