Biologi dan Statistik Demografi Coccinella transversalis Thunberg (Coleoptera: Coccinellidae), Predator Aphis gossypii Glover (Homoptera: Aphididae)

Biology and demographic statistics of lady beetle Coccinella transversalis Thunberg (Coleoptera: Coccinellidae) using Aphis gossypii (Hemiptera: Aphididae) as prey was studied in laboratory. Development of C. transversalis from egg to adult was 31.02±4.73 days. The egg stage lasted for 2.33±0.58 days. Larva stage has four instars, which lasted for 2.43±0.19 days (instar I); 2.53 days±0.19 (instar II); 2.64±0.04 days (instar III), and 2.77±0.21 days (instar IV). A female laid 90.44±14.38 eggs. Meanwhile, gross reproduction rate (GRR) of C. transversalis was 74.80 individuals per generation, the net reproduction rate (R0) was 18.22 individual per female per generation, the innate capacity for increase (rm) was 0.46 individual female per day, the mean generation time (T) 12.40 days, and the double population value (DT) was 1.51 days. IntisariMasa perkembangan pradewasa dan imago serta keperidian Coccinella transversalis (Thunberg) (Coleoptera: Coccinellidae) telah diteliti di laboratorium dengan menggunakan Aphis gossypii (Glover) (Homoptera: Aphididae) sebagai mangsa. Masa perkembangan C. transversalis sejak stadium telur hingga menjadi imago adalah 31,02±4,73 hari. Perkembangan larva terdiri dari empat instar, masa perkembangan instar I sampai IV berturut-turut adalah 2,43±0,19 hari; 2,53±0,19 hari; 2,64±0,04 hari, dan 2,77±0,21 hari, dengan masa pupa 3,18±0,77 hari. Umur imago betina C. transversalis lebih panjang jika dibandingkan dengan imago jantan yakni 15,14±1,90 dan 13,63±1,00 hari. Imago betina meletakkan telur setelah melewati masa pra oviposisi selama 2,67±0,58 hari. Masa oviposisi C. transversalis yakni 8,97±0,89 hari dengan jumlah telur yang diletakkan yakni 90,44±14,38 butir. Parameter demografi C. transversalis adalah laju reproduksi kotor (GRR) adalah 74,80 individu per generasi; laju reproduksi bersih (Ro) 18,22 individu per induk per generasi; laju pertumbuhan intrinsik (rm) sebesar 0,46 individu per induk per hari; masa rata-rata generasi (T) selama 12,40 hari; dan nilai pelipatgandaan populasi (DT) adalah 1,51 hari.

Life cycle of the predatory mite Cheyletus malaccensis (Acari: Cheyletidae) fed on Poultry Red Mite Dermanyssus gallinae (Acari: Dermanyssidae)

This study evaluated the biological characteristics of predatory mite Cheyletus malaccensis fed on Dermanyssus gallinae at different temperatures. The study started with thirty individual eggs of C. malaccensis each isolated in an experimental unit, which developed throughout their life stages while feeding on D. gallinae at each temperature tested (20ºC, 25ºC and 30±1ºC and 80±5% relative humidity). Emerged adult females were not mated, thus producing only male offspring (arrhenotoky). Fecundity was the highest at 25°C (415.62±24.78 eggs/female) and lowest at 20°C followed at 30ºC. The mean length of a generation did not displayed difference among the three temperatures, but the net reproductive rate (Ro), innate capacity for increase (rm) finite increase rate (λ) were significantly higher at 30°C and lower at 20°C. Cheyletus malaccensis was able to develop and reproduce successfully when fed D. gallinae, and the optimum temperature for development, fertility and survival was 25°C. Our findings proved that C. malaccensis might be a natural enemy of D. gallinae, because it was able to develop and reproduce while feeding exclusively on this ectoparasite.

Temperature-dependent reproduction and survival of Gyrodactylus salaris Malmberg, 1957 (Platyhelminthes: Monogenea) on Atlantic salmon (Salmo salar L.)

SUMMARYThe relationship of survival and reproduction of Gyrodactylus salaris Malmberg on the Atlantic salmon (Salmo salar) to water temperature (2·5–19·0 °C), was studied on the basis of temporal sequence of births and age at death of individual parasites on isolated salmon, and of infrapopulation growth on isolated and grouped salmon. Mean life-span of the parasite was negatively correlated with water temperature: 33·7 days at 2·5 °C and 4·5 days at 19·0 °C. The average number of offspring per parasite peaked between 6·5 and 13·0 °C, and was approximately 2·4 at these two temperatures. Both the period between the successive births of the offspring (max 4) and the estimated generation time were negatively correlated with temperature. The innate capacity for increase (rm) was positively correlated with temperature: from 0·02 (/parasite/day) at 2·5 °C to 0·22 (/parasite/day) at 19·0 °C. Growth of the infrapopulations was positively correlated with water temperature and was higher on isolated fish than on grouped fish, though less than the potential parasite population growth estimated from rm. In the infrapopulations the mean intensity of parasites continued to increase throughout all the experiments on both isolated fish and on grouped fish.

BIOLOGY, LIFE TABLES, AND INNATE CAPACITY FOR INCREASE OF THE TWOSPOTTED SPIDER MITE, TETRANYCHUS URTICAE (ACARINA: TETRANYCHIDAE)

The threshold temperature of development, life table, and innate capacity for increase of the twospotted spider mite, Tetranychus urticae Koch, were established from life stage development studies at constant temperatures. The threshold for development was determined to be 10.0°C. The durations in degree-days above 10°C from the beginning of the egg stage to adult for females were 141.3, 152.3, and 139.8; for males 134.2, 144.7, and 135.2 at 15°, 18°, and 21°C, respectively. Life tables were constructed and innate capacity for increase was .069, .156, and .372; net reproduction rate 20.8, 38.4, and 58.1; and mean generation time 44.0, 23.4, and 10.9 at 15°, 18°, and 21°C, respectively.