Adult and larval identification of Diabrotica can be difficult. Some adult identifications require considerable taxonomic experience while larvae of many Diabroticaspecies are morphologically indistinguishable. This study was conducted to determine whether 12 pest and non-pest Diabrotica species could be separated using polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). A 1308 bp portion of the mitochondrial cytochrome oxidase subunit I gene (COI) was amplified using PCR and digested using several restriction endonucleases. Double digests of COI amplicons with AluI and MspI resolved on polyacrylamide gels revealed several diagnostic inter- and intraspecific polymorphisms. A key to the 12 species was constructed using the PCR–RFLP patterns.

An incomplete ring of electric nets was evaluated as a means of estimating trap efficiency for Glossina spp. This methodology assumes flies approach the trap directly, and then enter, or leave directly in random directions. These results showed that the ratio of the number of flies intercepted on the outside of the electric nets to the number on the inside was lower than predicted by this single-approach behavioural model. Moreover, an incomplete ring of nets around a trap reduced trap catch more than the model predicted. These inconsistencies were greater early in the day, and greater for females than for males. It is suggested that flies may make several approaches to a trap before entering or departing. This mixes arriving and departing flies on each side of the electric nets. Use of a complete ring of nets around a trap to estimate trap efficiency entails fewer behavioural assumptions. Catches at a complete ring around a trap were compared to catches in a trap without nets, replicated in a cross-over design. The efficiency of an odour baited NG2G trap was estimated to be 58% for males and 37% for females. Biconical traps were much less efficient. Both trap types were less efficient in the early morning, suggesting entry response is temperature dependent. The NG2G trap was more efficient for non-teneral nulliparous females than for other ages. For both trap types there was little difference between mean fat content of approaching and trapped males, but the mean fat content of trapped females was lower than that of approaching females.

Performance and genetic variability of clonal lineages derived from one Californian and one German population of grape phylloxera, Daktulosphaira vitifoliae Fitch were studied on their natal grape rootstock host and on three novel hosts over four generations in an aseptic dual culture system. The ability of D. vitifoliae to adapt to new hosts was measured by changes in fitness (rm) over four generations. The performance of a given clonal lineage changed over successive generations, depending upon the host plant and the phylloxera group. Analysis of amplified fragment length polymorphism–polymerase chain reaction (AFLP–PCR) banding patterns from 40 individual parthenogenetic D. vitifoliae revealed equal levels of genetic variation both among the four clonal lineages analysed and within the different generations of one lineage. Analysis of molecular variance (AMOVA) showed no significant differences between the D. vitifoliae lineages reared on different host plants, nor was a correlation between host performance and genotype found.

Laboratory and screenhouse studies were carried out to assess the relationship between pod age and pod position of cowpea and damage by different pod bug species. The coreids Clavigralla tomentosicollis Stäl and Riptortus dentipesFabricius caused significant damage to young pods of cultivated genotypes, in contrast to the coreid Anoplocnemis curvipes Fabricius and the pentatomid Aspavia armigera Fabricius which exhibited minor feeding activity. Percent seed damage declined with pod age, the critical stage for pod bug infestation being when pods were about eight days old. Clavigralla tomentosicollis and R. dentipescaused significantly higher damage to pods located within the leaf canopy, thus behaving differently from Anoplocnemis curvipes which showed a distinct preference for pods growing above the leaf canopy. The feeding activity of Aspavia armigerawas not affected by the position of pods on the plant. Overall, the study suggests that cowpea genotypes with a short flowering period and pods held above the leaf canopy offer the most promise in the management of pod-sucking pests.

The ichneumonid Diadromus collaris (Gravenhorst) has been recorded in many parts of the world as an important parasitoid of the diamondback moth, Plutella xylostella (Linnaeus), a serious pest of brassica vegetable crops worldwide. Some aspects of its biology and its interactions with Oomyzus sokolowskii(Kurdjumov), another major parasitoid of the same pest, were studied in the laboratory. At 25°C, female wasps did not have mature eggs in their ovaries until about 12 h after emergence. Both males and females mated successfully 24–48 h after emergence, and females started to oviposit one to two days after emergence. Unmated females produced male progeny only; mated females produced progeny of both sexes. The development rate of the parasitoid increased linearly with temperature from 15 to 30°C, with an estimated low temperature threshold of 7.4°C and a thermal constant of 225.1 day-degrees for development from egg to adulthood. Rates of survival from larva to adulthood were about 90% between 20 and 28°C and decreased as temperature decreased or increased. No immatures survived to adulthood at 35°C. When provided with honey solution, the females lived on average 8.3, 11.5 and 7.0 days, and parasitized 26, 44 and 46 host pupae at 20, 25 and 30°C, respectively. Female wasps could be stored at 15°C for up to four weeks without detrimental effects on reproduction. Females of D. collaris attacked host pupae already parasitized by O. sokolowskii, inserting their ovipositor into the hosts at a similar frequency as into unparasitized host pupae, but they did not lay eggs inside the hosts.

Genetic sexing systems based on a conditional lethal require good discrimination between the different phenotypes. DDT resistance in the early instars of Anopheles stephensi Liston is not a good candidate when based on mortality, but this study shows that the knockdown response gives exceptional discrimination between heterozygous resistant and homozygous susceptible individuals. One- and two-day-old larvae of the DlDDT strain showed high (417-fold) resistance to knockdown by DDT, but very low resistance to mortality (3.3-fold). This changes with the onset of the third instar, so that by the fourth instar, mortality resistance is high (108-fold) and knockdown resistance is low (6.5-fold). Susceptibility to DDT decreases from first to fourth instar in the susceptible strain by 443-fold for knockdown and 15-fold for mortality and in the resistant strain by 8.5-fold for knockdown and 491-fold for mortality. The DDT knockdown response in young larvae was successfully used to identify two Y-autosome translocations linked to the resistance gene, DDT. T(Y-3)69 and T(Y-3)72 gave recombination values between the translocation breakpoint and the DDT locus of 4.1 and 10.1 crossover units, respectively. T(Y-3)69 proved to be an adequate genetic sexing system for laboratory studies.

The development, survival, and reproduction of the black citrus aphid Toxoptera aurantii (Boyer de Fonscolombe) were evaluated at ten constant temperatures (4, 7, 10, 15, 20, 25, 28, 30, 32 and 35°C). Development was limited at 4 and 35°C. Between 7 and 32°C, developmental periods of immature stages varied from 44.2 days at 7°C to 5.3 days at 28°C. Overall immature development required 129.9 degree-days above 3.8°C. The upper temperature thresholds of 32.3, 28.6, 29.3, 27.2, and 28.6°C were determined from a non-linear biophysical model for the development of instars 1–4 and overall immature stages, respectively. Immature survivorship varied from 82.1 to 97.7% within the temperature range of 10–30°C. However, immature survivorship was reduced to 26.3%at 7°C and 33.1% at 32°C. Mean adult longevity was the longest (44.2 days) at 15°C and the shortest (6.2 days) at 32°C. The predicted upper temperature limit for adult survivorship was at 32.3°C. Total nymph production increased from 16.3 nymphs per female at 10°C to 58.7 nymphs per female at 20°C, declining to 6.1 nymphs per female at 32°C. The estimation of lower and upper temperature limits for reproduction was at 8.2 and 32.5°C, respectively. The population reared at 28°C had the highest intrinsic rate of increase (0.394), the shortest population doubling time (1.8 days), and shortest mean generation time (9.5 days) compared with the populations reared at six other temperatures. The population reared at 20°C had the highest net reproductive rate (54.6). The theoretical lower and upper temperature limits for population development, survival and reproduction were estimated at 9.4 and 30.4°C, respectively. The biology of T. aurantiiwas also compared with three other citrus aphid species.