The tolerance of immature stages of four stored product moths to methyl bromide

Eggs, last instar larvae, and pupae of the Pyralid moths, Ephestia elutella (Hübner). E. kuehniella Zeller, E. cautella (Walker) and Plodia interpunctella (Hübner) reared at 25°C were exposed to methyl bromide over a wide range of concentrations and times at 10–30°C. One laboratory stock, and one field stock of each species were tested, but differences between stocks of the same species were small.P. interpunctella required lower CT products than the other species for complete kill of each stage. At 10°C, larvae of the field stock of E. cautella required a CT product of 110 mg h/l. for complete control. All stages of all species succumbed to a CT product of 64 mg h/l. at 15°C. When exposed at 20°C or above, pupae aged 0–3 days were more tolerant than other stages. Eggs aged 2 days or over were more tolerant than younger ones.The fertility of survivors from fumigated eggs resembled that of controls, but that of some individuals fumigated as pupae was depressed. For fumigated eggs of E. elutella and P. interpunctella at 15°C, the CT relationship held over concentrations from 4·2 to 10·8 mg/l. and exposure periods from 1 to 16 h.     

The toxicity of phosphine to all developmental stages of thirteen species of stored product beetles

The toxicity of phosphine to all stages of 13 species of stored product beetles was determined using large numbers of test insects which made possible more accurate assessments of mortality. Species tested were Acanthoscelides obtectus, Caryedon serratus, Cryptolestes ferrugineus, C. pusillus, Lasioderma serricorne, Oryzaephilus surinamensis, Ptinus tectus, Rhyzopertha dominica, Sitophilus granarius, S. oryzae, S. zeamais, Tribolium castaneum and Trogoderma granarium. Tests were conducted as appropriate at 10, 15, 25 and 30°C, all at 70% r.h., with concentrations ranging from 0.013 to 2.96 mg/l and exposure times from 1 to 16 days. Sitophilus spp. proved the most tolerant, and in all species other than T. granarium, in which diapausing larvae were the more tolerant in longer exposures, eggs and pupae were the most tolerant stages. Phosphine was most effective at the higher temperatures, whilst long exposures at low concentrations were far more effective than short exposures at high concentrations. The use of phosphine to control these species of stored-product insects will only be effective at 15°C or below if long exposures can be guaranteed.     

Problems in the laboratory investigation of the toxicity of phosphine to stored product insects

The principles to be observed in determining the toxicity of fumigants to stored product insects by means of laboratory experiments, and the circumstances in which these must be modified for phosphine are discussed. After assessing the published literature two kinds of experiment are recommended, to imitate the levels of concentration and exposures used in practice and to limit the exposure period to 8 or 24 hr. For the latter exposures higher concentrations than are used in practice would be required and it might not be possible to achieve complete mortality of test samples. However, this technique should separate the tolerant and susceptible stages of the life cycle and reveal any stages of intermediate susceptibility. The maximum duration of the developmental period of the tolerant stages would represent the minimum exposure period for phosphine desirable in practice provided all the individuals in a tolerant stage developed and reached a susceptible one.     

The toxicity of methyl chloroform to stored product insects

The susceptibility to methyl chloroform of all developmental stages of Cryptolestes ferrugineus, Ephestia kuehniella, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitotroga cerealella, Sitophilus granarius, S. oryzae and Tribolium confusum, diapausing larvae of Ephestia elutella, E. cautella, Plodia interpunctella and Trogoderma granarium and adults of Tribolium castaneum, was studied. Tests were conducted at 15, 20 and 25°C, 55–75% r.h. with concentrations ranging from 25 to 200 mg/l and exposure times from 8 h to 16 days. The toxicity of methyl chloroform was in general similar to that of carbon tetrachloride. Immature stages of R. dominica, S. cerealella and Sitophilus spp, and diapausing larvae of T. granarium, showed the highest levels of tolerance. Methyl chloroform was more effective at the higher temperatures but a concentration of 50 mg/l was below the threshold level for full toxicity against 5 species at 25°C. Depending on the species concerned, the concentration × time (CT) product required for control varied from 3,700 mgh/l at 25°C to 60,000 mgh/l or more at 20°C. At 15°C fewer species were tested but five out of nine survived CT products in the region of 30,000 mgh/l. There was no appreciable difference between the susceptibility of the immature stages of malathion-resistant and susceptible strains of O. surinamensis. Neither were any consistent differences observed between adults of normal susceptibility and those resistant to methyl bromide or phosphine.     

Assessment of Australian Trichogramma species (Hymenoptera: Trichogrammatidae) as control agents of stored product moths

Trichogramma species (T. brassicae, T. pretiosum and T. carverae) were assessed for their suitability as bio-control agents against Ephestia cautella and E. kuehniella which are important pests in food manufacturing and processing facilities in Australia. Parameters examined were longevity, fecundity on eggs of E. kuehniella, walking speed of adult wasps, reaction to moth scales, and host acceptance and host suitability of eggs of E. cautella and E. kuehniella. T. pretiosum and T. carverae performed better than T. brassicae in all traits examined apart from fecundity. T. pretiosum and T. carverae differ mainly in higher fecundity and host acceptance in T. pretiosum, and a better host-finding ability (walking speed, reaction to moth scales) in T. carverae. The suitability of the Trichogramma species for use as control agents is discussed with respect to these results.     

The efficacy and persistence of diatomaceous earths admixed with commodity against four tropical stored product beetle pests

The efficacy and persistence of two commercially available enhanced diatomaceous earth (DE) products (Dryacide^® and Protect-It^®) against four common tropical storage pests (Prostephanus truncatus, Sitophilus zeamais, Callosobruchus maculatus and Acanthoscelides obtectus) were studied when admixed with typical host commodities at different application rates and relative humidities. Persistence of the enhanced DE treatments was considered after 3 and 6 months storage by assessment of both adult mortality and F1 progeny emergence. Both DEs usually increased parental mortality and reduced progeny emergence of all four insect species in comparison with the untreated control at both 50% and 60% r.h., and at all storage periods. However, efficacy was inversely related to duration of storage and over time the host commodity also became less suitable for insect development. Each insect species differed in its susceptibility to the DE treatments, highlighting the need for field application rates to be based upon the entire spectrum of pest species likely to be present during storage.     

Fumigation toxicity of monoterpenoids to several stored product insects

Twenty naturally occurring monoterpenoids were evaluated in a preliminary fumigation screening test on some important stored-product pest insects, including the rice weevil, Sitophilus oryzae, the red flour beetle, Tribolium castaneum, the sawtoothed grain beetle, Oryzaephilus surinamensis, the house fly, Musca domestica, and the German cockroach, Blattella germanica. Cineole, l-fenchone, and pulegone at 50 μg/ml air caused 100% mortality in all five species tested. Ketone compounds were generally more toxic than other monoterpenoids. Three monoterpenoids, the ketones pulegone, l-fenchone, and the aldehyde perillaldehyde, were selected for further study. They were effective against T. castaneum in the fumigation assay; however the toxicity was relatively low in comparison to dichlorvos. LC₅₀ values of these three monoterpenoids tended to decrease at longer exposure times and higher temperatures. Inclusion of either maize kernels or house fly medium (HFM) increased LC₅₀ values, HFM more so than maize kernels. Monoterpenoids may be suitable as fumigants or vapor-phase insecticides because of their high volatility, fumigation efficacy, and their safety.     

The susceptibility of the immature and adult stages of Sitophilus granarius to phosphine

A concentration of 4 mg/l. of phosphine applied for 8 hr at 25°C permitted a considerable survival of the developmental stages of Sitophilus granarius (L.). Eggs of 3–4 days old were very tolerant and pupae even more so but larvae were very susceptible. A concentration of 1 mg/l. applied for 32 hr completely killed all stages except pupae. The most tolerant eggs were 2–4 days old. At 0·5 mg/l., pupae were again the most tolerant stage and eggs were most tolerant at 1–2 days old. At 0·3 mg/l. or less the majority of eggs were killed during the fifth day of development irrespective of their age at the start of fumigation, but over half were dead by 4 days old at 0·4 mg/l. and about a third survived beyond the sixth day at 0·05 mg/l. It is only at these latter concentrations at these ages that mortality of eggs was clearly related to dosage.

The physiological age range of pupae in samples was more dispersed. Pupae were most tolerant to phosphine at about 32 days old. From 5 to 7 days were needed for complete mortality at concentrations of 0·1–0·05 mg/l.

Adults were very susceptible to phosphine, all being killed by 8 hr at 1 mg/l. which permitted survival of some larvae. Freshly emerged adults were the most tolerant; older adults were very susceptible, at 1 month old being killed by 4 hr at 1 mg/l. and 3 days at 0·01 mg/l. Insects surviving fumigation as larvae or pupae usually laid fewer eggs than controls though their longevity was unaffected. Those surviving fumigation as eggs were not adversely affected. There is a possibility that some individuals surviving, as eggs or pupae, a fumigation causing very high mortality may lay more rapidly than controls.     

磷化氢对六种甲虫的抗性品系和敏感品系的发育未成熟的毒力与防治关系

<正> 试验用谷象、米象、谷蠹、锈赤扁谷盗、锯谷盗和赤拟谷盗6个品种甲虫的13个品系(有的叫小种)的各个发育期,在15℃和25℃温度下,置于密闭的熏蒸箱内熏蒸。其中已知7个品系的成虫对磷化氢抗性。结果发现除抗品系的成虫具有抗性外,其发育未成熟期即卵、幼虫、和蛹也具有抗性,在抗性品系甲虫的整个生活史中,抗性最大的是蛹。锯谷盗、赤拟谷盗、锈赤扁谷盗和谷蠹的敏感品系各发育期,在15℃和25℃温度下,密闭4天,可以控制,虽然其中后两者在15℃时的磷化氢剂量要高达2克/米~3,但相     

Effect of cultural factors on the development of four stored-product moths

Survival and developmental rate of Ephestia cautella, E. kuehniella, E. elutella and Plodia interpunctella in a constant food volume were improved by rearing in cultures of greater cross-sectional area, but not by increasing the depth of the food bulk in cultures of constant cross-sectional area. In cultures of similar shape and size, increase of the population density decreased percentage survival, at first gradually and then more sharply. Ephestia cautella was more sensitive than other species to crowding, and produced fewer moths in each type of culture. Development was delayed at population densities depressing percentage survival to 75% or below. In cultures of E. cautella reared at population densities of 4 or more larvae per cm², two peaks of emergence were observed, the second following the first by about 3 weeks and comprising up to 20% of the total population.Metabolic heating which was observed in densely populated 14 cm diameter cultures of all 4 species, raised the temperature by 4° to 7°C above ambient during the latter half of larval development. The highest temperatures were recorded near the centre of the culture at the food surface. Two temperature peaks were observed in cultures of E. kuehniella, the second corresponding with a downward movement of larvae. Adults emerging from cultures of E. kuehniella, in which maximum temperatures exceeded 30°C, proved fertile. The rapid temperature changes in cultures influenced humidity at the food surface.The temperature rise measured in cultures was proportional over a limited range to the logarithm of the initial number of insects added.When a thousand or more insects were present in cultures 14 cm in diameter, E. cautella produced a greater temperature rise than other species.     

Susceptibility of thirteen stored product beetles to entanglement by Trogoderma hastisetae

Factors affecting the susceptibility of adults of 13 and larvae of 2 species of stored product beetles to entanglement by Trogoderma larval hastisetae were studied. The length, diameter, shape, density, and angle of the test insects' setae probably affected susceptibility. The setae on the hindwings of Trogoderma adults were susceptible to permanent hastisetal attachment which prevented normal closure of elytra over the hindwings. Sitophilus oryzae (L) and Cryptolestes pusillus (Schönherr) were susceptible, with 93 and 83% mortality, respectively, at the end of 72 hr exposure. Tribolium castaneum (Herbst), T. confusum (duVal), Gibbium psylloides (Czenpinski), and Tenebroides mauritanicus (L.) resisted hastisetal attachment. Scanning electron micrographs revealed the attachments of heads of hastisetae to setae of several beetles exposed to larval Trogoderma.     

The effect of diapause on the tolerance of larvae of Ephestia kuehniella to methyl bromide and phosphine

Larvae from a stock of Ephestia kuehniella Zeller, recently collected from an unheated flour store in southern England, were exposed at 10 and 15°C to two fumigants commonly used for the control of this species in the U.K. Various exposure periods were tested and the mortality of larvae which had entered diapause was compared with that of non-diapausing larvae.

Diapause increased the tolerance of larvae to methyl bromide and phosphine at low temperatures. The minimum dosage of methyl bromide for complete control of diapausing larvae was about 80 mgh/l during a 20-h exposure period at 10°C and less than 70 mgh/l during a 16-h exposure at 15°C. Complete kill of diapausing larvae at 10°C was obtained after a 4-day exposure to phosphine with a CT product of 8.1 mgh/l, but a slighly higher dosage was required in a test at 15°C.     

Susceptibility of stored product insects to high concentrations of ozone at different exposure intervals

Ozone is a highly reactive gas with insecticidal activity. Past studies have indicated that ozone technology has potential as a management tool to control insect pests in bulk grain storage facilities. The objective of this study was to determine the efficacy of short periods of exposure to high ozone concentrations to kill all life stages of red flour beetle (Tribolium castaneum (Herbst)) (Coleoptera: Tenebrionidae), and Indianmeal moth (Plodia interpunctella (Hübner)) (Lepidoptera: Pyralidae), adult maize weevil (Sitophilus zeamais (Motsch.)) (Coleoptera: Curculionidae) and adult rice weevil (S. oryzae (L)) (Coleoptera: Curculionidae). Insects were treated with six ozone concentrations between 50 and 1800 ppm. The specific objective was to determine minimal time needed to attain 100% mortality. The most ozone-tolerant stages of T. castaneum were pupae and eggs, which required a treatment of 180 min at 1800 ppm ozone to reach 100% mortality. Eggs of P. interpunctella also required 180 min at 1800 ppm ozone to reach 100% mortality. Ozone treatments of 1800 ppm for 120 min and 1800 ppm for 60 min were required to kill all adult S. zeamais and adult S. oryzae, respectively. The results indicate that high ozone concentrations reduce the treatment times significantly over previously described results. Our results also provide new baseline information about insect tolerance to ozone treatment.     

美商经营幼儿玩具看重创意

美国玩具业界不少人士认为，推出有创意、能刺激感官和带科技元素的婴幼儿和青少年产品，能满足父母对娱乐与促进成长相结合的玩具的要求。而具有创意、又适应快节奏的幼儿玩具和电子玩具受到欢迎。[编者按]     

The effects of temperature on flight initiation in a range of moths, beetles and parasitoids associated with stored products

The effects of temperature on flight initiation in a range of stored-product pests and their parasitoids have been studied in laboratory flight chambers. Tests were conducted between 10 and 32.5 °C at intervals of 2.5 °C. The minimum temperatures for flight initiation in the stored-product moths Ephestia kuehniella, E. elutella and Plodia interpunctella were in the range 12.5-15 °C. For the stored-grain beetles, minimum temperatures for flight initiation varied from 17.5 °C for Ahasverus advena and Typhaea stercorea, 20 °C for Rhyzopertha dominica, 25 °C for Tribolium castaneum, to 27.5 °C for Sitophilus oryzae. The minimum temperature for flight initiation in the hymenopteran parasitoids, Anisopteromalus calandrae and Lariophagus distinguendus, was 17.5 °C. Flight is discussed as a factor in sustainable pest management strategies for storage insects; its importance in the spread of infestation and the likely success of physical and biological control methods is highlighted.     

Action of amorphous diatomaceous earth against different stages of the stored product pests Tribolium confusum, Tenebrio molitor, Sitophilus granarius and Plodia interpunctella

Environmental and human health problems associated with the use of synthetic pesticides have prompted the demand for non-polluting, biologically specific insecticides. The current study tested the use and action of diatomaceous earth against several stored product pests. Fossil Shield(R) applied to wooden plates was lethal to adult Tenebrio molitor and Tribolium confusum, but larvae of the mealworm were unaffected. Beetles died within 14 days exposure in the absence of food to a dose of 2 and 4 g/m(2), but mortality was reduced in those fed grain bran. Fossil Shield(R) was lethal to first instar larvae of Plodia interpunctella, but not lethal to older larval stages. Two-week old larvae of T. confusum were more sensitive to diatomaceous earth than P. interpunctella at the same age. Contact with diatomaceous earth caused adult Sitophilus granarius, T. molitor and T. confusum to lose weight and reduced their water content, suggesting disruption of "the water barrier". Death of stored product insects treated with diatomaceous earth decreased with increased r.h., due to reduced transpiration through the cuticle. High r.h. delays, or above 60% can prevent, the drying action of diatomaceous earth.     

Tolerance of the diapausing stages of four species of Lepidoptera to methyl bromide

The diapausing stages exposed to methyl bromide were larvae of Ephestia elutella (Hübner) and Plodia interpunctella (Hübner), pupae of Pieris brassicae (L.) and eggs of Bombyx mori (L.). Diapausing larvae of Ephestia elutella were highly tolerant, a few surviving to the adult stage after exposure to concentration-time (CT) products of up to 150 mg hr/l at 25°C and 260 mg hr/l at 15°C. Diapausing larvae of Plodia interpunctella were tolerant at low temperatures but quite susceptible at 25°C. In both species, larvae in diapause were four to six times more tolerant than other larvae at 15°C or below, and strains recently collected from the field were more tolerant than laboratory reared stocks.In E. elutella, differences in the method of induction, maintenance or termination of diapause did not affect tolerance to fumigation. P. interpunctella larvae reared at high population density were more susceptible than those reared at low density. Among strains of these species, a correlation was observed between the duration of larval diapause and tolerance to methyl bromide. Adults emerging after fumigation of diapausing larvae were of lowered fertility but rarely sterile. The CT products required for the complete control of moths in diapause were higher than those currently recommended for the disinfestation of stored products.Diapausing pupae of an outdoor species Pieris brassicae required the very high CT product of 403 mg hr/l for complete control at 25°C and were at least six times more tolerant than non-diapausing pupae. Diapausing eggs of Bombyx mori required 179 mg hr/l for complete control, while non-diapausing eggs were all killed by 125 mg hr/l.     

Toxicity of phosphine to the diapausing stages of Ephestia elutella, Plodia interpunctella and other lepidoptera

Diapausing larvae of the stored product moths Ephestia elutella (Hübner) and Plodia interpunctella (Hübner) were tolerant of phosphine only in short exposures, the tolerance of E. elutella being at least twice that of P. interpunctella. The tolerance of a freshly collected wild stock of each species was, at some temperatures, about two or three times that in a laboratory reared stock. The wild stock of E. elutella required concentration-time (CT) products of 36 mg hr/l in 4-day exposures at 10° and 15°C, and 18 mg hr/l in 2-day exposures at 20°C and above for 100% kill. The tolerance of E. elutella larvae in diapause was not dependent on the manner in which diapause was induced, maintained or subsequently terminated. Longer exposures to phosphine were more effective than shorter ones of similar CT product because an initial period of about a day in each exposure was required for insects in diapause to be killed. At 25°C, a concentration of 0.03 mg/l was below the threshold level for mortality of some larvae, long exposures at such very low concentrations proving ineffective.

Diapausing pupae of an outdoor species, Pieris brassicae (L.), and eggs of the univoltine race of Bombyx mori (L.) were highly tolerant of phosphine at 10°C.