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Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a highly polyphagous herbivore. This research was conducted to compare the development of B. tabaci reared in a multi-plant treatment (polyculture) with those in single-plant treatments (monocultures). Adult B. tabaci females fed on a mixture of tomato, cabbage, cotton, cucumber, and kidney bean survived longer and laid more eggs than those fed exclusively on one of these plant species. Egg numbers per plant laid in the polyculture treatment were positively correlated with those laid on the same plant species in the monoculture treatments, and egg numbers per plant laid on tomato, cotton, and cucumber in the polyculture were significantly higher than those laid on the same plants in the monocultures. Concentrations of total protein and trehalose in B. tabaci were not significantly different after 7 days of feeding in the respective treatments, but activities of superoxide dismutases (SOD) and alkaline phosphatase (AKP) of B. tabaci in polyculture were lower than those in monoculture. Conversely, activities of trehalase, sucrase, and amylase in B. tabaci kept in polyculture were higher than those of insects from the monoculture. In each of the monoculture treatments, there was a negative correlation between AKP in B. tabaci and oviposition, and also between AKP and amylase. SOD and sucrase activities in B. tabaci were positively correlated with polyphenol oxidase (PPO) and peroxidase (POD) activities in plants. In the plants damaged by whiteflies in the polyculture treatment, activities of SOD in cucumber, PPO in cotton and kidney bean, and POD in tomato and cucumber were lower than those in the monoculture treatments, whereas SOD in cabbage and catalase (CAT) in tomato in the polyculture treatment were higher than those in the monoculture treatments.

BACKGROUND Control of pests in stored grain and the evolution of resistance to pesticides are serious problems worldwide. A stochastic individual-based two-locus model was used to investigate the impact of two important issues, the consistency of pesticide dosage through the storage facility and the immigration rate of the adult pest, on overall population control and avoidance of evolution of resistance to the fumigant phosphine in an important pest of stored grain, the lesser grain borer. RESULTS A very consistent dosage maintained good control for all immigration rates, while an inconsistent dosage failed to maintain control in all cases. At intermediate dosage consistency, immigration rate became a critical factor in whether control was maintained or resistance emerged. CONCLUSION Achieving a consistent fumigant dosage is a key factor in avoiding evolution of resistance to phosphine and maintaining control of populations of stored-grain pests; when the dosage achieved is very inconsistent, there is likely to be a problem regardless of immigration rate. © 2012 Society of Chemical Industry

Increasing resistance to phosphine (PH 3) in insect pests, including lesser grain borer (Rhyzopertha dominica) has become a critical issue, and development of effective and sustainable strategies to manage resistance is crucial. In practice, the same grain store may be fumigated multiple times, but usually for the same exposure period and concentration. Simulating a single fumigation allows us to look more closely at the effects of this standard treatment.We used an individual-based, two-locus model to investigate three key questions about the use of phosphine fumigant in relation to the development of PH 3 resistance. First, which is more effective for insect control; long exposure time with a low concentration or short exposure period with a high concentration? Our results showed that extending exposure duration is a much more efficient control tactic than increasing the phosphine concentration. Second, how long should the fumigation period be extended to deal with higher frequencies of resistant insects in the grain? Our results indicated that if the original frequency of resistant insects is increased n times, then the fumigation needs to be extended, at most, n days to achieve the same level of insect control. The third question is how does the presence of varying numbers of insects inside grain storages impact the effectiveness of phosphine fumigation? We found that, for a given fumigation, as the initial population number was increased, the final survival of resistant insects increased proportionally. To control initial populations of insects that were n times larger, it was necessary to increase the fumigation time by about n days. Our results indicate that, in a 2-gene mediated resistance where dilution of resistance gene frequencies through immigration of susceptibles has greater effect, extending fumigation times to reduce survival of homozygous resistant insects will have a significant impact on delaying the development of resistance. © 2012 Elsevier Ltd.

In this article, we describe and compare two individual-based models constructed to investigate how genetic factors influence the development of phosphine resistance in lesser grain borer (R. dominica). One model is based on the simplifying assumption that resistance is conferred by alleles at a single locus, while the other is based on the more realistic assumption that resistance is conferred by alleles at two separate loci. We simulated the population dynamic of R. dominica in the absence of phosphine fumigation, and under high and low dose phosphine treatments, and found important differences between the predictions of the two models in all three cases. In the absence of fumigation, starting from the same initial frequencies of genotypes, the two models tended to different stable frequencies, although both reached Hardy–Weinberg equilibrium. The one-locus model exaggerated the equilibrium proportion of strongly resistant beetles by 3.6 times, compared to the aggregated predictions of the two-locus model. Under a low dose treatment the one-locus model overestimated the proportion of strongly resistant individuals within the population and underestimated the total population numbers compared to the two-locus model. These results show the importance of basing resistance evolution models on realistic genetics and that using oversimplified one-locus models to develop pest control strategies runs the risk of not correctly identifying tactics to minimise the incidence of pest infestation.

A mite which is polyphagous, widespread and abundant should be relatively easy to rear. However, mass rearing redlegged earth mite, Halotydeus destructor, for use in screening plants for resistance, has been very difficult. They are found in regions of Australia with winter growing annual crops and pastures, where they are active in winter and have a summer diapause. Mites are field collected in winter for screening, but cold storage only improves availability by 2 weeks. If mites are held in controlled climate cabinets under winter conditions with short daylength, the onset of diapause is not triggered and egg laying continues. Host plant suitability is a key factor affecting the rate of multiplication of mites, and common vetch, Vicia sativa cv Blanchefleur is an optimum host for rearing. The mites spend 90% of the time on the soil surface and only climb to the upper plant canopy in pastures to feed for 10% of the time. They are thus earth mites. High humidity at the soil surface is very important for their survival and optimal multiplication. If it is too wet dead mites on the surface are attacked by verticillium fungus, and active mites are adversely affected by hyphae. Mite multiplication is greater on well-drained sandy loam soil than a loamy soil, sand or pure loam as a substrate. Mass rearing has now been achieved after overcoming these problems.

The Australian Entomological Society was founded in 1965 and provides a journal of world-class and annual scientific meetings for members. The world-wide impact of entomology publications is growing faster than that of the Australian Journal of Entomology, and membership of the society is declining slowly. In a recent survey members were generally happy with the society, but much of the exciting research involving insects is probably being published in specialist journals. Challenges identified for the future include building membership through greater connection with amateur entomologists and with students interested in ecology and insects. The growth area for entomology is seen to be in the application of insect biodiversity to the sustainable management of Australia's ecosystems. This special issue of the journal includes 10 papers illustrating the breadth and depth of entomology in the society.

Halotydeus destructor feeding on subterranean clover cotyledons can cause severe damage. The mites live on the soil surface and move up onto plants to feed. Foraging behaviour consists of palpating, probing, and feeding with frequent transitions between them. Sustained feeding is made up of a series of short (1–2 min) feeds separated by periods of palpating. The mites tend to feed in aggregations, and are attracted to cotyledons damaged by other mites feeding or by mechanical damage. Mites can distinguish between resistant and susceptible cotyledons within 30 min and resistance is antixenotic due to deterrence. Study of the mechanisms shows this to be induced plant resistance. Several green leaf volatiles are involved in the plant/mite interaction. After feeding commences, 2-E-hexenal is released that at low concentrations is attractive to mites, perhaps causing the feeding aggregations. The wound-induced C8 compound, 1-octen-3-one, plays a significant role in the deterrence of cotyledons of resistant subterranean clover varieties to H. destructor. Damaged cotyledons of resistant varieties produce more 1-octen-3-one that those of susceptible varieties. Screening for resistance has identified varieties from Italy showing resistance. H. destructor does not occur in Europe. Production of damage-induced volatiles by the resistant plants may have resulted from invasion by herbivores or pathogens, but not from coevolution with these mites. The responses of H. destructor are probably an adaptation to these general plant defensive compounds. Arch. Insect Biochem. Physiol. 51:170–181, 2002. © 2002 Wiley-Liss, Inc.

The feeding behavior of cowpea aphid, Aphis craccivora Koch (Hoinoptera: Aphididae) was examined on seedlings of narrow leafed lupin, Lupinus angustifolius L., and yellow lupin. L. luteus L., using electronic monitoring of insect feeding behavior (EMIF). Aphid feeding behavior was first compared between resistant (cv. Kalya) and susceptible (cv. Tallerack) varieties of narrow-leafed lupin. Aphids spent significantly more time in non penetration and stylet pathway activities, and significantly less time in the sieve element phase on Kalya than on Tallerack, suggesting that feeding deterrence is an important component of aphid resistance in Kalya. Aphid feeding on a susceptible yellow lupin variety (cv. Wodjil) was then compared with that on two resistant lines, ones (Teo) with high and the other (94D024-1) with low seed alkaloid content. There were no consistent differences in aphid feeding behavior between Wodjil and Teo. Total, mean and percentage sieve element phase times were significantly lower, and total and percentage times in non-phloem phase were greater on 94D024-1 than on Wodjil. suggesting the possibility of phloem-based deterrence in 94D024-1.

The volatile compounds produced by the leaves of Trifolium glanduliferum , T. strictum and T. subterraneum were collected by trapping on Tenax TA adsorbent and the major components were identified by GC–MS. The volatiles obtained from T. glanduliferum and T. strictum were shown to deter the redlegged earth mite ( Halotydeus destructor ) from feeding, whereas those from T. subterraneum did not. β-Ionone and coumarin, detected in the volatiles of T. glanduliferum , T. strictum , showed strong deterrent activity at 100 ppm. Phenylethanol, a component of the volatiles of T. strictum , was inactive.

Host plant acceptance behavior of redlegged earth mites (Halotydeus destructor) on cotyledons of subterranean clover (subclover) lines was investigated in the laboratory. Sustained feeding consisted of a series of short bouts of feeding; rather than one long period of feeding. H. destructor preferred to feed at mite-damaged rather than undamaged sites on cotyledons. With time the numbers of mites feeding in aggregations increased, as mites were attracted to damaged patches. Most feeding occurred in aggregations, and mites in such groups benefited by greater weight gain. The sequence of foraging leading to feeding was similar between subclover lines, however, feeding and aggregation activities were markedly reduced on a resistant line. Host plant acceptance occurred during probing but only after some feeding had occurred.

The impacts of infestation by the green peach aphid (Myzus persicae) on sweetpotato whitefly (Bemisia tabaci) settling on tomato were determined in seven separate experiments with whole plants and with detached leaves through manipulation of four factors: durations of aphid infestation, density of aphids, intervals between aphid removal after different durations of infestation and the time of whitefly release, and leaf positions on the plants. The results demonstrated that B. tabaci preferred to settle on the plant leaves that had not been infested by aphids when they had a choice. The plant leaves on which aphids were still present (direct effect) had fewer whiteflies than those previously infested by aphids (indirect effect). The whiteflies were able to settle on the plant which aphids had previously infested, and also could settle on leaves with aphids if no uninfested plants were available. Tests of direct factors revealed that duration of aphid infestation had a stronger effect on whitefly landing preference than aphid density; whitefly preference was the least when 20 aphids fed on the leaves for 72 h. Tests of indirect effects revealed that the major factor that affected whitefly preference for a host plant was the interval between the time of aphid removal after infestation and the time of whitefly release. The importance of the four factors that affected the induced plant defense against whiteflies can be arranged in the following order: time intervals between aphid removal and whitefly release > durations of aphid infestation > density of aphids > leaf positions on the plants. In conclusion, the density of aphid infestation and time for which they were feeding influenced the production of induced compounds by tomatoes, the whitefly responses to the plants, and reduced interspecific competition.

Control of pests in stored grain and the evolution of resistance to pesticides are serious problems worldwide. A stochastic individual-based two-locus model was used to investigate the impact of two important issues, the consistency of pesticide dosage through the storage facility and the immigration rate of the adult pest, on overall population control and avoidance of evolution of resistance to the fumigant phosphine in an important pest of stored grain, the lesser grain borer.A very consistent dosage maintained good control for all immigration rates, while an inconsistent dosage failed to maintain control in all cases. At intermediate dosage consistency, immigration rate became a critical factor in whether control was maintained or resistance emerged.Achieving a consistent fumigant dosage is a key factor in avoiding evolution of resistance to phosphine and maintaining control of populations of stored-grain pests; when the dosage achieved is very inconsistent, there is likely to be a problem regardless of immigration rate.

Beetles make up one quarter of all described animal species, with over 300,000 named species of Coleoptera, making them themost speciose taxon on planet earth (Hunt et al., 2007). One of the larger groups is the Scarabaeoidea, with approximately 35,000 known species including the stag beetles, the scarabs and the dung beetles (Scarabaeinae) (Hunt et al., 2007). Currently there are 6,000 known species and 257þ genera of dung beetles distributed across every continent on earth with the sole exception of Antarctica (Chapter 2). What better taxon could there be for the study of biodiversity, and the evolutionary and ecological processes that generate that biodiversity? Given their abundance and species richness, it is little wonder that dung beetles have attracted significant attention both from early naturalists and contemporary scientists. As we shall see throughout this volume, the unique biology of dung beetles makes them outstanding empirical models with which to explore general concepts in ecology and evolution. The extreme diversity of beetles generally appears due to the early origin, during the Jurassic period (approx. 206–144 million years ago) of numerous lineages that have survived and diversified into a wide range of niches (Hunt et al., 2007). In Chapter 2 Keith Phillips reviews our current understanding of the phylogenetic history of the dung beetles, which seem to have appeared during the Mesozoic era (around 145million years ago), in the region ofGondwana that would later become Southern Africa.

Insect pests are estimated to cause losses of 16% to world attainable crop production with post-harvest losses another 10%, in spite of widespread use of pesticides. Losses due to pests have been estimated for key rainfed crops in different regions of the world. Pest species attack every phenological stage of crop growth; sometimes they are the same species and sometimes different. No one tool can be used to successfully control a pest; integrated pest management principles have been widely adopted and include determining the economic threshold at which control is cost effective. Chemical control is widely used but excessive use can cause resistance in the insect and adverse environmental effects. The enhancement of use of natural enemies of pest insects, and use of crop cultivars resistant to the insects are both very important. Crop management practices used to reduce the impact of pests include crop rotations, intercropping, sowing rates, sowing time and soil tillage. Management of pests requires growers to understand the interactions between the pests and crops in their regions and to use the most appropriate tools to reduce the potential damage. While no one system would be applicable to a crop or to a pest in all rainfed farming systems, some general principles are relevant across regions.

Publisher Summary This chapter discusses the reproductive behavior, evolution, and evolution-level patterns of dung beetles. Dung beetles are medium to large-sized beetles, which are specialized to feed and breed on an ephemeral and discrete food resource, consisting mainly of the piles of dung produced by herbivorous warm-blooded animals. There are about 5000 species in the subfamily Scarabaeinae. The behavior for which the dung beetle is best known is the removal of dung from the pat and compaction in tunnels in the ground as provisioning for their offspring. The reproductive behaviors of tunneling and rolling are associated with characteristic body morphologies. Rollers often have elongated hind limbs for pushing the ball along the substrate. But perhaps the most striking morphological adaptations occur in the tunnelers, where males, and sometimes also females, have enlarged horns located on various regions of the body.

Two new isoflavonols (1, 2) with insect antifeedant activity have been isolated from the trifoliates of Trifolium subterraneum (Leguminosae). The structures of the compounds were determined by spectroscopic analyses. In addition, oct-1-en-3-yl arabinopyranosyl-(1→6)-β-glucopyranoside (3), a new metabolite, and phaselic acid (4), previously obtained from Trifolium repens, were isolated and characterized.

A prediction for the onset of a summer diapause in the eggs of the redlegged earth mite, Halotydeus destructor , was developed for Australia. In this species diapause eggs pass the summer in the cadavers of adult female mites. Adult female mites were collected for several weeks from pastures in spring at 18 sites in south-western Australia and dissected to determine the timing of the production of diapause eggs. Some sites were sampled for several years between 1990 and 1997. A model was developed to predict the time for onset of diapause. The week at which 90% of eggs were in diapause was predicted best by daylength (80.1% of the variability), then by duration of the long-term plant growing season (10.4%, of variability), leaving 9.5% due to other factors. A single chemical spray in spring 2 weeks before the production of 90% diapause eggs resulted in 99% fewer mites present in autumn 7–8 months later at three sites. The timing of the spring spray was the factor leading to successful control. This model was tested at 17 sites across the whole geographical distribution of the redlegged earth mite in Australia between 1998 and 2001. The observed week of 90% diapause was within 1 week of the predicted week on 81% of occasions, and 2 weeks earlier on 15% of occasions. A database was created for the predicted date of onset of 90% diapause for the whole distribution of the redlegged earth mite in southern Australia on a 10 km 2 grid. Australian farmers are using this for timing a spring spray to control mites in the following autumn.

We have examined a number of statistical issues associated with methods for evaluating different tests of density dependence. The lack of definitive standards and benchmarks for conducting simulation studies makes it difficult to assess the performance of various tests. The biological researcher has a bewildering choice of statistical tests for testing density dependence and the list is growing. The most recent additions have been based on computationally intensive methods such as permutation tests and boot-strapping. We believe the computational effort and time involved will preclude their widespread adoption until: (1) these methods have been fully explored under a wide range of conditions and shown to be demonstrably superior than other, simpler methods, and (2) general purpose software is made available for performing the calculations. We have advocated the use of Bulmer's (first) test as a de facto standard for comparative studies on the grounds of its simplicity, applicability, and satisfactory performance under a variety of conditions. We show that, in terms of power, Bulmer's test is robust to certain departures from normality although, as noted by other authors, it is affected by temporal trends in the data. We are not convinced that the reported differences in power between Bulmer's test and the randomisation test of Pollard et al. (1987) justifies the adoption of the latter. Nor do we believe a compelling case has been established for the parametric bootstrap likelihood ratio test of Dennis and Taper (1994). Bulmer's test is essentially a test of the serial correlation in the (log) abundance data and is affected by the presence of autocorrelated errors. In such cases the test cannot distinguish between the autoregressive effect in the errors and a true density dependent effect in the time series data. We suspect other tests may be similarly affected, although this is an area for further research. We have also noted that in the presence of autocorrelation, the type I error rates can be substantially different from the assumed level of significance, implying that in such cases the test is based on a faulty significance region. We have indicated both qualitatively and quantitatively how autoregressive error terms can affect the power of Bulmer's test, although we suggest that more work is required in this area. These apparent inadequacies of Bulmer's test should not be interpreted as a failure of the statistical procedure since the test was not intended to be used with autocorrelated error terms.

A number of chemical compositions known to attract several synanthropic and pest fly species were tested against the Australian bush flyMusca vetustissima, a severe and persistent pest of man and domesticated and wild mammals. A standard composition containing small quantities of trimethylamine and indole, blended with large amounts of ammonium sulfate and anchovy meal, showed good attractancy against this fly. Deletion of ammonium sulfate did not significantly alter attractancy. Similarly, incorporation ofn-butyric acid and linoleic acid into the formulation did not alter attractancy, nor did addition of several carbonates and bicarbonates. Skatole, a closely related compound to indole, decreased attractancy significantly. In all the tests, the attractant compositions lured greater number of females than males. The attractancy of the standard composition was studied and compared with equal amount of fresh cattle dung. Chemical attractants lured bush flies and not dung beetles, while dung attracted both flies and beetles. The dung resource was 4.6 × more attractive to flies than the standard attractant composition. This suggests that there are other chemical attractants emanating from dung that warrant isolation and identification work. Nevertheless, the chemical attractants studied here provide a starting point for further investigations. The ratio of female to male flies attracted to humans was greater than the ratio of flies attracted to chemicals. The sex ratio of flies netted from human host was 3.0, while the sex ratio of flies attracted to chemical attractants was 1.8. The preponderance of females attracted to both sources was probably due to physiological requirements of the sexes.

The western corn rootworm (Diabrotica virgifera virgifera LeConte (WCR)) is a major pest of corn in USA. The pest arrived in Croatia in 1995, and today over 250.000 ha are infested. Insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to resistance. Growing corn that is resistant to corn rootworms would be a valuable alternative to insecticides. Nine Croatian (Institute of Agriculture, Osijek) and two Pioneer Hi-Bred Int. Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at two locations using complete randomized block design with four replications. One location was in east Croatia (Osijek) and one was in the USA (Iowa). The hybrids’ tolerance to larval feeding was rated using root injury, root regrowth and root size. Root injury was rated using the Node-Injury Scale 0-3 and evaluation of root size and root regrowth were done by scale 1-6. In an analysis of variance combined across locations, root injury didn’ t show any significantly differences among hybrids, but root regrowth and root size were significantly different.