Variability in the reproductive performance of beneficial insects in standard laboratory toxicity assays - Implications for hazard classification of pesticides

Nowadays the development of pesticides is not only directed to design compounds with sufficient efficacy against resistant and non-resistant strains of pests as well as with a high margin of safety for man and the environment, but also to allow their potential use in IPM (Integrated Pest Management) programmes. For identification of IPM suitable pesticides, a whole battery of standardised laboratory and semi-field test protocols have been developed. Based on the observed lethal and sublethal effects in those tests, compounds are categorised into different hazard groups which should advise farmers on their suitability for IPM. For a valid classification of compounds on the basis of laboratory test results, threshold values for lethal and sublethal effects have to be developed which reliably differentiate between harmful and safe compounds without bearing the risk of erroneous labelling and/or too frequent requests for higher tier testing. As an evaluation criterion for sublethal effects of pesticides, the reproductive performance of beneficial insects is frequently considered in standard laboratory assays. A preliminary analysis of available data on the reproductive performance of several standard test species elaborated during regulatory testing indicates that this evaluation criterion is subject to high variability. As expected, individual test species differed in their reproductive performance. Aleochara bilineata (Coleop-tera: Staphylinidae) and Orius insidiosus (Heteroptera: Anthocoridae) showed a fairly homogeneous reproductive performance within test series. Based on the observed variability of the reproductive performance in control groups, the average probability of an erroneous labelling of pesticides for these two species was only 4% and 6% (maximum probability: 13% and 19%), respectively, when an adverse effect threshold value of 30% (= actual value of the EU (European Union)) was applied. In contrast, Coccinella septempunctata (Coleoptera: Coccinellidae), Chryso-perla carnea (Neuroptera: Chrysopidae), Aphidius rhopalosiphi (Hymenoptera: Aphidiidae) and Trichogramma cacoeciae (Hymenoptera: Trichogrammatidae) exhibited a high variability in their reproductive performance, giving a mean probability between 25% and 35% (maximum probability: 36–64%) to label a pesticide either false positive or false negative. Besides species-inherent variability, there was an indication that test-inherent factors including parent sex ratio and parent breeding density may have had an influence on the reproductive performance of these insect species. Seasonal influences on the reproductive performance of the beneficial insects in laboratory testing were not evident. Based on our data analyses, there is a significant risk of erroneous classification of pesticides when the reproductive performance is quantitatively assessed following the currently established test protocols and an adverse effects threshold value of 30% is applied. We propose therefore that either the testing procedure for assessing the reproductive performance, or the effect threshold value for this evaluation criterion is reconsidered in the light of the high “species-inherent” variability in the reproductive performance of some beneficial insects.     

The beneficial sexually transmitted microbe hypothesis of avian copulation

Several hypotheses have been proposed to explain why femalebirds either copulate repeatedly with a single mate or copulatewith multiple partners even though only a single copulationmay be sufficient to fertilize an entire clutch. We hypothesizethat females may directly benefit from high frequencies of copulationand multiple copulation partners if they receive a cloacal inoculationof beneficial sexually transmitted microbes (STMs) that caneither protect them against future encounters with pathogensand/or serve as therapy against present infections. Experimentsin domestic animal production, wildlife rehabilitation, andclinical medicine indicate that inoculations of beneficial microbesderived from the indigenous microflora of hosts can lead tonutritional benefits, resistance to colonization by pathogens,the elimination of infection, and improved immune system functioningin recipients. Our hypothesis predicts greater copulatory rateswhen the probability of the transmission of beneficial microbesexceeds that of pathogens and when the positive effects of beneficialmicrobes on host fitness exceed the negative effects of pathogens.Patterns of copulatory behavior in birds suggest the potentialutility of our hypothesis. We discuss our hypothesis in thecontext of observed patterns of copulation in birds and proposesome ways to directly test our hypothesis. Information on the probabilitiesof transmission during copulation of beneficial and pathogenic microbesand their relative potencies in birds are needed to directlytest the predictions of our hypothesis.     

Plant and Soil Nematodes: Societal Impact and Focus for the Future.

Plant and soil nematodes significandy impact our lives. Therefore, we must understand and manage these complex organisms so that we may continue to develop and sustain our food production systems, our natural resources, our environment, and our quality of life. This publication looks specifically at soil and plant nematology. First, the societal impact of nematodes and benefits of nematology research are briefly presented. Next, the opportunities facing nematology in the next decade are outlined, as well as the resources needed to address these priorities. The safety and sustainability of U.S. food and fiber production depends on public and administrative understanding of the importance of nematodes, the drastic effects of nematodes on many agricultural and horticultural crops, and the current research priorities of nematology.