TECHNIQUE FOR MASS REARING CTENARYTAINA THYSANURA (FERRIS AND KLYVER) (HEMIPTERA: PSYLLIDAE)

Abstract

A mass rearing technique for consistent production of large numbers of Cfenarytaina thysanura for laboratory studies is described. The number of ovarioles of laboratory-reared and field-collected C. thysanura was compared. The boronia psyllid, Ctenaryfaina thysanura (Ferris and Klyver), is an important pest of Boronia megastigma (Nees) (Mensah and Madden, unpubl. data). The psyllid, originally identified in New Zealand on Boronia sp., was thought to be of Australian origin but remained largely unknown prior to commencement of intensive boronia culture. The effects of the infestation on B. megastigma demanded a need for basic biological and behavioural studies including aspects of the insect host plant interaction, the role of exotic and indigenous natural enemies as well as studies determining appropriate methods of control. Such studies required an abundant, reliable and consistent supply of insects of uniform age and bionomic background. Reported here is a mass-rearing method which provided a simple, highly responsive system for the mass production of large numbers of C. thysanura on demand. Mass-rearing trials were conducted in a glasshouse illuminated by a single, Im 40W fluorescent tube with a photoperiod of 12L:12D, thermostatically controlled with a fan heater and air conditioner. Temperature ranged from 18-20°C and relative humidity was between 65-75% as measured by a 7-day recording thermohygrograph. C. thysanura adults were collected in September 1986 from foliage of naturally-infested field-grown boronia at Copping (eastern Tasmania) using a sweeping net. The psyllids were anaesthetised with ether, sexed and the culture established by placing 2 pairs of males and females onto each of 20 potted seedlings of 6-month-old, 10-20 cm-high boronia plants. Each infested plant was inserted into the mouth of an inverted 2L clear plastic soft drink container 30 cm in height and with a diameter of 10 cm and ventilated by means of 2 opposing gauze-covered lox 10 cm windows. The height of the cage could be altered as the infested plant grew by moving it up the supporting sticks inserted into the soil beside the plant. As the basal opening was lifted from the soil, cotton gauze was inserted at the end to prevent entry or escape of insects. After adult emergence, one 6-day-old female from each cage was dissected in water under a binocular microscope. The number of ovarioles from each was recorded and compared with that of the field collected females of the same age. Emergence of F1 offspring commenced 41 d after infestation. The number of eggs within ovarioles of the laboratory reared female did not differ significantly from that of wild females (P>0.05). A number of cage designs have previously been employed for psyllid culture, e.g. cut twigs immersed in glass vials (Van der Merwe 1941), cellulose acetate cylinder cages (Watmough 1968), perforated plastic bags (Annecke and Cilliers 1%3; Moran and Blowers 1%7), and organdie bags (Clark 1962). The advantages of using ventilated plastic cages on potted plants are that they avoid the wilting associated with cut stems (Van der Merwe 1941; Moran and Blowers 1967) and exclude natural enemies and other unwanted insects such as spiders, scales and aphids (Watmough 1968). It provides a more constant environment and optimal conditions for both plant and insect growth and permits direct observation of the insects through the wall of the plastic cages without disturbance. It also overcomes the problem of excessively prolonged instar development encountered by Van der Merwe (1941) and Moran and Blowers (1967). The only problem with our method was that the potted seedling had to be replaced as the numbers of insects increased. This was due to intraspecific competition for food and space and reduced the efficiency of output. When insects were subcultured to new plants on a regular basis, this technique provided a consistent insect population for laboratory studies.