lirSect Sei. Applic. Vol. 8. Nos 4/5/6. pp. 841-844. 1987 0191-9040!87 $3.00 + 0.00 Printcd in Great Britain. Ali rights reserved Ç' 1987 ICIPE-ICIPE Science Press

IMPORTANCE OF IN BIOLOGICAL CONTROL

GILBERTO J. DE MORAES Centro de Pesquisa Agropecuraria do Tropico SemiArido (CPTSA):EMBRAPA. 56300-Petrolina. PE. Brazil

(Received 27 .Vorember 1986)

Abstrllct-Taxonomy is the starting poínt o f any basic or applied biological research. In biological control work, the pest species, its probable area o f origin. and. consequently. the location where promising natural enemies may be found. are identified. The dose co-operation o f taxonomists during pre- and post-release surveys of natural enemies in target arcas helps to indicate the indigenous fauna present and the progress of a biological control programme. Biological control programmes should budget for appropriate taxo­ nomic studies in areas where the local fauna is poorly known. Instructing local researchers on the correct collection, preservation, and identification of relevant indigenous and exotic species should be emphasized.

Key Words: Taxonomy, classification. identification. biological control. biosystematics

Réswné--La taxonomie est !e point de départ de toute recherche biologique fondamentale ou appliquée. Dans Ie cadre de Ia Iutte biologique, son étude permet. Iorsqu'elle est correctement menée, d'identifier Ies différentes espéces de ravageurs. leur Iieu d'origine éventuel et. par conséquent. les sites ou I'on a !e plus de chance de trouver des ennemis naturels prometteurs. La collaboration étroite des taxonomistes au cours des enquétes antérieures et ultérieures aux lâchers d'ennemis naturels dans les zones cibles permet d'évaluer la réussite du programme de lutte biologique. Dans Ies régions ou I'on posséde peu de données précises sur la faune locale, les programmes de Iutte biologique doivent prévoir dans leur budget une étude taxonomique. L'importance de la formation, au niveau local, de chercheurs aptes à identifier les especes indigénes et exotiques devrait être soulignée.

Mots C/éfs: Taxonomie. classification, identification. Iutte biologique. biosystématique

INTRODUCfiON co-operation between biological control specialists and taxonomists. The need for co-operation starts Taxonomy is the theory and practice of classifying with the proper identification of the target pest. organisms. The term classification has two different Incomplete or wrong identification of the pest may meanings: the product of the activity of the taxon­ lead to the wrong determination of its place o f origin. omist and the activity o f classifying, which consists o f where efficient natural enemies are expected to be ordering populations and groups ofpopulations (taxa) found. This can result in considerable amounts of at ali leveis by inductive procedures (Mayr, 1969). money and time spent without obtaining useful results. Identification consists of placing individuais into One of the best examples of the consequences of previously established taxa by deductive procedures. improper identification o f a pest species was a project This field of research is of utmost importance for for the biological control of the coffee in any area of basic and applied biology, and without it Kenya (LePelley, 1943; DeBach, 1974). This mealy­ scientific communication among biologists would be bug, Planococcus kenyae (LePelley), was first consi­ severely limited. dered to be the citrus mealybug, Pseudococcus citri Biological control specialists recognize the import­ (Risso), and !ater to be Pseudococcus li/acinus Ckll. ance of taxonomy as a starting point for the intro­ For this reason, 12 years were spent in exploration duction, conservation and augmentation of natural and introduction of the wrong natural enemies from enemies, as extensively discussed by severa! authors four continents. The ultimate success of this project (Ciausen, 1942; DeBach, 1974; Eickwort, 1983; was achieved after it was evident that the coffee Schlinger and Doutt, 1964; Smiley and Knutson, mealybug was a species distinct from P. /i/acinus, 1983). which led to the importation of Anagyrus sp. near The purpose of this paper is to show the relation kivuensis Compére from nearby Uganda: where P. between biological control work and taxonomy, the kenyae was present but rare. reasons for limitations that might exist in identifica­ In a biological control project, surveys of the area tion services, and some possible approaches to reduce where natural enemies are supposed to be released those problems. will indicate the native species present. A comparison o f the complex o f natural enemies in that area and in ROLE OF TAXONOMY IN BIOLOGICAL other areas where the pest also occurs but is not a CONTROL EFFORTS problem will help the biological control worker to select the natural enemies that show the most poten­ Any biological control project requires continuous tial for trial introductions. A maior contribution is 841 842 GILBERTO J. DE MoRAES provided at this point by the taxonomist through are reproductively isolated from other such groups identification of the candidate natural enemies. The (Mayr, 1969). This concept is not based on phenotype available literature on the identified species gives the and thus allows for considerable variation as long as biological control worker some indication of the the groups of organisms that are called species main­ natural enemies' expected behaviour based on histor­ tain their individualities as "reproductive units". ical evidence. about the particular family, genus or Taxonomists that advocate the biological concept of species. species may make use of morphological characters After introduction of natural enemies. Jt 1s Im­ to separate them, however, there is a fundamental portam to monitor their activity and establishment difference between using morphological characters to by periodic evaluations of the population dynamics infer reproductive affinities and basing the species of the particular pest and its introduced natural concept on morphology (Simpson, 1961). enemies. Here again the co-operation of taxonomists In many cases, morphological evidence alone is not in determining the different species is important. A sufficient to separate organisms imo species, because comparison of the pre- and post-release surveys of variations presented by conspecific individuais as should be encouraged since any change in the fauna well as similarities presented by sibling species. In may be indica tive o f the progress o f the programme. those cases, field ecological observations. laboratory But the work of taxonomists goes beyond naming crossings or other biological studies are necessary new species or identifying species already described. to indicate whether one is dealing with a single or It also considers the relationship between species, more than one species. For instance, studies of the seeking to arrange them in meaningful groups. This variation of morphological characters within and is important for biological control workers for severa! between species of predatory mites of the family reasons, especially in determining places of origin of Phytoseiidae have shown considerable variation pests. Furthermore, the work of taxonomists takes within one species according to geographical distribu­ into account the biological differences between popu­ tion. season and host plant (Chant et a! .. 1977; Croft, lations of a same species that indica te the occurrence 1970; Davis, 1970; Hoying and Croft. 1977; Muma of biotypes, which are populations of individuais of and Denmark. 1962), whereas great similarities have similar genetic composition for a biological attribute been found in closely related sibling species (Muma (Gonzalez cr a!., 1979). When studying the potential and Denmark. 1969). of a particular natural enemy, the adaptability of The simple rearing of organisms in the laboratory distinct biotypes to different ecological conditions. as for subsequent morphological studies often shows the identified in taxonomic comparisons o f population o f variations to be expected in a particular species. a same species from different areas. is also important Thus. the tools of taxonomists are not restricted to to biological comrol workers. microscopes, mounting material. cabinets for preserv­ Reference collections prepared by taxonomists ing specimens and the literature related to their are of major importance not only for ongoing, but specialty. but must also include collecting material also for future biological control projects. Those and laboratory facilities for biological studies. collections should include both native and imroduced For example. a species in need of detailed bio­ species. In the case of natural enemies. specimens systematic study at the presem time is the predaceous originally introduced and their laboratory and field phytoseiid mite. Typhlodromalus sp. near limonicus offspring (collected at different periods) should be (Garman & McGregor). This is one of the most preserved for studies of possible morphological alter­ common species on in Colombia, and is ation in the new environment. Reference collections potentially importam as a predator of cassava green may provide hints to places of origin of different mites. Mononychellus ranajoa (Bondar) sensu latu, in organisms. A good example of this was reported by Africa. lt is morphologically similar to T. limonicus Pemberton, as mentioned by Clausen (1942). A single and T. rapax (DeLeon l (the former descrihed from specimen present in a private collection at Sydney Californ i~. USA, and ihe latter described from was the clue that led Pemberton to discover the place Puerto Rico), but still presents some differences that of origin of the fem weevil. Synagrius(ulritarsis Pasc., indicate that it is an undescribed species. Laboratory a serious pest in Hawaii. This ultimately resulted crossing studies and evaluation of morphological in the introduction and establishment of a natural variation in populations reared under controlled enemy from Australia (Ciausen. 1978). laboratory conditions may be helpful to indicate the Reference collections are also helpful for local identity of the Colombian species. researchers. making it possible for non-taxonomists to have an idea of the identity o f specimens collected FIELD STlJDIES locally, by comparing them with specimens available in the collection. The biological concept of species does not allow In addition. taxonomists gather information on the the taxonomists to rely on only a few preserved distribution and habitat of differem species. When museum specimens to classify or identify species. facilities are available. these data can be computer­ Sound information on field ecology. which often ized and made available to workers in biological cannot be expressed in the laheb attached to each control as well as in other specialities. specimen, is of major importancc to a taxonomist. I f this type of work cannot be conducted directly by METHODS lJSED BY TAXONOMISTS ANO a taxonomist. personal communication with the MATE RIALS NEEDED scientists most directly interested in thc identification In a biological sense. species are groups of actually is extremely helpful. or potentially interbreeding natural populations that The initial identification o f the cassava mealybug is Taxonomy in biological control 843 an excellent example of the importance of commun­ An approach to the first factor mentioned is to ication between the taxonomist and the interested provide funds for necessary taxonomic studies. An scientist. Field observations conducted by biological approach to the second factor is to invest in training control workers and laboratory rearings indicated local researchers with some inclination to taxonomy, that the externai appearance and biology of the soas to develop a functional capability in identifying mealybug from Africa differed considerably from local species. which could then be periodically verified that found in northern South America and some by taxonomic experts (Yaninek, 1984 ). Caribbean islands (Cox and Williams, 1981 ). Most markedly, those from Africa were pink and partheno­ genetic and those from northern South America and the Caribbean Islands were yellow and bisexual. REFERENCES After the discovery of those facts. other characters were found to vary consistently between populations Chant D. A .• Hansell R. I. C. and Rowell H. J. (1977) An originating from the two continents. Thus, that from analysis of interspecific and intraspecific morphological differences in two closely related species of Amblyseius Africa Phenaccocus manihoti Mat.-Ferr. was con­ Berlese using methods of numerical taxonomy (Acarina: sidered to be a species different from that from Phytoseiidae). Can. Enr. 109, 1605-1618. northern South America and the Caribbean Islands Clausen C. P. ( 1942) The relationship of taxonomy to (Phenacoccus herreni Cox and Williams). Today. P. biological control. J. econ. Ent. 35, 744-748. manihoti is also known to occur in Bolívia, Paraguay Clausen C.P.• ed. (1978) Introduced parasites and predators and southwestern Brazil (Yaseen, 1986). o f pests and weeds: a world review. U.S. Dept. Agric. Handbk. 480, Washington, D.C. Cox J. M. and Williams D. J. ( 1981) An account o f cassa va (: Pseudococcidae) with a descrip­ NEEO OF SUPPORT FOR TAXONOMIC WORKS tion of a new species. Buli. Ent. Res. 11, 247-258. 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In Bio/ogical Contra/ of Pests by Mires (Edited by Hoy M. A., Cunningham G. L. and Knutson Very often, biological control workers need the L.), pp. 148- 164. Univ. California Press, Berkeley. identification of a particular species in a very short Yaninek J. S. (1984) Recognizing and identifying phyto­ time. Limiting factors to a fast identification may be phagous and predaceous mites found on cassava. In unresolved taxonomic problems and/or the absence lntegrated Pest Management of Cassava Green Mire o f a taxonomist near where the species was collected. (Edited by Greathead A. H., Markham R. H ., Murphy 844 GILBERTO J. DE MORAES

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