Bull. zooi. Surv. , '7 (2-3): 179-183, 1985

PREDATORY BEHA \lIOUR OF THE PHOLCiD CROSSOP RIZA LYONI (BLACK WALL) ON MOSQUITOES ( SP.)

N. C. NANDI* Zoological Survey of India, Kakdwip Field Station, Kakdwip, 24-Parganas, West Bengal.

AND s. K. RAUT Department of Zoology, Calcutta University, 35, Ballygunge Circular Road, Calcutta-19

ABSTRACT

Predatory behaviour of the pholcid spider, 'yolli (Blackwall), on mosquitoes (Aedes sp.) displays fascinating style of wrapping of the prey with silk. The spider takes about two hIS to complete the preying-feeding action for each and may "consume" 12-20, on an average 15 mosquitoes (Aedes sp.), in a 24 hrs period. The predator also disposes off the prey-residues after feeding, perhaps, to keep the web clean.

INTRODUCTION They have been observed on several occassions since June 1980 in a room of an During the course of investigations on electrIfied, single storeyed, residential building the behavioural biology and biological control where C. lyoni were allowed to live potentials of some , the authors "undisturbed" for study. The time requ ired observed the predatory behaviour of Crosso­ for handling a prey has been recorded from priza lyoni (Blackwall) on a variety of insects time to time. The methods of prey-capture, at Kakdwip, 24-Parganas, West Bengal. duration and frequency of feeding, etc., These spiders displayed fascinating ethology were noted accordingly. The predatory of predation on various insect preys, of potential is estimated by supplying freshly which predation on mosquitoes (Aedes sp.) killed mosquitoes. is, herein, communicated.

MATERIALS AND METHODS OBSERVATION Crossopriza lyoni (Blackwall) is a house c. lyoni construct irregular snares in all dwelling pholcid spider which prepares four corners, ceiling and other suitable sites, irregular snares at the very inside of houses. preferably nearer to the source of light.

* Present Address: Zoological Survey of India, Canning Town-743329, 24-Parganas, West Bengal. 182 Bulletin of the Zoological Survey of India residue after feeding and tries to keep the that construct trapping webs. This prevents preferred site for feeding and I or resting free prey from falling out of the web from the from prey-waste-residue. However, prey­ spider's elevated sites during feeding, groom­ residue may be sonletimes seen hanging on ing, or subsequent capture attempts (Eber­ the underside of the snare constructed at hard, 1967). Rovner and Knost (1974) also corner. suggested that wrapping by lycosids might serve to free the spider from subsequent attacks on additional prey, as occurring in

DISCUSSION web-weavers.

Great differences exist among spiders as The preys are normally wrapped after the regards the manner in which they obtain prey has been subdued by biting in the their prey (Bristowe, 1958 ; Tikader, 1980). diguetid and linyphiid web-weavers (Eberhard, The spiders are, accordingly, categorised as 1967). However, this sort of post-immobili. weavers, those who trap their prey by pre­ zation wrapping has not been observed in paring webs, and non-weavers, those who the present . This might be due to hunt their prey by chasing or by stalking. the fact that the preys were held in a tightly The pholcid spider, Crossopriza lyoni, belongs wrapped package and that wrapping began to the former group. Individuals of this after the prey had ceased most of its vigorous species spin an extremely· fine but irregular struggling movements. Our findings in this cobweb, from which they lie suspended regard supported Rovner and Knost's (1974) upside down. This type of orientation is hypothesis that the absence of vigorous unlike that of the most of the aerial web­ movements by the prey is a necessary part of weaving spiders as they orient themselves in the stimulus situation for the onset of a face-down position while resting in their wrapping. webs (Eberhard, 1967). Duration and frequency of feeding along Informations are available on the preda­ with waste disposal of prey residue have been tory behaviour of lycosid spiders (Cragg, studied in the present species. Our data on 1961; Edgar, 1969; Rovner and Knost, the frequency of feeding in C. lyoni as obser­ 1974; Greenquist and Rovner, 1976), ved by supplying freshly killed mosquitoes diguetid spiders (Eberhard, 1967), linyphiid may lend support to their biological control spiders (Tumball, 1960; Eberhard, 1967), potentials, as a single individual may devour dictynid spiders (Jackson, 1979a, b) and as many as 20 mosquitoea in a 24 hrs araneid spiders (KaJek, 1965). However, very period. little is known on the prey-capturing Since the preys of this spider-species are mechanisms of pholcid spiders (Bristowe, widely incriminated as vectors of various 1958). diseases of man and domestic , the In the pholcid spider, C. lyoni, prey­ present study will supply certain useful wrapping is a prerequisite to feeding as informations to the biological control pro­ known to 1:)~ ~ssoci~teq With. those spiclers ~ramme of mosquitoes. NANDI & RAUT: Behaviour of Crossopriza lyoni on Mosquitoes 183

ACKNOWLEDGEMENTS and prey-wrapping. Psyche, 83: 197 .. 209. The senior author is thankful to Dr. B. K. Tikader, Director, Zoological Survey of India, JACKSON, R. R. 1979a. Predatory behaviour Calcutta for facilities provided for the work. of the social spider Mal/os gregalis: He is also thankful to Dr. Bijan Kr. Biswas is it cooperative? Illsectes soc., Paris, and Dr. Badal Ch. Das, Z. S. I., Calcutta, for 26 : 300-312. identifying the spider and mosquitoes res­ JACKSON, R. R. 1979b. Comparative studies pectively. of Dictyna and Mallos (Araneae: Dicty­ nidae) : III Prey and behaviour. Psyche, 83 : 267-280. REFERENCES KAJAK, A. 1965. An analysis of food rela­ BRISTOWE, W. B. 1958. The World of Spiders, tions between the spiders-Araneus cornu­ London; Collins. tus Clerck and Araneus quadratus CRAGG, J. B. 1961. Some aspects of the Clerck-and their prey in meadows. ecology of moorland animals. J. Anim. Ekol. pol. (A) 13 : 717-764.

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