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 THE OVIPOSITION RESPONSE OE INSECTS 3 



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Ephestia kuehniella Zell. indicate that oviposition is considerably 

 delayed and the number of eggs reduced if copulation has not taken 

 place. Guyenot (31) and Adolph (1) obtained evidence f rom Droso- 

 phila wnelanog aster that mating is a stimulus for egg-laying; the 

 former thought it was a mechanical stimulus because the first eggs 

 deposited were frequently unfertilized. Picard (61) has also observed 

 this effect in Phthorimaea and HesperopJianes griseus F. A recent 

 work by Glaser (26) indicates clearly that association with the male 

 sex stimulates egg production in Musca domestica L. and Stomoxys 

 calcitrans L. Virgin females of the imported pine sawfly (Diprion 

 simile Hartig) apparently wait 2 days before oviposition and 

 although they can reproduce parthenogenetically, if not mated they 

 lay only half as many eggs as fertile females (53) . Mating is not a 

 factor in the oviposition of many parasitic Hymenoptera (34, 61), 

 nor in certain social Hymenoptera. 2 



INTERNAL PERIODICITIES 



Adolph cites the work of Back and Pemberton (3) on the melon 

 fly (Bactrocera cucwrbibae Coq.) to show that internal periodicities 

 may be responsible for the intermittent deposition of eggs by cer- 

 tain species. Such periodic egg-laying occurs in other insects (9) 

 though few references to it have been found. Bishop, Dove, and 

 Parman (8) mention that the house fly (Musca domestica) lays eggs 

 at 8-day intervals. 



EXTERNAL INFLUENCES AFFECTING OVIPOSITION 



TEMPERATURE 



Temperature influences the rate of many life processes, among 

 which may be counted the activities connected with oviposition. 

 Within the range of each species there is probably an optimum tem- 

 perature for egg-laying. In the alfalfa weevil (Phytonomus posti- 

 cus Fab.) mean daily oviposition follows in general the curve of mean 

 daily temperature (57) ; a similar relation holds for the cotton boll 

 weevil (Anthonomus grandis) (76). A reduction of 3° or 4° C. has 

 been observed to lengthen the oviposition period of Tomicus- (Ips) 

 Ujpographicus L. from 1 to 8 days (35). A cool night retards the 

 oviposition of Hypera punctata Fab. and it ceases between 7° and 

 10° C, according to Hudson and Wood (39). A recent study by 

 Detouches (19) on the wax moth (Galleria mellonetta ~L.) shows how 

 markedly temperature may affect the quantity of eggs laid. At 37° 



2 Some additional instances of fertility as a stimulus for oviposition have come to 



light since the above was written. According to Baker and Davidson (Jour. Agr. Re- 



e.-irch, vol. C, pp. 351-360, 1016), the female of ErioNoma pyrieola Baker and Davidson 



mils to deposit the winter egg unless fertilized directly after the last integument has 



been caxt. Htopodatnla lS-punctata L. will oviposit without being fertilized but scarcely 



one-fourth of the usual number of eggs are laid (Outright, Ann. Ent. Soc. Amor., vol. 17, 



pp. 188-102, 1034). Sen (Kept, i'roc. 5th Rnt. Meeting Pnsa, February, 1023, pp. 



215-225, Calcutta, 1024) was not able to obtain eggs from unfertilized females of 



\c<ien {Btegomyla) albopieta Skuse even after the insects were allowed to bite and 



blood.' Studies on Ohloropa tdenlopus Meig. by Frew (Ann, Appl. Biol., vol. II, 



pp. 17o-21!i, Hiiil) .-bow that unfertilized females commence ovipositing JO to 12 days 



emergence, while fertilized females begin laying in 4 to 5 days, unfertilized files 



' o lay fewer eggs than fertilized flies. Apparently the mite Tyroglyphua tnycophome 



.■.in) will not lay eggs unless it. has. been fertilized (Schulze, Zedtschr. wlssen. 



Biol., Abt. A. Morpb, and Okologie, 2, Heft 1 and 2, pp. 1-57, J024). It is not yet 



< bar whether this .stimulus is a mechanical one, as Cuyenof has suggested, or an internal 



• resulting from substances transferred to the female during eoition. 



