Understanding tolerance of thermal extremes by pest insects is essential for developing integrated management strategies, as tolerance traits can provide insights into constraints on activity and survival. A major question in thermal biology is whether thermal limits vary systematically with microclimate variation, or whether other biotic or abiotic factors can influence these limits in a predictable manner. Here, we report the results of experiments determining thermal limits to activity and survival at extreme temperatures in the stalk borer Eldana saccharina Walker (Lepidoptera: Pyralidae), collected from either Saccharum spp. hybrids (sugarcane) (Poaceae) or Cyperus papyrus L. (Cyperaceae) and then reared under standard conditions in the laboratory for 1–2 generations. Chill‐coma temperature (CTmin), critical thermal maximum (CTmax), lower lethal temperatures (LLT), and freezing temperature between E. saccharina collected from the two host plants were compared. CTmin and CTmax of E. saccharina moths collected from sugarcane were significantly lower than those from C. papyrus (CTmin = 2.8 ± 0.4 vs. 3.9 ± 0.4 °C; CTmax = 44.6 ± 0.1 vs. 44.9 ± 0.2 °C). By contrast, LLT of moths and freezing temperatures of pupae did not vary with host plant [LLT for 50% (LT50) of the moth population, when collected from sugarcane: −3.2 ± 0.5 °C, from C. papyrus: −3.9 ± 0.8 °C]. Freezing temperatures of pupae collected from C. papyrus were −18.0 ± 1.0 °C and of those from sugarcane −17.5 ± 1.8 °C. The E. saccharina which experienced the lowest minimum temperature (in C. papyrus) did not have the lowest CTmin, although the highest estimate of CTmax was found in E. saccharina collected from C. papyrus and this was also the microsite which reported the highest maximum temperatures. These results therefore suggest that host plant may strongly mediate lower critical thermal limits, but not necessarily LLT or freezing temperatures. These results have significant implications for ongoing pest management and thermal biology of these and other insects.

Country‐wide surveys of lepidopteran stem borers in wild host plants were undertaken between 2006 and 2009 in South Africa and 2005 and 2010 in Mozambique. A total of 4438 larvae were collected from 65 wild host plants in South Africa and 1920 larvae from 30 wild host plants in Mozambique. In South Africa and Mozambique, 50 and 39 stem borer species were recovered, respectively, with four new species and two new genera among noctuids. Less than 5% of the total number of species collected are considered to be economically important in Africa. These species were Busseola fusca (Fuller) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae) and Sesamia calamistis Hampson (Noctuidae). Data from this study and others in East Africa on the very low abundance of stem borers in wild host plants question the putative role of wild host plants as reservoir for stem borer pests. One new host plant family (Prioniaceae), as well as 24 and 13 wild hosts from South Africa and Mozambique respectively, was added to the list of known hosts in Africa.

Caterpillars of key moth pests can cause significant losses in cropping systems worldwide, and globalization is spreading such pests. Failure to control some species can jeopardise the economics of food production. A Global Eradication and Response Database (http://b3.net.nz/gerda) was reviewed on known government-level incursion response programs specific to invasive Lepidoptera. Geographic range expansion of Lepidoptera was evident from 144 incursion response programs targeting 28 species in 10 families. The countries involved in responses to Lepidoptera were USA (104), Australia (8), Canada (7), New Zealand (6), Italy (3), Mexico (2), with the remainder with one programme each (Brazil, Czech Republic, France, Hungary, and Spain). Most programs have been undertaken since the 1990’s. Control options exist for the long-term management of Lepidoptera, but most have issues of cost, efficacy or non-target impacts that reduce their acceptance. Pheromone-based technologies are increasingly available and are generally highly compatible with other tactics. The development of tactics for new targets is a major undertaking, although previous programs can be invaluable. New and improved socially-acceptable technologies are needed to counteract range expansion in Lepidoptera, and usually need to be used in combinations to achieve eradication. The sterile insect technique, which involves mass-rearing and release of sterile insects to reduce wild populations of the pest, has been used successfully against a number of lepidopteran species. Several sterile moth programs are under development. New technologies must have a social license to operate in urban areas, where new incursions are frequently detected. This factor is likely to reduce tactical flexibility and increase the complexity of insect eradication.