Bionomics of Mussidia nigrivenella (Lepidoptera: Pyralidae) on three host plants

Abstract

Life table studies of Mussidia nigrivenella Ragonot, a pest of maize in Benin, showed that host plant species had a significant effect on larval survival and developmental time. The maximum percentage of larvae surviving was recorded on jackbean, Canavalia ensiformis (36%) and lowest on maize (18%). Mean developmental time for larvae was longest on maize (19.8 days) and shortest on jackbean (17.2 days). The number of eggs laid was highest for females from larvae fed on jackbean (x -= 176), followed by velvetbean, Mucuna pruriens (x -= 143), and lowest for females where larvae had fed on maize (x -= 127). Longevity of ovipositing females was higher on jackbean (5.4 days) than of those from any other host plants. According to the growth index and life table statistics, jackbean was the most suitable host plant, followed by velvetbean, and maize, the least suitable. Thus, jackbeans should be recommended for use in mass rearing programmes of M. nigrivenella, e.g. as a host for parasitoids in future biological control programmes. Because of the high suitability of jack-and velvetbeans for M. nigrivenella, planting of these increasingly important cover crops should be timed in such a manner that the emergence of female moths from mature pods does not coincide with maize plants in a suitable developmental stage for oviposition and development of young M. nigrivenella larvae.

Resistance to Pyrethroids and Organophosphates Increased Fitness and Predation Potential of <I>Chrysoperla carnae</I> (Neuroptera: Chrysopidae)

“…Therefore, the Þtness advantage in resistant populations of C. carnea may have been linked with a monooxygenase mechanism of resistance as suggested previously (Roush and Plapp 1982a). The GI emphasizes the importance of both survival and developmental time in measuring food quality and its impact on physiology of the insects (Setamou et al 1999). Higher survival rates and shorter developmental times yield higher values of GI, indicating better food quality and no adverse affect on physiology (life traits) of C. carnea.…”

“…For each insecticide and location, the jackknife program of (Hulting et al 1990) was used to calculate the net reproductive rate (R 0 ), the intrinsic rate of natural increase (r m ), the Þnite capacity of increase (l, deÞned as the number of times a population multiplies itself per unit of time), the mean generation time (T), the doubling time (DT) of the population, and the total progeny produced per female. The growth index (GI) was calculated by dividing the percentage survival of immature by developmental time (Setamou et al 1999).…”

Feeding and Life History of Alabama argillacea (Lepidoptera: Noctuidae) on Cotton Cultivars Producing Colored Fibers

“…A feeding index was calculated hy dividing mean pupal weight by mean weight of leaf tissue consumed for each cotton cultivar. The growth index (CI) was calculated as the ratio between the percentage of adults emerged and the duration of the immature period (larval and pupal stages) (Sétamou et al 1999).…”

“…For each cotton cultivar, linear or quadratic regression analysis was used to examine the relationship between the amount of diet consumed and pupal weight. For each type of relationship, parallel line analysis was applied to compare the regressions of the three cotton cultivars by using the PROC MIXED procedure SAS (Littell et al 1997, Sétamou et al 1999. First, homogeneity of the regression coefficients between the different cotton cultivars was tested, and whenever the slopes were homogeneous, the least square (LS) means were compared using multiple f-tests (Littell et al 1997).…”

Reproductive Potential of Overwintering, F1, and F2 Female Boll Weevils (Coleoptera: Curculionidae) in the Lower Rio Grande Valley of Texas

“…For each treatment, the jackknife program of Hulting et al (1990) was used to calculate the net reproductive rate (R 0 ), the intrinsic rate of natural increase (r m ), the Þnite capacity of increase (, deÞned as the number of times a population multiplies itself per unit of time), the mean generation time (T), the doubling time (DT) of the population, and the total progeny produced per female. The growth index (GI) was calculated by dividing the percentage survival of immatures by development time (Setamou et al 1999).…”