Agricultural and Forest Entomology

1 The pine processionary moth Thaumetopoea pityocampa is expanding its geographical range in Europe, as a consequence of enhanced winter survival under a warmer climate. A combination of daytime nest temperatures and night air temperatures determines the number of hours larvae are able to feed (hours above realized feeding threshold, RFT).

2 We tested the RFT‐based model for survival across multiple areas of the insect’s range in the Italian Alps over a 2‐year period. In a series of translocation experiments using natural temperature gradients as spatial analogues for global warming, we transferred colonies of T. pityocampa larvae to sites within zones of historical distribution, recent distribution, and outside the present range. The sites included traditional (Pinus nigra, Pinus sylvestris) as well as novel (Pinus mugo, Pinus uncinata, Pinus cembra) hosts.

3 Survival during precold (August to November), cold (December to February) and postcold (March to May) periods were analysed against climatic variables (temperature and rainfall) and predictors developed by the model.

4 Host species did not significantly affect final survival, with the exception of slower larval development, and resulting lower cold tolerance, on P. cembra than on P. mugo at the same site.

5 Across all the sites and hosts, final survival of colonies depended on the number of feeding hours during the cold period (RFT), which explained 82% of the variance in a regression model. We recommend using RFT, or its surrogate daily mean minimum temperature when nest temperature is not available, in predictive models of range expansion of T. pityocampa under climate change scenarios.

1 Adult wheat stem sawflies Cephus cinctus, pests of cultivated cereals that also infests wild grasses, migrate into wheat fields where they oviposit in elongating, succulent stems.

2 Volatiles released by wheat plants at susceptible stages were analyzed to determine potential semiochemical compounds. Seven major compounds were identified and quantified.

3 A Y‐tube bioassay was developed to evaluate upwind orientation of adult sawflies in response to an airstream that passed over elongated wheat plants. The bioassay was also conducted with synthetic volatile compounds. The compounds were tested using a range of concentrations spanning those identified in the airstream passing over wheat plants.

4 A significant number of adult females were attracted to wheat plants when given a choice of either purified air or the air passing over plants.

5 A significant number of female C. cinctus were attracted to (Z)‐3‐hexenyl acetate, β‐ocimene, and (Z)‐3‐hexen‐1‐ol, but were repelled by 6‐methyl‐5‐hepten‐2‐one. Females did not respond to (E)‐2‐hexenal, or (E)‐2‐hexenyl acetate. The behavioural responses were concentration dependent; the highest tested concentration of (Z)‐3‐hexenyl acetate was repellent to females of this species.

6 Adult males did not discriminate between air passing over wheat plants and air from a purified airstream. Males did not respond to any tested synthetic compound at any concentration.

7 The present study demonstrates for the first time that adult females of wheat stem sawfly display innate behaviours in response to synthetic volatiles. These results provide a basis for the potential development of resistant wheat varieties and for the development of semiochemically‐based pest management.

Africa hosts several economically significant lepidopteran cereal stemborer species belonging to the Crambidae, Noctuidae and Pyralidae families. The invasive spotted stemborer (Chilo partellus Swinhoe), which is native to Asia, is one of the most damaging cereal stemborers in Africa. The impact of C. partellus on indigenous stemborer species remains unclear, although recent work demonstrates its increasing ecological influence and numerical advantage over Sesamia calamistis and Busseola fusca in African landscapes.

1 When laying eggs, adult female Diprion pini discriminated between clones of Scots pine, Pinus sylvestris.

2 Larval survival was affected by Scots pine clone but was not correlated with oviposition preference.

3 Diprion pini laid most eggs on tougher needles of Scots pine.

4 There was no evidence to suggest that D. pini is responding to the monoterpene composition of the foliage.

Individual mark–release–recapture is an important method for gathering data on insect movement, although it is limited by the constraints of tagging small insects with individual information.