On Some Hyperparasites of Opisina arenosella The Black-Headed Caterpillar Pest of Coconut in Malabar, India

Investigations carried out on the parasite-hyperparasite complex of the coconut pest Opisina arenosella Walker indicate that the hyperparasites considerably reduce the population of the parasites and thus lower the efficiency of the latter as biological control agents. Over half the cocoons of the parasitoid Apanteles taragamae Vier., were parasitised by the hyperparasites, with Aphanogmus manilae Ashmead accounting for 27.14/. followed by Meteoridea hutsoni (Nixon) (17.14/), Brachymeria nephantidis Gahan and Pediobius imbreus (Walker) (2 .86 / each) and Eurytoma albotibialis Ashmead (1.42/) . P. imbreus also caused 29.8 / parasitism on Bracon brevicornis Wesmael. Brief descriptions of the biology of some of the hyperparasites are also given. I N T R O D U C T I O N Of the many parasites and predators that attack the different stages of the pest Opisina arenosella Walker ( = Nephants serinopa Meyr.), (Lepidoptera: Aecophoridae) some species are utilized in the biocontrol programmes against this notorious pest. A few species of such parasites in its turn serve as hosts for many hyperparasites. The present paper deals with some of the hyperparasites attacking the braconid parasites of 0. arensetta. MATERIALS A N D METHODS The larvae and pupae of the pest, Opisina arenosella were collected regularly at monthly intervals, from various parts of Malabar. From these samples the percentage of parasitism and its hyperparasitism were studied. Various aspects of the biology of the hyperparasites were studied by rearing them in the laboratory ( T = 28.65*2.65., RH = 57.32 T 5.43), and presenting them with appropriate, stages of parasites as hosts. OBSERVATIONS A N D DISCUSSION Hyperparasites attacking Apanteles taragamae Vier. Apanteles taragamae (Braconidae) is an important parasitoid of Opisina arenosella attacking its early larval stages. The percentage parasitism in the study area varied from 1.25 to a maximum of 16.6, with an average of 8.9. However more than 5 0 / of the parasitoid cocoons collected 29 S. M. G H O S H and G. C. A B D U R A H I M A N from the Held were parasitised by hyperparasites, thus reducing the efficiency of A. taragamae as a primary parasite to nearly half. Aphanogmus munilue (Calliceratidae). Meteor idea hutsoni (Braconidae), Brachymeria nephantidis (Chalcididae), Pediobius imbreus (Eulophidae) and Eurytoma albotibialis (Eurytomidae) were found to be the important hyperparasites of this primary parasite. Aphanogmus manilae parasitised the pupae of Apanteles taragamae. The hyperparasite laid 3 to 6 eggs in a single host pupa. The adults that emerge within 16 to 20 days lived for 23 days when given 5 0 ' / honey as food. On 50 / . sucrose they lived for 15 days and when starved they survived only for 3 days. A. manilae caused 2 7 . 1 4 / parasitism on A. taragamae. Meteor idea hutsoni was originally recorded as a primary parasitoid of Opisina arenoselh as it was found to attack the late instar larvae of the pest (Sudheendra kumar et al., 1979; Ghosh and Abdurahiman, (1984). Recently it has also been reported as a hyperparasite of 0. arenosella (Ghosh and Abdurahiman, 1985) and caused 1 7 . 1 4 / parasitism on Apanteles taragamae in the present study. Brachymeria nephantidis and Eurytoma albotibialis are primary parasitoids of Opisinu arenosella, and act as hyperparasites on the pupae of Apanteles taragamae (Rao et al., 1948). As a hyperparasite E. albotibialis completes its life stages in 12 to 15 days. B. nephantidis and E. albotibialis caused 2.86 / and 1.42'/ parasitism, respectively, on their host, A. taragamae. Pediobius imbreus caused 2.86 7. parasitism on A. taragamae Hyperparasite attacking Bracon brevicornis Wesmael The eulophid Pediobius imbreus has been found to parasitise Bracon brevicornis soon after the latter has spun its cocoon. The total developmental period of P. imbreus from egg to adult is completed in 17 days at 28 ± 2°C. This includes the egg stage lasting for 1 day, the larval period of 6 to 8 days and pupal period of 9 to 10 days. The total develop­ mental period of its host, B. brevicornis is completed in 7 to 8.5 days (Sudheendrakumar et al, 1982). With 50 / honey as food the adult hyperparasite lived for more than 30 days. Thus a single hyperparasite can lay eggs in the pupae of nearly three successive generations of B. brevicornis. Present studies revealed that nearly half of the parasite clutch of Bracon brevicornis collected were sometimes found parasitised by Pediobius imbreus. However, the rate of its parasitism on B. brevicornis varied considerably with a mean of 29.57 percent Thus nearly one-third of its population is reduced, which in turn, adversely affects its field efficiency. Hyperparasite attacking Meteor idea hutsoni (Nixon) When the late stage pupae of Meteoridea hutsoni which were enclosed inside the pupal case of its host, Opisina arenoselh were presented to Eurytoma albotibialis females, they readily oviposited The eggs were mostly deposited inside the pupae of M. hutsoni, and the larva that hatches from the egg feeds on M. hutsoni pupa. This observation confirms the fact that E. albotibialis, though a primary parasitoid of Opisina arenosella also serves in the field as a hyperparasite of M. hutsoni, thus making it difficult to estimate its percen­ tage of hyperparasitism. However, since the number of E. albotibialis emerging from the pupae of Opisina is very low, the rate of its hyperparasitism is rather negligible.