The Host-Plant Origin Affects the Morphological Traits and the Reproductive Behavior of the Aphid Parasitoid Aphelinus mali

Diversifying agroecosystems through habitat management inside or outside production fields can provide alternative hosts and/or prey for natural enemies. In semi-natural habitats, parasitoids may find alternative host-plant complexes (HPC) that could allow their development when pest hosts are scarce in the field. However, morphological and physiological differences between alternative and targeted HPCs could affect the preference and fitness of the parasitoids, possibly altering their efficacy in regulating pests. In the present study, we examined two Aphelinus mali parasitoid populations developing on Eriosoma lanigerum from two host plants (Malus domestica-apple trees and Pyracantha coccinea). We hypothesized that A. mali from both HPCs will show different life history traits and behaviors because primary and alternative host-plants are known to induce variations in parasitoid biological performance. Our findings indicate that A. mali originating from E. lanigerum on P. coccinea parasitized more aphids and are smaller than those originating from E. lanigerum on apple. Furthermore, these parasitoids did not significantly vary their ability to attack and oviposit apple E. lanigerum, suggesting that P. coccinea could function as a suitable banker plant for A. mali. We discuss the potential use of P. coccinea in conservation biological control of E. lanigerum in apple orchards.

Differences in Morphology, Mitochondrial Genomes, and Reproductive Compatibility Between Two Clades of Aphelinus Mali in China

Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) in China is comprised of two clades (Shandong and Liaoning). In order to clarify the genetic relationship of them, we compared and analyzed the morphological characteristics and the mitochondrial genome of each, and ran a hybridization experiment between these clades. Morphological results showed that both males and females of the Liaoning clade were larger than Shandong clade, in terms of whole body, abdominal lengths and antennal lengths, but there were no significant differences between clades for total lengths of the middle and hind foot of females. The arrangement of the mitochondrial genomes was same in both clades, and each contained 31 genes, including 13 protein-encoded genes, 16 tRNA genes, and 2 rRNA genes. The highest AT levels among the 13 protein-coding genes for the two clades were the same gene (atp8) (Shandong clade, 91.52%; Liaoning clade, 90.91%). By hybridization and backcrossing, we found there was no cross incompatibility between these two clades of A. mali. Our results indicate that the historic geographical isolation between these two A. mali clades has not yet caused reproductive isolation of these two geographically separated populations, and they belong to the same species.

Comparison of the toxicity and repellency of two conventional neonicotinoids and a coconut-derived insecticide soap toward the parasitoid wasp Aphelinus mali Haldeman, 1851

<p><strong></strong>The parasitoid wasp <em>Aphelinus mali</em>,Haldeman, 1851 (Hymenoptera: Aphelinidae) is the most important biological control agent against the woolly apple aphid,<em> Eriosoma lanigerum</em> (Hausemann, 1802) (Hemiptera: Aphididae), which is an important apple orchards pest throughout the world. Based on the importance of using low-risk compounds to protect beneficial agents, the present study was carried out to evaluate the toxic and repellent effects of two conventional chemicals (imidacloprid and thiacloprid) and coconut-derived biopesticide soap (Palizin^Ò) toward <em>A. mali</em>. The results of residual bioassays on apple leaf discs indicated that imidacloprid after 24 h and insecticide soap after 72 h exposure time categorized at the highest and no/little toxicity rates, respectively. Ingestion bioassays on filter papers revealed that imidacloprid and thiacloprid had moderate toxicity rate, while insecticide soap had a low-level toxicity rate. Repellency test at Y-tube olfactometer showed that the repellent effects of both chemicals were more than that of insecticide soap. It is concluded that coconut-derived soap was compatible with the parasitoid activity, and the caution should be paid when including the two neonicotinoid insecticides imidacloprid and thiacloprid for <em>E. lanigerum</em> management.</p>

Use of Predators for the Biological control of Eriosoma lanigerum (wooly apple aphids) on apple

Due to increase demand of organic products, biological control methods have gained interest all over the world. Eriosoma lanigerum, commonly known as Wooly apple aphid, is a serious pest of apple. The negative impacts of pesticides on environment and human life make Biological control an important model in the control of the Wooly apple aphid. Some of the biological control agents that have been used in the control of this pest are predators, parasitoids, nectar of flowers etc. The role of the parasitoid Aphelinus mali in the biological control of wooly aphid has been studied by many researchers and found that use of parasitoids Aphelinus mali is not effective when they attack WAA solely in apple orchards. However, efficiency of use of Aphelinus mali in control of WAA is higher when these parasitoids are used along with natural predators (Gontijo, 2011).In recent days, there has been increasing use of predators for the control of aphids. This review focuses on some of the mostly used predators like syrphids, lacewings, earwigs etc. and their role in WAA management. This review focuses on the feeding habits of predators used as biocontrol agents against WAA as well as the occurrence time of these predators before their integration in management practices. Also; this review provides insight into the integration of predators along with other natural enemies for productive control of WAA. This review can be source of information for producers, as well as researchers who are focusing on organic production of apples and integrated wooly aphid management.Int. J. Appl. Sci. Biotechnol. Vol 5(4): 410-414

Laboratory comparison of twoAphelinus maliclades for control of woolly apple aphid from Hebei Province, China

Aphelinus mali(Haldeman) is an effective natural enemy of woolly apple aphid (WAA),Eriosoma lanigerum(Hausmann). Previous studies have found that, with WAA from Shandong Province (Qingdao) as the host, there are significant differences in various biological characteristics between a Shandong clade and Liaoning clade ofA. mali. The ability of the Shandong clade to control this aphid was significantly higher than that of the Liaoning clade in Shandong Province. In order to determine whether differences were caused by better adaptation of the Shandong parasitoid clade to the population of the host in that province or if it represents a more general fitness of this clade to control the host regardless of location, we compared the same parasitoid clades with hosts from Hebei Province. We found no significant differences in the developmental threshold temperature, effective accumulated temperature, fecundity, longevity, and oviposition period of the two clades, but the duration of host searching of the Shandong clade was significantly longer than that of the Liaoning clade. The instantaneous attack rate, the control ability (a/Th), the search parameter (Q) of the Shandong clade (0.0946, 0.543, 0.0725) ofA. maliwere higher than that of the Liaoning clade (0.0713, 0.382, 0.0381), and therefore, with WAA from Hebei Province as the host, the host adaptability of the Shandong clade ofA. maliwas not worse than that of the Liaoning clade, while the pest control ability of the Shandong clade was still greater than that of the Liaoning clade.