Interaction Between Chrysocharis flacilla and Diglyphus isaea (Hymenoptera: Eulophidae), Two Parasitoids of Liriomyza Leafminers.

Agromyzid Liriomyza leafminer flies are a major threat to horticultural production in East Africa with low natural control reported. The endoparasitoid Chrysocharis flacilla (Walker; Hymenoptera: Eulophidae) was introduced from Peru into quarantine facilities at ICIPE in Kenya for a leafminer classical biological control program. Interaction assays with one of the dominant local parasitoids, Diglyphus isaea (Walker; Hymenoptera: Eulophidae), using Liriomyza huidobrensis (Blanchard; Diptera: Agromyzidae) was assessed through sole, simultaneous and sequential releases. C. flacilla resulted to superior host parasitism rates over D. isaea. When used separately, specific parasitism rates of D. isaea and C. flacilla were 26.33 ± 2.07% and 60.27 ± 2.53% respectively but, when simultaneously used, the total parasitism rose to 72.96 ± 4.12%. Presence of C. flacilla after D. isaea reduced significantly parasitism rate of D. isaea. Both parasitoids caused separately and simultaneously additionally significant nonreproductive host mortalities of between 48.33 ± 3.75% and 69.33 ± 3.92 for D. isaea and C. flacilla respectively. Sex ratios of C. flacilla and D. isaea F1 progenies were female biased and were not affected by interspecific interactions. Implications of these results for subsequent combined use of C. flacilla and D. isaea against Liriomyza leafminers in East Africa are discussed.