Worldwide, food grain is lost due to damage by insects, mites and micro-organisms. Any additional approaches towards preventing farm-storage losses could contribute to saving more grain. In one paper of this issue, the authors assess the effect of a lectin-like protein on lepidopteran larvae causing loss in stored food.

Tree-hole phytotelmata encompass the internodal water pools that form in many species of bamboo (Gramineae). Using bamboo traps, we sampled macroinvertebrate communities in a habitat within the subtropical cloud forest of Henri Pittier National Park, Rancho Grande, north-central Venezuela, and quantified the temporal differences in their abundance and composition. In total, 1024 invertebrates were collected during the 7 months between February and August 2008. The insect orders Diptera and Coleoptera were abundant, particularly Culex (Anoedioporpa) conservator Dyar & Knab, Culex (Culex) mollis (Dyar & Knab), Wyeomyia (Wyeomyia) arthrostigma (Lutz) and Toxorhynchites (Lynchiella) theobaldi (Dyar & Knab). The traps also contained predators, detritivores and collectors (filtering and gathering). Macroinvertebrate abundance in the traps was higher during the rainy season. This observation was attributed to a greater abundance of Ephydridae, Blattaria and Culicidae during wetter months, and an increased availability of potential new breeding sites in the environment, which resulted in increased adult eclosion, and higher rates of oviposition in the bamboo traps. Temporal differences in pH and dissolved oxygen levels of trap water were observed.

The abundance and distribution of Ceratitis capitata (Wiedemann) in Late Valencia citrus orchards and other alternative host crops was investigated using trimedlure-baited traps at the University of Ghana's Agricultural Research Centre in the Eastern region of Ghana. The effect of some climatic factors on the population dynamics of the pest was also studied. The population of C. capitata increased from September to October 2006 and from February to March 2007, when Late Valencia citrus fruits were ripening or ripened. The fruit fly population was the lowest from November 2006 to January 2007 when citrus fruits were in the immature green stage. Ceratitis capitata was not trapped in mango, pawpaw and pepper fields and did not emerge from fruits of these crops. Multiple regression analyses also revealed that rainfall and temperature significantly influenced the pest population. The results of this study have important implications on the decision-making process for the safe, effective monitoring and management of C. capitata in Late Valencia citrus orchards in the study area in Ghana and probably in other areas as well.

The effects of sublethal concentrations of the insect growth regulators (IGRs) diflubenzuron and methoprene on some fitness components of an Aedes aegypti (L.) population in south-eastern Brazil were investigated. The fourth instar larvae of the mosquito were exposed to 20 ppb methoprene and 3 ppb diflubenzuron, and adult survivors were evaluated for fitness parameters, including body size and biomass, fecundity, fertility, longevity and symmetry. The sublethal concentrations had negative effects on longevity, but biomass, fecundity and fertility were not affected by either IGR. In separate experiments, A. aegypti individuals' surviving concentrations of 2, 3 and 3.5 ppb diflubenzuron and 5, 10 and 20 ppb methoprene were used for morphological analyses (size and symmetry). Diflubenzuron had negative effects on the mosquito's body symmetry. The observed decreases in longevity and symmetry may have negative impacts on the population dynamics of A. aegypti.

Larvae of the Mediterranean flour moth (Anagasta kuehniella Zeller) cause major losses in stored grains throughout the world. In this study, pouterin, a lectin-like protein isolated from Pouteria torta (Mart.) Radlk. seeds, was tested for activity against A. kuehniella larvae. Pouterin did not produce significant effects on survival; however, at c. 1% w/w concentration in artificial diet, it produced a 71.4% reduction in average weight of the larvae. A dietary utilisation assay showed a reduction in efficiency of conversion of ingested food, efficiency of conversion of digested food and approximate digestibility, as well as an increase in metabolic cost. Pouterin increased the level of trypsin in the midgut and faeces of larvae. We conclude that pouterin possesses an insecticidal effect against A. kuehniella larvae and this effect may be mediated by the binding of pouterin to chitin components of the peritrophic membrane, or glycosylated proteins in the insect midgut.

Maize pests feeding on grains can transmit with their movement fungi harmful to human and animal health. The aim of the present work was to study the immigration and the dynamics of storage pests in traditional African maize granaries and the fungal spectrum associated with these insects. Treatments were (i) maize cobs protected just after pollination with gauze and stored thereafter, and (ii) unprotected maize cobs as controls. Eight different species of insects were identified in stores. No Prostephanus truncatus (Horn) was found in ‘protected’ maize during the 6 months of storage, but their mean number reached 239 individuals per kilogram after just 3 months of storage in the ‘unprotected’ stores. Similarly, significantly more Sitophiluszeamais (Motschulsky) were recovered from the unprotected than the protected maize treatment. Nine fungal species were found to be associated with the storage insects. On ‘non-protected’ cobs the genus Fusarium (36.05%) was the most frequently identified, followed by Penicillium (23.50%), Rhizoctonia (5.65%) and Aspergillus (3.95%). On protected cobs, Rhizoctonia sp. was most frequent (16.76%), followed by Fusarium spp. (16.62%), Penicillium spp. (8.24%) and Aspergillus spp. (2.33%). The toxigenic species encountered were Aspergillus flavus Link, Aspergillus parasiticus Speare and Fusarium verticillioïdes (Sacc.). Cathartus quadricollis (Guérin) appeared to carry more fungi towards the store, mainly Penicillium spp. (51.47%), Aspergillus spp. (46.56%) and Fusarium spp. (32.01%). Storage pests, in particular C. quadricollis and S. zeamais, play an important role in the contamination of maize with fungi, especially those that produce toxins.

The effects of larval crowding on growth, development and reproductive output of the Parthenium beetle Zygogramma bicolorata Pallister were investigated. Experimental manipulations of larval densities indicated that crowding creates intraspecific competition among the larvae, which negatively affected their growth and development. Larvae at high densities grew more slowly and exhibited longer larval periods compared with those at lower densities. Best-fit curves of developmental rates against larval densities were drawn, which revealed maximum theoretical density for 95% (6 or 15 larvae/63.6 cm2) and 50% developmental rate (1.75 larvae/63.6 cm2), respectively. The reproductive potential of the beetle reared at different larval densities was also observed, but no effect of increased larval densities was observed.

The effect of different constant temperatures on several reproductive attributes of the Mexican beetle, Zygogramma bicolorata Pallister, was studied. Fecundity and egg viability, pre- and post-oviposition period, and age-specific fecundity were assessed at 20, 25, 27, 30 and 35 °C. Maximum fecundity and per cent egg viability were recorded at 27 °C (928 eggs and 75.6%, respectively). Pre-oviposition and post-oviposition period declined with increasing temperature up to 27 °C, then increased at temperatures beyond that. Oviposition period decreased from 92.9 to 27.5 days with temperature increment. Age-specific fecundity was also temperature dependent. Z. bicolorata is a biological control agent of the parthenium weed Parthenium hysterophorus Linnaeus, and these findings may be useful in mass rearing programmes for the natural enemy.

The measurements of the hind femur and activities of five enzymes (α-glucosidase, amylase, cellulase, proteinase and lipase) were determined in the femoral muscles of all post-embryonic developmental stages of Zonocerus variegatus (Linnaeus). The length, width and weight of the hind femur increased during the post-embryonic developmental stages. The enzymatic activities in the femoral muscles of the adult stage were significantly (P < 0.05) higher than the lower instar stages. Proteinase and lipase activities were higher than the carbohydrases (α-glucosidase, amylase and cellulase), reflecting the nature and composition of the food plants consumed.