Seasonal prevalence and histopathology of Beauveria bassiana infecting larvae of the leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae)

The natural epizootic potential of the fungus, Beauveria bassiana, against larvae of the leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae) was investigated under natural conditions in two different locations for two seasons (2015–2016 and 2016–2017) in Rasheed, Behiara Governorate, Egypt. In an orchard, located in the old cultivated land, Beauveria infected 1.9–5.6% of larvae of Z. pyrina in autumn (September to November), increased to 3.4–7.2% in winter (December to February). The infection did not exceed 3.1% in spring (March to May), and no infection was recorded in summer (June to August). While in an olive farm, located in a newly reclaimed land, in both seasons of survey, no infections were recorded from May to September, while in winter, the epizootics ranged from 1.4–3.1%, from 0.4 to 1.3% in spring, and from 0.3 to 2.1% in autumn. Histopathological analysis revealed that Beauveria most commonly penetrated larvae directly through the intersegmental integument and the first symptoms were observed 3 to 4 days later. Hyphae radiated inward from the point of ingress and the fungus developed sparsely within the body cavity prior to the death of the larva. Hyphal bodies were concentrated around the point of ingress, but some were found at distance from this site. Only in the vicinity of penetration, the hypodermis showed signs of histolysis. The saprophytic phase developed rapidly and the fungus invaded all internal organs. The conidiophores seemed to rupture the cuticle by mechanical pressure and emerged all over the host cadaver, with sporulation occurring 48 h later. Pathological changes in the hemolymph appeared to be the primary cause of larval mortality.

Leopards and giants, tigers and woolly bears: casting a broader net in exploring heparin effects on Lepidoptera wing patterns

Background: Studies of heparin effects on Lepidoptera wing patterns have been restricted to a small number of species. I report observations from experiments on a broader range of taxa, including first results from swallowtails, tiger moths and microlepidoptera. Methods: Heparin injections were made in prepupal and early pupal stages of the following species representing several Lepidoptera lineages: Junonia coenia, Agraulis vanillae, Asterocampa clyton (Nymphalidae); Heraclides cresphontes, Pterourus troilus, Eurytides marcellus (Papilionidae); Hypercompe scribonia, Estigmene acrea, Hyphantria cunea (Erebidae); and Glyphodes sibillalis (Crambidae). Heparin-induced changes in wing pattern are illustrated, and advantages of using prepupal vs. pupal stages for this type of pharmacological manipulation of wing patterns are discussed. Results: In buckeyes, heparin-induced changes consisted of loss of orange parafocal elements as marginal and submarginal bands shifted basally. In gulf fritillaries, changes in black and silver markings were similar to those found in wild aberrant individuals. In tawny emperor, intermediate and extreme levels of transformation were achieved, pointing to homology of this species’ unusual eyespots to those of other nymphalids. In swallowtails, heparin-induced changes were much more restricted and proved harder to achieve, possibly indicating higher levels of stability and compartmentalization of wing patterns in this butterfly family. In tiger moths, elongation of black markings occurred so that normally distinct spots sometimes merged; in leopard moth, these changes were restricted to areas adjacent to discal spot. In pyraloid moth, changes were mostly restricted to expansion of wing marginal bands and hindwing border. Conclusions: Variation in wing pattern response to heparin found between different species and families in this study warrants further taxonomic widening of exploration of wing pattern formation mechanisms in Lepidoptera. While there are many similarities, there also seem to be very significant differences in the ways wing patterns are formed in different families of butterflies and moths.