International Journal of Tropical Insect Science

—The eggshell fine structure of a lepidopteran pest of mulberry, Amata passalis F. (Lepidoptera: Amatidae), was investigated using scanning electron microscopy. The micropylar rosette around the micropyle, shell imprints, aeropyles and regional differentiation were studied. The surface of the amatid eggshell had a highly decorated chorion with structural difference at the anterior and posterior poles. The micropylar structure was at the anterior pole of the spherical eggs (488 ± 0.595 mm in diameter), opposite to its side of attachment to the substratum. The micropylar rosette measured 51.20 ± 0.52 mm in diameter and was formed of 15–19 petal-shaped primary cells. The micropylar opening into the micropylar canal was 3.76 ± 0.52 mm in diameter. The entire surface of the chorion had a reticulate pattern of pentagonal and hexagonal cells, each of which was boarded by 3 to 6 aeropyles of similar size (0.36 ± 0.008 mm in diameter).

The ovipositional responses of the stem-borer, Chilo partellus, to the susceptible maize genotype, inbred A, are higher than to the resistant genotype, ICZ1-CM. These responses are elicited by certain characters of the plants that are perceivable prior to the moths’ arrival on the plants (distance-perceivable) as well as those perceivable after arrival on the plant (contact-perceivable). Distance-perceivable characters were not found to be responsible for the differences in the oviposition on the two genotypes tested. The contact-perceivable characters of the two genotypes differ markedly in eliciting oviposition by moths. Contact with the resistant ICZ1-CM elicits much less oviposition than with the other genotype.

The Muscid flies belonging to the order Diptera, Family Muscidae, are notoriously famous for their ability to transmit disease-causing organisms to humans, livestock, and even plants. The huge species count of this group not only makes the classical method of identification laborious but also error-prone. Therefore, in this study, we analysed cytochrome oxidase 1 (cox1) barcodes to test their ability to discriminate between studied taxonomic groups. In our study, we used a total of 42 specimens, excluding the outgroup, of 14 species belonging to 5 genera representing 4 subfamilies were used. 11 specimens were collected from the lower Gangetic Plains of West Bengal, India, including the vulnerable Sagar Islands, each showing a very high AT content (average = 69%), especially in the 1st codon position. Cox1 barcodes were able to distinguish between species with very high interspecific genetic divergence. The percentage of intraspecific genetic divergences ranges from 0% to 2.2% for the studied dataset, with the interspecific range being very high, from 0.58% to 28.8%. 1000 bootstrapped Maximum likelihood (ML) with Kimura-2-parameter phylogenetic tree and similar bootstrap-based IQ-Tree was constructed based on cox1 gene, for clarity. The ML tree is used to understand the delimitation of the species using Poisson Tree Process (PTP) analysis. The phylogenetic and delimitation study determined that most of the genus level clusters are monophyletic. The subfamily Muscinae showed non-monophyletic lineage as seen by the separation of genera Musca from genera Haematobia in both ML and IQ-Tree.

The efficiency and profitability of an integrated pest management system consisting of a phytosanitary survey and threshold interventions (based on levels of insect damage) was tested at the Vallée du Kou irrigated rice scheme in Burkina Faso, for two consecutive crop seasons in 1987. There was a considerable advantage in cost, number of insecticidal applications and yield of a threshold intervention-based system over arbitrary or routine insecticidal application methods. The proposed method is considered to be environmentally friendly.

Pearl millet, sorghum, maize and cowpea are important food crops in dryland areas of the Sahel. Losses caused by insects on these low input crops are variable but generally substantial. Basic information on the role of natural enemies is scant. An example of a recent applied research which is mainly directed towards the management of millet earhead caterpillar, Raghuva albipunctella Joannis is narrated. Results of a study initiated on conservation and encouragement of Bracon hebetor Say against Raghuva in a traditional village environment are highlighted. These results demonstrate that such an approach of biological control has a place in even the temporary, already fragile agro-ecosystems and in habitats of low durational stability in the drought-hit Sahel. Extensive additional base field data have been assembled since 1981 on the natural enemies of other pests, including Heliothis armigera (Hb.) in Senegal. Based on these results, the scope of conservation and encouragement on natural enemies in the Sahelian zone is discussed. Future research, development and training needs, for both short and more importantly long-term planning in this important aspect of pest management are briefly mentioned.

This paper is a compilation of abstracts of 91 published articles on the red locust, Nomadacris septemfasciata (Serville) for the period 1940–1998. The summaries have been compiled from material held in the library of IRLCO-CSA at Ndola, Zambia and the University of Zambia, Lusaka. The articles deal with different aspects of the biology, ecology and control of the red locust with about equal coverage.

In this study, the effect of four temperatures (23,27, 31, and 35 °C) were evaluated on the development and predatory potential of Exochomus nigripennis (Erichson) (Col.: Coccinellidae) fed on Gossyparia spuria (Modeer) (Hem.: Eriococcidae) under laboratory conditions (60 ± 5% RH, and a photoperiod of 16:8 (L:D) h). The longest developmental time of total immature stages was at 23 °C (49.0 days) and the shortest was at 35 °C (22.5 days). Also, the mortality of immature stages significantly decreased as the temperature was increased from 23 to 31 °C, and then increased at 35 °C. The larvae reared at 31 and 35 °C consumed more prey than those reared at the other rearing temperatures. In contrast, larvae reared at 23 °C ate less prey than those reared at the others. Adults who came from larvae reared at 31 °C were heavier than those reared at the other temperatures. Based on the linear model, the low-temperature threshold for egg incubation, total larval stage and pupal stage was 10.54, 13.91 and 8.34 °C, respectively. In this model, the amounts of thermal requirement for egg incubation, total larval stage and pupal stage was 90.09, 270.27 and 101.01 °C, respectively. The nonlinear estimates were higher than the linear estimates. Overall, the results of the development of immature stages together to the predation rate and the adult weight would have led to the conclusion that 31 °C was favorable to E. nigripennis. Also, our findings support this hypothesis that the development of ectothermic animals like insects is closely linked to environmental temperature.

The efficacy of natural embelin isolated from berries of Embelia ribes Burm. against Tribolium Castaneum Herbst is discussed. Embelin mixed with wheat samples at concentrations of 0.1875% and above exhibited high efficacy by bringing about adult mortality even after 8 months of storage. Productivity (progeny/adult-day) of the test insect was also reduced significantly in treatments as compared to controls at different intervals of storage. After 8 months of storage, significant reduction in F1 progeny at the lowest concentration was mainly due to larvicidal action of embelin. In the present study, embelin did not exhibit any chemosterilant action or contact toxicity to adult beetles. Germination of wheat treated with embelin even at the highest concentration of 0.750% was not impaired to any significant extent.