Sexual transfer of prostaglandin precursor in the field cricket, Teleogryllus commodus

ABSTRACT. When injected into the haemolymph of newly emerged adult males of the field cricket, Teleogryllus commodus (Walker), [³H]arachidonic acid is incorporated into tissue phospholipids. Two reproductive tissues, testes and accessory glands, incorporate and preserve the labelled arachidonic acid for at least 49 days. With onset of circadian rhythm-controlled spermatophore production, radioactive arachidonic acid is incorporated into spermatophore phospholipids. After mating with untreated females, radioactivity was detected in spermathecae and in haemolymph from females. Some of the transferred radioactive arachidonic acid is subsequently converted into prostaglandins. Hence, males of T. commodus transfer prostaglandin synthetase activity and substrate by way of spermatophores during mating     

Egg-laying in response to prostaglandin injections in the Australian field cricket, Teleogryllus commodus

ABSTRACT. We report the effects of prostaglandin (PG) injection on egg-laying by sexually mature virgin crickets, Teleogryllus commodus Walker. High egg-laying activity is associated with PGE₁ PGE₂, 6-keto-PGE₁ and 15-keto-PGE₂, compounds that share the basic prostanoid backbone (C20 substituted fatty acid, 5 membered ring, a 7- and an 8-carbon aliphatic chain), and 9-keto, 11-hydroxyl ring substitutions. PGs without these ring features and other compounds that lack the prostanoid backbone have no or only intermediate egg-laying effects. Adding oxygen functionalities or an aliphatic double bond tends to increase egg-laying activity. Hence, 15-keto-PGF₂ and TxB₂, both of which have an additional backbone oxygen compared with their less active analogues, are highly active compounds. Two of the most active PGs, 15-keto-PGE₂ and 15-keto-PGE_2α, are the products of inactivating metabolism in mammalian systems, describing a fundamental difference in PG biochemistry with respect to mammals and insects.     

Do female black field crickets Teleogryllus commodus benefit from polyandry?

Female insects that mate multiply tend to have increased lifetime fitness, apparently because of greater access to male-derived resources (e.g. sperm, nuptial gifts) that elevate fertility/fecundity. Experiments that standardize the number of matings per female also show that polyandry can improve aspects of offspring performance, most notably early embryo survival (egg hatching success). This improvement is widely attributed to genetic benefits which would arise if polyandrous females skew paternity to produce fitter offspring. In two separate experiments with field crickets (Teleogryllus commodus) polyandrous females (two, three or four mates) did not have higher egg hatching success than monandrous females (effect sizes: r = 0.03 and 0.08 for the respective experiments), which is consistent with our finding of no sire effect on hatching success. Polyandry also had no effect on post-hatching offspring survival. Polyandrous females' offspring took significantly longer to mature but their sons were not heavier and their daughters were actually significantly smaller than those of monandrous females. Finally, after controlling for relative male size, monandrous females' sons were more successful when directly competing for a mate.     

A survey for pathogens of the black field cricket, Teleogryllus commodus, in the Western District of Victoria,Australia

A pathogen survey of the black field cricket, Teleogryllus commodus, in the Western District of Victoria, Australia, during 1979 revealed that cricket paralysis virus (CrPV) was present in 42.7% of the 232 sites sampled. The fungus Metarhizium anisopliae was detected in 5.2% of the sites and represents a new pathogen record for T. commodus. The distribution of both pathogens throughout the sites sampled appeared to be random. There was a positive correlation between sample size and the likelihood of detecting a pathogen, while analysis showed that approximately 30% of the sites were probably virus free. The results are discussed in terms of the potential of CrPV and M. anisopliae as biological control agents for the black field cricket.     

Acoustically-orienting parasitoids in calling and silent males of the field cricket Teleogryllus oceanicus

Abstract.

• 1 On three Hawaiian Islands, the introduced Australasian field cricket Teleogryllus oceanicus Le Guillou (Orthoptera: Gryllidae) was found to be attacked by the phonotactic parasitoid tachinid fly, Ormia ochracea Bigot.
• 2 Noncalling males occurred with callers in all locations, but silent males were more heavily parasitized than callers.
• 3 Body size was unrelated to both calling status and the likelihood of harbouring parasitoid larvae.
• 4 An experiment examining the likelihood of calling in the laboratory by males collected as silent or calling individuals showed no difference between the two classes of males, after accounting for parasitoid levels; males harbouring larvae were less likely to call.

     

Sensitivity of wild and genetic sexing strain Ceratitis capitata to high-temperature disinfestation of Valencia oranges

Abstract:  The purpose of this research was to investigate post-harvest heat treatment of Valencia oranges as an effective disinfestation protocol (fast, no fruit damage) for the Mediterranean fruit fly Ceratitis capitata (Wiedemann). Forced high-temperature air was applied under the following conditions: (a) exposure to air temperature of 56°C, for fast increase of temperature in the interior of the fruit, (b) reduction in air temperature to 47°C when the fruit centre reached 47°C and (c) maintenance of fruits in the chamber for another 30 min. Relative humidity in the treatment chamber was kept between 50% and 65% during treatment. Forced air at 47°C applied for 30 min on eggs before hatch or late third instar larvae (the most heat-tolerant stages) resulted in complete kill. Egg and larval sensitivity to high temperature differed between a wild strain and a laboratory genetic-sexing strain based on white pupa mutation. In this strain males emerge from brown pupae and females from white pupae. In particular, mature eggs from the wild strain were significantly more temperature resistant than eggs from the laboratory strain. Exposure of Valencia oranges of a diameter of 7–7.5 cm to 56°C forced air for about 86 and 99 min was required to increase temperature to 47°C at 1.5 cm depth and the fruit centre respectively. Treated oranges showed no substantial peel or interior deterioration, or change in colour and taste when kept at 25°C and 50–60% RH for a period of up to 1 month following treatment. Treatment in 1% O₂ atmosphere, produced by flushing of CO₂ into the treatment chamber, resulted in about 1°C reduction in killing temperature and faster increase in temperature inside the fruit to a lethal level.     

Diet, sex, and death in field crickets

Senescence is shaped by age-dependent trade-offs between fitness components. Because males and females invest different resources in reproduction, the trade-offs behind age-dependent reproductive effort should be resolved differently in the sexes. In this study, we assess the effects of diet (high carbohydrate and low protein vs. equal carbohydrate and protein) and mating (once mated vs. virgin) on lifespan and age-dependent mortality in male and female field crickets (Teleogryllus commodus), and on male calling effort. Females always had higher actuarial ageing rates than males, and we found a clear lifespan cost of mating in females. Mated males, however, lived longer than virgin males, possibly because virgins call more than mated males. The fastest age-dependent increases in mortality were among mated males on the high-carbohydrate diet. Males on a high-carbohydrate diet showed a faster increase in calling effort earlier in life, and a more pronounced pattern of senescence once they reached this peak than did males on a diet with equal amounts of protein and carbohydrates. Our results provide evidence that the cost of mating in this cricket species is both diet and sex-dependent, and that the underlying causes of sex differences in life-history traits such as lifespan and senescence can be complex.     

Sounds different: inbreeding depression in sexually selected traits in the cricket Teleogryllus commodus

If male sexual signalling is honest because it captures genetic variation in condition then traits that are important mate choice cues should be disproportionately affected by inbreeding relative to other traits. To test this, we investigated the effect of brother-sister mating on advertisement calling by male field crickets Teleogryllus commodus. We quantified the effect of one generation of inbreeding on nightly calling effort and five finer-scale aspects of call structure that have been shown to influence attractiveness. We also quantified inbreeding depression on six life history traits and one morphological trait. Inbreeding significantly reduced hatching success, nymph survival and adult lifespan but had no detectable effect on hatching rate, developmental rate or adult body mass. The effect of inbreeding on sexually selected traits was equivocal. There was no decline in calling effort (seconds of sound production/night) by inbred males, but there were highly significant changes in three of five finer-scale call parameters. Sexually selected traits clearly vary in their susceptibility to inbreeding depression.     

温度对蟋蟀若虫生长发育的影响

澳洲黑蟋蟀Teleogryllus commodusWalker若虫在22℃下,有9个龄期,在28℃下,只有8个龄期。若虫在22℃和28℃的平均历期分别是159d和79d,并且若虫胸部和腹部相对于头部的生长速率在低温条件下均小于高温条件下的若虫。     

Circadian locomotory rhythm and the influence of moulting in Australian field cricket nymphs

ABSTRACT. Evidence is presented for a circadian control of locomotory activity in the larval stadia of the cricket, Teleogryllus commodus Walker. Under light—dark cycles (LD), maximal activity occurs around the L/D transition and/or in the hours preceding it. Free-running rhythm patterns longer than 24 h are observed in constant light. Re-entrainment to phase advances in the LD cycle is also accompanied by several transient cycles. However, free-running rhythms under constant darkness or transients when exposed to LD cycle delays were not found. LD cycles during the eighth stadium set the phase of a free-running rhythm in the adult, even if the nymph does not show a rhythm. Nymphal activity is often erratic and is disrupted periodically by the moulting cycle, but moulting does not interrupt the operation of the circadian system. The daily timing of the moult itself is not under circadian control.     

Effect of carbon dioxide on the Oriental cockroach Blatta orientalis

Exposure to high concentrations of carbon dioxide (CO2) killed adult and nymphal stages of the oriental cockroach Blatta orientalis L. (Dictyoptera: Blattidae) with LT50 values of 11.5-16.2 h for 60% CO2 in air and 5.7-7.1 h for 100% CO2 at 20 degrees C; corresponding LT50s at 28 degrees C were 2.8-4.6 h for 60% CO2 in air and 2.3-3.6 h for 100% CO2. Complete kill of mobile stages was obtained within 24 h using 60% CO2 at 20 degrees C. Survivors of treatments with 100% CO2 at 28 degrees C remained completely paralysed for up to 3 days post-treatment and took up to 5 days to regain normal movement, but adult females then resumed production of oothecae with no significant loss in fecundity. Oothecae 5 or 30 days after deposition required 60-84 h exposure to 60% CO2 at 20 degrees C to prevent emergence of nymphs but less time using 100% CO2 at 28 degrees C. At 28 degrees C, when adult females were treated with 100% CO2 and 52% r.h. for 6 h (giving 100% mortality) loss of weight was significantly greater than that following treatment with air at 52% r.h. for 6 h (giving no mortality). However, significantly greater weight loss also occurred when they were treated with dried air (< 10% r.h.) for 6 h, also with no mortality. The toxicity of CO2 to mobile stages of the oriental cockroach appeared to result from irreversible effects on the nervous system, rather than from water loss during exposure.     

Reduced reproductive effort in male field crickets infested with parasitoid fly larvae

Some populations of the field cricket Teleogryllus oceanicusare parasitized by the phonotactic fly Ormia ochracea. Flieslocate crickets by their song and deposit larvae onto them.The larvae develop inside the cricket for 1 week before killingthe host upon emergence. The reproductive compensation hypothesispredicts that parasitized crickets should increase their reproductiveeffort during the initial stages of infestation to offset theloss of fitness resulting from their shortened life span. An alternative hypothesis predicts that parasitized crickets willdecrease reproduction, either because they are unable to reproduceor because selection acting on the parasitoid favors decreasedhost reproduction. In laboratory experiments, parasitized malecrickets had reduced reproductive effort (spermatophore production,calling, mating activity, and mass allocated to reproductivetissue) compared to unparasitized males. Parasitized males fedad libitum showed no evidence of allocating a greater proportionof their resources to reproduction. Parasitized and healthymales did not differ significantly in resting or maximal metabolicrates, although this may have been due to the substantial contributionof larval respiration to the metabolic rate of the host—parasitoidcomplex. These results are consistent with previous studiesand suggest that T. oceanicus males parasitized by O. ochraceado not increase their reproductive effort. We discuss potentialreasons that crickets do not increase reproductive effort inresponse to fly larvae and address difficulties in demonstratingaltered life-history patterns in response to parasitism.     

Variation in paternity in the field cricket Teleogryllus oceanicus: no detectable influence of sperm numbers or sperm length

Recent attention has focused on the role that sperm competitionmay play in the evolution of sperm morphology. Theoretical analysespredict increased sperm size, decreased sperm size, and no changein sperm size in response to sperm competition, depending onthe assumptions made concerning the life history and functionof sperm. However, although there is good evidence that spermmorphology varies widely within and between species, the adaptivesignificance of this variation has not been examined. Here wedocument significant intraspecific variation in sperm lengthin the field cricket, Teleogryllus oceanicus. Sperm length didnot influence the rate of migration of sperm from the spermatophoreto the female's spermatheca. We performed sperm competitiontrials in which we varied the numbers of sperm transferred byeach of two males that differed in the length of sperm theyproduced. Neither sperm length nor the number of sperm transferredinfluenced paternity. The same results were obtained using twodifferent methods for assigning paternity. The distributionof paternity across a female's mates was highly variable, withfrequently one, or more in the case of females mated to fourmales, principal sire. There were no mating order effects onpaternity. These data show that sperm do not mix randomly inthe female's spermatheca. We discuss several alternative explanationsfor the patterns of paternity observed.     

Populations of North American bean thrips, Caliothrips fasciatus (Pergande) (Thysanoptera: Thripidae: Panchaetothripinae) not detected in Australia

Abstract  Caliothrips fasciatus is native to the USA and western Mexico and overwintering adults are regular contaminants in the 'navel' of navel oranges exported from California, USA to Australia, New Zealand and elsewhere. Due to the long history of regular interceptions of C. fasciatus in Australia, a survey for this thrips was undertaken around airports, seaports, public recreational parks and major agricultural areas in the states of Queensland, New South Wales, Victoria, South Australia and Western Australia to determine whether C. fasciatus has successfully invaded Australia. Host plants that are known to support populations of C. fasciatus , such as various annual and perennial agricultural crops, urban ornamentals and weeds along with native Australian flora, were sampled for this thrips. A total of 4675 thrips specimens encompassing at least 76 species from a minimum of 47 genera, and three families were collected from at least 159 plant species in 67 families. Caliothrips striatopterus was collected in Queensland, but the target species, C. fasciatus , was not found anywhere. An undescribed genus of Thripidae, Panchaetothripinae, was collected from ornamental Grevillea (var. Robyn Gordon) at Perth (Western Australia) Domestic Airport, and is considered to be a native Australian species. This survey has provided valuable information on the background diversity of thrips species associated with various native and exotic plant species around major ports of entry and exit for four of five states in Australia. We suggest that the major reason C. fasciatus has not established in Australia is due to high adult mortality in navels that are kept at low storage temperatures (2.78°C) during an 18- to 24-day transit period from California to Australia.     

Susceptibility of western flower thrips, Frankliniella occidentalis (Pergande) to fumigation with methyl bromide

All life stages of the western flower thrips (Frankliniella occidentalis Pergande) were tested for their response to the fumigant methyl bromide and dose response curves were established. Pseudo-pupae were the most tolerant stage with a calculated LD99 of 53.1 mg litre“¹ h at 15^oC with a gas concentration of 13.5 mg litre”¹, but no survivors were found in any test above a concentration time product of 40 mg litre“¹ h. Standard 4 h fumigations achieving a CTP of 54 mg litre”¹ h that are used to control other pests are therefore likely to give very high levels of control of western flower thrips.