No abstract

Decision support systems have been developed for risk analysis and management of root-feeding white grubs (Coleoptera: Scarabaeidae: Melolonthinae) in Queensland, Australia, sugarcane (Saccharum spp.), based partly on manual inspection of soil samples. Acoustic technology was considered as a potential alternative to this laborious procedure. Field surveys were conducted to detect the major pests Dermolepida albohirtum (Waterhouse) near Mackay, and Antitrogus parvulus Britton near Bundaberg. Computer analyses were developed to identify distinctive scrapes and other sounds produced by D. albohirtum and Antitrogus species and to distinguish them from sounds of nondamaging white grubs (Rutelinae, Dynastinae), as well as from extraneous, wind-induced tapping signals. Procedures were considered for incorporating acoustic methods into surveys and sequential sampling plans. Digging up and inspecting sugarcane root systems requires 10-12 min per sample, but acoustic assessments can be obtained in 3-5 min, so labor and time could be reduced by beginning the surveys with acoustic sampling. In a typical survey conducted in a field with low population densities, sampling might terminate quickly after five negative acoustic samples, establishing a desired precision level of 0.25 but avoiding the effort of excavating and inspecting empty samples. With a high population density, sampling might terminate also if signals were detected in five samples, in which case it would be beneficial to excavate the samples and count the white grubs. In intermediate populations, it might be necessary to collect up to 20 samples to achieve desired precision, and acoustic methods could help determine which samples would be best to excavate.

Acrodipsas illidgei (Waterhouse and Lyell) has mynnecophagous larvae associated with the ant Crematoguster sp. (laeviceps group). Eggs were found on the trunk and branches of the mangrove Avicennia marina colonised by the host ant. Two types of epidermal organs, possibly glandular, were identified in first instar larvae, and a Newcomer's organ was present from the second instar onwards. Biology was observed in artificial ant colonies. First instar larvae were camed by the ants and placed near the ant brood where they fed, apparently imbibing the fluid contents of the ant larvae through a hole chewed in the cuticle. Older larvae consumed the whole ant larva or pupa. The function of the larval organs in myrmecophily is discussed.

Immature Chrysopa sp. and Nabis capsiformis required 335 and 325 d°, respectively, for development from egg to adult, while larvae of Micromus tasmaniae were able to complete development at 5°. Mean adult female longevity and oviposition rate at 23° were 52 d (max. 83 d) and 18.1 eggs/d, and 30 d (max. 43 d) and 10.4 eggs/d for C. sp. and N. capsiformis respectively, and oviposition rate of M. tasmaniae averaged 19.1 eggs/d during 5 weeks. Reduced longevity and increased oviposition rate at higher temperatures were accounted for by basing adult biology on physiological time above the immature developmental thresholds. Intrinsic rates of increase were thus calculated as 9.820, 6.868, and 8.366 ♀ eggs/103 d° above thresholds of 10.5°, −2.9°, and 11.3° for C. sp., M. tasmaniae, and N. capsiformis, respectively. RÉSUMÉ INFLUENCE DE LA TEMPERATURE SUR LA BIOLOGIE DE CHRYSOPA SP., MICROMUS TASMANIAE ET NABIS CAPSIFORMIS L'examen a porté sur l'influence de différentes températures constantes sur le développement et la biologie imaginale de trois espèces prédatrices (Chrysopa sp., peut‐être C. signata, Micromus tasmaniae et Nabis capsiformis) récoltées dans des champs de coton du sud‐est du Queensland en Australie. C. sp. et N. capsiformis ont besoin respectivement de 335° au dessus d'un seuil de 10.5° et de 325° au dessus d'un seuil del 1.3°, pour se développer de l'oeuf à l'adulte. Les larves de M. tasmaniae pouvant effectuer la totalité de leur dévelopment a 5°. A 23° les longévités des femelles adultes et les taux de ponte de C. sp. et N. capsiformis sout en moyenne de 52 j. (maximum 83) et 30 j. (maximum 43) d'une part et 18.1 et 10.4 œufs par jour d'autre part. Le taux de ponte de M. tasmaniae est de 19,1 œufs par jour pendant 5 semaines à 23°. La longévité réduite et le taux de ponte accru aux températures supérieures sont interprétés en basant la biologie imaginale sur le temps physiologique au dessus des seuils de développement. Les taux d'accroissement intrinsèque (rm) sont plus élevés aux températures élevées, principalement à la suite du taux de développement accru. M. tasmaniae possède le rm le plus élevé à toutes les températures par suite d'un développement rapide et de seuils thermiques bas, d'une brève période précédant la ponte et d'une date de ponte maximum précoce. Le rm de C. sp. est plus élevé que celui de N. capsiformis à la suite de son taux de ponte plus élevé. Les valeurs de rm fixées à partir du temps physiologique sont respectivement: 9,820, 6.868 et 8,366 œufs femelles/103 d° au dessus des seuils de 10,5°, −2,9° et 11,3° pour C. sp., M. tasmaniae et N. capsiformis.