Myzus persicae (Sulzer) collected in Scotland were characterized for four microsatellite loci, intergenic spacer fingerprints and the resistance mechanisms modified acetylcholinesterase (MACE), overproduced carboxylesterase and knockdown resistance (kdr). Microsatellite polymorphisms were used to define a limited number of clones that were either fully susceptible to insecticides or possessed characteristic combinations of resistance mechanisms. Within these clones, intergenic spacer fingerprints could either be very consistent or variable, with the latter indicating ongoing evolution within lineages, most likely derived from the same zygote. Two clones (termed A and B) possessed all three resistance mechanisms and predominated at sites treated with insecticides. Their appearance on seed potatoes and oilseed rape in Scotland in 2001 coincided with extensive insecticide use and severe control failures. Clones C, I and J, with no or fewer resistance mechanisms, were found in samples from 1995 and were dominant at untreated sites in 2001. A comparison of Scottish collections with those from other UK and non-UK sites provides insight into the likely origins, distribution and dynamics of M. persicae clones in a region where asexual (anholocyclic) reproduction predominates, but is vulnerable to migration by novel genotypes from areas of Europe where sexual (holocyclic) reproduction occurs.

1. The increase in weight of flies of both sexes is followed on several diets. Unfed flies and flies fed on water alone or on meat and water lose weight. Males fed on meat, sugar and water, or on sugar and water, increase in weight rapidly during the first day of adult life and then lose weight until they die. Females fed on sugar and water increase in weight rapidly for the first day and then more slowly until the twelfth day, when they commence to lose weight until death occurs. A similar rapid increase in weight on the first day occurs in females fed on meat, sugar and water, but a second period of rapid increase occurs between the fourth and sixth days. The first period corresponds to the growth of the imaginal fat-body and the second to the growth of the ovaries. The percentage dry weight of flies fed on meat, sugar and water and on sugar and water increases rapidly at first but then decreases slowly until death occurs.

2. The disappearance of the pupal fat-body cells and the growth of the imaginal fat-body on several diets is described. It is suggested that the inclusions of the pupal fat-body cells are transferred to the rapidly growing imaginal fat-body.

3. The hypothesis is put forward that the abdominal air-sacs in flies of the Muscid type have but little respiratory function and are chiefly concerned in

(a) preserving the increased volume of the newly-emerged fly ;

(b) providing ample space within the abdomen for growth of the imaginal fat-body in the male and for the fat-body and ovaries in the female, both of which organs increase greatly in size.

Increasing rates of insecticide use against the coffee leaf miner Leucoptera coffeella (Guérin-Méneville) and field reports on insecticide resistance led to an investigation of the possible occurrence of resistance of this species to some of the oldest insecticides used against it in Brazil: chlorpyrifos, disulfoton, ethion and methyl parathion. Insect populations were collected from ten sites in the state of Minas Gerais, Brazil and these populations were subjected to discriminating concentrations established from insecticide LC99s estimated for a susceptible standard population. Eight of the field-collected populations showed resistance to disulfoton, five showed resistance to ethion, four showed resistance to methyl parathion, and one showed resistance to chlorpyrifos. The frequency of resistant individuals in each population ranged from 10 to 93% for disulfoton, 53 to 75% for ethion, 23 to 76% for methyl parathion, and the frequency of resistant individuals in the chlorpyrifos resistant population was 35%. A higher frequency of individuals resistant to chlorpyrifos, disulfoton and ethion was associated with greater use of insecticides, especially other organophosphates. This finding suggests that cross-selection, mainly between organophosphates, played a major role in the evolution of insecticide resistance in Brazilian populations of L. coffeella. Results from insecticide bioassays with synergists (diethyl maleate, piperonyl butoxide and triphenyl phosphate) suggested that cytochrome P450-dependent monooxygenases may play a major role in resistance with minor involvement of esterases and glutathione S-transferases.

Maintaining bee colonies in a healthy state throughout the year is one of the main concerns of apiculture researchers. The phenomenon of disappearance of bee colonies is determined by several factors, one of which is bee disease. Due to the organizational structure of the bee colony, disease transmission is rapid, especially through infected food or via the nurse worker bees that feed the brood bees of the colony concerned. The practice of stimulating the bee colonies in spring using sugar syrup feeds with added prebiotic products (lactic acid or acetic acid) and probiotics (Lactobacillus acidophilus LA-14 and Bifidobacterium lactis BI-04) by using an Enterobiotic product (Lactobacillus casei), marketed as Enterolactis Plus, for three weeks, resulted in a significant reduction of the total number of bacteria in the digestive tracts of the bees, compared with the control group. By contrast, intestinal colonization with beneficial bacteria contained in probiotics products administered to the bees was observed. This resulted in an improved health status and bio productive index of the bee colonies studied.

In the fragmented landscape of arable farmland, hedgerows and other non-crop habitats provide refuges of food and shelter for invertebrates, and corridors through which they can move to other habitats. Their role as corridors is likely to depend on their connectivity, both to each other and to other patches of suitable habitat. The effects of connectivity on the carabid beetle Nebria brevicollis (Fabricius) were analysed by observing movement between hedgerow intersections (nodes) and the linear section of the hedgerow, and across gaps in the hedgerow. Capture–mark–recapture of N. brevicollis revealed a uniformly higher activity at hedgerow nodes than at mid-section strips of comparable area. This is consistent with previous studies of hedgerow fauna including butterflies, plants and birds. Gaps in the hedgerows typically measured 7–9 m and functioned as a passage between fields for farm machinery. These were readily crossed by N. brevicollis as was the hedge bottom. Some movement along the hedgerow was found indicating their use as a corridor.

The red spider, Oligonychus coffeae (Nietn.), is the most widely distributed and probably also the most serious pest of tea in north-eastern India, and also occurs on tea in other parts of India and in other countries. It attacks jute, Corchorus capsularis, in India and has been recorded on a wide variety of other plants in India and other countries.

The life-history of O. coffeae in north-eastern India is described. The duration of the life-cycle varies with the season depending on the temperature and humidity.

In May and June the life-cycle is completed in 9·4–12 days outdoors, while in the cold weather it may take as much as 28 days. The maximum length of life of a female has been found to be 29 days indoors. The males usually die within four or five days. Parthenogenetic reproduction may take place under induced conditions, the progeny being all males.

Red spider normally attacks the upper surface of the mature leaves in which the sap is not flowing freely. In a severe infestation, particularly under conditions of dry weather, the lower surface and the young leaves are almost equally attacked. The affected leaves turn brown, then bronze, and may eventually dry up and fall off.

The red spider mites live under a cover of web that they spin as a protection against inclement weather. The pest occurs in severe form from March to June but with the monsoon rains it practically disappears. A second, light, attack may, however, develop in September or October.

During the cold weather, the mites are present in very small numbers on a few old leaves of the tea bushes, and with the rise in temperature in the spring, they multiply rapidly, resulting in subsequent heavy infestations.

Various factors influence the incidence of red spider and the intensity of its attack. Pruned bushes properly cleaned out are less affected. Bushes defoliated after pruning, and medium pruned tea remain practically unaffectsd. Prolonged dry weather during the early part of the flushing season normally increases the red spider incidence. It prefers bright sun and unshaded areas are more severely attacked.

The red spider spreads from bush to bush by crawling. Dispersal is also effected by various agencies such as wind, cattle, goats and labourers.

A number of predatory insects attack eggs and other stages of the red spider, often keeping it considerably in check.

A simple field method for direct detection of an altered acetylcholinesterase (AChE)-type organophosphate and carbamate resistance mechanism in individual insects was developed. The test will allow accurate differentiation by eye, on the basis of a colour change, of homozygous-susceptible and heterozygous or homozygous-resistant individuals. In initial field trials of this test in Sri Lanka, Anopheles nigerrimus Giles and Culex tritaeniorhynchus Giles were shown to contain this type of resistance gene, while a further nine species of mosquito had no evidence of it. Frequencies of the altered AChE gene in A. nigerrimus were estimated to be higher than those of C. tritaeniorhynchus, where the gene was found in only one of three localities in the island. The implication of the increase in prevalence of the AChE resistance gene in mosquito populations is discussed.

The pattern and cause of mortality of the early stages of Helicoverpa armigera (Hübner) on cotton was investigated in both field and glasshouse situations for two seasons. In 1987, egg losses were high (32–88%) over days 1–3 following oviposition, more so from the lower than upper leaf surface. The mortality of first instar larvae was 93–100% over days 4–5 following oviposition, and losses were higher from seedling stage than squaring cotton. Wind, rain (or watering), aerial predators, dispersal of first instar larvae, and host plant effects (including leaf orientation) were important mortality factors. In 1988 trials, egg losses over days 1 to 3 after oviposition on plants in glasshouse and field situations, respectively, were 0–1% and 5–6% due to changing leaf orientation alone; 4–22% and 16–32% due to rain/watering and changing leaf orientation combined; 14–31% and 12–31% for wind and changing leaf orientation combined; and 4–38% and 23–52% for the combination of wind, rain/watering and changing leaf orientation. Mortality of first instar larvae on day 4 was 32% and 29% on plants in glasshouse and field, respectively, from which the action of such mortality factors had been excluded. Mortality on plants with changing leaf orientation alone was 30% and 68%, with rain/watering and changing leaf orientation combined 48% and 74%; with wind and changing leaf orientation combined 40% and 63%; and with all factors combined 45% and 69%, respectively. The highest losses (of eggs) occurred on day 1 after oviposition, and similarly for first instar larvae on day 4, which coincided with hatching.

Four dispersal phases occur during larval development of Chilo partellus (Swinehoe) on young host plants, phase 1, ballooning of newly hatched larvae when moving from egg batch to plant whorl, phase 2, ballooning of first and second instars which leave the plant whorl in the week after egg eclosion, phase 3, walking prior to stem penetration, and phase 4, walking after stem penetration. In laboratory experiments larval dispersal was density dependent during dispersal phases 1, 3 and 4 and there were clear differences between maize and sorghum in the percentage of migrating lavae and time of migration. Maize plants accommodated many more pupae than sorghum plants which suggests that the distribution of older larvae in the field can be more clumped in maize than in sorghum. Pupal weight descreased with infestation level on sorghum but seemed less affected on maize. Resistance to starvation in four combinations of temperature and relative humidity increased with age. All hatchlings survived six hours′ starvation but with considerably reduced crawling capacity. Seven- and 15-day old larvae were descreasingly affected. Older larvae survived and maintained their mobility after 48 hours. Successful dispersal will depend on host-plant, egg load, and costs of migration; these costs will change with larval age.

Examination of infested bean plants (Phaseolus vulgaris) showed that “bean fly” in East Africa consists of three species, Melanagromyza phaseoli (Tryon), M. spencerella sp. n. and Ophiomyia centrosematis (de Meij.). M. spencerella is described, and notes are given on the life-cycle, host-plants and distribution for all three species. Their importance in East Africa is discussed and it is concluded that M. spencerella is the most damaging because it oviposits and feeds in the hypocotyl, is frequently the most abundant species and is less effectively parasitised. Bean plants able to produce adventitious roots freely are able to grow away from the important early attack in the stems. Published work on chemical control measures is summarised.

The parasite complex associated with bean fly in East Africa was studied, and notes are given on the species present, the recognition of their early stages, their host ranges and abundance. Parasitism is discussed in relation to the infestations found on beans, with special reference to Opius melanagromyzae Fisch., the most important parasite of M. phaseoli, and Eucoilidea sp., the most important parasite of M. spencerella. It is concluded from graphical analysis that O. melanagromyzae is density-dependent and an important factor in limiting M. phaseoli populations in East Africa. Eucoilidea sp., on the other hand, shows signs of delayed density-dependence and is less effective in controlling its principal host. O. melanagromyzae has recently been sent to Hawaii for release against M. phaseoli; some field recoveries have been made already.

Emergence of coffee berry borer, Hypothenemus hampei (Ferrari), from infested coffee berries (Coffea arabica) was studied in the laboratory under controlled temperature and relative humidity (RH) regimes. Low humidities (<60% RH, 25°C) provoked rapid evacuation of adults. Emergence was at a minimum at 90% RH. A steady increase in emergence occurred at values from 90 to 100% RH. Emergence was low below 20°C (90 and 100% RH) and increased markedly between 20 and 25°C. There was no significant increase in emergence above 25°C. Using a simple flight event recorder, emergence flight times were found to peak at the time of maximum daily ambient temperatures on successive days. Under constant temperature conditions successive peaks of emergence were not seen. Results are discussed in relation to control and sampling procedures.

Diapause induction in Heliothis armigera (Hb.) from the Sudan Gezira was investigated under controlled conditions. A maximum incidence of diapause occurred in response to exposure to low temperature (22°C) and short daylength (12 h) during the larval stage. However, the prepupal and early pupal stages were also sensitive to temperature; if they were exposed to 26°C, diapause was averted. After more than two months at low temperature, some pupae remained in diapause for more than two months after transfer to high temperature (34°C) and only commenced developing when the temperature was lowered again. This may provide a mechanism to bridge the hot dry season and to synchronise emergence with the start of the rainy season. A high incidence of diapause in H. fletcheri (Hardwick) was observed to occur at the end of the rainy season under ambient conditions in the Sudan. Emergence from these diapause pupae occurred in the following rainy season. The different phenologies of diapause in the two species are discussed in relation to their distribution in rain-fed and irrigated vegetation in the Sudan.

The integrated use of biconical traps, insecticide-impregnated targets and the sterile insect technique was developed for the eradication of Glossina palpalis palpalis (Robineau-Desvoidy) in a 1500-km2 area of central Nigeria. Six weeks or more of continuous removal trapping, using biconical traps, reduced the target tsetse population by more than 90% but failed to eradicate it. Males sterilized by irradiation from a 60Co source that were then released weekly induced significant sterility in target females and were successful in helping to eradicate the target population. A minimum ratio of 10:1 of sterile to wild males was required to achieve eradication in a central area of 300 km2. In marginal habitats, insecticide-impregnated targets were found adequate to control the tsetse population. The targets were also efficient as barriers to prevent reinvasion of the area. The combined effect of removal trapping and sterile male release is expected to eradicate G. p. palpalis from the entire study area.

The small, hooked epidermal hairs on french beans (Phaseolus vulgaris) may have a profoundly detrimental effect on colonies of Aphis craccivora. The hairs are present on the petioles, stems and undersurfaces of the leaves but are absent on the uppersurfaces of the leaves. They are most dense and therefore most injurious to the Aphids on the growing shoots. The Aphids' legs become impaled on the hooks and the results of the subsequent bleeding, starvation and exhaustion are decreased longevity and reproductive rate, high larval mortality, increased time of larval development and decreased size; this last factor is associated with a reduced fecundity. On some varieties of beans the hairs are less dense than on others and on these varieties the action of the hairs in inhibiting predators may be more important than their effect on the Aphids.

Silicon (Si) can improve resistance of plants to insect attack and may also enhance tolerance of water stress. This study tested if Si-mediated host plant resistance to insect attack was augmented by water stress. Four sugarcane cultivars, two resistant (N21, N33) and two susceptible (N26, N11) to Eldana saccharina Walker were grown in a pot trial in Si-deficient river sand, with (Si+) and without (Si−) calcium silicate. To induce water stress, irrigation to half the trial was reduced after 8.5 months. The trial was artificially infested with E. saccharina eggs after water reduction and harvested 66 days later. Silicon treated, stressed and non-stressed plants of the same cultivar did not differ appreciably in Si content. Decreases in numbers of borers recovered and stalk damage were not associated with comparable increases in rind hardness in Si+ cane, particularly in water-stressed susceptible cultivars. Overall, Si+ plants displayed increased resistance to E. saccharina attack compared with Si− plants. Borer recoveries were significantly lower in stressed Si+ cane compared with either stressed Si− or non-stressed Si− and Si+ cane. Generally, fewer borers were recovered from resistant cultivars than susceptible cultivars. Stalk damage was significantly lower in Si+ cane than in Si− cane, for N21, N11 and N26. Stalk damage was significantly less in Si+ combined susceptible cultivars than in Si− combined susceptible cultivars under non-stressed and especially stressed conditions. In general, the reduction in borer numbers and stalk damage in Si+ plants was greater for water-stressed cane than non-stressed cane, particularly for susceptible sugarcane cultivars. The hypothesis that Si affords greater protection against E. saccharina borer attack in water-stressed sugarcane than in non-stressed cane and that this benefit is greatly enhanced in susceptible cultivars is supported. A possible active role for soluble Si in defence against E. saccharina is proposed.

Four morphologically cryptic species of the Bactrocera dorsalis fruit fly complex (B. dorsalis s.s., B. papayae, B. carambolae and B. philippinensis) are serious agricultural pests. As they are difficult to diagnose using traditional taxonomic techniques, we examined the potential for geometric morphometric analysis of wing size and shape to discriminate between them. Fifteen wing landmarks generated size and shape data for 245 specimens for subsequent comparisons among three geographically distinct samples of each species. Intraspecific wing size was significantly different within samples of B. carambolae and B. dorsalis s.s. but not within samples of B. papayae or B. philippinensis. Although B. papayae had the smallest wings (average centroid size=6.002 mm±0.061 SE) and B. dorsalis s.s. the largest (6.349 mm±0.066 SE), interspecific wing size comparisons were generally non-informative and incapable of discriminating species. Contrary to the wing size data, canonical variate analysis based on wing shape data discriminated all species with a relatively high degree of accuracy; individuals were correctly reassigned to their respective species on average 93.27% of the time. A single sample group of B. carambolae from locality ‘TN Malaysia’ was the only sample to be considerably different from its conspecific groups with regards to both wing size and wing shape. This sample was subsequently deemed to have been originally misidentified and likely represents an undescribed species. We demonstrate that geometric morphometric techniques analysing wing shape represent a promising approach for discriminating between morphologically cryptic taxa of the B. dorsalis species complex.

Use of the insect growth regulator (IGR) pyriproxyfen (Nemesis®) for the control of red scale Aonidiella aurantii (Maskell) (Homoptera: Diaspididae) on citrus in southern Africa has led to extensive disruption of the biocontrol of cottony cushion scale Icerya purchasi Maskell (Homoptera: Margarodidae) provided by the coccinellids Rodolia cardinalis (Mulsant) and other indigenous Rodolia spp. Similar effects on field populations of Chilocorus nigrita (Fabricius), a coccinellids predator of A. aurantii, have also been observed. The adverse effects of field-weathered residues of IGRs on the fecundity and egg viability of the coccinellids C. nigrita and Cryptolaemus montrouzieri Mulsant were determined in a laboratory bioassay. Residues of pyriproxyfen, a juvenile hormone analogue, and two chitin synthesis inhibitors, buprofezin (Applaud®) and triflumuron (Alsystin®), were tested. Exposure to residue-bearing leaves did not affect the number of eggs laid by Chilocorusnigrita, but a complete, or near complete failure of eggs to hatch ensured when adults were exposed to either 3, 7 or 19 week old weathered residues from a single application of pyriproxyfen or triflumuron. Three week old residues of buprofezin had the same effect, but both 7 and 19 week old residues no longer significantly reduced egg viability. Adults of both C. nigrita and Cryptolaemus montrouzieri commenced laying viable eggs within 20 days of being separated from all residue-bearing leaves. One week old residues of pyriproxyfen and triflumuron both significantly reduced progeny production by C. montrouzieri. Ten week old triflumuron residues were still detrimental to this species but pyriproxyfen residues of the same age were not. It was concluded that IGRs are not compatible with integrated pest management (IPM) for citrus in southern Africa, where coccinellid biocontrol agents play an important role.

Phlebotomus perfiliewi perfiliewi Parrott and Phlebotomus perniciosus Newstead (Diptera: Psychodidae,) known vectors of Leishmania infantum were caught in light traps in five different sites in Italy. Sandflies were cryopreserved and transported to the laboratory where they were thawed and aqueous extracts of the crushed flies were analysed for their carbohydrate content using high performance liquid chromatography. Several sugars were detected, including significant amounts of the trisaccharide melezitose, known to be available as a natural source from aphid or coccid honeydew. There was no difference between the analyses of sugar meals of P. p. perfiliewi from different sites within its range, or between P. p. perfiliewi and P. perniciosus. The results indicate that both males and females of P. p. perfiliewi and P. perniciosus feed on honeydew.

Mating disruption of Cydia molesta (Busck) was attempted by treating, with pheromone, all orchards in a small but discrete peach-growing district in New South Wales for two successive years. In the final year of the trial, two former control orchards were also treated with pheromone. The efficacy of the treatment was examined by monitoring fruit and shoot damage, male captures in pheromone traps, captures of both sexes in feeding lures, mated status of wild females and numbers of immature stages in trap bands. It was concluded that mating disruption was a viable alternative to conventional insecticides.

The potential of carabid beetles as natural control agents of slugs was investigated using a quantitative indirect enzyme-linked immunosorbent assay (ELISA). The crop contents of two species, Abax parallelepipedus (Piller & Mitterpacher) and Pterostichus madidus (Fabricius) collected between May and December 1990, were analysed using an anti-mollusc haemolymph antiserum. The mass, immunological reaction and calculated mollusc content of each beetle crop was determined. Mollusc content was calculated as ‘fresh mollusc equivalent’, and the probable quantities of degraded material present are discussed in relation to predator and prey species. 89.5% of A. parallelepipedus and 42% of P. madidus were found to contain mollusc proteins. Although approximately the same proportion of male and female A. parallelepipedus tested positive, females contained greater quantities of mollusc remains. Approximately 39% of male and 45% of female P. madidus tested positive, and overall female crops contained significantly more material. The calculated amount of mollusc remains found in females was also greater. Over time, the immunological reactivity of A. parallelepipedus crop samples varied significantly. However, when crop weight was taken into consideration, the calculated quantity of mollusc found in strongly reacting samples was not significantly different between months in either species. Neither the immunological response nor the quantity of mollusc remains varied over time in P. madidus, although significant differences were found in overall crop weights. A significant correlation was found between the proportion of mollusc in beetle crops and crop mass in A. parallelepipedus, but not in P. madidus. Correlations between soil temperatures and crop mass, immunological reactivity and mollusc content were not significant in either species. The improved methods of quantifying predation from ELISA data, employed in this study, were an important part of a larger on-going investigation of the role of predation in slug population dynamics within agricultural systems.