Laboratory evaluation of certain natural compounds against the melon ladybird beetle,Epilachna chrysomelinaF. attacking cucurbit plants

Abstract

Neem Azal-T/S, Neudosan and Spruzit flu¨ssig at different concentrations were evaluated against the second and fourth instar larvae of E. chrysomelina under laboratory conditions. In case of acute effects, the highest mortality was recorded when larvae were offered squash leaves treated with the highest concentration (2%) of Neem Azal-T/S, and the lowest mortality was, however recorded after treating them with the lowest concentration (0.25%). On the other hand, the second instar larvae were more susceptible to any compound at any concentration than the fourth instar one. One per cent Neudosan formulation showed the highest toxicity to both the 2nd and 4th instar larvae. As the concentration of this compound decreased the mortality percentage of treated larvae decreased to reach the minimum at the lowest concentration (0.25%). The same trend could be applied for Spruzit flu¨ssig compound. When Neem Azal-T/S was compared with Neudosan, the later at any concentration was more toxic than the former. Generally, Neudosan and Spruzit flu¨ssig seemed to be active against E. chrysomelina during the first three days after treatment, then, deterioration occurred among this compound. In case of latent effects, the duration of the treated fourth instar larvae of E. chrysomelina with any tested compound, was prolonged. An increase in the concentration caused prolongation of this period to reach the longest at the highest concentration. This prolongation, was more pronounced after Neem Azal-T/S treatment followed by Neudosan and Spruzit flu¨ssig. The same trend could be applied for the duration of the pupal stage as being affected by the different concentrations of the tested compounds which were applied to the fourth instar larvae. However, adults of E. Chrysomelina treated as fourth instar larvae with high concentrations of Neem Azal-T/S showed some adult malformations. The sex ratios of adults produced from fourth instar larvae treated with different concentrations of the tested natural compounds were about 1 : 1, except for two cases; 1% Neudosan where the number of females were double the number of males and 0.5% Spruzit flu¨ssig where the number of males were double the number of females. An increase in the concentration of any tested compound caused an obvious decrease in the percentage of emerged adults. The least emergence percentage was recorded in the case of Spruzit flu¨ssig, followed by Neudosan and Neem Azal-T/S. Treating the fourth instar larvae with the different concentrations of the tested natural compounds significantly shortened the longevity of produced adults and decreased the fecundity.

HOST PLANT PREFERENCE OF THE MELON LADYBIRD BETTLE Epilachna chrysomelina (F.) (COLEOPTERA: COCCINELLIDAE) ON DIFFERENT CUCURBIT VEGETABLES IN MANSOURA REGION.

“…The melon ladybird beetle, Epilachna chrysomelina F.(coleoptera : coccinellidae) is considered a serious pest of cucurbit plants in Egypt (Gameel 2004, Gameel and Abdel-Gaid 2007and Sayed and Gameel 2008 and is widely distributed (El-Seady,1978, Ali and El-Seady,1986and Abdel-Moniem et al,2004. Both larvae and adults cause great damage in a short time.…”

Adult host‐plant preference and larval performance in an oligophagous insect (Chnootriba elaterii)

“…For example, our results suggest that loofah could be a promising ‘push’ species, to protect cucurbits crops from C. elaterii . This perspective could be interesting because several insecticides are recommended to control oligophagous pests; still, most of them are unsuitable or with low efficacy, owing to the emergence of resistant strains and toxicity to human and non‐target organisms (Abdel‐Moniem et al, 2004). In this context, the present results could significantly enhance the control of C. elaterii in organic cucurbit crops and introduce further studies to deepen the knowledge of the complex preference performance of these insects.…”

Effect of Certain Cultural Practices on the Population Density of Epilachna Chrysomelina F. (Coleoptera-Coccinellidae) at the New Valley Governorate in Egypt

“…Data in Table (1) show the average number of E. chrysomelina (larva and adults) recorded on three cucurbit crops (watermelon, sweet melon and cantaloupe) during 2007and 2008 seasons regardless the effect of planting dates and fertilization rates.…”