The southern African shrubs Chrysanthemoides monilifera monilifera and C. m. rotundata (Compositae) are serious weeds of native vegetation in Australia and are targets for classical biological control. In host specificity tests using 69 species from 25 families, two leaf-feeding chrysomelid beetles, Chrysolina picturata (Clark) and Chrysolina sp. B, were able to complete development on only Chrysanthemoides monilifera and C. incana. The subspecies Chrysanthemoides m. monilifera was the superior host for both Chrysolina picturata and Chrysolina sp. B. Feeding and limited development of both species occurred on Calendula officinalis; limited development by Chrysolina picturata larvae occurred on Helianthus annuus, Tussilago farfara and Cymbonotus priessianus. Chrysolina picturata and Chrysolina sp. B are considered to be Chrysanthemoides-specific and have been approved for release in Australia. Potential release sites for both Chrysolina species were chosen by comparing the climate of the insects' African distribution with climate stations within the range of Chrysanthemoides monilifera in Australia. Chrysolina picturata and Chrysolina sp. B are suited for release within the western distribution of Chrysanthemoides m. monilifera in coastal areas of south eastern South Australia.

The status of pyrethroid resistance in some field populations of Helicoverpa armigera (Hübner) from Pakistan was determined using an IRAC leaf-dip method. Resistance factors varied between populations, and the general trend was for a moderate to high resistance to cypermethrin and cyfluthrin; a low to moderate resistance to deltamethrin and alpha-cypermethrin; and a comparatively low resistance to bifenthrin, lambda-cyhalothrin and zeta-cypermethrin. Depending on which physiological mechanisms are shown to be present in Pakistani field strains, the latter group of pyrethroids may serve as useful tools in the management of insecticide resistance.

Long term changes in the size of populations of the tsetse Glossina pallidipes Austen and G. longipennis Corti were monitored over a 12 year period at Nguruman in south-western Kenya. Tsetse populations were subject to droughts of varying intensity and, from 1987, to trapping, initially by a research organization, and later by a community-based development project. Populations were mainly sampled using odour-baited biconical traps, with data from other monitoring traps corrected accordingly. Mark–release–recapture studies were carried out to relate trap catches to absolute population size, and to quantify movement between subpopulations. Trypanosomiasis incidence rates in a herd of local cattle were also monitored for much of this period. Trap catches were shown to be well correlated with estimates of absolute population size, with no evidence of any seasonal change in trap efficiency. The intensity of trapping and level of seasonal immigration appeared to be the main determinants of population trends, with effective control being achieved when traps were well maintained. Movement between the two lowland subpopulations was shown to be greater for females, and to be inversely related to temperature. An analytical model was used to investigate the responses of a partially isolated population to trapping pressure. Predictions of a deterministic simulation model demonstrated that the observed changes are consistent with an adult trapping mortality of 4–8% per day, and immigration of 100,000 G. pallidipes females per month in the long rains (April and May), 5000 per month in the short rains (November), and about 500 per month during the dry seasons. Trypanosomiasis incidence in local cattle was greatly reduced during the period of community-based tsetse control. When tsetse were sampled exactly where the cattle were grazing, disease incidence was shown to be linearly related to G. pallidipes catches. Arguments for trap resistance and residual populations were examined, and found to be inconsistent with the data. The future for tsetse control by the Nguruman community is considered.

The diversity of macromoths in the various fast-growing exotic tree plantations and natural secondary forest in Brumas, Sabah, Malaysia was assessed by means of an annual cycle of light-trap samples. The moth diversity in the forest plantations, viz. Acacia mangium, Gmelina arborea, Paraserianthes (=Albizia) falcataria, Pinus caribaea, and in particular Eucalyptus deglupta, was unexpectedly high. Eucalyptus deglupta showed moth diversity as high as that in the natural secondary forest, a finding attributed to the fact that the E. deglupta plantation had a very diverse understorey both in terms of plant species (secondary regrowth species) and architecture, and thus supported a more diverse moth fauna. Subsidiary samples showed that primary natural forest in the neighbouring Danum Valley does not show higher moth diversity compared to the disturbed forest habitats in Brumas, though moth diversity at Danum is lower than that recorded in other Bornean primary forests. The value of plantation forests for conservation of invertebrate diversity is discussed, together with the implications for plantation management strategy.

Rice green leafhopper Nephotettix virescens (Distant) populations were collected in 1985 from fields planted with a leafhopper resistant rice, Oryza sativa cultivar IR64 in South Cotabato, Philippines. The populations were reared on IR64 for eight generations and tested on six cultivars, including susceptible TN1, moderately resistant IR26 and IR36, and resistant IR54, IR62, and IR64. Leafhoppers excreted larger amounts of basic honeydew, efficiently transmitted two tungro associated viruses, and showed greater population increase and lower nymphal mortality on all cultivars except IR62 than a greenhouse population reared on TN1. Nephotettix virescens were transferred and maintained on TN1, IR26, IR36, IR64, or a mixture of the four cultivars plus IR54 and IR56 in equal proportion. When the TN1-maintained colony was tested at the third generation, its feeding behaviour and tungro transmission rates on test cultivars were similar to those of the original population but amounts of basic honeydew excretion and the transmission rate on the resistant test cultivars were greatly reduced at the seventh or later generations. When the IR26-maintained colony was tested at the sixth, ninth, or 13th generation, it exhibited lower amounts of basic honeydew excretion on the resistant test cultivars but exhibited similar transmission efficiencies on other test cultivars. When the colonies maintained on IR36, IR64, or the cultivar mixture were tested similarly, their population characteristics and virus transmission efficiency were similar to the original population. These results indicate that N. virescens retain their ‘virulence’ to resistant cultivars when maintained on resistant cultivars, but quickly lose their ‘virulence’ when maintained on a susceptible cultivar. Colonies continuously reared on IR26, IR36 or IR64 showed ‘cross-virulence’ to many cultivars possessing a variety of genes for N. virescens resistance but often differed in feeding behaviour, virus transmission efficiency, and nymphal mortality on cultivars with the same genes for leafhopper resistance.

An insecticide impregnated fabric (IIF) trap was developed at the Vector Control Research Centre, India. The mosquito sampling efficiency of this new trap, relative to hand catches of indoor resting mosquitoes, was evaluated in human dwellings and cattle sheds in a filariasis endemic area. The predominant species collected in human dwellings was Culex quinquefasciatus Say, a vector of bancroftian filariasis; whereas mosquitoes of the Culex vishnui group Theobald and Anopheles subpictus Grassi were caught in relatively greater numbers in cattle sheds. The numbers of mosquitoes in the trap were significantly correlated with the numbers caught in hand catches, and the numbers of mosquitoes collected per two traps per day in the three habitats during the study period were 1.79, 0.95 and 2.27x those collected by hand-catches. The number of occasions on which mosquitoes were detected by both methods was comparable. There was no evidence for a systematic difference in the age-structure and parasite distribution between the two sampling methods, suggesting that the trap is able to monitor both insect vectors and parasite infections. Therefore, the calculation of infection and infectivity rates necessary to monitor filariasis transmission should be possible from the IIF trap in filariasis endemic areas where control measures are being taken.

McPhail traps baited with hydrolysed protein and borax to trap mainly female fruit flies, Jackson traps baited with trimedlure to attract male Ceratitis capitata Wiedemann, and Jackson traps baited with cuelure and methyl eugenol to trap Bactrocera spp., were hung in fruit trees at 50 sites and serviced weekly from June, 1994 to March, 1995, over an area of 350 km2 in Nicaragua. Samples of fruit were collected and kept separately to rear adult fruit flies and their hymenopterous parasitoids from known host plants. No Bactrocera spp. was trapped or reared from fruit at any site. Ceratitis capitata was caught in high numbers in McPhail and Jackson traps at nearly all sites in the dry season, attacking coffee berries and fruit of Citrus species. Toxotrypana curvicauda Gerstaecker was attracted to the food lure McPhail traps in low numbers and was widespread throughout the year, attacking papaya (Caricaceae). Of 29 Anastrepha species known to occur south of Mexico and north of Panama, ten were found during the study, occurring mainly in the rainy season; only two of them were trapped frequently and reared from collected fruit. Anastrepha obliqua Macquart proved to be the second most abundant fruit fly species, with a population peak from June to October when its preferred host plants Mangifera indica, Spondias mombin (Anacardiaceae) and Psidium friedrichsthalianum (Myrtaceae) were ripening. Anastrepha striata Schiner, trapped at 45 sites, occurred from June to November, attacking P. friedrichsthalianum and P. guajava. Sampled fruit of a further eight species in seven families were not attacked by tephritid flies. Parasitism by introduced braconid Diachasmimorpha longicaudata (Ashmead) was very low (3.7% in C. capitata, 2.7% in A. obliqua and 5.3% in A. striata).

Seasonal occurrence and abundance of redlegged earth mite, Halotydeus destructor (Tucker), was measured by weekly sampling in grazed annual pastures near Keysbrook (1990–1992) and Narrogin (1991–1992) in southwestern Australia. Mites were active for 27 weeks from the late autumn (May) to mid-spring (October), completing three generations at approximately 8 week intervals. The summer is spent as diapause eggs in the cadavers of adult female mites. In 1991 and 1992, active H. destructor was on average twice as abundant at Keysbrook (mean 11,300 mites/m2), as at Narrogin (mean 6400 mites/m2). Three times more eggs were laid at Keysbrook than Narrogin (mean 8500 and 2900 eggs/m2 respectively). Rainfall at Keysbrook was twice that at Narrogin, and temperatures were higher. We suggest that the rate of oviposition was less at Narrogin, probably because of resource limitation. The mature adult sex ratio was female biased, but was lower at Keysbrook (0.669) than at Narrogin (0.813). Neozygites acaridis, a fungal disease, was detected in less than 4% of the population, mainly in adult mites in late spring. Rainfall and temperatures were lower in the spring of 1992 than 1991 at both sites. Pasture was grazed considerably shorter in the spring of 1992, and numbers of H. destructor were lower, but numbers of eggs laid in the two years were similar. We suggest that active mite mortality was greater in spring of 1992, probably due to lower relative humidity. There were fewer adult mites in spring, and fewer diapausing eggs in summer at both sites in 1992 (36,600 diapause eggs/m2) than in 1991 (148,000 diapause eggs/m2). It is proposed that controlling mites in spring should lead to lower numbers of diapause eggs in summer and of mites emerging in autumn.

The aphid Therioaphis trifolii (Monell) is indigenous to the western Palaearctic region, where it colonizes lucerne (alfalfa), clovers and related legumes. A form of the species, T. trifolii f. maculata (the spotted alfalfa aphid, SAA), has been known in Australia since 1977, feeding almost exclusively on Medicago sativa (lucerne). Since 1989, T. trifolii has been found in Australia colonizing Trifolium subterraneum (subclover). We have compared samples of T. trifolii in Australia collected on lucerne and subclover using several techniques: survival and reproduction on different hosts, morphology, cuticular hydrocarbon profile, karyology, and a combination of RAPD-PCR and mitochondrial DNA (cytochrome oxidase) genetic markers. Whereas there were no distinct differences in cuticular hydrocarbons and karyology, we found significant correlated differences between the host on which aphids were collected, some morphological characters, and the genotypes of the aphids. Aphids collected from lucerne were always of one genetic type, and nearly all those from subclover were of another. Both groups of aphids are morphologically distinguishable from the yellow clover aphid (YCA), the other form of the species recognized so far. We conclude that the clover-colonizers (spotted clover aphid, SCA) and the lucerne-colonizers (SAA) are each host-restricted forms (biotypes) of T. trifolii. Estimates of mtDNA divergence are in the range of conspecific to closely congeneric, as compared with other insects including aphids. We developed simple diagnostic DNA tests to distinguish the two pest aphids.