CHAPTER I INTRODUCTION Systematics, the language of biology is the study of the kinds and diversity of organisms and of any and all relationships among them (Simpson, 1961).The knowledge on biosystematics of any group of organism is the foundation for all meaningful research. Without studying systematics it is virtually impossible to study the biodiversity of any group of organism. Hence, it is essential that efforts should be made to study the systematics of our flora and fauna before attempting to know their diversity. The multitude of species occurring in nature are studied, classified and named so that they can be identified in future. Once its correct name is known, then it becomes a label by which information concerning that organism including all past work done on it can be stored and retrieved (Narendran, 2000 & 2001b). A Importance of Systematics to Biological Control Systematics has importance in biological control programmes. When natural enemies are being sought or transferred from one region to another in order to bring about biological control of a pest, the correct identification of both the species of pest and natural enemy is of utmost importance (Narendran, 2006). Parasitic Hymenoptera is the most important group of entomophagous insects utilized in various biological control programmes against insect pests. They are innumerable, diverse, ecologically significant and economically important. Majority of parasitic hymenoptera are primary parasitoids of pests of agricultural crops. Out of 393 species of parasitoids established in classical biological control programmes, 344 (87%) were parasitic Hymenoptera (Greathead, 1986).There are several examples of successful biological control programmes using parasitic hymenopterans. However there have also been failures. The failures in biological control are mostly attributed to poor or inadequate taxonomic knowledge on the pest, parasitoid and predator. Any advance in the knowledge of the biosystematics of 1
parasitic hymenopterans can supply a lot of information necessary for undertaking biological control or integrated pest management programmes using these insects. B Biology of Torymidae Biologically the family is diverse, host records exist for only about one third of its species and detailed biological studies have been undertaken for only a fraction of this number. Based on host records approximately 85% of torymids are entomophagous and 15% are phytophagous. Both types occur in each subfamily, but Megastigminae is primarily phytophagous with a few entomophagous species, whereas Toryminae is primarily entomophagous. The entomophagous species of Toryminae are associated with 51 families of insects in eight orders with hosts predominantly gall forming Hymenoptera and Diptera. Lepidoptera and Coleoptera form a considerably smaller group of hosts, and about 10% of known torymids are egg parasitoids with the majority of these attacking mantid egg cases. Many species act as facultative hyperparasites and a few are known to consume both plant and animal tissues. Strictly phytophagous species of Toryminae (several species of Torymus Dalman) are seed feeders in Rosaceae and Aceracea. Phytophagous species of Megastigminae (about 90% of the subfamily) have been reared from at least seven plant families and most are associated with seeds of coniferous trees and rosaceous plants. The entomophagous species of the subfamily are mostly associated with hymenopterous and dipterous gall formers (Grissell, 1995a). Majority of the species of the subfamily Toryminae, and a few species of Megastigminae are found to be ectoparasitoids of the inhabitants of plant galls. Torymoides are main parasites of various galls of Diptera such as cecidomyiid galls and tephritid galls (Bouček, 1988). Phytophagous species include seed eating Megastigmus, Bootanelleus and Torymus. Species of Megastigmus, Torymus, Mangostigmus, Torymoides, Liodontomerus, Odopoia are found associated with various galls. Species of Podagrion are parasitic on eggs of mantids. Species of Rhynchoticida and Chrysochalcissa are parasitic on eggs of Heteroptera. Podagrionella indarbelae Narendran and Sureshan was found in the emergence cages where egg clusters of 2
bark borer Indarbelae tetraonis on cashew are kept. Some species of Monodontomerinae are parasitic on the cocoons of Lepidoptera and Hymenoptera. Amoturoides develop in the tachnid parasitizing polistine wasp. Some members of the genera Torymus and Ecdamua are parasitic on Sphecidae (Narendran, 1994 & 2001a). Megastigmus brevivalus (Girault) parasitizing on the gall chalcid Eurytoma fellis Girault in Australia (Noble, 1938). The female M. brevivalus oviposits on any of the immature stages of the host. In the beginning the development of the immature stages of the host takes place far ahead of the development of the parasite. If the parasite has laid egg on the egg of its host, then the incubation of the egg of the parasite prolongs until the host has attained first larval stage. When the host attains larval maturity the parasite is still in its first stage. Soon afterwards the parasite larva accelerates its development and consumes the entire body contents of the host before the host larva pupates. After the completion of the feeding, the mature final instar larva of the parasite emerges out of the skin of the host and pupates in the gall tissue. This synchronization in the development of the parasite and host is quite distinct in the biology of Torymidae. Members of the genus Podagrion are parasitic on the eggs of Mantidae. Podagrion insidiosus shows an interesting behavior (Bordage, 1913). The female Podagrion clings to the wings of the female mantid host until the time of formation of ootheca and then it descends to the frothy mass of the ootheca and oviposits on it. In the case of some other species such as Podagrion pachymerum (Walker) the female parasite was found ovipositing on older oothecae. C Role of Torymids in Biological Control Programmes Since their hosts include several pests of agricultural importance, torymids are used as biological control agents against insect pests. The conventional pest control strategy using chemical pesticides is posing many ecological problems, biological control methods are gaining importance in recent years. Biological control programmes have been launched in twentieth century against agricultural pests. Torymus sinensis Kamijo was used as a parasitoid of the chestnut gall wasp 3
Dryocosmus kuriphilus Yasumatsu (Cynipidae) in Japan (Otake et al., 1984; Moriya et al., 1989 & 1990).The effectiveness after colonization of imported Toryms sinensis was also studied (Murakami, 1977; Murakami et al., 1977; 1987; 1989 & 2001). Preliminary studies have been made on the efficacy and establishment of Roptrocerus xylophagorum, a parasitoid of Ips grandicollis (Coleoptera: Scolytidae) in Australia (Samson & Smibert, 1986). Torymids play both positive and negative roles in the ecosystem. Majority of torymids are primary parasitoids of pests of agricultural crops (eg.tephritidae), and some torymids are phytophagous pests in the seeds of various plants. Thus in view of their positive role as beneficial primary parasitoids of pests of crops and negative role as primary pests of crops, studies on the biosystematics of Torymidae is very important in the economic point of view. D Systematic Position of Torymidae The family Torymidae comes under super family Chalcidoidea of the order Hymenoptera. The superfamily Chalcidoidea includes 20 families. Walker (1833) proposed the name Torymidae. The family is divided into two subfamilies, viz., Toryminae and Megastigminae (Grissell, 1995a). Parasitic and phytophagous wasps of the family Torymidae are found throughout the world. The family currently include about 77 genera and 1138 species in two subfamilies. About 29 genera and 182 species were reported from the Oriental region. 23 genera and 107 species were reported from India, and 13 genera and 36 species were reported from Kerala (Noyes, 2003) E Objectives of study The objectives of the present investigation are the following: a) To discover and describe the new taxa of Torymidae from Kerala and adjacent areas. b) To redescribe the poorly known taxa from the available holotypes or paratypes and plesiotypes 4
c) To prepare workable illustrated keys for the identification of subfamilies, genera and species of Torymidae of Kerala and adjacent areas. d) To prepare a catalogue of host parasitoid index of Torymidae. e) To prepare a check list of torymid fauna of India. 5