Dr. Murai Éva szerk.: Parasitologia Hungarica 23. (Budapest, 1990)

Table 1. Effect of Hydrotaea aenescens as a biolarvicide against Musca domestica in pig manure Number of immature stages/sample

1 H. aenescens M. domestica Mortality of M. domestica 20 20 E 2U Ll

2 2

0 Ll 20 L

2 20 L

2 20 L

3 20 L

3 20 L

2 20 E 20 L

2 20 Ll 20 L

3 20 E 20 L

3 20 Ll 20 L

3 20 L

2 30 L

2 90 E 30 L

2 120 E 30 L

2 150 E 30 L

2 90 Ll 30 L

2 120 Ll 30 L

2 150 Ll 30 L

3 90 E 30 L

3 120 E 30 L

3 150 E 30 L

3 90 Ll 30 L

3 120 Ll 30 L

3 150 Ll 15 30 100 100 100 99 100 100 100 99 98' 100 99 86 99 93 95 9 9 99 99 100 100 grams of pig manure/sample E - egg; Lj_3 - first, second or early third (4-day-old) larvae the mean of three replicates corrected for control mortality by Abbott's formula rates were between 15 and 100 %. This result shows that if eggs or first instar larvae of both species are seeded in pig manure, despite the long period of joint development, the dump fly larvae will not be able to prey on Musca larvae. This can probably be explained by the fact that Musca domestica develops faster in pig manure - which is its most favoured larval medium - than Hydrotaea aenescens. For this reason Hydrotaea larvae can kill only a few, or none, of the bigger prey ones. ANDERSON and POORBAUGH (1964) obtained a similar result when studying Ophyra leucostoma. MÜLLER (1982) also found that if the females of both species laid their eggs at the same time no prédation was observed but 90-100 % of