Seasonal population fluctuation of the coffee leafminer, Leucoptera coffeella (Guérin-Méneville & Perrottet) (Lepidoptera: Lyonetiidae), led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. Life-table data were colleted from insecticide-free plots within a 3 ha coffee plantation on the upper, medium and lower canopy. Leafminer mortality was similar among the canopy parts but varied in the two seasons studied. During the rainy season, the generational mortality averaged 94.3%, with 50.2, 33.7 and 10.4% occurring during egg, larval and pupal stages, respectively. During the dry season, total mortality was 89%, with 13.2, 61.0 and 14.8% occurring during egg, larval and pupal stages, respectively. Marginal mortality rates during the rainy season were highest for physiological disturbances, rainfall and egg inviability; but, in the dry season, they were highest for predaceous wasps, physiological disturbances and parasitoids. Egg and larval stages accounted for most of the mortality variation in the rainy season, while the combination of larval and pupal mortality better described the generational mortality in the dry season. Variation in mortality during the rainy season was primarily associated with egg inviability, rainfall and parasitoids. In contrast, predatory wasps and physiological disturbances were the main factors associated with mortality variation during the dry season. These results suggest that weather conditions, natural enemies and plant quality attributes are the main determinants of the population dynamics of L. coffeella.

Hop plants were sprayed with (Z)-jasmone, at a rate of 50 g ha−1, during the spring migration of the damson–hop aphid Phorodon humuli (Schrank) in 2002 and 2003. Numbers of P. humuli spring migrants colonizing hop plants, Humulus lupulus L., 2–6 and 7–11 days after applying this treatment were assessed in both years. During the first five-day period, significantly more spring migrants were found on hop plants treated with (Z)-jasmone, in comparison with control plants, in 2002. By contrast, no significant difference was evident in the second five-day period. Although the migration in 2003 was much lighter than in 2002, greater numbers of migrants were again removed from treated plants. Indeed, more spring migrants were removed from plants sprayed with (Z)-jasmone in this year during both five-day periods (11 and 44%, respectively) compared with the 23% greater numbers removed in the first five-day period in 2002. Therefore, unlike some other species of aphid, where numbers were consistently lower on plots sprayed with (Z)-jasmone, spraying the secondary host of P. humuli with this compound appears to increase colonization by spring migrants.

Predatory beetles contribute to the control of crop pests and are an important food resource for farmland birds. Many of these beetle species overwinter as larvae within agricultural soils, however, their spatio-temporal emergence patterns are poorly understood, even though such knowledge can assist with their management for biocontrol. Soil moisture is considered to be a key factor influencing oviposition site selection and larval survival. The time, density and spatial pattern of Carabidae and Staphylidae emergence was therefore measured across two fields and compared to soil moisture levels in the previous winter and adult distribution in the previous July. The mean density of Carabidae and Staphylidae that emerged between April and harvest within each field was 157 and 86 m−2, indicating that soils are an important over-wintering habitat for beneficial invertebrates and should be managed sympathetically if numbers are to be increased. Of the species that were sufficiently numerous to allow their spatial pattern to be analysed, all showed a heterogeneous emergence pattern, although patches with high emergence were stable over the sampling period. The distribution of eight species was influenced by soil moisture levels in the previous winter and eight species, although not the same, were spatially associated with the distribution of adults in the previous summer suggesting that the females selected oviposition areas with the appropriate soil wetness.

Fitness costs associated with resistance genes expressed in the absence of insecticides affect the evolution of insecticide resistance and the outcome of resistance management programmes. However, measurements of fitness costs may not be straightforward as they vary with environmental conditions. The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), has developed resistance to spinosad, the first insecticide of the Naturalyte class, after only a few years of field application of this product. In this study, we compared the performance of two homogenous strains of P. xylostella, one susceptible (SS) and the other resistant (RR) to spinosad at an unfavourable, low natural temperature regime, a favourable median-fluctuating temperature regime and an unfavourable high-fluctuating temperature regime. The RR strain showed only marginal fitness cost at the median temperature regime. At the low temperature regime, the RR strain failed to produce any viable offspring, while the SS strain achieved positive population growth. At the high temperature regime, the RR strain showed a 33% decrease in intrinsic rate of increase compared to the SS strain. The results demonstrate that fitness costs of resistance to spinosad are temperature-dependent, increasing in scale at unfavourably low and high temperatures; costs were particularly high at low temperatures. Suggestions for designing effective management programmes are made to delay or avoid development of resistance to spinosad by P. xylostella under different temperature conditions.

Reticulitermes flavipes (Kollar) colonies established by field-collected alates were reared in the laboratory for 11 years. Weights of members of each caste and full-colony censuses were performed regularly; the most recent 2003–2004 data are reported. Colonies averaged 11623.5±910 individuals, and with the exception of primary queens from one genetic lineage, mean weights for all castes had increased since 2001. Female replacement reproductives, or neotenics, developed to replace dead queens in clusters of either few, large individuals or many, small individuals. Regardless of cluster size, female neotenics comprised more reproductive biomass per colony than primary queens. The number and size of female neotenics was independent of colony size or time elapsed since a founding queen's death.

Bemisia tabaci biotype B is one of three genetic groups able to induce silverleafing in squash. Several earlier studies had observed that this physiological change was induced only through the feeding of juvenile whiteflies. This study uses adult males only to show that after 11 days the adult males were able to begin to induce silverleafing. Further, the response was density dependant with 120 adults inducing the first signs of silverleafing in 11 days, 90 adults in 13 days and 60 adults in 15 days.

Species of the genus Pnigalio Schrank are ectoparasitoids on several pest insects. Most species are polyphagous parasitoids of lepidopteran and dipteran leafminers. Despite their potential economic importance, information on intraspecific phenotypic variability is insufficient. Pnigalio soemius (Walker) was reared at five different temperatures (10, 15, 20, 25, 30°C) on mature larvae of one of its natural hosts, Cosmopterix pulchrimella Chambers (Lepidoptera: Cosmopterigidae), to investigate the influence of temperature on size, colour and other morphological traits, and to measure the range of variation of several characters. Thermal developmental reaction norms, which represent the effect of temperature during growth and development on the value of some adult traits, were produced. The results confirmed the influence of temperature on numerous characters and that these characters had a larger range of variation than realized previously in the construction of taxonomic keys to species. In particular, the number and position of the costulae on the propodeum and colour of the gaster were affected by rearing temperature.

Fruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.

The area planted to genetically engineered crops has increased dramatically in the last ten years. This has generated many studies examining non-target effects of bioengineered plants expressing Bacillus thuringiensis endotoxins. To date, most have focused on population-level effects in the field or laboratory evaluation of specific plant-herbivore or plant-herbivore-predator trophic pathways. Using a post-mortem enzyme-linked immunosorbent assay, we examined the uptake of Cry1Ab-endotoxins by predatory coccinellids and the importance of anthesis to this trophic pathway. Adult Coleomegilla maculata, Harmonia axyridis, Cycloneda munda and Coccinella septempunctata contained low, but detectable, quantities of Bt-endotoxin when screened by ELISA. This was most evident in C. maculata, with 12.8% of 775 individuals testing positive for Cry1Ab-endotoxins. Interestingly, the presence of endotoxins in gut samples was not confined to periods around anthesis, but coccinellid adults tested positive two weeks before and up to ten weeks after pollen was shed, suggesting tri-trophic linkages in their food chain facilitates the transfer of endotoxins into higher-order predators. This contrasts with adult Coleomegilla maculata entering overwintering sites where Bt-endotoxins were not detected in gut samples, indicating low levels of persistence of Cry1Ab-endotoxins within coccinellid predators. This study enhances our understanding of complex interactions between transgenic crops and non-target food webs, but further research is required to quantify the significance of specific trophic linkages in the field.