Ethylene-releasing agents such as ethephon (2-chloroethylphosphonic acid) are used widely to induce flowering in pineapples (Ananas comosus (L.) Merrill). However, ethephon treatment is less reliable in summer, particularly if plants are treated on abnormally hot days. [(14)C]ethephon was used to follow uptake and translocation in leaf tissues. Up to 30% of the ethephon entered the leaf within 4 h, and up to 60% by 24 h. Uptake was dramatically modified by temperature, relative humidity, solution pH, and the surface on which solution droplets were placed. Entry occurred across the leaf cuticle and probably also by way of stomatal pores, and label was recovered at all depths within the leaf. (14)C label entered more rapidly through the abaxial epidermis than through the adaxial epidermis. Low-volume spray applications to whole plants resulted in rapidly drying droplets mainly on the adaxial, distal epidermis and were rather ineffective at inducing flowering, possibly because little ethephon or ethylene reaches the shoot apex. High-volume sprays may facilitate ethephon entry because solution accumulates in leaf axils and hence remains in prolonged contact with abaxial epidermis of leaf bases close to the shoot apex. When poured into the center of the plant, 20% of a normal commercial ethephon dose induced full flowering even under adverse temperatures. It is suggested that high-volume evening spraying and avoidance of hot days may reduce the incidence of flowering failure.

Three surveys were carried out to determine the extent of migration in a grain farming area by 4 stored products beetles: Tribolium custuneum (Herbst), Rhyzoperthu dominica (F.), Siiophilus oryzue (L.), and the Cryptolesres spp. group. Two involved the use of sticky traps and grain traps placed in farm and storage buildings and in locations distant from these buildings. The third used a vehicle mounted "truck" trap in a farming area. T. castancum and R. dominicu were the predominant migrants, being active in the field from October to May. Traps in farm buildings and central storages caught many more insects than did traps in the field. There was no clear relationship ofcatch with nearby infestations, except over short distances. With the truck trap, tli ht in the field was detected between 4 and 7 p.m. on relatively calm days and when temperature was greater ttfan 26°C. Average density of beetles during these times was estimated as ca 52 Mrf3. These insects represent a serious potential for reinfestation of stored grain.

In a survey of 60 grain farms on the Darling Downs, Queensland, during 1977-78, the flat grain beetles Cryptolestes spp., which are germ feeders in stored grains, were found on 39 of the farms and in 15% of the 483 samples taken. Ninety percent of infestations involving Cryptolestes spp. were found in bag or bulk stores of seed and feed grain, where they were usually associated with heavy infestations of the three more common stored grain pests, the rice weevil Sitophilus oryzae (L.), the lesser grain borer Rhyzopertha dominica (F.), and the red flour beetle Tribolium castaneum (Herbest.). Three species of Cryptolestes were detected: C. pusillus (Schonherr) (45.6% of farms surveyed), C. ferrugineus (Steph.) (28.1 %), and C. pusilloides (Steel and Howe) (15.8%). During the farm survey, samples were also collected from 8 of the 11 central storages reported infested with Cryptolestes spp. C. ferrugineus was present in each of these samples, C. pusillus in only one, whilst C. pusilloides was not found. The three species were tested for resistance to malathion and fenitrothion, the most commonly used grain-protectant chemicals, by exposing adults to treated wheat. C. pusillus and C. pusilloides were susceptible to both malathion and fenitrothion (LC99.9 < 1 mg kg-1). C. ferrugineus, whilst susceptible to fenitrothion (LC99.9 < 1 mg kg-1) was resistant to malathion, with LC99.9 of 300-400 mg kg-1 compared with the recommended dose of 18 mg kg -1. Although C. pusillus was the most common species on farms, it was concluded that C. ferrugineus was the most important overall because it is biologically better suited to the grain in central storages, which is typically hot (>30�C) and of low moisture content (< 12% for wheat).

One hundred unsexed adults of each of the following coleopterous species were added to 27 .3 kg of clean wheat: Sitophilus oryzae (L.) (rice weevil), Rhyzopertha dominica (F.) (lesser grain borer), Tribolium castaneum (Herbst) (rust-red flour beetle), and the flat grain beetles Cryptolestes pusillus (Schonherr), C. ferrugineus (Stephens), and C. pusilloides (Steele and Howe). For 15 months, measurements were made of population size and emigration from this wheat bulk. The highest populations recorded for each species were: 138 850, 65 680, 9 060, 47 000, 15 530, 11 940, respectively, and total emigrant numbers during the period were: 774 682, 278 094, 123 784, 335 588, 39 070, 9 352, respectively. Such high numbers of emigrants in relation to relatively low source populations emphasize the significance of small amounts of infested grain as sources of infestation of large grain bulks, and hence the importance of grain hygiene. The proportion of females in the populations of four species changed significantly from 0.50 as populations developed. Emigration behaviour was influenced most commonly by temperature, insect numbers, and wheat age, but these factors did not act uniformly on all species. Negligible numbers of emigrants returned to the food source. Low numbers caught in food traps away from the source were consistent with these not being attractive but traps near the shed walls caught greater numbers than expected.

Three surveys were undertaken to obtain estimates of the numbers of insects in stored products on farms on the Darling Downs, Queensland. In one survey, 57 farms were sampled once during 1977-1 978. In another, samples were taken at four-weekly intervals from three farms throughout 1977 and in the third, 16 of the first 57 farms were revisited in 1979. Samples were taken from grain stored for farm use, or grain spills and residues. Live adult insects were removed by mechanical sieving, counted and identified. The mean amounts of grain per farm, estimated visually, were 950 kg of bulk and bagged stocks of feed and seed grain, 270 kg of grain spills, 65 kg in auger boots, 100 kg in trucks and in headers, and 75 kg in other residues. Modal amounts were less, being in the range of 0-100 kg per farm for bagged and bulk grain, and spills on earthen floors, and 0-50 kg for other residues. Sitophiius oryzae (L.) (the rice weevil), Rhyzopertha dominica (F.) (the lesser grain borer), the Cryptolestes spp, group (flat grain beetles), and Trifolium castaneum (Herbst.) (rust-red flour beetle) were the most common pests, being 46.5%, 20.9%, 10.8% and 7.3% of the 52 330 insects found in the first two surveys. These four pests were found on 89.3%, 87.5%, 62.5% and 91.1% of the 57 farms in the first survey. The mean farm populations of these four pests combined was estimated at 360 000 adults (with a modal population per farm in the range of 0-50 000) of which approximately 88% were in bulk and bagged stocks of grain. However, this mean was inflated by a small number of farms having very large populations. An estimated 54% of farms had less than 50 000 adult pests. The second survey showed that insect populations peaked in late autumn, and reached a minimum in early summer.