Analysis of Biological Control of Cassava Pests in Africa. II. Cassava Mealybug Phenacoccus manihoti

1988 ◽  
Vol 25 (3) ◽  
pp. 921 ◽  
Author(s):  
A. P. Gutierrez ◽  
P. Neuenschwander ◽  
F. Schulthess ◽  
H. R. Herren ◽  
J. U. Baumgaertner ◽  
...  
1988 ◽  
Vol 120 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Daniel J. Sullivan ◽  
Peter Neuenschwander

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.


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.


1994 ◽  
Vol 4 (3) ◽  
pp. 254-262 ◽  
Author(s):  
J. Chakupurakal ◽  
R.H. Markham ◽  
P. Neuenschwander ◽  
M. Sakala ◽  
C. Malambo ◽  
...  

1987 ◽  
Vol 77 (2) ◽  
pp. 177-189 ◽  
Author(s):  
P. Neuenschwander ◽  
R. D. Hennessey ◽  
H. R. Herren

AbstractAbout 130 species of parasitoids and predators are reported, most of them for the first time, to be associated directly or indirectly with the cassava pest Phenacoccus manihoti Matile-Ferrero and its parasitoid, Epidinocarsis lopezi (De Santis), newly introduced into Africa as a biological control agent. About 20 species are common. The species are grouped in 11 guilds, which include the indigenous hyperparasitoids, which originally attacked parasitoids of other mealybugs, the predators with which E. lopezi competes for the same food source and their antagonists.


1996 ◽  
Vol 86 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Janine W.A.M. Pijls ◽  
Jacques J.M. van Alphen

AbstractThe encyrtid parasitoid Apoanagyrus diversicornis (Howard) (formerly known as Epidinocarsis diversicornis) failed to establish itself in Africa where it was introduced, in addition to A. lopezi De Santis for the biological control of the cassava mealybug, Phenacoccus manihoti Matile-Ferrero. Apoanagyrus lopezi is a better competitor and available evidence suggests that competition prevents the coexistence. Yet, both parasitoid species were reared from P. manihoti in the same locality in their native South America. Competition should prevent coexistence on P. manihoti in South America as well as in Africa. We investigated how A. diversicornis persists in South America. The use of alternative hosts could explain its persistence. We aimed at finding possible alternative hosts for A. diversicornis that can serve as a refuge from competition with A. lopezi. The existing information on the distribution of A. lopezi and A. diversicornis and their known hosts in South America is reviewed. Candidate alternative hosts for A. diversicornis were selected and tested. Alternative hosts should at least be suitable for development of A. diversicornis and unsuitable for development of A. lopezi. Only Phenacoccus herreni Cox & Williams met these requirements. Phenacoccus madeirensis Green, P. solani Ferris and Ferrisia virgata (Cockerell) were unsuitable hosts for both species. In cages with continuous parasitoid populations under strong interspecific competition, A. diversicornis did significantly better if half the population of P. manihoti was replaced by P. herreni. This supports the hypothesis that P. herreni can serve as an alternative host for A. diversicornis in South America and that its presence enhances coexistence of A. diversicornis and A. lopezi. Phenacoccus herreni is absent in Africa.


1981 ◽  
Vol 71 (2) ◽  
pp. 247-258 ◽  
Author(s):  
Jennifer M. Cox ◽  
D. J. Williams

AbstractThe literature on the history and biology of the cassava mealybug in Africa Phenacoccus manihoti Matile-Ferrero is reviewed, and reports on the search for natural enemies of this species in the Neotropics for biological control purposes are summarised. Further records of the distribution of P manihoti in Africa are presented. A new closely-related species of Phenacoccus, P. herreni sp. n., which causes distortion to cassava in the Neotropical Region is described, and a key is provided to separate it from P. manihoti and from a similar species from the Neotropical Region, P. surinamensis Green, which apparently does not occur on cassava. P. surinamensis is redescribed and illustrated.


1993 ◽  
Vol 83 (1) ◽  
pp. 15-22 ◽  
Author(s):  
A. R. Cudjoe ◽  
P. Neuenschwander ◽  
M. J. W. Copland

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.


2017 ◽  
Vol 17 (1) ◽  
pp. 1
Author(s):  
Budi Abduchalek ◽  
Aunu Rauf ◽  
Pudjianto .

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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