Experimental comparison of laboratory reared vs. wild-typeTrichogramma confusum [Hym.: Trichogrammatidae] I. Fertility,fecundity and longevity

A comparative study was made of the fertility, fecundity and longevity ofTrichogramma confusum Vigg. reared in the laboratory on eggs ofCorcyra cephalonica St., vs. a wild type population of the same species. Laboratory reared females showed a significantly higher degree of sterility than wild-type females while sterility amongst males did not differ significantly. Under laboratory conditions, laboratory reared females lived longer than wild-type females but produced fewer progeny as indicated by life-table data suggesting that their “effective” life is shorter. The high precentage of sterility amongst laboratory reared females should be taken into account when making inundative field releases. As size of the host may influence the fecundity and behaviour of laboratory rearedTrichogramma, the use of a suitable host which produces larger eggs would have to be considered in any mass-breeding programme.