has b een registered halding som e p rotozoan s, eg. N osem a locustae or fungi, eg. H irsutella th om pson i lethal for m ites living on citrus plants and L agen idiu m giganteum - a parasite o f m osqu ito larvae.
Preparations based on insecticidal fungi such Beauveria bassiana, M etarhizium ani- sopliae, Verticillium lecanii, are being produced b esid es U S A in such cou n tries as form er C zech oslovak ia, Switzerland or China. In P oland on the basis conidial fungi: B. bassiana and V. lecanii an industrial p roduction o f biopreparation has b een elaborated. M eth od s w ere p aten ted (P atent N o 288661, 1993, N o 169335, 1996). M. anisopliae is a factor w hich caused so-called green m uscardine d isease n am e such on account o f green coloration o f hyphae.
T h e aim o f th ese investigations w as to d eterm in e p ath ogen ic p rop erties o f chosen strains o f M. anisopliae against B. germ anica L. as w ell as to estim ate their u sefulness for con trolling the num bers o f th ese insects.
MATERIALS AND METHODS
Experiment were carried out on cockroach, B. germanica L. with various strains of M. anisopliae (Metsch). Strains of M. anisopliae were taken from Department of Agrocenology, Institute of Ecology, PAS. Five strains of M. anisopliae were investigated. Separate strains of M. anisopliae were introduced to the insects together with food mixture LSK used to feed laboratory animals. Each strain of fungi was added to food at 3 germ concentrations. Simulta neously water was supplied. Each glass container was suplemented with strip o f filter paper accordion-pleated with width about 7 cm.
Experiments were conducted in week jars at ambient temperatures on adults of both sexes of cockroach. The experimental insects originated from the culture run in the National Institute of Hygiene.
A total 1620 cockroaches of both sexes: 1350 nourished on food with admixture of fungus M. anisopliae with different germ density and 270 individuals used as the control were employed in the experiment.
RESULTS
M ortality o f cockroach es feed in g on food con tam in ated w ith fungus M. anisopliae d erived from differend regions o f Poland are p resen ted in T ab le 1. T h e results thus ob tain ed proved the high path ogen ecity o f th ese strains. D uring 30 days o f experim ent, at low est density o f fungus germ s in food , m ortality o f fem a les ranged 30 - 80% that o f m ales: 59 - 85%. A t th e highets germ con centration s, on the oth er hand, m ortality o f cock roach es was higher: 58 - 90% in fem ales, and 68 - 95% in m ales. A fter 50 days o f exp erim en t the m ortality increased to 60 - 99% in fem ales and 80 - 100% in m ales. In th e control in sects m ortality w as always low - 5%. O ut o f strains tested В strains o f M. anisopliae from B row sk show ed high p ath ogen ecity. T his strain even at th e low est density o f spores show ed high m ortality in th e two period o f investigation (Tab. 1). Strain M o f M. anisopliae d eserved also attention . It sh ow ed high activity at all sp ore d en sities during the two experim ents (Tab. I). A t the low est density o f spores after 30 days o f experim ent it caused 80% m ortality in fem a les and 85% in m ales. At th e h ighest sp ores d en sities the m ortality o f insects reached 90% in both sexes. A fter 50 days th e se valu es w ere still higher. It should b e stressed thad the d en sities o f spores
o f strain M u sed w ere m ore than 9 tim es higher as com p ared with th o se u sed for Browsk strain (Tab. I).
T a b l e I. Mortality of B. germanica L. (% ) fed with food contaminated with various strains of fungus Metarhizium anisopliae.
1) Bi - Browsk 2) B2 - Brynek 3) M - Pruszyn 4) ZP, - Złoty Potok 5) ZP2 - Złoty Potok К - control
(30, 35 and 45% ) as com pared with strains derived from Browsk (B i), Pruszyn (M ), th e se strains caused 65 and 80% mortality (Tab. I).
M ales treated with th e sam e strains as fem ales turned to b e m ore su sceptib le after 30 days o f treatm ent. T h eir m ortality am oun ted to 58, 65 and 60% o f strains from Brynek (B 2), Z łoty P otok (Z P i, Z P 2), respectively, and from Browsk (B i) and Pruszyn (M ) such m ortality am oun ted to 70 and 85% , respectively. T h e ob tain ed results after 30 and 50 days o f experim ents prove that the strains B t (from Brow sk) and M (from Pruszyn) are m ost u seful for controlling the cockroach es o f all strains in vestigated.
E xp erim en ts with en to m o p a th o g en ic fungi and harmful in sects have b een con d ucted earlier. U n d er th e laboratory con d ition the p ath ogen ic p roperties o f several strains o f Beauw eria bassiana and P acilom yces farin osus against cockroach es (В . germ anica L .) w ere in vestigated [9,10]. T h e findings suggest that properly ch osen strain o f B. bassiana can con trol th e num bers o f B. germ anica. Trial was also m ade to evalu ate the en tom o p a th o g en ity o f P aecilom yces farin osus against the cockroach es [10]. T h e lab o ratory results p oint to th e fact that path ogen icity against cockroach es is diversified d ep en d in g on strains. O ut o f 10 strains o f P. farin osus tested three caused high m ortality am ontg in sects tested . D iversified path ogen icity found that m ortality o f test in sects d ep en d ed on strain, spore density and insect sex. T his d ifferen tiation o f p ath ogen icity o f en to m o p a th o g en ic fungi (В. bassiana and P. farin osu s) against cock roaches w as also corroborated by results o f investigations carried out b oth strains o f M. anisopliae. P ath ogen icity o f various sp ecies o f fungi can b e affected by different factors (eg. substratum type, tem perature, hum idity, etc). B ajan and K m ito w a [2] reported that en to m o p a th o g en ic fungi can undergo various alteration leadin g to form ation o f groups, form s or strains etc., m ore or less aggressive and p ath ogen ic. T he authors draw attention to taking into account this p h en o m en o n w hen exam ining the u sefu ln ess o f sp ecies o f en to m o p a th o g en ic fungi for biological control. O ur stud ies on B. bassiana, P. farin osus [9, 10] and M. anisopliae seem to confirm this op in ion . A m on g strains o f sp ec ies just m en tion ed , th ese w ere so m e w hich even at a low density of sp ores yield ed high m ortality o f the test insects, and on th e contrary, high density of sp ores o f so m e strain caused low mortality o f insects tested u nder th e so m e experi m en tal con d ition s. T his p h en o m en o n can result from vulnerability or resistan ce o f in sects against th e fungal strain applied. Bajan and K m itow a [2] reported that the o b served d ifferen ces in P. farin osus strains such as growth rate, spore form ation tim e, am ount o f sp ores prod uced it and their path ogen icity against various d evelopm en tal stages o f C olorad o b eetle can b e m anifestation o f appearance o f d ifferen t form s or m orp ho- p hysiological races or different biotyp es o f P. farinosus.
E n to m o p a th o g en ic B. bassiana is already u sed for p rod uction o f b iopreparation to p rotect forest against D en drolim us sp. [5] or to control a pest, H ylobius abietis. It was foun d that during 8 years o f storage in the form o f pow der, B. bassiana has lost only 50% o f its activity [8]. T h e Polish preparation based on B. bassiana sp ores have m aintain ed viability in 50% after 3 years o f storage at a tem perature o f 4°C (Bajan et al. [3]). In our sou th ern neighbours, sim ilarly as in Poland tech n ology w as elaborated to p rod uce b ioprep aration based on sp ores o f B. bassiana and V. lecanii to con trol the C olorad o b e e tle and orchard and green h ou se p ests [3, 6, 9]. W e hawe also inform ation on p roducing preparation with the u se o f spores o f B. brongniartii in Sw itzerland [1]<
4. Jenkins W.E., Prior С.: Production of conidia by Metarhizium flavoviride in submerged culture. Program an Abstracts of XXV Annual Meeting of Society for invertebrate Pathology. Heidelberg 1992, 164.
5. Riba G., Silvy С.: Combattre les revageurs des cultures, 1989, INRA, 230 pp.
6. Samsinakova A., Kalalova S.: Mass cultivation of entomophagous fungus Verticillium lecanii. Ceska Mykol., 1976, 30, 18.
7. Samsinakova A., Kalalova S.: Mass production of Beauveria bassiana for regulation of Leptimotorsa dedemlineata populations. J. Invert. Pathol. 1981, 38, 169.
8. Starcova H., Weiser J.: Shelf life of Boverol the formulated bioinsecticide with conidia of Beauveria bassiana. Program and Abstracts o f XXV Annual Meeting o f Society for Invertebrate Pathology, Heidelberg, 1992, 228.
9. Żukowski К , Bajan С.: Badania przydatności Beauveria bassiana do zwalczania prusaków (Blattella germanica L.). Roczn. PZH, 1996, 47, 333.
10. Żukowski K., Bajan C. \ Badania laboratoryjne aktywności szczepów owadobójczego grzyba Paecilomyces farinosus w redukcji liczebności prusaków Blattella germanica L., Roczn. PZH, 1997, 48, 133.