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Belowground symbiosis of plants with beneficial microbes is known to confer resistance to aboveground pests such as herbivorous arthropods and pathogens. Similarly, microbe-induced plant responses may also impact natural enemies of pests via the elicitation of plant defense responses and/or alteration of plant quality and growth. Nesidiocoris tenuis is a zoophytophagous predator and an efficient biological control agent of greenhouse pests. Its usefulness in plant protection is often hindered by its ability to damage plants at high predator population densities or when prey is scarce. In this study, we investigated the effect of Fusarium solani strain K (FsK), an endophytic fungal isolate that colonizes tomato root tissues, on the capability of N. tenuis to cause necrotic rings, an easily discernible symptom, on tomato stems and leaves. We found significantly less necrotic rings formed on FsK-inoculated plants for all tomato cultivars tested. FsK has been previously shown to confer ethylene-mediated tomato resistance to both foliar and root fungal pathogens; thus, the ethylene-insensitive Never ripe (Nr) and epinastic (epi) tomato plant mutant lines were included in our study to assess the role of ethylene in the recorded FsK-mediated plant damage reduction. The jasmonic acid (JA)-biosynthesis tomato mutant def-1 was also used since JA is known to mediate major anti-herbivore plant responses. We show that ethylene and JA are required for FsK to efficiently protect tomato plants from N. tenuis feeding. No necrotic rings were recorded on FsK-inoculated epi plants suggesting that ethylene overproduction may be key to tomato resistance to N. tenuis feeding.

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Abstract. The taxonomic status of the aphid parasitoid Aphidius colemani Viereck has been questioned, especially in regard to Aphidius transcaspicus Telenga (Hymenoptera: Braconidae). The genetic association between A. colemani and A. transcaspicus was studied by cross mating individuals of A. colemani and A. transcaspicus (A.c.& × A.t.% and A.c.% × A.t.&) and applying appropriate molecular methods. The cross mating resulted in offspring (female and males) that were fertile. Therefore, the cross mating assays performed in an artificial environment showed that these two populations are potentially compatible. The mean number of mummies that developed and the sex ratio of the offspring of each cross were similar. Most of the male and female offspring from each cross were assigned to A. transcaspicus. Furthermore, the genetic divergence between the ribosomal internal transcribed spacers (ITS2) of the A. colemani and A. transcaspicus studied was 16%. These results indicate that A. colemani might be a complex of species with different morphological and biological characters attacking different host aphids.

Abstract. Body size is a main fitness component of insect parasitoids. We assessed the potential influence of maternal size of the parasitoid wasp Aphidius colemani Viereck (Hymenoptera: Braconidae: Aphidiinae) on its ability to parasitize the different instars of Aphis gossypii Glover (Hemiptera: Aphididae) on eggplant and cucumber. In the experiments "small" vs "large" parasitoid females were used. Females oviposited in all instars but more of the smaller hosts were parasitized. Host selection was affected by female size and the larger hosts were more frequently mummified by the large than the small females. Thus, parasitoid female size influenced host selection. This could affect the potential of the parasitoid to exploit populations of aphids that differ in their size structure. The importance of these results in terms of the ecological adaptations of the parasitoid and their implication for biological control are discussed.