The randomly amplified polymorphic DNA technique was used to trace the geographic origin of Liposcelis bostrychophila Badonnel populations in Australia from unknown geographic sources internationally. Haplotype (or clonal) diversity was high, with 474 unique haplotypes found from 616 individuals genotyped. Gene diversity estimates (0.10–0.28) and percent polymorphic loci (38.1–88.1%) were moderate to high for most populations. This resulted in genetic distance estimates that ranged from 0.04 to 0.26 and were significantly different for most pairwise population combinations. GST values for all populations were also moderate (0.04–0.54) and again were significantly different for most pairwise population comparisons. Analysis of molecular variance revealed that the majority of variation was apportioned among individuals within populations regardless of the level at which they were grouped. Gene flow (Nm) was mostly low for all pairwise populations comparisons with an average Nm = 1.8. A non-significant negative correlation between genetic distance and geographic distance was found for worldwide populations. In contrast, within Australian populations a significant positive correlation between genetic distance and geographic distance was detected. Genetic relationships explored using unweighted pair group method analysis and non-metric multidimensional scaling indicated a mixed pattern of genetic similarities among all populations. Multiple introductions, from a wide range of international source populations, have obscured the ability to accurately determine the geographic origin of L. bostrychophila in Australia.

The insecticidal and repellent properties of Lantana camara and Tephrosia vogelii were evaluated against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in stored maize grain. Five treatment rates (1.0, 2.5, 5.0, 7.5 and 10.0% w/w) of each powdered plant material, an untreated control and a synthetic insecticide (Actellic Super™ 2% dust) were used to investigate treatment efficacy on mortality of the adult insect (five to eight days old), F1 progeny emergence and repellency against S. zeamais adults. After 21 days, L. camara and T. vogelii caused 82.7–90.0% and 85.0–93.7% insect mortality, respectively. The mean lethal exposure times (LT50) to achieve 50% mortality varied from five to six days (7.5–10.0% w/w) to seven to eight days (2.5–5.0% w/w) for both plants. Probit regression analysis showed a significant relationship between plant powder concentration and insect mortality. The plant powders and synthetic insecticide reduced adult F1 insects by more than 75% compared to the untreated control. Tephrosia vogelii was most repellent to S. zeamais at 7.5–10.0% (w/ w), repelling 87.5% of the insects, followed by T. vogelii at 2.5% w/w and L. camara at 10% w/w which repelled 65.0 and 62.5% of insects respectively. The implications of these results are discussed in the context of smallscale farmer usage of these plants for stored product protection.

In view of the losses of harvested grain incurred due to problems related to storage, marketing, transport, and handling, this paper reviews the situation on storage of food grains in developing countries. It lists the insect pests that frequently attack stored food grains in these countries and discusses strategies that would minimise the damage caused by the pests.