Within- and Between-Population Variation in Host-Plant Preference and Specificity in Australian Helicoverpa Armigera (Hubner) (Lepidoptera: Noctuidae).

1996 ◽  
Vol 44 (5) ◽  
pp. 503 ◽  
Author(s):  
MFA Jallow ◽  
MP Zalucki

Using a tethered-insect technique, we investigated within- and between-population variation in the post-alighting host-plant preference and specificity of female Helicoverpa armigera from four populations. No significant difference occurred among populations in host-plant preference. Differences in host-plant preference existed among female moths within a population, and these differences are under genetic control and heritable. Most females ranked maize, sorghum and tobacco highest, followed by cotton varieties DP90 and HG660. The least-preferred plants were cowpea and lucerne. A few females (20%) differed from this general pattern and among each other, and reversed the rank order of host plants. Within a population, individual female moths differed in their host-plant specificity, with some individuals being more generalist than others. Similarly, significant differences occurred in host-plant specificity among populations. The relevance of these findings are discussed in relation to polyphagy in H. armigera.

1998 ◽  
Vol 46 (3) ◽  
pp. 291 ◽  
Author(s):  
Mustapha F. A. Jallow ◽  
Myron P. Zalucki

We examined the effect of age-specific fecundity, mated status, and egg load on host-plant selection by Helicoverpa armigera under laboratory conditions. The physiological state of a female moth (number of mature eggs produced) greatly influences her host-plant specificity and propensity to oviposit (oviposition motivation). Female moths were less discriminating against cowpea (a low-ranked host) relative to maize (a high-ranked host) as egg load increased. Similarly, increased egg load led to a greater propensity to oviposit on both cowpea and maize. Distribution of oviposition with age of mated females peaked shortly after mating and declined steadily thereafter until death. Most mated females (88%) carried only a single spermat-ophore, a few females (12%) contained two. The significance of these findings in relation to host-plant selection by H. armigera, and its management, are discussed.


2000 ◽  
Vol 51 (1) ◽  
pp. 107 ◽  
Author(s):  
Peter A. Wilson ◽  
Peter M. Room ◽  
Myron P. Zalucki ◽  
Sukumar Chakraborty

Glasshouse experiments determined effects of a moth, Helicoverpa armigera (Lepidoptera: Noctuidae), and the anthracnose pathogen, Colletotrichum gloeosporioides (Penz.) Penz. and Sacc., on each other when attacking the same host plant, Stylosanthes scabra (Vog.) (Leguminosae) cv. Fitzroy. The host was treated with both organisms in 2 ways of succession and at 2 different life stages each. Larvae of the moth preferred to feed on healthy plants rather than plants recently infected with C. gloeosporioides, and preferred such newly infected plants to severely diseased ones. Adult female moths laid more eggs on healthy and recently infected plants than on diseased plants, when given a choice of all 3 plant types. Severity of anthracnose disease was neither promoted nor retarded by damage to leaves caused by larvae of the moth.


1989 ◽  
Vol 37 (6) ◽  
pp. 665 ◽  
Author(s):  
S Firempong ◽  
MP Zalucki

Helicoverpa armigera in Australia is found in many different geographic locations and has been recorded on a large number of host plants. We partly investigated the nature of this polyphagy by offering moths from six different sources the same set of host plants in oviposition trials. Laboratory H. armigera ranked the plants offered into the following categories: most preferred-tobacco, maize, sunflower; least preferred-cabbage, pigweed and linseed; intermediate-soybean, cotton and lucerne. Moths reared from field collected larvae showed a similar basic rank order, although there were a number of differences between populations. Further work will be needed to clarify if these small differences represent real geographic variation or simply reflect differences between batches of test plants. Tobacco and sunflower were consistently ranked highly by virtually all populations and, cotton, on which H. armigera is a major pest, was ranked very low. The possibility of exploiting the non- attractiveness of cotton in pest management is discussed.


1991 ◽  
Vol 39 (3) ◽  
pp. 343 ◽  
Author(s):  
S Firempong ◽  
MP Zalucki

The effect of various 'herbivore' attributes on oviposition in Helicoverpa armigera were considered in a series of laboratory experiments. Larval diet did not influence the rank order of adult host preference, but early adult experience around a host increased oviposition on that host in subsequent trials. The presence of eggs laid 12 h before did not influence subsequent oviposition on a plant, although newly laid eggs may have. The presence of larvae, larval damage to plants and larval frass reduced oviposition on a plant. These results are discussed in relation to polyphagy in H. armigera.


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