Secondary Parasite Research Articles

Summary. The breeding operations and accumulation of supplies of Alysia manducator Panz. and Nasonia brevicornis Ashm. commenced in July and ceased in December 1919. Alysia manducator oviposits in the larvae of several carrion‐feeding Diptera. Only one parasite emerges from each host puparia. Over‐parasitism kills the larva. The mean average of the life‐cycle is 52 days, and as short as 25. Both sexes are capable of sustained flight, and lived over a month in captivity. Average percentage of parasitism over three years was 43 per cent., observed by Graham‐Smith (4). Average contents of ovaries 366 eggs for 12 females. Nasonia brevicornis oviposits in the puparia of several species of stercoral and carrion‐feeding Dipterous larvre. From one to 62 individuals have been found in single puparia parasitized in captivity. The length of the life‐cycle ranges from 11 to 22i days in different countries. Only the female can fly, and then only very short distances, and can live, whilst ovipositing, from 4 to 6 weeks, but for a considerably less period without host puparia. The male remains nea.r the vicinity of emergence, where its life is spent in fighting and mating. Average progeny in the case of five females–observed by Girault & Saunders and McCarthy– was 113 per female, and affecting on the average only 16‐4 hosts, Nasonia can act as an accidental secondary parasite upon A. manducator if and when puparia containing the latter are within its limited reach. Both parasites in their hibernating stage–i. e., full‐grown larvse—can successfully withstand over 6 weeks at 2o C. Alysia manducator appears to be a more important parasite as a natural control for the Blow‐fly than Nasonia brevioomis, which appears to be more effective as a natural control of Diptera which constantly breed in permanent refuse‐ and garbage‐heaps, and where hosts would be within crawling distance, such as primarily the Common House‐fly, Musca domestica.

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