Experimental parasitization of eggs of Triatoma maculata (Erichson) by the oriental microhymenopteran,Gryon triatomae Masner and comment on the susceptibility of other neotropical triatomines

The oriental microhymenopteran wasp, Gryon triatomaeMasner, 1975 was reared in eggs of triatomine bugs, including vectors of Chagas' disease. In particular, G. triatomae was maintained for 31 generations in eggs of Triatoma maculata (Erichson). Only one parasite develops in each bug egg and 30 to 40 days are required for completion of development at 24 ± 1 °C. Mean parasitization rate of 7484 eggs of T. maculata, in 54 rearings, was 34·7% with a range from zero to the highest rate of 86·7%. Mated females produce predominantly female progeny (mean sex ratio, 1 male : 6·7 females). Unmated females produce parthenogenetic males. The wasp reproduces in fertile eggs, from those recently laid to those with well-advanced bug embryos. Infertile eggs are not usually parasitized. Both sexes survive for one to two weeks unfed, but for several weeks (up to 16 for females) if fed (on honey). Frequent ovipositions may reduce survival. Successful parasitization by females persisted for about three weeks but declined subsequently.Abortions of developing Gryon were usually 10% or less. Brief comparison with other neotropical triatomine species indicates that eggs of Triatoma spp. are susceptible to G. triatomae; Panstrongylus spp. seem relatively poor hosts, and there is little or no parasitization of Rhodnius spp.