Summary Molecular methods are facing increasing application on a broad remit in ecological studies, including work on parasites, parasitoids and pathogens. These studies can entail the screening of large sample numbers to monitor the establishment of parasitoid and pathogen infection rates over extended periods of time. However, when infection or parasitism rates are low, testing many samples individually quickly becomes tedious and costly. To optimize the application of molecular diagnostics in such situations, we developed a pooling approach that is applicable to any host–pathogen and host–parasite/parasitoid system. In a first step, host individuals are pooled along the two axes of a grid and screened for pathogen/parasite DNA via multiplex PCR. Already from these results a rough estimation of the pathogen/parasitism rate in the pooled samples is possible. To determine the exact infection/parasitism rate in the sample or if it is relevant to identify the respective infected/parasitized individuals, only those samples belonging to two pathogen/parasitoid DNA‐positive pools need to be retested individually. The efficacy of the pooling approach was statistically and empirically evaluated for different infestation levels using three host–parasitoid systems and a newly developed diagnostic multiplex PCR assay. The established multiplex PCR assay allows to reliably identifying three agro‐economically important lepidopteran pest species (Phthorimaea operculella, Symmetrischema tangolias and Tuta absoluta) and five relevant parasitoids (Copidosoma koehleri, Apanteles subandinus, Orgilus lepidus, Dolichogenidea gelechiidivoris and Diadegma mollipla). Compared to individual testing and even to standard one‐dimensional pooling approaches, the new method reduces the number of PCRs substantially. At parasitism rates <10%, the pooling approach allowed for a reduction in the screening effort for up to 90%. In general, its efficacy decreases with increasing parasitism rates with a breakeven point at about 20%. As such the pooling approach presents an efficient and sensitive means for screening of large sample numbers at low parasitism and infection rates. Since it drastically reduces time and costs in diagnostic screenings, it is especially suited for studies with limited financial resources, allowing for extended investigations and routine monitoring screenings when infection/parasitism rates are low.

A strain (ARP14) of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin was isolated from field-collected Riptortus pedestris (Fabricius) (Hemiptera: Alydidae). The lethal median concentration of the ARP14 strain was compared with that of a commercialized strain (GHA) of the same fungus against R. pedestris and its two egg parasitoids, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Platygastridae). Mortality and mycosis rates were evaluated after exposure to five concentrations of the fungus, i.e., 1×109, 1×108, 1×107, 1×106, and 1×105 conidia/mL, using a glass scintillation vial as an exposure arena in 25.0 ± 0.5°C and 93.7 ± 2.9% RH. The lethal median concentrations (LC50) for 2nd and 4th instar nymphs, and adults of R. pedestris were not significantly different between the two strains of B. bassiana. However, the mycosis rate of ARP14 was 1.3 and 1.8 times higher than that of the GHA strain in 4th instar nymphs and adult females of R. pedestris, respectively, at the 1×108 conidia/mL concentration. More interestingly, the mycosis rates at 1×108 conidia/mL concentration in the parasitoids G. japonicum and O. nezarae were much lower in the ARP14 strain (15.0 and 0%) than in the GHA strain (73.3 and 66.0%), respectively, suggesting that the B. bassiana strain ARP14 is less virulent to these parasitoids than the commercially available strain. Our results suggest that B. bassiana ARP14 may be a potential new biopesticide against R. pedestris with fewer negative effects on beneficial parasitoids than currently available options.

Annual monitoring of potato tuber moth (PTM) was made in 2008/09 in15 districts of Nepal to understand the distribution and seasonal abundance. The locally made pheromone trap was installed and observed in 24 hours intervals. The activity of PTM was observed in plain, mid hills (below 2200 masl) and high hill districts. The population of PTM was found more in mid-hills than in plain whereas PTM was absent in high hill districts. The highest average number of PTM was observed in May (480±238 moth/month) with no adult moths in October to December in plain whereas 522±174 moth/month was observed in July and 18±4 moth/month in December in mid-hills of Nepal. The seasonal abundance of PTM observed from March to July (74±63 to 126±100 moth/month) in Plain and March to October (191±157 to 104±60 moth/month) in mid-hills. The understanding of PTM population dynamics could be useful to make suitable management decision.

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Spirotetramat, a lipid biosynthesis inhibitor, is effective against sucking insect pests but harmless to insect natural enemies. As spirotetramat can be registered for the management of sucking insect pests such as aphids and bugs in soybeans, we evaluated the insecticide against Riptortus pedestris (Fabricius) (Hemiptera: Alydidae), one of the most important soybean pests in Korea, as well as its effect on two of its important egg parasitoids, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead; Hymenoptera: Platygastridae). Oral toxicities of five concentrations of spirotetramat (1.00, 0.50, 0.25, 0.13, and 0.06 ml/liter) were tested by feeding these test solutions to insects for 24 h after 12 h of starvation. The lethal median concentration (LC50) for second instars of the bean bug was 0.3 ml/liter after 48 h while values for fourth instars and adults were 9.2 and 19.0 ml/liter, respectively. The median lethal time (LT50) for bean bugs when exposed to a concentration of 0.50 ml/liter was 1.2-1.5 times less than that of the control, while in G. japonicum and O. nezarae it was 1.1-1.2 times less than the control. These results show that spirotetramat is less toxic to the egg parasitoids of bean bug than to bean bug itself and would thus be useful in an integrated management program for this pest.