S.H. Ho

Toxic and antifeedant action of nutmeg oil against Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch

The essential oil extracted from nutmeg seeds using steam distillation was tested against the stored product insect pests, Tribolium castaneum (Herbst) and Sitophilus zeamais Motsch., for contact toxicity, fumigant toxicity and antifeedant activity. Filter paper impregnation was employed for contact and fumigant toxicity studies, whereas a flour disc bioassay was used to investigate antifeedant effects. Adults of S. zeamais were about ten times more susceptible than T. castaneum adults to contact action (LC50 values of 1.7 mg/cm2 and 18 mg/cm2 respectively). However, S. zeamais adults were only 1.7 times more susceptible than T. castaneum adults to fumigant action (LC50 values of 4.5 mg/cm2 and 7.7 mg/cm2 respectively). Furthermore, the larvae (10–16 days old) of T. castaneum were more susceptible than the adults, but the susceptibility of the larvae decreased with age. Nutmeg oil also significantly (P < 0.05) affected the hatching of T. castaneum eggs and the subsequent survival of the larvae in the concentration range 1.4–3.2 mg/cm2. The production of F1 progeny of both T. castaneum and S. zeamais exposed to media treated with nutmeg oil was significantly (P < 0.05) reduced at all concentrations tested. F1 progeny production was totally suppressed at nutmeg oil concentrations of 1.05 g/100 g rice for T. castaneum and 0.35 g/100 g wheat for S. zeamais. Nutritional studies showed that nutmeg oil significantly (P < 0.05) affected the growth rate and food consumption of both insect species, depending on the concentrations used, but the antifeedant activity was more pronounced against S. zeamaisthan against T. castaneum. At 20 g nutmeg oil/100 ml, the feeding deterrence index of T. castaneum was only about 7%, whereas that of S. zeamaiswas 33%. These results suggest that nutmeg oil may be useful as a grain protectant with contact, fumigant and antifeedant activities against these insects.

Subjective visual experience during phacoemulsification and intraocular lens implantation under topical anesthesia.

OBJECTIVE The aim of this study was to investigate the subjective visual experience of patients during phacoemulsification and intraocular lens (IOL) implantation under topical anesthesia. DESIGN Postoperative questionnaire survey. PARTICIPANTS The study cohort consisted of 52 patients with cataracts. There were 18 male (34.6%) and 34 female (65.4%) patients. Their mean (+/- SD) age was 67.5 (+/-10.8) years. INTERVENTION The patients underwent routine phacoemulsification and IOL implantation under topical anesthesia. MAIN OUTCOME MEASURES The patients were interviewed on the same day after their operation regarding their visual experience in the operated eye during surgery. RESULTS All patients (100%) reported that they could see at least some light during the surgery. Some patients reported they could also see one or more colors (50 patients, 96.2%), movements (32 patients, 61.5%), flashes (24 patients, 46.2%), the surgeons fingers/hands (13 patients, 25%), instruments (12 patients, 23.1%), and/or the surgeon (4 patients, 7.7%). The colors seen included red (24 patients, 46.2%), yellow (23 patients, 44.2%), blue (12 patients, 23.1%), green (7 patients, 13.5%), and orange (6 patients, 11.5%). Eight patients (15.4%) saw the spectrum of colors similar to that of the rainbow. Twenty-four patients (46.2%) reported that the brightness of light changed during the course of the operation. Eight patients (15.4%) found their visual experience frightening. There was no statistically significant association between those who found the visual experience frightening and the sex or age of the patient, a history of cataract operation in the fellow eye, the type of visual sensation experienced, or the presence of coexisting ocular pathology. CONCLUSION All patients undergoing phacoemulsification under topical anesthesia experience a variety of visual sensations that may be frightening in a small proportion of patients.

Effects of carbon dioxide on the mortality of Liposcelis bostrychophila Bad. and Liposcelis entomophila (End.) (Psocoptera: Liposcelididae)

Abstract The reduction in adult emergence of Liposcelis entomophila eggs treated with CO2 was observed to be a direct consequence of egg mortality. Adult emergence was inversely related to the CO2 concentration to which the eggs were exposed. The response of liposcelid eggs to hypercarbia (30–95% CO2) did not differ from the simple Ct relationship, Ct = k. Eggs of Liposcelis bostrychophila were noted to be > 2 times more tolerant to CO2 treatment than those of L. entomophila. Based on LT50 and LT95 values for 1-to 3-wk-old females exposed to 45 and 60% CO2, L. bostrychophila was the more tolerant species. Increasing the CO2 concentration from 45 to 60% did not reduce the LT95 in either species. At a fixed exposure period of 4 h, no corresponding increase in mortality was observed in either species for CO2 concentrations > 45%. Similar responses were observed in L. bostrychophila for 3 and 5 h exposures to various CO2 concentrations. The use of CO2-enriched atmospheres in the control of L. bostrychophila and L. entomophila is also discussed.

Techniques in the culturing and handling of Liposcelis entomophilus (Enderlein) (Psocoptera: Liposcelidae)

Liposcelis entomophilus (Enderlein) was maintained on diets composed of various combinations of wheat flour, skimmed milk powder and yeast. After 6 weeks, a diet comprising the above components in 10:10:1 proportions respectively resulted in the highest increase in liposcelid population (P < 0.05). Subsequently, L. entomophilus was successfully cultured on this medium at 30 ± 1°C and 72–78% r.h. A method for maintaining stock cultures was established. The use of an aspirator in the handling of these liposcelids was tested and proved adequate, the optimum suction pressure being 60 mmHg (P < 0.05). A separating sieve, used with a 60 W incandescent bulb, was specially constructed to extract these liposcelids from infested grains. Modifications to this apparatus and its other uses are discussed.

Relative tolerance of Liposcelis bostrychophila (Bad.) and L. entomophila (End.) to some organophosphorus and carbamate insecticides

A simple method for the insecticide bioassay of liposcelids is outlined. The contact toxicity of five organophosphorus insecticides (OPs) and two carbamate insecticides (CBMs) was ascertained for Liposcelis bostrychophila and L. entomophila. Liposcelis entomophila was more tolerant to all the insecticides tested than the other species. Malathlon was the least toxic OPs to both species, while chlorpyrifos-methyl was the most toxic insecticide tested against L. bostrychophila. These findings are discussed in relation to the infestation of these liposcelids in rice storages.RésuméUne méthode simple pour l’essai biologique des insecticides contre les liposcelides est presentée. La toxicité de cinq insecticides organophosphoreux (OPs) et de deux insecticides carbamates (CBMs) contre Liposcelis bostrychophila et L. entomophila a été étudiée. Pour tous les insecticides essayés dans cette étude, L. entomophila s’est montrée plus résistante que L. bostrychophila. Contre ces deux espèces, le malathlon est un des OPs moins efficaces, mais le chlorpyrifos-méthyle est l’insecticide le plus toxique contre L. bostrychophila. Ces découvertes sont evaluées par rapport aux infestations de ces liposcelides dans les entrepôts de riz.

In vitro inhibition of esterase activity in Liposcelis bostrychophila bad. and L. entomophila (end.) (Psocoptera: Liposcelididae)

Abstract Methods for assaying AChE and non-specific esterase activity from Liposcelis spp. were outlined. Liposcelis bostrychophila AChE was less sensitive to inhibition than L. entomophila to malaoxon and DDVP. Non-specific esterases of L. bostrychophila were more susceptible to inhibition than those of L. entomophila. Totals of 10 and 14 esterase bands were detected on PAGE for L. bostrychophila and L. entomophila, respectively. The link between esterase sensitivity to inhibition and the differential insecticide tolerance between the two Liposcelis spp. is examined.

Life cycle of Liposcelis entomophila (Psocoptera: Liposcelididae) and a culturing regime for liposcelids

The life cycle of Liposcelis entomophila (Enderlein) (Psocoptera: Liposcelididae) was studied at 30 ± 1°C and 75 ± 3% r.h. The mean developmental period of the females was 22.3 days and that of the males was 18.4 days. This corresponded to the males undergoing three, and the females four, nymphal stages. A 28% developmental mortality was observed. The average number of offspring produced in the first fornight was 9.6 and the natural mortality of the females was noted only from the sixth week, increasing to 54.1% by the 12th week. An extraction and culturing regime to obtain populations of one- to three-week old adult females was developed. This procedure was also found to be ideal for L. bostrychophila Badonnel.

Spatial distribution of flying Tribolium castaneum ( Coleoptera: Tenebrionidae) in a rice warehouse

The vertical and horizontal distribution of Tribolium castaneum (Herbst) in a rice warehouse was studied using flight traps hung around selected stacks of bagged rice. Traps hung at 4 m or higher from the floor caught more T. castaneum than other insect species in the warehouse. At 6 m height, the traps caught mainly this species and were easy to maintain. The horizontal distribution pattern of T. castaneum sampled at 6 m was not homogeneous. The factors influencing distribution are discussed.

Development of a PC-based automatic monitoring system for Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in a rice warehouse

Flight traps were constructed and hung 6 m from the floor of a rice warehouse, with a 5 m polyvinyl chloride (PVC) tube attached to the base of each trap. The PVC tube channelled any Tribolium castaneum (Herbst) caught into a plastic specimen vial at the bottom. A pair of traps was placed at each of four designated locations in the warehouse. One of the pair of traps at each location had the vial resting on a top pan balance. The four balances were interfaced with an IBM-compatible personal computer. The signals from the balances were recorded as the weights of the insects by the computer sequentially and continually. The other trap at each location was set 1 m from the computer-controlled trap and acted as a reference trap. The insects collected from it were weighed manually on a daily basis. Trap catches using both methods were recorded for 50 days. The system was not influenced by temperature and r.h. changes, and dust fall was negligible. The weights of individual live beetles recorded monthly for 6 months did not change significantly. Thus the weights obtained during monitoring could be converted to the number of T. castaneum. A good correlation was obtained between the computer and manual trap catches, with a mean correlation coefficient of 0.898 (P < 0.001). These results demonstrate the feasibility of using a technique which monitors flight trap catches electronically and remotely.