Tritrophic interactions involving cabbage Brassica oleracea var. capitatacultivars ± fertilizer, Brevicoryne brassicae (Linnaeus) and Myzus persicae (Sulzer), and the parasitoids Diaeretiella rapae (M’cIntosh) and Aphidius sp. were conducted in 1998 and 1999. Brevicorne brassicaewas the dominant aphid species on all cultivars ± fertilizer, except for some treatments in late season 1998. Ruby Ball (red-leaved with antixenosis factors for B. brassicae alates) ± fertilizer was consistently less colonized by aphids in early stages of plant growth, although only significantly so compared with Derby Day (green-leaved, susceptible to aphids) without fertilizer for B. brassicae and Minicole (green-leaved with antibiosis factors for B. brassicae) with fertilizer for M. persicae. In early 1999, only B. brassicae was present and no significant differences between cultivars were seen. In the mid to late season 1998, the highest aphid infestations were usually found on Derby Day, although only significantly so for B. brassicae, in some treatments. In 1999, higher aphid infestations were observed on Derby Day in mid to late season and some significant differences were found for M. persicae as well as for B. brassicae. In both years, Ruby Ball had the greatest mummy:aphid ratios early season, with no consistent difference between the other cultivars. Later in the season, mummy:aphid ratios were generally highest on Minicole. Parasitism differed in seasonal occurrence and relative abundance. Diaeretiella rapae mummies were found earlier than Aphidius sp. There was evidence of a beneficial interaction between the degree of plant resistance and biological control in early to mid season.

Adelges tsugae infested western hemlock trees were sampled periodically for 1 year at two locations in Oregon and Washington to compare the phenology and abundance of three associated predators (Leucopis argenticollis, Leucopis piniperda, and Laricobius nigrinus) and their host. On each sample date, two 3–10 cm long terminal twigs were collected from each tree and brought to the laboratory to count all life stages of A. tsugae and the three predators. Peak larval abundance of Leucopis spp. and La. nigrinus coincided with the presence of A. tsugae adults and eggs. Leucopis spp. larvae were present for a much longer period of time than were La. nigrinus larvae. Furthermore, Leucopis spp. larvae were present during both the progrediens and sistens egg stages, while La. nigrinus larvae were only present during the progrediens egg stage. Overall, we collected 2.3–3.5 times more Leucopis spp. of all life stages than La. nigrinus. These results support the continued study of Leucopis spp. from the Pacific Northwest as biological control agents for A. tsugae in the Eastern USA.

The object of the present paper is to describe the results of some cage experiments with Zonocerus variegatus, L., carried out at Ibadan between March 1932 and December 1937.

The cages used for the breeding experiments were about 2-05 metres in height and were filled with soil to a depth of about 51 cm. The upper part of each cage was made of wire gauze and had a cubic capacity of about 1-43 cubic metres (154 cm. high by 102 cm. by 91 cm.). The grasshoppers were fed on the leaves of sweet cassava (Manihot utiHssima) and water was sprinkled on the food.

Brief notes are given on the distribution of 34 species of sandflies (Phlebotomus) recorded in Kenya. Mention is also made of two other species not so far known from Kenya but from areas close to its border, since these may ultimately be found within it.

The distributions of the 36 species in Kenya and bordering areas, based on published work supplemented by many unpublished records, are shown on a series of maps.

A method based upon Yeager's technique is described permitting the study of the surviving heart of Periplaneta americana under varying conditions for several hours.

Rotenone causes diastolic contractions, decrease of frequency and cessation in diastole, threshold <0·0000005 per cent. Presumably it produces an inhibitory action on the neurogenic automatic cardiac centre.

The latent period of the rotenone action is dependent upon the concentration. Using this principle a method is developed for quantitative estimation of the activity of derris preparations.

Tetraethyl pyrophosphate has a strongly accelerating action on the frequency of the heart and increases the amplitude; in this case there is no latent period. Threshold 0·000008 per cent. Presumably TEPP activates the neurogenic heart automatism by its vigorous anticholinesterase activity.

Sitophilus oryzae (L.) is a serious pest of stored cereal grains, but recently a few populations have been found able to feed and breed on certain legumes also. Legumes contain many toxic phytochemicals. A technique is described to generate data suitable for probit analysis, enabling a dose- response line to a toxic food to be constructed. The toxic effects of two legumes, yellow split-pea and adzuki bean, on adult survival and reproduction in three geographical strains of S. oryzae were examined. The strains were shown to vary in their abilities to tolerate legume phytotoxins, but there was no correlation between the abilities to survive on different legumes in the same strain. Yellow split-pea was shown to have residual effects on adult survival and reproduction, but performance was enhanced rather than impaired. It is suggested that improved performance results from induction of certain enzymes by substances within yellow split-pea. The use of legumes mixed with cereals as a control measure against S. oryzae is also discussed.

Populations of the wingless form of Myzus persicae (Sulz.), infected with severe yellows (SBYV), mild yellows (SBMYV), and both viruses, were introduced to single sugar-beet plants which were growing in a normal crop.

The aphids and their progeny walked readily from plant to plant, both along and across the rows, during the following eight weeks. Although they were heavily attacked by ladybirds, their mobility saved the population from total destruction. They carried and transmitted the viruses; within a month patches of sugar beet more than 11 feet in diameter had become infected, and within two months the diameter had extended to about 20 feet.

SBMYV spread to more than twice as many plants as SBYV. When introduced alone, either virus spread to twice as many plants as when the two viruses were introduced together. The rate of increase of the infection fell off during the season; it was estimated as eight- to sixteen-fold per month in June—July, about three-fold in August, and 1·5- to 1·9-fold in September. Natural infections-appear to behave similarly.

Apterae of M. persicae are considered to be predominantly responsible for yellows virus transmission within the crop, and their mobility, in contrast to the immobility of those of A. fabae Scop., is considered to be the principal reason why M. persicae is a much more important vector than A. fabae.

The extent of spread of virus by apterae shown to occur in the root crop must inevitably be much greater in the seed crop, in which aphid populations are much higher. This consideration serves to explain why existing control measures in the seed crop do not protect the root crop from infection. The risk from the seed crop, which is the reservoir of the disease, would be countered if seed crops were grown only in alternate years.

In Peninsular Malaysia, 18 species of hymenpterous parasitoids were reared either from the oil palm bagworms, Metisa plana Walker and Mahasena corbetti Tams, or from their parasitoids. Both Metisa plana and Mahasena corbetti share the common parasitoids Goryphus bunoh Gauld, Aulosaphes psychidivorus Muesebeck, Brachymeria carinata Joseph, Narendran & Joy, Eupelmus catoxanthae (Ferrière), Eurytoma sp., Sympiesis sp., Tetrastichus sp., and Aphanogmus thylax Polaszek & Dessart. Other parasitoids are associated with only one of the bagworm species: Paraphylax varius (Walker), Dolichogenidea metesae (Nixon), Elasmus sp., Nesolynx flavipes Ashmead, Pediobius anomalus (Gahan), Pediobius imbreus (Walker) and Teleopterus sp. from M. plana; and B. lasus (Walker), B. lugubris (Walker) and P. elasmi Ashmead from Mahasena corbetti. A key to species is included and a table summarizing the host range and distribution records are listed from the Indo-Australasian region.

Eggs of Austrosimulium pestilens Mack. & Mack, were separated from sandy loam deposits in river beds in Queensland by washing the deposit through a 64·5 mesh/cm plankton sieve; the eggs were then picked off the surface of the sieve. Viable eggs were recovered only from permanently wet deposits; deposits above the water table contained only empty egg shells or dead eggs. Since eggs are laid directly into the water, their distribution in the river bed is related to its topography and the degree of scour and fill. Eggs stored in the laboratory in wet river deposits were still viable after 2½ years of storage, but died rapidly when exposed to relative humidities of 96% or less. Only a few eggs hatched from samples of riverbed deposits in water following up to four days' agitation with compressed air.

In spite of the fact that since the end of the eighties, the horse chestnut leafminer, Cameraria ohridella, has established itself throughout Europe, native predators such as ants and birds are not attuned to this neozoic species. In contrast, several parasitic wasp species already started to exploit the invasive horse chestnut leafminer, but until now parasitation rates are quite low, mainly because of asynchrony in the lifecycles of parasitoids and host. Only the removal of leaf litter, in which pupae hibernate, is at the moment a strategy to reduce the infestation level in the next year. Unfortunately, not only hibernating horse chestnut leafminers but also parasitoids are removed, and important resources for biocontrol are unused. In the current study, we investigated the potential efficiency of the horse chestnut leafminer parasitoid complex extracted from leaf litter in defined environments. Parasitoids were released at different densities to investigate density dependence in parasitation rates.

Although seven different species were released in our experiments, only Pnigalio agraules turned out to be responsible for biocontrol of C. ohridella. We recorded parasitation rates of up to 35%. Overall, parasitation rates were independent of the leafminer density but increased fourfold if ten times more parasitoid individuals were released. Unfortunately, none of the parasitoid species could be established in the experimental units in the long run. Results are compared to other parasitoid-leafminer systems, and promotion of horse chestnut leafminer parasitoids to support natural selection and biological control of the horse chestnut leafminer is discussed.

The flight distance, flight time and individual flight activities of males and females of Dendroctonus armandi were recorded during 96-h flight trials using a flight mill system. The body weight, glucose, glycogen and lipid content of four treatments (naturally emerged, starved, phloem-fed and water-fed) were compared among pre-flight, post-flight and unflown controls. There was no significant difference between males and females in total flight distance and flight time in a given 24-h period. The flight distance and flight time of females showed a significant linear decline as the tethered flying continued, but the sustained flight ability of females was better than that of males. The females had higher glycogen and lipid content than the males; however, there was no significant difference between both sexes in glucose content. Water-feeding and phloem-feeding had significant effects on longevity, survival days and flight potential of D. armandi, which resulted in longer feeding days, poorer flight potential and lower energy substrate content. Our results demonstrate that flight distances in general do not differ between water-fed and starved individuals, whereas phloem-fed females and males fly better than water-fed and starved individuals.

The effects of different prey regimes on the performance and digestive physiology of the spined soldier bug, Podisus maculiventris (Say) (Hemiptera: Pentatomidae), were assessed. Specifically, P. maculiventris nymphs were fed on Colorado potato beetle (CPB), Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), larvae; Egyptian cotton leafworm (ECW); Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae); larvae; Calliphora spp. (CAL) (Diptera: Calliphoridae) pupae or a mixture of the three prey. No differences in development and weight gain were observed when P. maculiventris nymphs were fed different prey species (CPB, ECW or CAL). However, an increase in weight gain and a reduction in the duration of the stadia were observed for nymphs fed with a mixture of the three prey. To investigate the physiological background, biochemical analysis were carried out on insects dissected at the end of the feeding assay. We have found that the proteolytic activity in the salivary glands of P. maculiventris nymphs was not affected by prey species, whereas the relative activity of these proteases in the midgut depends on the prey. Moreover, gel assays proved that the proteolytic profiles of midguts from P. maculiventris nymphs feeding on CPB, ECW and CPB closely resembled those of their prey. All together, these results suggest that P. maculiventris may utilize enzymes from the prey they consume that may facilitate the process of digestion.

The purpose of this note is to illustrate the importance of searching for resting tsetse when making a fly survey. Highly experienced entomologists and fly boys, who are accustomed to making surveys for G. palpalis (R.-D.), G. tachinoides Westw. and G. morsitans Westw., get into the habit of expecting tsetse to be attracted to themselves or to screens or to bait animals, and may easily fail to detect the less common species unless they appreciate that these should be searched for in their resting haunts.

The life-history of Pseudorhyssa sternata Merrill was investigated under natural and artificial conditions.

When P. sternata and Rhyssa persuasoria (L.) females were present on Siricidinfested logs, P. sternata observed the primary parasite making drill shafts, and after the primary withdrew its ovipositor and moved away, P. sternata located the shaft and inserted its ovipositor to gain access to the host. P. sternata was able to locate R. persuasoria drill shafts aged 1–38 days.

P. sternata females were stimulated to oviposition behaviour when presented with paper drilled by R. persuasoria, and this response was enhanced by the presence of wet Siricid frass, or the symbiotic fungus of Siricids. Ovipositor probing was also made through artificial holes into frass. Bioassay of R. persuasoria vaginal and venom glands resulted in considerable probing into filter paper impregnated with vaginal gland extract.

It was concluded that P. sternata females probably locate Siricid-infested trees by responding to a generalised stimulus that is potent in larval frass, and which possibly derives from the symbiotic fungus. The cleptoparasite probably finds the drill-shaft by responding to a secretion of the vaginal gland of the primary parasite.

The work which resulted in this paper was carried out in the Department of Entomology of the British Museum (Natural History) at the request of Professor J. W. Munro and on behalf of the Pest Infestation Laboratory of the Department of Scientific and Industrial Research.

Genetically modified crops with insect resistance genes from Bacillus thuringiensis Berliner (Bt-plants) are increasingly being cultivated worldwide. Therefore, it is critical to improve our knowledge of their direct or indirect impact not only on target pests but also on non-target arthropods. Hence, this study evaluates comparative leaf consumption and performance of Spodoptera eridania (Cramer), a species that is tolerant of the Cry1Ac protein, fed with Bt soybean, MON 87701×MON 89788 or its non-Bt isoline. We also assessed the comparative performance of the egg parasitoid Telenomus remus Nixon on eggs of S. eridania produced from individuals that fed on these two soybean isolines as larvae. Results showed that Bt soybean reduced by 2 days larval development and increased by 3 days adult male longevity. Therefore, we conclude that the effect of Bt soybean MON 87701×MON 89788 on S. eridania development and reproduction is small, and favorable to pest development. These differences are less likely to directly result from the toxin presence but indirectly from unintended changes in plant characteristics caused by the insertion of the transgene. Our results should be viewed as an alert that S. eridania populations may increase in Bt soybeans, but on the other hand, no adverse effects of this technology were observed for the egg parasitoid T. remus which can help to prevent S. eridania outbreaks on these crops.

Locally-produced clear plastic water traps (12 cm × 14 cm base and 21 cm height) were optimized for use in large-scale mass trapping trials for control of brinjal fruit and shoot borer, Leucinodes orbonalis Guenée. Changing the shape (square and triangular) and number (two and four) of entry holes in the water trap had no significant effect on trap catch. Significantly more male moths were caught in traps treated with water containing powdered detergent than liquid detergent, light gear oil or insecticide. All water traps tested caught significantly higher numbers of moths than sticky delta traps with open sides under farmers' field conditions. Trap catches per 100 m2 were found to increase with increasing number of traps from 3 to 6 but the difference in catch between 4 and 6 traps per 100 m2 was not significant. Two small-scale replicated integrated pest management (IPM) trials were conducted consisting of the optimized water trap placed out with 10 m spacing (4 per 100 m2) and infested shoots pruned and destroyed. The first season trial had two treatments, IPM and farmers' practice in which farmers applied insecticide every two days in the peak harvest period. Overall, the percentage of healthy fruit and yields in both treatments were comparable at 53.8 and 49.6% and 20 and 19.4 tonnes per ha in the IPM and farmers' practice plots respectively. However, the initial infestations in the IPM plots (68%) were significantly higher than in farmers' practice plots (16%) due to the proximity of the nurseries used for the IPM plots to stacks of brinjal crop residues from the previous season that acted as a source of infestation. The second season's trials contained a third treatment in which IPM and farmers' practice were combined. The percent total healthy fruits harvested were 46.1, 58.6 and 69.1% respectively for the farmers' practice, farmers' practice plus IPM and IPM alone. Averaged total fruit yields were approximately 12 tonnes per ha for the farmers' practice plots and 30 tonnes per ha for each of the IPM-treated plots. The IPM plot had significantly fewer infested fruit than the IPM plus farmers practice plots and this was attributed to the activity of the larval parasitoid Trathala flavo-orbitalis (Cameron) that was suppressed in trial plots treated with insecticides.

Four insect parasites of the carrot fly have been encountered and of these three have been identified as Dacnusa gracilis, Loxotropa tritoma, and Aleochara sparsa. The fourth is a member of the genus Kleidotoma, species not yet ascertained.

The life-history, development and host relations of D. gracilis and L. tritoma are given together with data on their distribution and range of parasitism.

L. tritoma also occurs as a hyperparasite of D. gracilis but this appears to be quite fortuitous.

Experimental evidence is brought forward to show that the first instar larva of L. tritoma goes into a diapause in early July, that a period at a low temperature is necessary to break this and hence development is only completed in the following spring.

A description is given of the three larval stages of A. sparsa.

Brief reference is made to the Kleidotoma sp. which appears to be of rare occurrence.

The possibility to cross-species amplify microsatellites in fruit flies of the genus Ceratitis was tested with the polymerase chain reaction (PCR) by analysing 23 Ceratitis capitata (Wiedemann) microsatellite markers on the genomic DNA of three other economically important, congeneric species: C. rosa (Karsch), C. fasciventris (Bezzi) and C. cosyra (Walker). Twenty-two primer pairs produced amplification products in at least one of the three species tested. The majority of the products were similar, if not identical in size to those expected in C. capitata. The structures of the repeat motifs and their flanking sequences were examined for a total of 79 alleles from the three species. Sequence analysis revealed the same repeat type as the homologous C. capitata microsatellites in the majority of the loci, suggesting their utility for population analysis across the species range. A total of seven loci were differentially present/absent in C. capitata, C. rosa, C. fasciventris and C. cosyra, suggesting that it may be possible to differentiate these four species using a simple sequence repeat-based PCR assay. It is proposed that medfly-based microsatellite markers could be utilized in the identification and tracing of the geographical origins of colonist pest populations of the four tested species and in the assessment of their risk and invasive potentials; thereby assisting regulatory authorities in implementing quarantine restrictions and other pest control measures.