Exclusion nets have been used successfully to protect fruit from insect pests of apples under various conditions, but the effect of each particular netting system on the plant itself has rarely been investigated. In this study, a complete exclusion system—in which the soil is also excluded—was used to grow ‘Honeycrisp’ apples for six years in southern Quebec, Canada. Abiotic conditions, as well as plant photosynthesis and fruit quality characteristics (colour, firmness, size, sugar content, number of seeds, ripeness and skin integrity) and yield were estimated yearly and compared in netted (either with or without a rainproof top) and unnetted row units. Although annual variations were high and results showed little or no difference between netted and unnetted rows for all measured variables, with the following exceptions; colour (increased red surface on fruits from unnetted rows some years), size (fruits from unnetted rows were smaller) and maturity (fruits from unnetted rows matured slightly faster). Fruits produced under nets had fewer microcracks at the surface than fruits produced without nets. Reduced cracking possibly helped decrease sooty blotch and flyspeck incidence and severity. Impacts for pest control and prospects for pesticide-free production are discussed.

The zoophytophagous mullein bug, Campylomma verbasci (Meyer-Dür) (Hemiptera: Miridae), is a beneficial predator of mites and aphids, but also a pest causing damage when it feeds on apples. The aim of this study was to evaluate three different parameters of phytophagy of the mullein bug both in laboratory (phytophagous behavior) and field (fruit damage) tests: 1) apple cultivar, 2) fruit size, and 3) nymphal instar. In the laboratory, nymphs were observed individually for 15 min in Petri dishes containing agar gel and an apple fruitlet to evaluate feeding punctures of four apple cultivars, four fruit sizes, and five nymphal instars. In the orchard, nymphs were caged at bloom in sleeve cages to evaluate damage on the developing fruit of seven apple cultivars and three nymphal instars on ‘Red Delicious’. The feeding punctures in the laboratory were higher on ‘Red Delicious’ than on ‘Honeycrisp’; fruit damage in the orchard did not differ among cultivars at mid-season, but was higher on ‘Red Delicious’ than on ‘Lobo’ and ‘Marshall McIntosh’ at harvest. The number of feeding punctures in the laboratory was higher on 7–9 mm than on 18–20 mm size fruit for ‘Red Delicious’, but not for ‘Honeycrisp’. The number of feeding punctures in the laboratory made by the fifth nymphal instar was higher than those made by younger nymphs, but fruit damage in the orchard did not differ among nymphal instars. Our results will help to elaborate a management chart for this insect by minimizing risks and promoting its use for biocontrol.

The efficiency of two Trichogramma species as biocontrol agents against the European corn borer (ECB) Ostrinia nubilalis (Lepidoptera: Crambidae) was investigated under field conditions. Five inundative releases of Trichogramma ostriniae and T. brassicae (Hymenoptera: Trichogrammatidae) were done in sweet corn plots. Ostrinia nubilalis sentinel egg masses were placed on corn plants in order to compare the efficiency of the two Trichogramma species. The parasitism rate of O. nubilalis egg masses by T. ostriniae was 13% higher than egg masses parasitized by T. brassicae. Likewise, the percentage of eggs parasitized per mass by T. ostriniae was significantly higher following two of the five releases. Attacked egg masses showed an average of 29% of eggs parasitized by T. ostriniae, versus 14% of eggs parasitized by T. brassicae. The rate of parasitoid emergence from sentinel egg masses was also significantly higher for T. ostriniae than for T. brassicae. Damages to plants due to ECB did not differ significantly in presence of the two parasitoid species. However, plants in plots receiving parasitoids showed less damage than plants in control plots. Overall, T. ostriniae was clearly more efficient than T. brassicae to parasitized egg masses of O. nubilalis in sweet corn.

The obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) [Lepidoptera: Tortricidae], a primary pest in Quebec apple orchards, can be naturally parasitized. Knowing that habitats around crop’s peripheries are reservoirs for natural enemies of pests, the objective of the present investigation was to assess parasitism and parasitoid guild composition associated with the OBLR. The two-year study included orchards under integrated pest management, their edges, and adjacent woodlands. Parasitism was assessed using sentinel OBLR larvae and considered spring, early summer and late summer. Parasitism rates between regions with different vegetation composition were not significantly different. The first year, late summer larvae showed higher parasitism in orchards (27%), compared to edges (7%) and woodlands (11%). The following year, larvae exposed in early summer had higher parasitism rate in edges (28%) compared to orchards and woodlands (17% in both zones). Nineteen parasitoid species parasitized sentinel larvae. The tachinid Actia interrupta (Curran), the most abundant species, represented 28 and 62% of species the first and the second year respectively. Our research demonstrates that natural biological regulation of the OBLR is the result of a highly diversified parasitoid guild and this should be taken into account in any Integrated Pest Management program.

Le granulovirus du carpocapse de la pomme (CpGV) et les parasitoïdes du genre Trichogramma sont des agents de lutte biologique du carpocapse de la pomme, mais leurs interactions sont inconnues. L’objectif de l’étude a été d’évaluer la compatibilité et la complémentarité de Trichogramma minutum et du CpGV. Des essais en laboratoire ont été menés la première année et des essais dans le verger ont été réalisés pendant deux ans avec les deux agents de lutte utilisés seuls ou en combinaison. Dans le laboratoire, le parasitisme a été réduit après que le CpGV a été appliqué sur les oeufs du carpocapse de la pomme, suggérant que les femelles parasitoïdes ont discriminé entre des oeufs recouverts de CpGV ou non. Au contraire, le CpGV n’a pas affecté le parasitisme causé par T. minutum dans le verger. Les deux agents de lutte ensemble ont causé 77 et 79 % de mortalité au carpocapse de la pomme dans le verger la première et la deuxième année respectivement. Nos résultats en verger montrent que l’effet combiné du CpGV et de T. minutum sur le carpocapse de la pomme est compatible. En conséquence, l’utilisation des deux agents de lutte biologique est une alternative prometteuse pour la lutte contre le carpocapse de la pomme dans les vergers de pommiers.